Adaptations of Metabolism Flashcards
Why does maternal metabolism change during pregnancy?
To ensure the foetus is supplied with nutrients
That nutrients are supplied at the right level
Foetus is buffered from any disturbances in maternal nutrient supply
How is Maternal Insulin involved in pregnancy?
Increases as pregnancy proceeds and it acts to promote the uptake and storage of nutrients
How are foetal-placental hormones involves in pregnancy?
Increasingly important as pregnancy proceeds, oppose the actions of insulin. They maintain the glucose concentration gradient to ensure it’s constant supply.
What is the metabolic change in metabolism during the first half of pregnancy?
Preparatory increase in maternal nutrient stores
What is the metabolic change in metabolism during the second half of pregnancy?
Demands of the fast growth are met by keeping the concentration of nutrients in the maternal circulation relatively high;
Maternal utilisation of glucose is reduced - tissues use fatty acids
Nutrient disposal delayed after meals
How does Maternal ketogenesis aid development?
Availability of fatty acids from the mobilisation of maternal adipose, coupled with the fall in the insulin/anti-insulin ratio switches on the production of ketone bodies by the maternal liver.
Used to fuel the developing foetal brain.
How do the Beta cells of the mother meet the demands of pregnancy?
Beta-cell hyperplasia and hypertrophy
Increased rate of insulin synthesis in the Beta-cell.
What is Gestiational Diabetes?
Endocrine pancreas is unable to meet the metabolic demand of pregnancy.
Fails to release the increased amounts of insulin required.
Loss of control of metabolism, blood glucose increases and diabetes results
After birth it disappears as metabolic needs reduce
When, during exercise, is anaerobic metabolism used?
High intensity activities, short duration as the supply of oxygen to the muscle is inadequate for aerobic metabolism.
When, during exercise, is aerobic metabolism used?
Lower intensity activities, longer duration as the oxygen supply to muscle is adequate.
How can ATP be replenished?
Creatine phosphate in muscle
ADP can be converted back to ATP by coupling it to the oxidation of fuel molecules using substrate level phosphorylation
How long can glycogen stores last under aerobic conditions?
60 minutes
33 moles of ATP produced
How long can glycogen stores last under anaerobic conditions?
2 minutes
3 moles of ATP produced
Why is using muscle glycogen advantageous?
Availability is not effected by blood supply
No need for membrane transport
Produces G-6-P without using ATP
Preserves the Liver’s store of glycogen so CNS is not starved of glycogen
Why is mobilisation of Glycogen rapid in muscle?
G-6-P enters glycolysis
Highly branched structure means many sites for enzyme attack
How is metabolism of Glucose limited in muscle cells?
Lactate and H+ build up
Level of H+ exceeds the buffering capacity, impairs their function (fatigue) by inhibiting glycolysis, interfering with Actin/Myosin interaction, causes SER to bind calcium (decreased contraction)
What limits the use of fatty acids in muscle cells?
Rate of lipolysis
Capacity of the blood to transport fatty acids (requires albumin)
Rate of fatty acid uptake into muscle cells
Fatty acid oxidation requires more oxygen per mole of ATP produced than glucose
Fatty acids can only be metabolised under aerobic conditions
What is the metabolic response to short duration, high intensity exercise?
Confined to skeletal muscle that works anaerobically
Muscle ATP, CP used. Then muscle glycogen –> G6P. G6P metabolised via anaerobic glycolysis = Build up of H+ = Fatigue
What is the metabolic response to medium duration and intensity exercise?
ATP is regenerated relying on adequate oxygen supply
What is the metabolic response to long duration, low intensity exercise?
Oxidation of fatty acids has to occur due to the carbohydrate stores being insufficient.
Aerobic respiration occurs
Changes are hormonally controlled
Muscle glycogen used –> Utilisation of blood glucose maintaned by Liver –> Fatty acid oxidation occurs
