1. Metabolism and Regulation of Body Temperature
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)
Digestion and fate of the digested material
GUT
INSTESTINE
BODY TISSUES
Intake
of feed
products
Absorption
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: a small fraction of the rumen microflora
but important in splitting plant fibers open to
make them more easily digested by the bacteria.

6. Protozoan covered with chains of bacteria
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
bacteria/ml of rumen fluid
- Protozoa – 20% (106 protozoa/ml of rumen content)
Fungus - very small number

8. Metabolism Metabolism Catabolism
- chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material
Anabolism
Constructive process
e.g. Synthesis of proteins from a/a
Metabolism
Catabolism
Destructive process
e.g. Break down of protein into individual a/a
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
Portein
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
Glycogen, lipid

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

14. Used for protein synthesis by all cells
Metabolism
Absorptive state
uptake of glucose by
Blood Glucose
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. (low density lipoproteins)
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
Glucagon (α cell) secretion
stimulate
What happened after stored glucose and glycogens are used up?

18. Metabolism Post-absorptive state Lipolysis - Adipose tissue Fasting
Maintenance
Lipolysis - Adipose tissue
Gluconeogenesis - proteins
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
45 – 80 mg/dL
Dog
mg/dL
Horse
60 – 110 mg/dL
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
(Phosphoenolpyruvate)

22. SIMPLIFIED GLYCOLYSIS
2 ATP lost
8 ATP from glycolysis
6 ATP from oxidation of pyruvate
24 ATP from Kreb cycle
Total: 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
(Phosphoenolpyruvate)

28. Body Temperature and Heat regulation