1 00:00:00,480 --> 00:00:01,313 [Instructor] Hi everyone. 2 00:00:01,313 --> 00:00:04,950 Today's lecture is on the topic of cell signaling 3 00:00:04,950 --> 00:00:07,380 and the hormonal response to exercise. 4 00:00:07,380 --> 00:00:11,970 And this PowerPoint comes out of information in chapter five 5 00:00:11,970 --> 00:00:15,660 of the Powers "Exercise Physiology" textbook 6 00:00:15,660 --> 00:00:18,993 On our AccessPhysiotherapy website. 7 00:00:24,510 --> 00:00:27,780 Please read through the following 11 objectives. 8 00:00:27,780 --> 00:00:30,480 And at the end of this screencast, 9 00:00:30,480 --> 00:00:32,040 come back to the slide 10 00:00:32,040 --> 00:00:33,990 and be sure that you are able to 11 00:00:33,990 --> 00:00:36,240 achieve all those elect objectives. 12 00:00:36,240 --> 00:00:38,730 So if you are not able to, say, 13 00:00:38,730 --> 00:00:41,730 graphically describe the changes in the following hormones 14 00:00:41,730 --> 00:00:43,953 during graded and prolonged exercise, 15 00:00:45,150 --> 00:00:48,873 go back and look at the slide or read the chapter again. 16 00:00:55,560 --> 00:00:57,180 To start off with, 17 00:00:57,180 --> 00:00:59,520 we've already gone over bioenergetics 18 00:00:59,520 --> 00:01:01,320 and we understand the fact 19 00:01:01,320 --> 00:01:05,730 that our body uses certain substances for fuel 20 00:01:05,730 --> 00:01:09,663 such as glucose or fats or proteins. 21 00:01:10,650 --> 00:01:12,330 And now we're gonna take a step back 22 00:01:12,330 --> 00:01:14,820 and talk about how does our body know 23 00:01:14,820 --> 00:01:18,150 which of these fuels to use. 24 00:01:18,150 --> 00:01:19,350 How, for example, 25 00:01:19,350 --> 00:01:20,970 does the body know 26 00:01:20,970 --> 00:01:25,203 to release free fatty acids for lipolysis? 27 00:01:26,040 --> 00:01:28,140 Well, it knows it 28 00:01:28,140 --> 00:01:30,990 because of our nervous system 29 00:01:30,990 --> 00:01:32,520 and our endocrine system, 30 00:01:32,520 --> 00:01:36,570 and they work together closely intertwined 31 00:01:36,570 --> 00:01:39,153 in the field of neuroendocrinology. 32 00:01:40,560 --> 00:01:44,310 The nervous system uses neurotransmitters 33 00:01:44,310 --> 00:01:46,800 to conduct messages 34 00:01:46,800 --> 00:01:51,333 and to signal and stimulate cells to act, 35 00:01:52,710 --> 00:01:56,460 and the endocrine system releases different hormones, 36 00:01:56,460 --> 00:02:00,240 which also will then bind to different receptors 37 00:02:00,240 --> 00:02:05,133 and will also stimulate different tissues to react. 38 00:02:06,930 --> 00:02:10,560 The endocrine glands are where our hormones are stored, 39 00:02:10,560 --> 00:02:12,180 and these endocrine glands 40 00:02:12,180 --> 00:02:14,700 will release hormones directly into our blood, 41 00:02:14,700 --> 00:02:18,930 which then circulates throughout our system. 42 00:02:18,930 --> 00:02:22,380 And the hormones will affect 43 00:02:22,380 --> 00:02:24,330 the activity of different tissues 44 00:02:24,330 --> 00:02:27,810 that possess the receptor that matches that hormone. 45 00:02:27,810 --> 00:02:32,760 So hormones can only bind to specific receptors 46 00:02:32,760 --> 00:02:36,060 that are targeted for that specific hormone. 47 00:02:36,060 --> 00:02:37,200 So you can have a lot of hormones 48 00:02:37,200 --> 00:02:38,400 floating around in your body, 49 00:02:38,400 --> 00:02:42,810 but they're only going to bind to a certain receptor. 50 00:02:42,810 --> 00:02:47,100 There are different types of classes of hormones, 51 00:02:47,100 --> 00:02:51,000 and we're gonna be going over some amino acid derivatives, 52 00:02:51,000 --> 00:02:53,583 peptides or proteins, and steroids. 53 00:02:58,980 --> 00:03:01,050 The effect of hormones 54 00:03:01,050 --> 00:03:05,160 are determined by several different constructs. 55 00:03:05,160 --> 00:03:09,120 So the first one is 56 00:03:09,120 --> 00:03:13,620 how much of that hormone is floating around in our plasma. 57 00:03:13,620 --> 00:03:16,350 So what's the concentration of it? 58 00:03:16,350 --> 00:03:21,350 And this concentration of hormone levels in our plasma 59 00:03:22,920 --> 00:03:26,940 is determined by the rate of secretion of that hormone 60 00:03:26,940 --> 00:03:28,620 from the endocrine gland. 61 00:03:28,620 --> 00:03:30,030 So how much or how little? 62 00:03:30,030 --> 00:03:35,030 And there's some inhibitory versus facilitatory stimuli 63 00:03:37,560 --> 00:03:41,370 that will determine if the endocrine gland is gonna 64 00:03:41,370 --> 00:03:42,840 release a lot of hormone 65 00:03:42,840 --> 00:03:45,483 or if it's gonna stop and not release anymore. 66 00:03:48,240 --> 00:03:53,240 The other effect on our circulating levels of plasma hormone 67 00:03:54,660 --> 00:03:56,640 is determined by the rate of metabolism 68 00:03:56,640 --> 00:03:58,230 or excretion of the hormones. 69 00:03:58,230 --> 00:04:01,290 So how quickly it kind of passes through our system 70 00:04:01,290 --> 00:04:06,003 and is processed by our kidneys and excreted out. 71 00:04:07,500 --> 00:04:12,500 And the other things that affect the concentration 72 00:04:13,830 --> 00:04:15,330 and the effect of a hormone and a tissue 73 00:04:15,330 --> 00:04:20,330 is determined by the quantity of the transport protein, 74 00:04:20,970 --> 00:04:22,380 for example, steroid hormones, 75 00:04:22,380 --> 00:04:24,513 and we'll talk about those in a bit, 76 00:04:25,680 --> 00:04:30,680 and changes in our blood volume or our plasma volume. 77 00:04:30,870 --> 00:04:32,970 So here's kind of an example. 78 00:04:32,970 --> 00:04:35,403 So you can look here. 79 00:04:38,790 --> 00:04:41,250 And so here's the pancreas. 80 00:04:41,250 --> 00:04:43,530 The pancreas secretes insulin. 81 00:04:43,530 --> 00:04:46,500 What tells a pancreas to secrete insulin 82 00:04:46,500 --> 00:04:48,540 or to stop secreting insulin? 83 00:04:48,540 --> 00:04:50,440 Well, that's determined by 84 00:04:51,810 --> 00:04:55,620 levels of glucose in the blood, 85 00:04:55,620 --> 00:04:57,780 levels of amino acids in the blood, 86 00:04:57,780 --> 00:05:01,590 sympathetic activity of our nervous system, 87 00:05:01,590 --> 00:05:03,270 or parasympathetic activity. 88 00:05:03,270 --> 00:05:06,980 So you can see here if the glucose levels 89 00:05:06,980 --> 00:05:10,050 or the amino acid levels in the plasma increase, 90 00:05:10,050 --> 00:05:11,070 that's facilitatory 91 00:05:11,070 --> 00:05:13,803 and that's gonna tell the pancreas to release insulin. 92 00:05:15,480 --> 00:05:18,663 If there is some sympathetic activity, 93 00:05:19,590 --> 00:05:21,600 sympathetic nervous system activity, 94 00:05:21,600 --> 00:05:23,040 epinephrine is gonna be released, 95 00:05:23,040 --> 00:05:26,640 which is gonna have an inhibitory effect on the pancreas, 96 00:05:26,640 --> 00:05:29,820 and so insulin will not be released. 97 00:05:29,820 --> 00:05:33,450 So there's different factors 98 00:05:33,450 --> 00:05:38,450 that will tell a tissue or an organ to do something. 99 00:05:39,630 --> 00:05:41,400 And it's this combination 100 00:05:41,400 --> 00:05:45,330 of inhibitory or facilitatory signals 101 00:05:45,330 --> 00:05:47,310 and whichever magnitude is the greatest 102 00:05:47,310 --> 00:05:50,010 will determine the effect on the tissue 103 00:05:50,010 --> 00:05:53,493 and whether or not, say, insulin will be secreted or not. 104 00:06:04,800 --> 00:06:08,280 So hormones only will affect the tissue 105 00:06:08,280 --> 00:06:12,240 that has its matching specific receptor. 106 00:06:12,240 --> 00:06:17,240 And when a hormone does find a receptor that it binds to, 107 00:06:18,300 --> 00:06:20,370 the magnitude of its effect 108 00:06:20,370 --> 00:06:23,280 will depend on the concentration of the hormone 109 00:06:23,280 --> 00:06:26,310 floating around in our plasma circulation, 110 00:06:26,310 --> 00:06:28,950 the number of receptors on the cell, 111 00:06:28,950 --> 00:06:31,260 and actually the number of receptors 112 00:06:31,260 --> 00:06:36,260 can vary from 500 to 100,000 receptors on any given cell. 113 00:06:40,650 --> 00:06:44,850 Receptor number isn't fixed. 114 00:06:44,850 --> 00:06:45,960 It can vary. 115 00:06:45,960 --> 00:06:50,460 And so the receptor number can decrease. 116 00:06:50,460 --> 00:06:51,630 For example, 117 00:06:51,630 --> 00:06:52,680 if it's exposed 118 00:06:52,680 --> 00:06:55,830 to a chronically elevated level of a hormone, 119 00:06:55,830 --> 00:06:57,353 and this is called downregulation, 120 00:06:58,530 --> 00:07:00,420 this will result in a diminished response 121 00:07:00,420 --> 00:07:03,900 for the same amount of hormones floating around. 122 00:07:03,900 --> 00:07:05,560 So regardless of 123 00:07:06,960 --> 00:07:09,750 if there's a high concentration of the hormone, 124 00:07:09,750 --> 00:07:14,310 if the number of receptor sites decreases, 125 00:07:14,310 --> 00:07:16,080 there will be a downregulation. 126 00:07:16,080 --> 00:07:19,620 The opposite case is if there's chronic exposure 127 00:07:19,620 --> 00:07:23,100 to a low concentration of a specific hormone, 128 00:07:23,100 --> 00:07:27,510 which leads the body to want to have more of an effect, 129 00:07:27,510 --> 00:07:29,940 so there will be an increase in a receptor number, 130 00:07:29,940 --> 00:07:31,590 or upregulation, 131 00:07:31,590 --> 00:07:34,080 with the tissue becoming really responsive 132 00:07:34,080 --> 00:07:35,583 to the available hormone. 133 00:07:44,730 --> 00:07:49,730 The way that hormones cause an effect on our body 134 00:07:51,000 --> 00:07:54,480 is by modifying cellular activity, 135 00:07:54,480 --> 00:07:56,430 and they do this in three different ways. 136 00:07:56,430 --> 00:07:59,790 So they can alter the activity of our DNA 137 00:07:59,790 --> 00:08:02,400 to modify protein synthesis 138 00:08:02,400 --> 00:08:07,400 to actually make our bodies produce more protein. 139 00:08:08,130 --> 00:08:10,980 They can activate secondary messengers 140 00:08:10,980 --> 00:08:14,820 or they can change the membrane transport capability. 141 00:08:14,820 --> 00:08:17,070 So for example, 142 00:08:17,070 --> 00:08:18,720 in the first one, 143 00:08:18,720 --> 00:08:23,720 the stimulation of DNA to modify protein, 144 00:08:24,930 --> 00:08:29,930 steroids are able to diffuse easily through cell membranes 145 00:08:30,390 --> 00:08:33,960 and they then bind to a protein receptor 146 00:08:33,960 --> 00:08:36,330 in the cytoplasm of the cell. 147 00:08:36,330 --> 00:08:41,330 This specific binding steroid receptor complex 148 00:08:42,870 --> 00:08:44,610 will enter the nucleus 149 00:08:44,610 --> 00:08:49,610 and it will carry instruction codes for protein synthesis 150 00:08:50,070 --> 00:08:52,110 and it will initiate the steps 151 00:08:52,110 --> 00:08:56,220 leading to the synthesis of a specific messenger RNA 152 00:08:56,220 --> 00:08:59,430 that carries the codes from the nucleus to the cytoplasm 153 00:08:59,430 --> 00:09:03,123 where the specific protein is then synthesized. 154 00:09:05,520 --> 00:09:08,560 Secondary messengers or second messengers 155 00:09:11,250 --> 00:09:14,580 address hormones that are not like steroids. 156 00:09:14,580 --> 00:09:17,310 So steroid hormones, as I said, 157 00:09:17,310 --> 00:09:21,480 they can easily move and diffuse through cell membrane 158 00:09:21,480 --> 00:09:23,493 and modify the protein synthesis. 159 00:09:25,200 --> 00:09:27,810 This process, actually I did neglect to say, 160 00:09:27,810 --> 00:09:32,010 this process of stimulating protein synthesis 161 00:09:32,010 --> 00:09:34,500 takes a long time to activate. 162 00:09:34,500 --> 00:09:36,300 So it's a slow process. 163 00:09:36,300 --> 00:09:37,800 But once the proteins are made, 164 00:09:37,800 --> 00:09:39,423 it has a long lasting effect. 165 00:09:40,950 --> 00:09:43,440 Other hormones, however, 166 00:09:43,440 --> 00:09:46,080 because of their size or their structure 167 00:09:46,080 --> 00:09:48,330 can't easily cross the cell membrane, 168 00:09:48,330 --> 00:09:52,980 so these hormones will bind to a receptor 169 00:09:52,980 --> 00:09:55,560 that is on the surface of the cell membrane 170 00:09:55,560 --> 00:09:57,060 and they won't really pass through 171 00:09:57,060 --> 00:10:00,330 and they'll activate proteins within the cell. 172 00:10:00,330 --> 00:10:03,150 So they'll activate a G protein, 173 00:10:03,150 --> 00:10:08,150 which will then create a reaction inside the cell. 174 00:10:09,584 --> 00:10:10,770 And the G protein, 175 00:10:10,770 --> 00:10:12,510 it may open an ion channel 176 00:10:12,510 --> 00:10:14,310 to allow calcium to enter the cell, 177 00:10:14,310 --> 00:10:18,300 or it may activate an enzyme in the membrane, 178 00:10:18,300 --> 00:10:23,300 and so it will activate other structures in the cell. 179 00:10:25,020 --> 00:10:29,010 And so these are then second messengers. 180 00:10:29,010 --> 00:10:32,673 So for example, cyclic AMP, calcium, 181 00:10:35,250 --> 00:10:38,580 and these are involved in, 182 00:10:38,580 --> 00:10:40,233 say, for example, 183 00:10:41,850 --> 00:10:42,873 cyclic AMP, 184 00:10:44,130 --> 00:10:46,320 it will activate proteins 185 00:10:46,320 --> 00:10:49,473 that directly alter cellular activity. 186 00:10:51,090 --> 00:10:54,509 They do this, for example, 187 00:10:54,509 --> 00:10:58,410 in converting glycogen to glucose in the muscle 188 00:10:58,410 --> 00:11:00,963 and triglycerides to free fatty acids. 189 00:11:02,430 --> 00:11:06,303 Cyclic AMP is inactivated by phosphodiesterase, 190 00:11:08,730 --> 00:11:13,083 which is an enzyme that converts cyclic AMP to 5 AMP. 191 00:11:16,800 --> 00:11:18,000 So an interesting fact 192 00:11:18,000 --> 00:11:22,680 with this cyclic AMP and phosphodiesterase 193 00:11:22,680 --> 00:11:27,680 is that caffeine interferes with phosphodiesterase activity. 194 00:11:29,888 --> 00:11:33,930 And so that's going to facilitate cyclic AMP 195 00:11:33,930 --> 00:11:37,680 to continue to exert its effect for longer period of time. 196 00:11:37,680 --> 00:11:42,330 So caffeine will exert this effect on adipose tissue, 197 00:11:42,330 --> 00:11:43,530 causing free fatty acids 198 00:11:43,530 --> 00:11:46,440 to continue to be mobilized at a faster rate. 199 00:11:46,440 --> 00:11:49,590 If the G protein activates calcium ion channel, 200 00:11:49,590 --> 00:11:51,510 then the calcium is gonna enter the cell 201 00:11:51,510 --> 00:11:55,380 and bind to and activate different proteins 202 00:11:55,380 --> 00:11:57,540 to influence cellular activity, 203 00:11:57,540 --> 00:11:59,640 kind of in the same way that cyclic AMP does. 204 00:11:59,640 --> 00:12:04,640 So these are hormones then activating second messengers 205 00:12:05,340 --> 00:12:06,723 to cause a reaction. 206 00:12:08,760 --> 00:12:11,430 Lastly, hormones can work 207 00:12:11,430 --> 00:12:16,430 to help substances move in and out of cells, 208 00:12:16,530 --> 00:12:17,910 so crossing the cell membrane. 209 00:12:17,910 --> 00:12:21,160 So they can bind to a receptor on the membrane 210 00:12:22,110 --> 00:12:24,750 and activate carrier molecules 211 00:12:24,750 --> 00:12:26,730 in or near the membrane surface 212 00:12:26,730 --> 00:12:29,280 to increase the movement of substrates or ions 213 00:12:29,280 --> 00:12:32,220 from outside to inside the cell. 214 00:12:32,220 --> 00:12:33,810 For example, 215 00:12:33,810 --> 00:12:36,690 insulin is gonna bind to receptors 216 00:12:36,690 --> 00:12:38,760 on the surface of the cell, 217 00:12:38,760 --> 00:12:41,280 which will mobilize glucose transporters 218 00:12:41,280 --> 00:12:43,080 located in the membrane. 219 00:12:43,080 --> 00:12:45,960 And so these transporters are gonna link up with glucose 220 00:12:45,960 --> 00:12:48,840 that's circulating outside the cell. 221 00:12:48,840 --> 00:12:51,723 And if the glucose, blood glucose levels are high, 222 00:12:52,830 --> 00:12:57,830 this hormone action will act to transport glucose 223 00:13:00,270 --> 00:13:03,213 to diffuse into the cell where it's needed. 224 00:13:04,260 --> 00:13:08,610 If the individual doesn't have enough adequate insulin, 225 00:13:08,610 --> 00:13:11,370 for example, in somebody with uncontrolled diabetes, 226 00:13:11,370 --> 00:13:14,070 the glucose accumulates within the plasma 227 00:13:14,070 --> 00:13:18,630 because the glucose transmitters or transporters 228 00:13:18,630 --> 00:13:20,073 are not activated. 229 00:13:23,430 --> 00:13:27,180 So here's an example of 230 00:13:27,180 --> 00:13:31,020 a hormone passing through the plasma membrane here 231 00:13:31,020 --> 00:13:33,400 and then binding with the receptors 232 00:13:35,640 --> 00:13:37,380 inside a target cell, 233 00:13:37,380 --> 00:13:39,000 so then it can go in, 234 00:13:39,000 --> 00:13:42,030 and this is where it's gonna stimulate protein synthesis. 235 00:13:42,030 --> 00:13:45,870 So it's affecting the DNA and the messenger RNA, 236 00:13:45,870 --> 00:13:48,063 creating a protein synthesis right here. 237 00:13:57,030 --> 00:14:00,870 Hormones are secreted from our endocrine glands. 238 00:14:00,870 --> 00:14:05,870 And the main glands are the pituitary gland, 239 00:14:07,710 --> 00:14:09,750 which is located at the base of the brain 240 00:14:09,750 --> 00:14:11,943 and attached to our hypothalamus. 241 00:14:13,260 --> 00:14:15,750 The gland, it has two lobes, 242 00:14:15,750 --> 00:14:19,593 an anterior lobe and a posterior lobe. 243 00:14:21,150 --> 00:14:25,560 And then we have our thyroid and parathyroid glands, 244 00:14:25,560 --> 00:14:26,490 adrenal glands, 245 00:14:26,490 --> 00:14:28,800 our pancreas, which we've talked a little bit about already, 246 00:14:28,800 --> 00:14:30,450 that releases insulin, 247 00:14:30,450 --> 00:14:32,103 and testes and ovaries. 248 00:14:35,580 --> 00:14:39,210 The hypothalamus is gonna stimulate the release of hormones 249 00:14:39,210 --> 00:14:41,490 from the anterior pituitary gland, 250 00:14:41,490 --> 00:14:43,620 which then provides hormones 251 00:14:43,620 --> 00:14:47,160 for release from the posterior pituitary gland. 252 00:14:47,160 --> 00:14:51,180 The anterior pituitary gland hormones 253 00:14:51,180 --> 00:14:55,800 include adrenocorticotropic hormone, or ACTH, 254 00:14:55,800 --> 00:14:59,220 follicle-stimulating hormone, FSH, 255 00:14:59,220 --> 00:15:00,423 luteinizing hormone, 256 00:15:01,470 --> 00:15:05,550 melanocyte-stimulating hormone, or MSH, 257 00:15:05,550 --> 00:15:07,950 thyroid-stimulating hormone, 258 00:15:07,950 --> 00:15:10,233 growth hormone, and prolactin. 259 00:15:15,870 --> 00:15:17,760 And as I noted, 260 00:15:17,760 --> 00:15:21,240 most or many of the hormones 261 00:15:21,240 --> 00:15:23,610 released from the anterior pituitary gland 262 00:15:23,610 --> 00:15:27,840 are going to stimulate other endocrine glands, 263 00:15:27,840 --> 00:15:30,090 with the exception of prolactin, 264 00:15:30,090 --> 00:15:32,040 which will affect, 265 00:15:32,040 --> 00:15:34,833 effectively target the breast to produce milk. 266 00:15:37,140 --> 00:15:41,400 So here's a list of the hormones 267 00:15:41,400 --> 00:15:43,350 that I just rattled off earlier. 268 00:15:43,350 --> 00:15:46,500 And our ACTH will stimulate cortisol 269 00:15:46,500 --> 00:15:48,663 to be released from the adrenal glands. 270 00:15:49,740 --> 00:15:50,910 Our luteinizing hormone 271 00:15:50,910 --> 00:15:54,933 will stimulate production of testosterone and estrogen. 272 00:15:57,120 --> 00:15:59,130 Thyroid-stimulating hormone will control 273 00:15:59,130 --> 00:16:02,283 the thyroid hormone release from our thyroid gland. 274 00:16:07,140 --> 00:16:10,380 Growth hormone stimulates the release 275 00:16:10,380 --> 00:16:13,920 of insulin-like growth factors. 276 00:16:13,920 --> 00:16:17,733 And this is responsible for our muscle growth. 277 00:16:22,590 --> 00:16:27,590 In addition to working to facilitate muscle hypertrophy, 278 00:16:28,500 --> 00:16:30,930 growth hormone also has important effects 279 00:16:30,930 --> 00:16:34,350 on other substrates such as protein, fat, 280 00:16:34,350 --> 00:16:36,780 and carbohydrate metabolism. 281 00:16:36,780 --> 00:16:37,860 The growth hormone, 282 00:16:37,860 --> 00:16:40,800 it's secreted from the anterior pituitary gland 283 00:16:40,800 --> 00:16:43,410 and it really affects many, 284 00:16:43,410 --> 00:16:45,540 the growth of all tissues 285 00:16:45,540 --> 00:16:49,410 through the release of insulin-like growth factors. 286 00:16:49,410 --> 00:16:52,230 Production of growth hormone increases with exercise 287 00:16:52,230 --> 00:16:56,130 to help maintain our plasma glucose concentration. 288 00:16:56,130 --> 00:16:58,150 So you can see that 289 00:16:59,820 --> 00:17:03,450 when we have growth hormone 290 00:17:03,450 --> 00:17:07,440 and insulin-like growth factors circulating 291 00:17:07,440 --> 00:17:12,117 and with increased production of them, 292 00:17:13,410 --> 00:17:15,660 there'll be an increase 293 00:17:15,660 --> 00:17:19,590 in the synthesis of new glucose in the liver, 294 00:17:19,590 --> 00:17:21,390 so gluconeogenesis, 295 00:17:21,390 --> 00:17:22,650 and there'll be an increase 296 00:17:22,650 --> 00:17:26,040 in the mobilization of fatty acids from adipose tissue, 297 00:17:26,040 --> 00:17:26,910 and so, 298 00:17:26,910 --> 00:17:29,493 which is what we want when you're exercising. 299 00:17:31,680 --> 00:17:34,800 So it's kind of sparing the plasma glucose, 300 00:17:34,800 --> 00:17:39,800 which as opposed to the insulin reaction in the pancreas. 301 00:17:39,810 --> 00:17:43,440 So the pancreas is gonna sense 302 00:17:43,440 --> 00:17:46,050 excessive blood concentrations of glucose 303 00:17:46,050 --> 00:17:47,940 and will act to produce insulin 304 00:17:47,940 --> 00:17:49,470 to move the glucose into cell. 305 00:17:49,470 --> 00:17:52,560 So again, it really depends what the body needs 306 00:17:52,560 --> 00:17:56,070 and there's this really fine balance 307 00:17:56,070 --> 00:17:59,133 to keep us all working and moving. 308 00:18:05,280 --> 00:18:07,950 Growth hormone, as noted on the other slide, 309 00:18:07,950 --> 00:18:10,260 it's gonna facilitate protein synthesis, 310 00:18:10,260 --> 00:18:13,590 so it's gonna help with muscle hypertrophy 311 00:18:13,590 --> 00:18:15,810 and it's gonna facilitate bone growth, 312 00:18:15,810 --> 00:18:17,280 our long bone growth, 313 00:18:17,280 --> 00:18:21,480 so femur, humerus, tibia. 314 00:18:21,480 --> 00:18:25,650 It has been used to treat childhood dwarfism. 315 00:18:25,650 --> 00:18:28,980 Some athletes use this to try to build up their muscles, 316 00:18:28,980 --> 00:18:32,133 and there are some issues with that. 317 00:18:35,370 --> 00:18:39,633 There are more adverse effects than there are benefits. 318 00:18:42,030 --> 00:18:43,860 So some of the adverse effects 319 00:18:43,860 --> 00:18:47,550 is that although growth hormone will increase 320 00:18:47,550 --> 00:18:49,860 the protein synthesis of muscle, 321 00:18:49,860 --> 00:18:53,490 it actually is a connective tissue protein. 322 00:18:53,490 --> 00:18:57,720 So it facilitates collagen production 323 00:18:57,720 --> 00:19:01,770 more than a contractile element. 324 00:19:01,770 --> 00:19:05,220 So what you see consistent with this 325 00:19:05,220 --> 00:19:10,080 is the fact that you will have some strength gains, 326 00:19:10,080 --> 00:19:15,080 but they're not gonna match gains in muscle size. 327 00:19:16,290 --> 00:19:21,290 So you're not gonna get that hypertrophy that you would get 328 00:19:21,540 --> 00:19:25,620 with just doing normal resistance training alone. 329 00:19:25,620 --> 00:19:28,140 The other issue is that 330 00:19:28,140 --> 00:19:32,760 there's definitely side effects of overuse. 331 00:19:32,760 --> 00:19:36,720 So chronic use of growth hormone can lead to diabetes, 332 00:19:36,720 --> 00:19:38,920 because of the fact that it's gonna 333 00:19:40,170 --> 00:19:44,100 keep that plasma glucose levels high, 334 00:19:44,100 --> 00:19:46,230 hyperlipidemia, arthritis, 335 00:19:46,230 --> 00:19:48,393 enlarged heart or cardiomegaly, 336 00:19:49,290 --> 00:19:54,123 it's been associated with carpal tunnel syndrome. 337 00:19:55,560 --> 00:19:59,530 So it's not advocated to take 338 00:20:00,570 --> 00:20:04,323 if you don't need it for some type of medical reason. 339 00:20:10,290 --> 00:20:12,303 The posterior pituitary gland, 340 00:20:13,350 --> 00:20:16,260 which is also under the control of the hypothalamus. 341 00:20:16,260 --> 00:20:17,760 So just to reiterate, 342 00:20:17,760 --> 00:20:19,560 the hypothalamus controls the activity of 343 00:20:19,560 --> 00:20:21,120 both the anterior pituitary 344 00:20:21,120 --> 00:20:23,070 and the posterior pituitary glands. 345 00:20:23,070 --> 00:20:24,940 Posterior pituitary gland 346 00:20:26,250 --> 00:20:29,970 releases oxytocin and antidiuretic hormone. 347 00:20:29,970 --> 00:20:34,380 And so oxytocin will stimulate smooth muscle 348 00:20:34,380 --> 00:20:37,440 during childbirth and milk production, 349 00:20:37,440 --> 00:20:39,540 so in the pregnant woman. 350 00:20:39,540 --> 00:20:41,460 And the antidiuretic hormone 351 00:20:41,460 --> 00:20:43,590 reduces water loss from the body, 352 00:20:43,590 --> 00:20:45,780 so it's antidiuretic, 353 00:20:45,780 --> 00:20:48,750 to maintain our plasma volume. 354 00:20:48,750 --> 00:20:50,310 It favors resorption of water 355 00:20:50,310 --> 00:20:55,310 from the kidney tubules to blood capillaries. 356 00:20:55,440 --> 00:20:58,750 This antidiuretic hormone is released 357 00:20:59,820 --> 00:21:01,530 when stimulated. 358 00:21:01,530 --> 00:21:05,340 And high plasma osmolarity 359 00:21:05,340 --> 00:21:07,830 and low plasma volume will stimulate this. 360 00:21:07,830 --> 00:21:12,830 So when we're sweating without water replacement, 361 00:21:14,610 --> 00:21:18,180 our plasma is gonna become really concentrated, 362 00:21:18,180 --> 00:21:20,670 and so the antidiuretic hormone 363 00:21:20,670 --> 00:21:23,850 will then be stimulated to produce, 364 00:21:23,850 --> 00:21:26,670 to kind of reduce our water loss. 365 00:21:26,670 --> 00:21:31,670 This ADH increases obviously during exercise 366 00:21:31,680 --> 00:21:34,530 at greater than 50% of our VO2, 367 00:21:34,530 --> 00:21:37,920 which is more that moderate to vigorous exercise. 368 00:21:37,920 --> 00:21:40,380 And this is to maintain our plasma volume. 369 00:21:40,380 --> 00:21:43,380 And so you can see here, 370 00:21:43,380 --> 00:21:46,230 here's our percent of VO2 max for exercising. 371 00:21:46,230 --> 00:21:47,880 So the exercise intensity. 372 00:21:47,880 --> 00:21:50,250 So low intensity down here, 373 00:21:50,250 --> 00:21:52,440 kind of starting to be moderate, 374 00:21:52,440 --> 00:21:55,140 and then when we're getting above 60, 375 00:21:55,140 --> 00:21:57,450 we're getting into that vigorous level. 376 00:21:57,450 --> 00:22:01,170 And you can see the ADH, the plasma levels of ADH, 377 00:22:01,170 --> 00:22:03,570 are pretty much zero at this low-intensity. 378 00:22:03,570 --> 00:22:05,883 And then as our intensity starts to increase, 379 00:22:06,750 --> 00:22:09,003 the plasma ADH levels are gonna increase. 380 00:22:12,780 --> 00:22:17,160 Our thyroid gland releases our thyroid hormones. 381 00:22:17,160 --> 00:22:19,960 And the thyroid hormones are 382 00:22:21,503 --> 00:22:26,503 the kind of key to establishing our overall metabolic rates. 383 00:22:29,520 --> 00:22:34,520 The thyroid gland produces two hormones, T3 and T4, 384 00:22:35,610 --> 00:22:40,610 or triiodothyronine and thyroxine. 385 00:22:41,910 --> 00:22:46,770 And the thyroid-stimulating hormone 386 00:22:46,770 --> 00:22:49,470 is what stimulates the thyroid gland 387 00:22:49,470 --> 00:22:52,293 to produce these two hormones. 388 00:22:56,325 --> 00:22:59,003 They have like what's called a latent period 389 00:23:00,840 --> 00:23:05,400 between the time that T3 and T4 are elevated 390 00:23:05,400 --> 00:23:08,490 and the time when their effects are observed. 391 00:23:08,490 --> 00:23:11,730 So it's not an immediate response. 392 00:23:11,730 --> 00:23:15,420 The latent period is like six to 12 hours for T3 393 00:23:15,420 --> 00:23:17,670 and two to three days for T4. 394 00:23:17,670 --> 00:23:21,150 So that's like if you're have a hypothyroid problem 395 00:23:21,150 --> 00:23:23,613 and you're taking thyroid replacement, 396 00:23:24,510 --> 00:23:26,280 you don't see an immediate effect 397 00:23:26,280 --> 00:23:28,480 when you first start taking this medication. 398 00:23:30,300 --> 00:23:32,310 There's evidence that during exercise 399 00:23:32,310 --> 00:23:36,840 there's an increase in secretion of these T3 and T4 400 00:23:36,840 --> 00:23:40,830 high thyroid hormones, 401 00:23:40,830 --> 00:23:45,830 but it doesn't appear to have any change 402 00:23:46,050 --> 00:23:50,070 in release of these hormones with resistance training. 403 00:23:50,070 --> 00:23:53,733 The thyroid also releases calcitonin, 404 00:23:55,140 --> 00:23:58,950 which is involved in a minor way 405 00:23:58,950 --> 00:24:01,773 in the regulation of plasma calcium levels. 406 00:24:03,000 --> 00:24:05,340 Calcium is a crucial ion 407 00:24:05,340 --> 00:24:07,503 for normal muscle and nerve function. 408 00:24:12,270 --> 00:24:17,270 As our plasma concentration of calcium increases, 409 00:24:18,000 --> 00:24:21,000 calcitonin is released, 410 00:24:21,000 --> 00:24:22,560 that's increased. 411 00:24:22,560 --> 00:24:26,490 And this calcitonin will block 412 00:24:26,490 --> 00:24:28,440 the release of calcium from the bone. 413 00:24:28,440 --> 00:24:30,060 So if you have high levels of calcium 414 00:24:30,060 --> 00:24:31,200 already in your bloodstream, 415 00:24:31,200 --> 00:24:34,890 you don't wanna be taking it out from your bone. 416 00:24:34,890 --> 00:24:37,470 And if you have high levels in your bloodstream, 417 00:24:37,470 --> 00:24:38,730 you wanna excrete it. 418 00:24:38,730 --> 00:24:40,860 So calcitonin will block 419 00:24:40,860 --> 00:24:42,990 the release of calcium from the bone 420 00:24:42,990 --> 00:24:45,780 and it will stimulate the excretion of calcium 421 00:24:45,780 --> 00:24:46,650 from the kidneys 422 00:24:46,650 --> 00:24:49,590 to lower the plasma concentration levels. 423 00:24:49,590 --> 00:24:54,590 As the calcium concentration is brought back to normal, 424 00:24:55,740 --> 00:24:58,713 the rate of calcitonin secretion is reduced. 425 00:25:03,870 --> 00:25:07,200 So from the prior slide, we just talked about calcitonin 426 00:25:07,200 --> 00:25:08,760 and the minor role it plays 427 00:25:08,760 --> 00:25:13,760 in regulating calcium levels in the plasma. 428 00:25:14,640 --> 00:25:17,163 And we talk specifically about high levels. 429 00:25:18,000 --> 00:25:21,510 The parathyroid hormone, on the flip side, 430 00:25:21,510 --> 00:25:26,510 is the primary hormone in regulating plasma calcium levels. 431 00:25:28,890 --> 00:25:32,100 The parathyroid gland will release parathyroid hormone 432 00:25:32,100 --> 00:25:36,750 in response to a low plasma calcium concentration. 433 00:25:36,750 --> 00:25:39,720 So this hormone will stimulate bone 434 00:25:39,720 --> 00:25:43,140 to release calcium into the plasma 435 00:25:43,140 --> 00:25:46,860 and simultaneously increase the renal absorption of calcium. 436 00:25:46,860 --> 00:25:48,270 So you're not excreting it. 437 00:25:48,270 --> 00:25:52,530 So the parathyroid hormone will do everything it can 438 00:25:52,530 --> 00:25:55,413 to boost the plasma levels of calcium, 439 00:25:57,000 --> 00:26:01,863 kind of the total opposite of the calcitonin. 440 00:26:03,720 --> 00:26:07,890 The parathyroid hormone also stimulates the kidney 441 00:26:07,890 --> 00:26:10,950 to convert a form of vitamin D into a hormone 442 00:26:10,950 --> 00:26:15,873 that increases the absorption of calcium from the GI tract. 443 00:26:17,010 --> 00:26:18,900 And exercise will increase 444 00:26:18,900 --> 00:26:23,580 the concentration of our parathyroid hormone in our plasma. 445 00:26:30,570 --> 00:26:33,210 The adrenal medulla is part of our 446 00:26:33,210 --> 00:26:35,520 sympathetic nervous system. 447 00:26:35,520 --> 00:26:40,520 And 80% of this gland's production is epinephrine. 448 00:26:42,870 --> 00:26:44,970 It also produces norepinephrine, 449 00:26:44,970 --> 00:26:46,800 but 80% is epinephrine. 450 00:26:46,800 --> 00:26:49,680 Again, part of the sympathetic nervous system. 451 00:26:49,680 --> 00:26:51,660 These are really fast-acting hormones, 452 00:26:51,660 --> 00:26:54,453 part of our fight-or-flight system. 453 00:26:55,830 --> 00:27:00,330 They affect receptors in our cardiovascular 454 00:27:00,330 --> 00:27:01,710 and respiratory systems, 455 00:27:01,710 --> 00:27:03,873 in our stomach, our GI tract, 456 00:27:04,890 --> 00:27:07,800 muscle, our fat adipose tissue. 457 00:27:07,800 --> 00:27:10,110 They're involved in the maintenance of our blood pressure 458 00:27:10,110 --> 00:27:12,990 and our plasma glucose concentration. 459 00:27:12,990 --> 00:27:16,680 They bind to adrenergic receptors, 460 00:27:16,680 --> 00:27:19,920 which are divided into two major categories. 461 00:27:19,920 --> 00:27:22,803 So the alpha receptor and the beta receptor. 462 00:27:25,230 --> 00:27:28,090 The effects of this hormone 463 00:27:29,100 --> 00:27:32,820 depend on which is used and the receptor type, 464 00:27:32,820 --> 00:27:36,213 and they can be both excitatory or inhibitory. 465 00:27:39,030 --> 00:27:40,680 For example, 466 00:27:40,680 --> 00:27:45,680 the alpha and the beta receptors have different effects. 467 00:27:45,960 --> 00:27:50,550 So if epinephrine or norepinephrine 468 00:27:50,550 --> 00:27:55,440 is attaching to a beta receptor, 469 00:27:55,440 --> 00:27:57,243 heart rate's gonna increase, 470 00:27:58,164 --> 00:27:59,940 pulse is gonna increase, 471 00:27:59,940 --> 00:28:02,553 bronchodilation is gonna increase. 472 00:28:03,450 --> 00:28:04,770 Conversely, 473 00:28:04,770 --> 00:28:07,710 if the epinephrine or norepinephrine 474 00:28:07,710 --> 00:28:10,680 is attaching to an alpha cell, 475 00:28:10,680 --> 00:28:12,720 we're gonna have vasoconstriction. 476 00:28:12,720 --> 00:28:17,310 So it's gonna kind of oppose the action 477 00:28:17,310 --> 00:28:19,830 of the beta cells 478 00:28:19,830 --> 00:28:21,882 where they're gonna be causing a vasodilation, 479 00:28:21,882 --> 00:28:23,253 a bronchodilation. 480 00:28:26,790 --> 00:28:28,140 And so here's the table 481 00:28:28,140 --> 00:28:30,600 depicting what I was just talking about. 482 00:28:30,600 --> 00:28:35,100 So here are our beta cells, our beta receptors, 483 00:28:35,100 --> 00:28:38,040 and if we stop right here, 484 00:28:38,040 --> 00:28:40,230 it's gonna have all of these effects 485 00:28:40,230 --> 00:28:41,640 on the different tissues. 486 00:28:41,640 --> 00:28:43,233 So increased heart rate, 487 00:28:44,310 --> 00:28:46,980 lipolysis, bronchodilation, vasodilation. 488 00:28:46,980 --> 00:28:49,650 And then the alpha receptors, 489 00:28:49,650 --> 00:28:52,083 there's gonna be more a vasoconstriction, 490 00:28:53,160 --> 00:28:57,303 an increase in the phosphodiesterase enzymatic activity. 491 00:29:00,600 --> 00:29:04,893 And now let's talk a little bit about the adrenal cortex. 492 00:29:05,940 --> 00:29:09,873 The adrenal cortex stimulates a variety of, 493 00:29:11,670 --> 00:29:14,430 or the release of a variety of different steroid hormones 494 00:29:14,430 --> 00:29:17,940 that can be categorized in three ways. 495 00:29:17,940 --> 00:29:20,640 So there's the mineralocorticoids, 496 00:29:20,640 --> 00:29:21,960 the glucocorticoids, 497 00:29:21,960 --> 00:29:23,520 and the sex steroids. 498 00:29:23,520 --> 00:29:26,310 And the mineralocorticoids are aldosterone, 499 00:29:26,310 --> 00:29:27,420 which is gonna maintain 500 00:29:27,420 --> 00:29:30,630 our plasma levels of sodium and potassium, 501 00:29:30,630 --> 00:29:32,610 our glucocorticoids, 502 00:29:32,610 --> 00:29:34,770 which is gonna regulate cortisol 503 00:29:34,770 --> 00:29:37,050 and regulation of our plasma glucose, 504 00:29:37,050 --> 00:29:38,790 and then our sex steroids, 505 00:29:38,790 --> 00:29:41,760 which is estrogens, androgens, 506 00:29:41,760 --> 00:29:45,243 support of, kind of starting up puberty. 507 00:29:50,700 --> 00:29:55,700 So aldosterone is one of the mineralocorticoids. 508 00:29:56,490 --> 00:29:59,010 And as we talked about on the prior slide, 509 00:29:59,010 --> 00:30:04,010 it's going to work to ensure the sodium potassium balance. 510 00:30:05,940 --> 00:30:10,210 So it will control sodium resorption and potassium secretion 511 00:30:11,160 --> 00:30:16,080 to help regulate and maintain that homeostasis. 512 00:30:16,080 --> 00:30:19,290 So aldosterone is directly involved 513 00:30:19,290 --> 00:30:22,020 in maintaining plasma volume and blood pressure. 514 00:30:22,020 --> 00:30:24,030 'Cause if our plasma volume drops, 515 00:30:24,030 --> 00:30:26,010 our blood pressure is going to drop. 516 00:30:26,010 --> 00:30:30,000 And there's two things 517 00:30:30,000 --> 00:30:32,580 that will control the aldosterone secretion. 518 00:30:32,580 --> 00:30:37,560 So aldosterone will be released from the adrenal cortex 519 00:30:37,560 --> 00:30:42,560 if there's an increase in the potassium concentration. 520 00:30:45,210 --> 00:30:47,880 So this increase in potassium concentration 521 00:30:47,880 --> 00:30:50,190 will stimulate aldosterone secretion, 522 00:30:50,190 --> 00:30:54,180 which is gonna stimulate the kidneys' transport mechanisms 523 00:30:54,180 --> 00:30:57,063 to secrete those potassium ions. 524 00:30:59,340 --> 00:31:02,380 Aldosterone secretion is also controlled 525 00:31:08,760 --> 00:31:11,340 by changes in our plasma volume 526 00:31:11,340 --> 00:31:13,800 or a fall in the blood pressure of our kidneys 527 00:31:13,800 --> 00:31:17,790 or an increase in sympathetic nerve activity to the kidney. 528 00:31:17,790 --> 00:31:22,790 So these changes will stimulate the kidney 529 00:31:23,220 --> 00:31:26,550 to secrete enzymes. 530 00:31:26,550 --> 00:31:30,480 And so these enzymes will enter the plasma 531 00:31:30,480 --> 00:31:33,573 and convert into angiotensin I, 532 00:31:35,190 --> 00:31:37,860 which is then converted into angiotensin II. 533 00:31:37,860 --> 00:31:41,100 And these are powerful, 534 00:31:41,100 --> 00:31:44,100 really, really powerful vasoconstrictors. 535 00:31:44,100 --> 00:31:45,720 So if you have high blood pressure, 536 00:31:45,720 --> 00:31:47,760 you don't want that vasoconstriction, 537 00:31:47,760 --> 00:31:50,850 and these people might be prescribed ACE inhibitors. 538 00:31:50,850 --> 00:31:55,850 And an ACE inhibitor is an angiotensin converting enzyme. 539 00:31:56,460 --> 00:32:00,300 So that produces angiotensin II, 540 00:32:00,300 --> 00:32:01,620 which is the vasoconstrictor. 541 00:32:01,620 --> 00:32:05,610 So then you get prescribed this ACE inhibitor, 542 00:32:05,610 --> 00:32:08,190 so it doesn't produce that enzyme, 543 00:32:08,190 --> 00:32:11,103 which will effectively decrease the vasoconstriction. 544 00:32:17,880 --> 00:32:22,880 So exercise will affect the changes in renin. 545 00:32:23,590 --> 00:32:25,410 Renin is that enzyme in the kidney 546 00:32:25,410 --> 00:32:27,600 that I talked about earlier. 547 00:32:27,600 --> 00:32:31,727 And this renin is what will convert 548 00:32:33,000 --> 00:32:35,163 to angiotensin I and angiotensin II. 549 00:32:38,520 --> 00:32:41,820 And you can see again with moderate to vigorous exercise 550 00:32:41,820 --> 00:32:44,790 the activity of aldosterone 551 00:32:44,790 --> 00:32:48,690 and these subsequent hormones will increase. 552 00:32:48,690 --> 00:32:50,370 And that's you're exercising, 553 00:32:50,370 --> 00:32:53,970 you do not want kind of vasodilation, 554 00:32:53,970 --> 00:32:55,050 you want vasoconstriction, 555 00:32:55,050 --> 00:32:58,410 you want your blood to be pumped fast and efficiently 556 00:32:58,410 --> 00:33:01,383 to your working muscles and organs. 557 00:33:04,890 --> 00:33:07,500 Cortisol is a glucocorticoid 558 00:33:07,500 --> 00:33:11,820 and it is secreted by the adrenal cortex as well. 559 00:33:11,820 --> 00:33:13,500 And cortisol contributes 560 00:33:13,500 --> 00:33:16,710 to the maintenance of our plasma glucose 561 00:33:16,710 --> 00:33:18,840 during long-term fasting 562 00:33:18,840 --> 00:33:23,280 and also during exercise through a variety of mechanisms. 563 00:33:23,280 --> 00:33:27,720 So it's gonna promote protein breakdown for gluconeogenesis. 564 00:33:27,720 --> 00:33:31,200 If we're exercising and we don't have enough glucose, 565 00:33:31,200 --> 00:33:33,780 it will stimulate free fatty acid mobilization 566 00:33:33,780 --> 00:33:35,580 from adipose tissue. 567 00:33:35,580 --> 00:33:38,250 It stimulates glucose synthesis 568 00:33:38,250 --> 00:33:41,640 and it blocks the uptake of glucose into the cells 569 00:33:41,640 --> 00:33:44,523 to promote the use of free fatty acids as fuel. 570 00:33:46,020 --> 00:33:50,490 And so cortisol, it's stimulated by exercise, 571 00:33:50,490 --> 00:33:53,823 but is also stimulated by stress. 572 00:33:57,218 --> 00:34:02,010 So cortisol will be stimulated by stress 573 00:34:02,010 --> 00:34:06,240 via the activity of the adrenocorticotropic hormone, 574 00:34:06,240 --> 00:34:08,610 which comes from the anterior pituitary gland, 575 00:34:08,610 --> 00:34:10,680 which we talked about earlier. 576 00:34:10,680 --> 00:34:12,090 And so this is, 577 00:34:12,090 --> 00:34:13,620 it could be good stress 578 00:34:13,620 --> 00:34:15,090 or it could be not good stress, 579 00:34:15,090 --> 00:34:16,230 and it's part of 580 00:34:16,230 --> 00:34:20,640 something called a general adaptation syndrome, or GAS. 581 00:34:20,640 --> 00:34:25,113 And this is looking at the kind of pathologic, 582 00:34:26,070 --> 00:34:28,170 physiologic effects of chronic stress. 583 00:34:28,170 --> 00:34:29,583 So you can look here, 584 00:34:31,050 --> 00:34:34,710 here's our immune system's adaptive response. 585 00:34:34,710 --> 00:34:37,290 And so here's kind of baseline level. 586 00:34:37,290 --> 00:34:41,280 And if something happens, some stressful activity, 587 00:34:41,280 --> 00:34:44,193 your body's alarm system is gonna go off, 588 00:34:45,690 --> 00:34:46,980 you may go in shock, 589 00:34:46,980 --> 00:34:51,980 which is going to totally deplete your response, 590 00:34:52,650 --> 00:34:55,230 but then it's gonna quickly revert 591 00:34:55,230 --> 00:34:57,603 more towards a resistance phase. 592 00:34:58,440 --> 00:35:00,150 But you can't maintain, 593 00:35:00,150 --> 00:35:04,030 your body can't maintain this resistance phase forever. 594 00:35:05,760 --> 00:35:09,630 So it might get to the point where you enter this fatigue, 595 00:35:09,630 --> 00:35:14,283 exhaustion, kind of overuse phase. 596 00:35:19,050 --> 00:35:21,450 We'll talk about this a little bit more 597 00:35:21,450 --> 00:35:23,130 in one of our other lectures 598 00:35:23,130 --> 00:35:26,490 when we're looking at exercise and fatigue 599 00:35:26,490 --> 00:35:28,413 and kind of over-training. 600 00:35:29,310 --> 00:35:31,410 So there's a perfect amount, 601 00:35:31,410 --> 00:35:34,380 it's like Goldilocks, the just right amount. 602 00:35:34,380 --> 00:35:36,810 Too little isn't enough to stimulate a change, 603 00:35:36,810 --> 00:35:41,643 and too much, it has adverse effects on our body. 604 00:35:45,720 --> 00:35:50,190 So our adipose tissue is also actually an endocrine organ, 605 00:35:50,190 --> 00:35:54,963 and our adipose tissue produces a hormone called leptin. 606 00:35:55,890 --> 00:35:58,500 And the primary function of the hormone leptin 607 00:35:58,500 --> 00:36:02,670 is the regulation of our adipose tissue mass 608 00:36:02,670 --> 00:36:07,670 through mediation of effects on the hypothalamus. 609 00:36:10,320 --> 00:36:14,403 And so leptin will act on the hypothalamus, 610 00:36:15,930 --> 00:36:20,930 which affects our perception of hunger, food use, 611 00:36:22,560 --> 00:36:25,653 physical activity and exercise and energy balance. 612 00:36:27,270 --> 00:36:32,270 So our appetite is influenced by our production of leptin. 613 00:36:37,230 --> 00:36:42,230 Some people have a decreased sensitivity to leptin. 614 00:36:47,190 --> 00:36:51,460 And so this can lead to obesity 615 00:36:54,094 --> 00:36:55,860 where people don't feel full. 616 00:36:55,860 --> 00:36:58,413 So in spite of high leptin levels, 617 00:37:00,810 --> 00:37:03,930 they never feel full. 618 00:37:03,930 --> 00:37:07,260 And so they'll keep eating 619 00:37:07,260 --> 00:37:09,810 even in spite of the fact that they have high energy stores 620 00:37:09,810 --> 00:37:11,583 and high levels of leptin. 621 00:37:15,810 --> 00:37:18,273 So we talked about the pancreas earlier, 622 00:37:19,470 --> 00:37:22,803 and the pancreas has exocrine and endocrine functions. 623 00:37:23,700 --> 00:37:27,120 It does secrete insulin from the beta cells 624 00:37:27,120 --> 00:37:29,730 and it works to promote the storage of glucose, 625 00:37:29,730 --> 00:37:32,010 amino acids and fats. 626 00:37:32,010 --> 00:37:34,440 If you're not producing insulin, 627 00:37:34,440 --> 00:37:37,143 this leads to diabetes mellitus. 628 00:37:39,540 --> 00:37:44,540 The pancreas also produces glucagon from the alpha cells. 629 00:37:45,210 --> 00:37:47,933 Remember we talked about the alpha and beta cells earlier. 630 00:37:48,930 --> 00:37:51,690 Actually, we talked about alpha and beta receptors earlier 631 00:37:51,690 --> 00:37:54,300 for norepinephrine and epinephrine. 632 00:37:54,300 --> 00:37:56,640 But glucagon is gonna promote 633 00:37:56,640 --> 00:38:00,360 the mobilization of fatty acids and glucose. 634 00:38:00,360 --> 00:38:03,600 It also produces somatostatin. 635 00:38:03,600 --> 00:38:06,600 And this controls the rate of entry of nutrients 636 00:38:06,600 --> 00:38:08,430 into our circulation. 637 00:38:08,430 --> 00:38:13,430 And the pancreas also secretes digestive enzymes and bicarb 638 00:38:14,280 --> 00:38:15,540 into the small intestine. 639 00:38:15,540 --> 00:38:20,540 So it is effective in helping our acid-base balance. 640 00:38:25,950 --> 00:38:28,770 Testosterone and estrogen and progesterone 641 00:38:28,770 --> 00:38:31,020 are the primary sex steroids 642 00:38:31,020 --> 00:38:36,020 that are secreted by our testes and our ovaries. 643 00:38:37,170 --> 00:38:39,780 The testosterone is released from the testes. 644 00:38:39,780 --> 00:38:43,180 It promotes tissue muscle building 645 00:38:44,430 --> 00:38:47,700 and enhance performance during athletic events. 646 00:38:47,700 --> 00:38:52,170 It also promotes the typical masculine characteristics 647 00:38:52,170 --> 00:38:53,913 such as like a deep voice, 648 00:38:57,270 --> 00:39:02,270 the high muscle mass to fat mass ratio in men 649 00:39:04,590 --> 00:39:05,913 as compared to women, 650 00:39:08,490 --> 00:39:10,323 where estrogen and progesterone, 651 00:39:11,640 --> 00:39:13,920 progesterone are release from the ovaries 652 00:39:13,920 --> 00:39:17,943 and work to maintain our reproductive function. 653 00:39:23,220 --> 00:39:27,417 Testosterone is both an anabolic and androgenic steroid, 654 00:39:30,330 --> 00:39:32,640 which causes size changes, 655 00:39:32,640 --> 00:39:35,523 increases lean body mass, muscle mass and strength. 656 00:39:37,110 --> 00:39:42,110 And so scientists have developed synthetic steroids 657 00:39:44,160 --> 00:39:45,760 to promote tissue growth 658 00:39:46,620 --> 00:39:49,380 in patients who experience atrophy 659 00:39:49,380 --> 00:39:51,510 as a result of prolonged bedrest. 660 00:39:51,510 --> 00:39:56,460 And so people think that they're effective 661 00:39:56,460 --> 00:39:58,770 in helping the average person 662 00:39:58,770 --> 00:40:00,633 increase their muscle mass. 663 00:40:02,310 --> 00:40:03,423 For athletes, 664 00:40:08,250 --> 00:40:13,250 the anabolic steroids do improve lean body mass 665 00:40:13,860 --> 00:40:15,240 and muscle mass and strength, 666 00:40:15,240 --> 00:40:20,240 particularly in combination with resistance training. 667 00:40:20,370 --> 00:40:22,740 But there's lots of negative side effects 668 00:40:22,740 --> 00:40:25,203 of taking these anabolic steroids. 669 00:40:28,710 --> 00:40:31,320 So now we're gonna talk about muscle 670 00:40:31,320 --> 00:40:34,743 and its effect on hormone production. 671 00:40:35,850 --> 00:40:40,500 Skeletal muscle produces myokines when the muscle contracts. 672 00:40:40,500 --> 00:40:45,500 And myokines are small proteins or proteoglycan peptides. 673 00:40:46,320 --> 00:40:49,420 And these small proteins 674 00:40:50,460 --> 00:40:52,710 are produced and released by the muscle cells 675 00:40:52,710 --> 00:40:54,750 in response to muscle contraction. 676 00:40:54,750 --> 00:40:59,750 And these myokines have endocrine type effects. 677 00:41:03,210 --> 00:41:07,560 They can stimulate glucose uptake and fatty acid oxidation. 678 00:41:07,560 --> 00:41:10,230 They can promote blood vessel growth within muscles, 679 00:41:10,230 --> 00:41:14,610 so to increase the circulation and capillary density. 680 00:41:14,610 --> 00:41:17,190 They can promote liver glucose production, 681 00:41:17,190 --> 00:41:21,060 so gluconeogenesis, 682 00:41:21,060 --> 00:41:22,650 and triglyceride breakdown, 683 00:41:22,650 --> 00:41:24,903 so breaking down the free fatty acids. 684 00:41:28,950 --> 00:41:33,950 Interleukin 6 or IL-6 is an anti-inflammatory myokine, 685 00:41:34,860 --> 00:41:37,860 so skeletal muscle produces myokines, 686 00:41:37,860 --> 00:41:40,683 and this is a specific type of myokine. 687 00:41:42,210 --> 00:41:47,210 And it will help give an anti-inflammatory effect 688 00:41:51,300 --> 00:41:55,020 while suppressing other pro-inflammatory hormones. 689 00:41:55,020 --> 00:41:57,933 So preventing inflammation. 690 00:41:59,730 --> 00:42:00,990 The important thing to know 691 00:42:00,990 --> 00:42:02,310 is that regular exercise 692 00:42:02,310 --> 00:42:04,770 will promote this anti-inflammatory environment, 693 00:42:04,770 --> 00:42:07,500 which is great to remember 694 00:42:07,500 --> 00:42:10,620 and talk about with our clients and our patients 695 00:42:10,620 --> 00:42:13,890 that exercise can have a aid 696 00:42:13,890 --> 00:42:16,170 and promote reduction in chronic inflammation 697 00:42:16,170 --> 00:42:17,940 and reduce risk of heart disease, 698 00:42:17,940 --> 00:42:20,673 type two diabetes, and certain types of cancers. 699 00:42:25,740 --> 00:42:30,243 So looking at our muscle glycogen utilization, 700 00:42:34,290 --> 00:42:39,190 glycogenolysis or the process of glycogen breakdown 701 00:42:40,380 --> 00:42:43,200 is related to our exercise intensity. 702 00:42:43,200 --> 00:42:44,670 And high-intensity exercise 703 00:42:44,670 --> 00:42:47,730 will result in greater and more rapid glycogen depletion. 704 00:42:47,730 --> 00:42:49,083 That makes sense. 705 00:42:50,130 --> 00:42:53,310 Plasma epinephrine, our hormone, 706 00:42:53,310 --> 00:42:57,210 is a powerful stimulator of this glycogenolysis. 707 00:42:57,210 --> 00:43:01,020 And so high-intensity exercise results in greater increases 708 00:43:01,020 --> 00:43:03,450 in our plasma epinephrine levels. 709 00:43:03,450 --> 00:43:08,380 So you can see here on this y-axis 710 00:43:09,240 --> 00:43:14,240 the epinephrine levels in nanomoles up to zero to nine, 711 00:43:15,360 --> 00:43:18,540 and then the time for exercise 712 00:43:18,540 --> 00:43:23,193 and the percent of our VO2 max. 713 00:43:31,410 --> 00:43:36,410 Our blood glucose balance during exercise 714 00:43:37,170 --> 00:43:40,050 is maintained through different processes. 715 00:43:40,050 --> 00:43:43,650 So we do need that constant turnover 716 00:43:43,650 --> 00:43:45,960 or that we need supplies of glucose 717 00:43:45,960 --> 00:43:49,470 to maintain our exercise and activity levels. 718 00:43:49,470 --> 00:43:54,183 And we have enough stored for about two hours of activity. 719 00:43:55,080 --> 00:43:56,730 Our plasma glucose is maintained 720 00:43:56,730 --> 00:43:58,050 through four different processes. 721 00:43:58,050 --> 00:44:01,500 So mobilization of glucose from liver glycogen stores, 722 00:44:01,500 --> 00:44:04,860 mobilization of free fatty acid from adipose tissue, 723 00:44:04,860 --> 00:44:06,870 which will spare the blood glucose 724 00:44:06,870 --> 00:44:09,273 and maintain the blood glucose levels, 725 00:44:10,110 --> 00:44:13,770 gluconeogenesis from amino acids, lactic acid and glycerol, 726 00:44:13,770 --> 00:44:15,183 which occurs in the liver, 727 00:44:16,080 --> 00:44:19,410 blocking the entry of glucose into the cells, 728 00:44:19,410 --> 00:44:23,430 which will force the use of free fatty acid as a fuel. 729 00:44:23,430 --> 00:44:28,430 So all ways to control and maintain a plasma glucose level, 730 00:44:28,860 --> 00:44:31,290 which is controlled by hormones. 731 00:44:31,290 --> 00:44:36,290 So the slow-acting hormones are gonna be our thyroxine, 732 00:44:37,080 --> 00:44:39,240 which is a thyroid hormone, 733 00:44:39,240 --> 00:44:41,520 cortisol, and growth hormone. 734 00:44:41,520 --> 00:44:43,590 And remember our fast-acting hormones 735 00:44:43,590 --> 00:44:46,803 are the epinephrine, norepinephrine, insulin, and glucagon. 736 00:44:49,590 --> 00:44:54,090 So the thyroid hormones will allow other hormones 737 00:44:54,090 --> 00:44:56,160 to exert the full effect. 738 00:44:56,160 --> 00:44:59,970 Our T3 will enhance the effect of epinephrine 739 00:44:59,970 --> 00:45:03,840 to mobilize free fatty acids from adipose tissue. 740 00:45:03,840 --> 00:45:07,563 And there isn't a real significant change during exercise. 741 00:45:09,480 --> 00:45:12,360 Cortisol, which is a slow-acting hormone, 742 00:45:12,360 --> 00:45:15,330 will stimulate free fatty acid mobilization 743 00:45:15,330 --> 00:45:17,250 from our adipose tissue. 744 00:45:17,250 --> 00:45:20,850 It will enhance the production of glucose in the liver 745 00:45:20,850 --> 00:45:22,680 or gluconeogenesis. 746 00:45:22,680 --> 00:45:24,720 It will decrease the rate of glucose 747 00:45:24,720 --> 00:45:26,493 being used by the cells. 748 00:45:27,480 --> 00:45:28,923 And exercise will, 749 00:45:33,840 --> 00:45:37,950 exercise will affect cortisol levels in different ways. 750 00:45:37,950 --> 00:45:40,830 So during high-intensity exercise, 751 00:45:40,830 --> 00:45:44,790 there's gonna be a linear increase with cortisol levels. 752 00:45:44,790 --> 00:45:48,600 So when we're at moderate to vigorous levels, 753 00:45:48,600 --> 00:45:51,060 the cortisol level is gonna increase. 754 00:45:51,060 --> 00:45:53,100 When we're doing low-intensity exercise, 755 00:45:53,100 --> 00:45:55,923 the cortisol level is actually gonna decrease. 756 00:45:58,170 --> 00:46:01,060 This is because of the fact that 757 00:46:04,260 --> 00:46:05,580 during light exercise, 758 00:46:05,580 --> 00:46:07,860 cortisol is removed faster 759 00:46:07,860 --> 00:46:10,590 than the adrenal cortex can secrete it. 760 00:46:10,590 --> 00:46:12,480 And during intense exercise, 761 00:46:12,480 --> 00:46:14,110 the increase in plasma cortisol 762 00:46:15,870 --> 00:46:18,730 was due to a high rate of secretion 763 00:46:19,920 --> 00:46:23,430 that more than doubled the rate of removal. 764 00:46:23,430 --> 00:46:25,863 So that's why there's a linear increase. 765 00:46:35,040 --> 00:46:37,140 Growth hormone during exercise. 766 00:46:37,140 --> 00:46:40,020 Recall that growth hormone plays a major role 767 00:46:40,020 --> 00:46:43,203 in the synthesis of protein tissues, 768 00:46:44,880 --> 00:46:48,100 acting through kind of enhanced secretion of 769 00:46:50,160 --> 00:46:53,580 insulin growth hormone factors from the liver. 770 00:46:53,580 --> 00:46:55,290 But growth hormone can also influence 771 00:46:55,290 --> 00:46:58,413 our fat and carbohydrate metabolism. 772 00:47:01,050 --> 00:47:05,670 The growth hormone will also support the action of cortisol 773 00:47:05,670 --> 00:47:08,970 and it will decrease the glucose uptake by the tissues. 774 00:47:08,970 --> 00:47:11,883 It will increase free fatty acid mobilization. 775 00:47:16,350 --> 00:47:20,010 It will enhance gluconeogenesis in the liver. 776 00:47:20,010 --> 00:47:23,463 So again, other ways to produce fuel. 777 00:47:24,870 --> 00:47:28,623 So the exercise effect of growth hormone. 778 00:47:29,460 --> 00:47:32,910 Exercise will cause an increase in plasma growth hormone 779 00:47:32,910 --> 00:47:35,043 with increased exercise intensities. 780 00:47:39,900 --> 00:47:42,840 This is just a schematic showing that. 781 00:47:42,840 --> 00:47:44,610 So plasma growth hormone, 782 00:47:44,610 --> 00:47:47,460 again, as the intensity of exercise increases, 783 00:47:47,460 --> 00:47:50,853 the plasma levels of growth hormone will also increase. 784 00:47:52,320 --> 00:47:53,400 Looking at the difference 785 00:47:53,400 --> 00:47:57,930 between control groups and runners, 786 00:47:57,930 --> 00:48:00,570 runners will see a significant increase 787 00:48:00,570 --> 00:48:01,830 in plasma growth hormone 788 00:48:01,830 --> 00:48:03,753 as compared to other people. 789 00:48:05,670 --> 00:48:07,500 Epinephrine and norepinephrine, 790 00:48:07,500 --> 00:48:11,013 we talked earlier, they're fast-acting hormones. 791 00:48:12,390 --> 00:48:15,660 They will help us maintain our blood glucose levels 792 00:48:15,660 --> 00:48:17,100 during exercise. 793 00:48:17,100 --> 00:48:20,910 They will facilitate muscle glycogen mobilization, 794 00:48:20,910 --> 00:48:22,830 increase liver glucose mobilization, 795 00:48:22,830 --> 00:48:25,233 increase free fatty acid mobilization, 796 00:48:26,430 --> 00:48:29,190 and interfere with glucose uptake. 797 00:48:29,190 --> 00:48:30,810 So the net effect 798 00:48:30,810 --> 00:48:35,810 is to ensure our blood plasma glucose levels 799 00:48:38,130 --> 00:48:40,683 remain stable. 800 00:48:43,020 --> 00:48:45,180 Our plasma epinephrine and norepinephrine 801 00:48:45,180 --> 00:48:47,160 increase during our exercise, 802 00:48:47,160 --> 00:48:50,280 and this is, we talked about this earlier, 803 00:48:50,280 --> 00:48:53,190 which helps us to keep exercising, 804 00:48:53,190 --> 00:48:55,410 increasing our heart rate, increasing our blood pressure 805 00:48:55,410 --> 00:48:58,923 through the vasoconstriction action. 806 00:49:01,320 --> 00:49:04,470 And we need less of this with training. 807 00:49:04,470 --> 00:49:06,270 So the more we train, 808 00:49:06,270 --> 00:49:08,790 the less our body is gonna need 809 00:49:08,790 --> 00:49:12,780 to produce the levels of epinephrine and norepinephrine. 810 00:49:12,780 --> 00:49:14,970 It'll take less of it to create... 811 00:49:14,970 --> 00:49:16,680 This can happen as quickly as 812 00:49:16,680 --> 00:49:18,723 within three weeks of training. 813 00:49:21,270 --> 00:49:26,270 So here's plasma catecholamines response 814 00:49:26,940 --> 00:49:28,860 to exercise following training. 815 00:49:28,860 --> 00:49:31,500 And here's our norepinephrine and our epinephrine. 816 00:49:31,500 --> 00:49:33,660 And here's our three-week mark. 817 00:49:33,660 --> 00:49:35,460 Initially when we first start off, 818 00:49:35,460 --> 00:49:36,810 when we exercise, 819 00:49:36,810 --> 00:49:38,460 we're producing higher levels 820 00:49:38,460 --> 00:49:41,010 of both norepinephrine and epinephrine. 821 00:49:41,010 --> 00:49:42,330 But as we train, 822 00:49:42,330 --> 00:49:47,330 we don't need to produce as much to get our body to respond. 823 00:49:47,430 --> 00:49:50,709 So looking at insulin and glucagon, 824 00:49:50,709 --> 00:49:51,960 they have opposite effects, 825 00:49:51,960 --> 00:49:53,700 they're both fast-acting hormones. 826 00:49:53,700 --> 00:49:55,510 And recall that insulin 827 00:49:56,520 --> 00:50:01,520 works to address the blood glucose 828 00:50:01,770 --> 00:50:03,570 or the plasma glucose level. 829 00:50:03,570 --> 00:50:06,963 So if there's too much glucose in the blood, 830 00:50:08,370 --> 00:50:10,110 insulin will be released 831 00:50:10,110 --> 00:50:15,110 to promote absorption of the glucose into the cell. 832 00:50:16,920 --> 00:50:21,660 So during exercise and activity, 833 00:50:21,660 --> 00:50:23,190 you don't want that to happen. 834 00:50:23,190 --> 00:50:26,520 So you want the muscles to be able to use 835 00:50:26,520 --> 00:50:28,290 that free floating glucose. 836 00:50:28,290 --> 00:50:30,540 You don't want it to be taken up by the tissues. 837 00:50:30,540 --> 00:50:33,423 So during exercise, 838 00:50:38,070 --> 00:50:40,980 the plasma concentration of insulin will decrease 839 00:50:40,980 --> 00:50:42,720 during exercise. 840 00:50:42,720 --> 00:50:46,110 And there's decreased insulin response with training. 841 00:50:46,110 --> 00:50:47,190 Conversely, 842 00:50:47,190 --> 00:50:49,410 with glucagon, 843 00:50:49,410 --> 00:50:51,210 the plasma concentration 844 00:50:51,210 --> 00:50:54,063 is going to increase during exercise. 845 00:50:55,650 --> 00:50:59,100 And also there's a decreased response following trainings. 846 00:50:59,100 --> 00:51:04,100 So this insulin and glucagon secretion 847 00:51:04,230 --> 00:51:07,953 are influenced by our catecholamines. 848 00:51:10,590 --> 00:51:15,543 So here's the drop in the insulin, 849 00:51:16,860 --> 00:51:19,680 and you can see the difference between an untrained person 850 00:51:19,680 --> 00:51:21,723 and a trained person. 851 00:51:22,770 --> 00:51:25,713 So over time, 852 00:51:27,810 --> 00:51:29,253 with exercise, 853 00:51:31,716 --> 00:51:36,643 the production of insulin is going to decrease, 854 00:51:38,220 --> 00:51:40,143 where conversely, 855 00:51:41,010 --> 00:51:45,303 glucagon is going to increase during exercise. 856 00:51:49,290 --> 00:51:51,810 And so this is showing the effect of the catecholamines, 857 00:51:51,810 --> 00:51:55,620 the epinephrine and norepinephrine 858 00:51:55,620 --> 00:51:59,400 on insulin and glucagon secretion. 859 00:51:59,400 --> 00:52:01,210 So epinephrine, norepinephrine 860 00:52:02,460 --> 00:52:06,963 will decrease the production of insulin, 861 00:52:08,520 --> 00:52:10,890 whereas the epinephrine and norepinephrine 862 00:52:10,890 --> 00:52:13,803 will increase the production of glucagon. 863 00:52:20,220 --> 00:52:23,520 Effect of the sympathetic nervous system 864 00:52:23,520 --> 00:52:25,410 on substrate mobilization. 865 00:52:25,410 --> 00:52:27,960 So during submaximal exercise, 866 00:52:27,960 --> 00:52:29,883 again just another schematic showing, 867 00:52:30,780 --> 00:52:33,600 when the sympathetic nervous system is activated, 868 00:52:33,600 --> 00:52:36,573 epinephrine and norepinephrine are going to be released, 869 00:52:37,860 --> 00:52:40,650 the production of insulin will drop, 870 00:52:40,650 --> 00:52:45,650 because we don't want the blood glucose levels to drop. 871 00:52:47,310 --> 00:52:49,623 The glucagon levels will increase. 872 00:52:51,240 --> 00:52:55,890 The adipose cells will be stimulated 873 00:52:55,890 --> 00:52:59,550 to release free fatty acids. 874 00:52:59,550 --> 00:53:03,573 And so the plasma levels of free fatty acid will increase. 875 00:53:05,040 --> 00:53:10,040 The liver is going to be producing glycogen, glucose, 876 00:53:14,970 --> 00:53:19,053 and the blood levels of glucose will be maintained. 877 00:53:25,260 --> 00:53:29,550 So looking at the hormonal response to exercise, 878 00:53:29,550 --> 00:53:34,533 notice that with increasing intensities of exercise, 879 00:53:36,390 --> 00:53:39,060 these hormones, epinephrine, norepinephrine, 880 00:53:39,060 --> 00:53:41,700 growth hormone, cortisol, glucagon, 881 00:53:41,700 --> 00:53:44,160 their levels will increase. 882 00:53:44,160 --> 00:53:46,140 The production and synthesis of those hormones 883 00:53:46,140 --> 00:53:47,580 will increase. 884 00:53:47,580 --> 00:53:51,390 And you can see the plasma concentration of those hormones 885 00:53:51,390 --> 00:53:55,323 is increased with increasing intensities. 886 00:53:58,560 --> 00:54:01,380 So this is blood or plasma concentration 887 00:54:01,380 --> 00:54:03,690 taken in response to graded exercise. 888 00:54:03,690 --> 00:54:07,560 And then this is a plasma hormone concentration 889 00:54:07,560 --> 00:54:09,270 with prolonged exercise. 890 00:54:09,270 --> 00:54:11,730 So here's now time. 891 00:54:11,730 --> 00:54:14,280 So you see the same type of response 892 00:54:14,280 --> 00:54:16,803 that as our time increases, 893 00:54:18,810 --> 00:54:20,370 you're gonna see an increase 894 00:54:20,370 --> 00:54:23,133 in the plasma concentrations of these hormones. 895 00:54:25,290 --> 00:54:27,510 That is it. The end. 896 00:54:27,510 --> 00:54:30,690 So go back to the first slide or the objective slide, 897 00:54:30,690 --> 00:54:35,043 and see if you have any questions. 898 00:54:35,880 --> 00:54:39,390 Again, look in chapter five at the Powers book 899 00:54:39,390 --> 00:54:41,340 and let me know if you have any questions. 900 00:54:41,340 --> 00:54:42,190 Talk to you soon.