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Metabolism and Regulation of Body Temperature

Physiology I. Metabolism and Regulation of Body Temperature. Dr Than Kyaw 23 October 2011. Nutritional Food and Energy Metabolism W hat are nutritional food? Types of food How they are used in the body? Body Temperature and Thermoregulation Heat production

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Metabolism and Regulation of Body Temperature

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  1. Physiology I Metabolism and Regulation of Body Temperature Dr Than Kyaw 23 October 2011

  2. Nutritional Food and Energy Metabolism What are nutritional food? Types of food How they are used in the body? • Body Temperature and Thermoregulation Heat production Heat exchange form and to the body Thermal control Hypothermia and hyperthermia

  3. Nutritional feeds • Food or Feed? • Feed: edible things containing nutrients essential for animal’s growth and production • Basic feeds Protein sources Carbohydrate and lipid sources Vitamins and mineral sources Water

  4. Nutritional feeds • Concentrates (mainly mono-gastric animals) What are they? • Roughages (mainly – ruminant animals) What are they? • Digestion and fate of the digested material GUT INSTESTINE BODY TISSUES products Absorption Intake of feed BLOOD Use store Digestion

  5. Rumen microbes (micro flora) • - Bacteria: digestion of sugars, starch, fiber, and protein for the cow. • - Protozoa: swallow and digest bacteria, starch granules, and some fiber. • Fungi: asmall fraction of the rumen microflora • but important in splitting plant fibers open to • make them more easily digested by the bacteria.

  6. Bacteria attacking a strand of Fiber taken from a cow’s rumen. Protozoan covered with chains of bacteria

  7. - Bacteria – account for about 80% of rumen metabolism • - 1011 bacteria/ml of rumen fluid • - Protozoa – 20% (106 protozoa/ml of rumen content) • Fungus - very small number

  8. - chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material Metabolism Anabolism Constructive process e.g. Synthesis of proteins from a/a Catabolism Destructive process e.g. Break down of protein into individual a/a Metabolism Both processes take place in the body at the same time

  9. Metabolism Basal metabolism (BM) - minimum amount of energy required to maintain vital functions in an animal at complete rest • BM - measured in a fasting individual who is awake and resting in a comfortably warm environment • Many hormones contributes to the regulation of metabolism

  10. Metabolism • Two periods of metabolism 1. Absorptive state - the period shortly following a meal during which nutrients are being absorbed from GI tract 2. Post-absorptive state - the period during which there is no net absorption Many hormones contributes to the regulation of metabolism

  11. Metabolism • During absorptive state blood level of glucose, amino/a, triglycrides increase (product of starch, glycogen, protein and cellulose) • Overall goals of metabolic processes during this period is to increase the use of these nutrients by cells of the body OR store them for later use

  12. Metabolism Absorptive state Glucose - predominant product of C/H digestion following a typical meal - blood glucose level – about 150% of fasting level - Insulin (produced by pancreas) – primary stimulant endocrine regulator - It affects – C/H, Protein (amino/a), lipid metabolism Portein Glycogen, lipid

  13. Absorptive period Metabolic fate of glucose, amino/a, and tryglycrides absorbed form GI tract Chylomicron = tryglyceride+ cholesterol+ Intracellular protein

  14. Metabolism Absorptive state Blood Glucose uptake of glucose by Muscle, Liver (Stored as glycogen) Insulin uptake of amino/a Amino acids Used for protein synthesis by all cells Insulin - All essential amino/a are needed (balanced ration)

  15. Metabolism Absorptive state • - Protein synthesis is slow; not all amino/a used up • Excess amino/a - cannot be stored as in glucose Triglyceride synthesis path way mainly in hepatocytes and secreted into the blood stream as lipoproteins (VLDLs, very low density lipoproteins) Enters Gluconeogenesis (liver, kidney) Chylomicrons – produced in Intestinal cells Lipoproteins – produced in liver Chylomicrons , Lipoproteins in blood LDLs (low density lipoproteins) Higher cholestrol Lipoprotein lipase

  16. Metabolism Absorptive state Formation of chylomicrons in an intestinal cell

  17. Metabolism Post-absorptive state After digestion & absorption - blood glucose level - Glucose storage - Synthesis of glycogen, protein, lipids stop Insulin ( cell) secretion • Release of stored glucose • Glucogenolysis stimulate Glucagon (α cell) secretion What happened after stored glucose and glycogens are used up?

  18. Metabolism Post-absorptive state Lipolysis - Adipose tissue Gluconeogenesis - proteins Fasting Maintenance Growth hormone Glucocorticoids Exercise Work Rapid depletion of stored glycogen in muscle ( within 2-3 min) Other energy supplies Glycogenolysis in liver & non-working muscles Lypolysis in adipose t/s Rapid mobilization - Catecholamines - Glucagon - Insulin

  19. Metabolism Post-absorptive state Blood glucose in Ruminants • lower than other animals (Why?) • Relatively small amount of glucose-yielding C/H digestion in S/I • Most C/H consumed – fermentative digestion in rumen • – products – VFAs (not glucose) • - acetic, propionic, butyric/a

  20. Metabolism Post-absorptive state Blood glucose is maintained by Glucagon Continuous, high rate of gluconeogenesis (liver) VFA (propionic/a) Maintenance of blood glucose level

  21. Simplified gluconeogenesis in ruminants Propionate CO2 (Phosphoenolpyruvate)

  22. SIMPLIFIED GLYCOLYSIS 2 ATP lost 8 ATP from glycolysis 6 ATP from oxidation of pyruvate 24 ATP from Kreb cycle Total: 38 ATP for each molecule of glucose 4 ATP gained

  23. Combustion of glucose molecule C6H12O6 + 6O2−→ 6CO2 + 6H2O. • One mole of glucose, this reaction releases 2.80 MJ of energy • That translates to 15.6 kJ, or 3.75 kcal, per gram. • generally rounded to 4 kcal/g of sugar • On a per-gram basis, all carbohydrates yield essentially the same amount of energy as glucose

  24. Summary of metabolic organs and mechanisms

  25. Ketosis Ketone Body Formation Acetone Acetoacetate β-hydroxybutyrate High in blood, urine, and milk • High milk production • Starvation – Negative Energy Balance (BCS 4 or 5) • Massive Fat Mobilization

  26. Ketosis • More common in dairy cows (peak milk production) • Rapid need of glucose for milk sugar synthesis • Increased mobilization of fat depot leads to ketone body production • Treatment – glucose infusion • Glucocorticoides injections • - enhance gluconeogenesis • Feeding sodium propionate (unpalatable)

  27. Simplified gluconeogenesis in ruminants Propionate CO2 (Phosphoenolpyruvate)

  28. Body Temperature and Heat regulation

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