Session 11- Metabolic and endocrine control during special circumstances Flashcards
What fuels are normally available in blood
Glucose and fatty acids
What fuels are available under special conditions
Amino acids
Ketone bodies
Lactate
Acute effects of hypoglycaemia
Trembling Weakness Tiredness Headache Sweating Sickness Tingling around the lips Palpitations Changes in mood Slurred speech Staggering walk
Actions of insulin
Increases glucose uptake and utilisation by muscle and adipose tissue
Promotes storage of glucose as glycogen in liver and muscle
Promotes amino acid uptake and protein synthesis in liver and muscle
Promotes lipogenesis and storage of fatty acids as triacylglycerols in adipose tissue
Effects of fasting
• Glycogenolysis in the liver to maintain blood glucose for the brain
and other glucose dependent tissues.
• Lipolysis in adipose tissue to provide fatty acids for use by tissues.
• Gluconeogenesis to maintain supplies of glucose for the brain.
How is insulin involved in maternal metabolism
Increases as pregnancy proceeds ad it acts to promote the uptake and storage of nutrients largely as fat in maternal adipose tissue
What is the role of the foetal-placental hormones
Oppose the actions of insulin
- impaired glucose uptake in maternal adipose and muscle
What are the anti- insulin hormones of placental origin
Human placental lactogen
Progesterone
Corticotropin releasing hormones
Metabolic changes during the first half of pregnancy
Related to a prep increase in maternal nutrient stores ready fo the more rapid growth of the foetus, birth and subsequent lactation
Increasing levels of insulin promote an anabolic state in the mother that results in increased nutrient storage
How are the demands of the foetal-placental unit for nutrients met during the second half of pregnancy
Reducing the maternal utilisation of glucose by switching tissues to the use of fatty acids
Delaying the disposal of maternal nutrients after meals
Releasing fatty acids from the stores built up during the first half of pregnancy
What is gestational diabetes
In some women the endocrine pancreas is unable to respond to the metabolic demands of pregnancy and the pancreas fails to release the increased amounts of insulin required. As a consequence there is a loss of control of metabolism, blood glucose increases and diabetes results (Gestational Diabetes).
After birth, when the increased
metabolic demands of pregnancy are removed and hormone levels change, the endocrine pancreas can respond adequately and the
diabetes disappears.
Metabolic response to exercise
• The increased energy demands of skeletal and cardiac muscle
are met by mobilisation of fuel molecules from energy stores.
• There are minimal disturbances to homeostasis by keeping the
rate of mobilisation equal to the rate of utilisation.
• The glucose supply to the brain is maintained (prevent
hypoglycaemia).
Advantages of using muscle glycogen over circulating glucose
Availability not affected by blood supply
No need for membrane transport into muscle cells
Produces G-6-P without using ATP
Mobilisation can be very rapid.
Metabolic response to short-duration high intensity exercise
- muscle ATP and C~P are used initially
- muscle glycogen is rapidly mobilised to provide glucose 6-P
- Glucose 6- is metabolised via glycolysis to provide ATP from ADP by substrate level phosphorylation
- build up of H+ causes fatigue
- dramatic increase in anaerobic resp
Effect of H+ on anaerobic metabolism
Build up of lactate and H+ which exceeds the buffering capacity of the muscle cells and impairs their function producing fatigue
