Make sure you answer your teaching evaluations on-line. Biological Clocks

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1 Review for test #4 Make sure you answer your teaching evaluations on-line This review only include the new material for the fourth test (all animal health and production related lectures). It highlights the main topics having in mind the test questions you will see on Wednesday. Remember all tests are cumulative. Life is a series of chemical reactions occurring in compartmentalized environments. 39 The main purpose of life is to keep itself alive Physiology, the study of how life works, is based on the simultaneous occurrence of the following three concepts: levels of organization structure / function relationship homeostatic regulation Biological Clocks It is thought that circadian regulation of physiology and behavior imparts survival advantages to organisms that use clocks. In mammals, a master clock resident in the SCN synchronizes other central and peripheral oscillators to evoke this regulation. This master oscillator consists of interlocking transcriptionaltranslational feedback loops, and it regulates both core clock genes necessary for oscillator maintenance as well as specific output genes that directly or indirectly mediate physiology under circadian control. It is now clear that both neuroanatomic and molecular outputs of the clock are necessary for proper circadian clock function (Panda S and Hogenesch JB, 2004). 1

2 Biological Clocks anticipation or what if afferent story line S sensor e.g. t C/F integration center (concept vs anatomy) negative feedback story line efferent story line E effector Biological Clocks Theoretically, a feedforward mechanism anticipates the logistics needed to carry on a specific physiological effect A B C D feedback feedforward S E Keep this thought in mind for the rest of this lecture. 2

3 Biological Clocks Evening (E) / morning (M) oscillators in mammalian photoperiodism. A A, oscillators entrained to a short night rhythm B, as nights get longer (PRC) the oscillators drift apart since their free running rhythms differ C, in long nights oscillators adopt an entrainment pattern where they overlap minimally entrainment (zeitgebers) B C one clock vs. two clocks entrainment vs. resetting Its all in the timing 3

4 Its all in the timing SCN Its all in the timing 4

5 Stress HPA axis and its story lines Stress and the HPA Axis HPA axis and its story lines Stress pushes the homeostatic envelope to a point from which the system might recover, or to the starting point of system pathologies 5

6 Stress and the HPA Axis HPA axis and its story lines Insulin-induced hypoglycemia, an example of homeostatic events set in motion in response to a stressor, to maintain system steady state Stress and Immunity HPA axis and its story lines The neuroendocrine - immune connection has driven a reversal of reductionist approaches IL-1 brain ventricle injection acute vs chronic stress Involvement of the PVN is a characteristic of the homeostatic response to stressors such as the hypoglicemic and other tests 6

7 Stress, Immunity and Animal Health and Production HPA axis and its story lines Animal Production involved homeostatic responses leading to a steady state that is borderline to a disease or pathological state Regulation of Growth A Chihuahua walking with a Great Dane more than 50 times its mass. 7

8 Growth & Muscle Development Growth, general and normal expansion of size as produced by accretion of tissues similar in constitution to that of original tissue or organ Hypertrophy, cells increase in size Hyperplasia, cells increase in number Accretion, cells accumulate or secrete True growth, e.g. increase in muscle/bone Fattening, accumulation of fat 1950 Whole body growth, from cell changes up Development, temporal collective changes today Muscle Production involve homeostatic responses leading to a steady state that is borderline to a pathological state (thus they are more susceptible to diseases). Human Growth & Development Mother & son. At 8-foot-4, Leonid Stadnik, 33 years old, is the tallest human being on the planet (2005) Arnold Schwarzenegger. He won several world bodybuilders competitions and is currently the governor of California. Average daily gain, or the daily increase in weight, is a direct reflection of the human and farm animal s ability to grow. Muscle growth, a main tissue that increased its weight, does so by multiple reasons, ultimately affecting undifferentiated muscle cells. 8

9 Animal Growth & Development Average daily gain, or the daily increase in weight, is a direct reflection of the human and farm animal s ability to grow. Muscle growth, a main tissue that increased its weight, does so by multiple reasons, ultimately affecting undifferentiated muscle cells. Skeletal Muscle Structure, Miogenesis, Growth Satellite cells are quiscent or dormants since they remain capable of re-entering the proliferative cell cycle without dividing. They are the apparent target for growth promotants used in adult animals, such as ßagonists, GH, IGF, steroids. 9

10 Whole Body Animal Growth double muscled normal Average daily gain, or the daily increase in weight, is a direct reflection of the animal s ability to grow. By increasing it, producers can rise more livestock in a given amount of time (compare increase efficiency or gain vs. fat / lean ratios vs. profitability). Exercise Physiology Metabolism Ventilation Circulation Temperature Exercise and Health ATP for muscle contraction is continuously produced by aerobic metabolism of glucose and fatty acids. During short bursts of activity, when ATP demands exceeds the rate of aerobic ATP production, anaerobic glycolysis produces ATP, lactate and H ions. 10

11 Exercise Physiology Metabolism Ventilation Circulation Temperature Exercise and Health Ventilation rates jumps as soon as exercise begins, despite the fact that neither arterial PCO2 nor PO2 has changed. This is an example of a feed-forward mechanism. Exercise Physiology Metabolism Ventilation Circulation Temperature Exercise and Health Blood flow is distributed differently at rest than during exercise. Vasoconstriction in non-exercising tissues combined with vasodilation in exercising muscle shunts blood to muscles. In which tissues does actual blood flow decreases. 11

12 Exercise Physiology Metabolism Ventilation Circulation Temperature Exercise and Health The rise in body temperature during exercise triggers two thermoregulatory mechanisms: sweating and increase cutaneous blood flow. Both mechanisms can help regulate body temperature, but both can also disrupt homeostasis in other ways. Exercise Physiology Metabolism Ventilation Circulation Temperature Exercise and Health The relationship between immune function and exercise. Individuals who exercised in moderation have fewer upper respiratory infections than sedentary individuals or those that exercise strenuously. 12

13 Exercise and Racing How great a running athlete is the horse??? O2 transport during exercise Training horses Stress and the racehorse fast? O2 uptake? RF/SF? CO? Hb? anaerobic capacity? respiratory capacity? EIPH? hypoxemia? hypertension? The horse has been bred selectively over six millennia based upon its ability to run fast Exercise and Racing How great a running athlete is the horse??? O2 transport during exercise Training horses Stress and the racehorse A mutation leading to an increase heart size explains a well above average performance 13

14 Exercise and Racing How great a running athlete is the horse??? O2 transport during exercise Training horses General, Physiology, Muscle Stress and the racehorse progressive loading precision training reduce variables LSD horse smartness weakest link good / bad training effects The training of horses must follow their anatomical and physiological development Exercise and Racing How great a Stressors running athlete is the horse??? S E O2 transport during exercise An example of circles, intersecting circels, intersecting Training horses Stress and the racehorse acute vs chronic stress Ultimately, training and associated activities should be progamed to disminished stress 14

15 Ovulation, Parturition, Lactation & Milk Production Adaptation to lactation diet, elimination of hypocalcemia, and immunomodulation to stimulate immune system at birth would reduce incidence of periparturient diseases in humans and cows. Ovulation, Parturition, Lactation & Milk Production Ruminal adaptation to lactation diet, elimination of hypoca, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows 15

16 Ovulation and Cyclicity E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids. The general pattern for the hormonal control of reproduction. Ovulation is triggered by estradiol induction of the preovulatory surge of LH, an obligatory event for reproduction to occur. Parturition and its Control P4 E2 E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids. Parturition is associated with a decrease in blood Progesterone (P4) and an increase in blood Estradiol (E2). These combination depolarize the membrane potential of myometrial cells making them more suceptible to oxytocin & prostaglandins. 16

17 Lactation and its Control E2 and P4 act in synchrony so that E2 promotes growth and P4 differentiation of their target tissues. E2 and P4 are steroids. E2 P4 Insulin IGFs TSH PRL Cortisol Aldosterone GH Milk production results from the interaction of multiple metabolic hormonal systems on the mammary gland: hormones such as insulin, IGFs, GH, TSH, PRL, cortisol and aldosterone. Periparturient Diseases How do we know that this THM is correct immune function DMI E2 and P4 cortisol stress immune suppression Ruminal adaptation to lactation diet, elimination of hypoca, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows 17

18 Periparturient Diseases How do we know that this THM is correct immune function DMI E2 and P4 cortisol stress immune suppression Ruminal adaptation to lactation diet, elimination of hypoca, and immunomodulation to stimulate immune system at calving would greatly reduce incidence of periparturient diseases in dary cows Thermoregulatory Control How do we know that this THM is correct effect on thermo- regulation by a minimal change in environmental temperature associated with the use of shade shows the sensitivity of the thermo- regulatory control system Supplemental shade lowers severity of heat stress, in calves housed in hutches in summer, as assessed by body t C and respiratory rate, after minimal increases in environmental t C 18

19 Thermoregulatory Control How do we know that this THM is correct effect on thermo- regulation by ingestion of a grass containing endophytes and summer high t C, shows how the thermo- regulatory control system can be modulated Losses in cow-calf productivity due to fescue toxicosity are significant. Endophyte ingestion interacts with high t C to exacerbate the signs of toxicosis. Low PRL and melatonin secretion appears to be associated with the disease. Thermoregulatory Control Based on data explored in the course, how would you explain results related to Ergot toxicity in humans Ergot: Claviceps purpurea, a parasitic fungus on spoiled rye and other grains. Its components and their derivatives include lysergic acid, lysergic acid amides, ergotamine,,ergocornine, ergocryptine, ergonovine, trimethylamine, histamine and acetylcholine, The most common early effects of ingesting the grains are nausea, vomiting, diarrhea, tachycardia, abdominal pain, and coma. effect on thermo- regulation by ingestion of a grass containing endophytes and summer high t C, shows how the thermo- regulatory control system can be modulated. Ergocryptine is a dopamine receptor agonist used to inhibit Prolactin secretion in humans. 19

20 Ca, Milk and Egg Production milk and egg production are linked by the control of Ca metabolism. Thus the role of PTH, VitD and calcitonin are important to understand management techniques used in both Industries, as well as in human lactation. Adequate blood calcium (Ca) and phosporus (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens. Ca, Milk and Egg Production Disorders of Ca metabolism may arise from abnormal levels of PTH or vitd. Possible consequences of hypercalcemia and hypophosphatemia Reduced excitability of muscle and nerve tissue leads to muscle weakness and neurological disorders. Cardiac disorders might also occur. Excess mobilization of Ca and PO4 from bone leads to osteoporosis. An increased incidence of Ca containing kidney stones occurs because the excess quantity of Ca being filtered may precipitate and form stones. milk and egg production are linked by the control of Ca metabolism. Thus the role of PTH, VitD and calcitonin are important to understand management techniques used in both Industries, as well as in human lactation. Adequate blood calcium (Ca) and phosporous (P) concentrations are vital to normal animal function. Homeostatic mechanisms normally achieved this. Ca & P are key minerals in bone development in humans and cows, and egg formation in chickens. 20

21 Ca, Milk and Egg Production PTH and Vit.D increase blood Ca while Calcitonin decreases it blood Ca decrease calcium receptor parathyroid gland PTH PTH receptor Gs / AC Gq / PLC intestine Vit. D absorption secretion Calcitonin filtration bone formation, osteoblast kidney, Ca filtration intestine, Ca secretion bone resorption, osteoclast kidney, Ca reabsorption, Vit. D intestine, Ca absorption blood Ca kidney PTH resorption formation Calcitonin reabsorption PTH Calcitonin thyroid gland calcium receptor bone Calcitonin receptor Gs / AC blood Ca increas e milk and egg production are linked by the control of Ca metabolism. Thus the role of PTH, VitD and calcitonin are important to understand management techniques used in both Industries, as well as in human lactation. There are three tissue target in Ca metabolism that control blood levels of Ca: bones, kidneys and gut. PTH acts on bone and kidneys, vitd acts on the gut, and calcitonin in all three of them. 21