Week 2 - Exercise Metabolism Pt.2 Flashcards
Define the neuroendocrine system
Nervous system uses neurotransmitters to relay messages from one nerve to another or from a nerve to a tissue
How do hormones work in the body
Hormones bind to specific protein hormone receptors to exert their effect
Sever classes of hormones include: amino acids derivatives, peptides or proteins, or steroids
What factors is blood hormones concentration determined by
Rate of secretion or hormone from endocrine gland
Rate of metabolism or excretion of hormone
Quantity of transport proteins
Changes in plasma volume
Define downregulation and upregulation in the context of hormones (hormone-interaction)
Downregulation is the decrease in receptor number in response to high concentration of hormone, whereas upregulation is the increase in receptor number in response to low concentration of hormone
What hormones do the hypothalamus & pituitary gland release
Hypothalamus: controls secretions from pituitary gland
Anterior PG: ACTH, FSH, LH,MSH,TSH,GH,Prolactin
Posterior PG: Oxytocin, ADH
What is the function of the hormone ADH
Reduces water loss from body to maintain plasma volume
Release stimulated by high plasma osmolality and low plasma volume
What is the function of the hormone aldosterone
Control of Na reabsorption and K secretion for Na/H2O balance
Regulation of blood volume and pressure
Secreted from the adrenal cortex
Stimulated by increased K concentration and decreased plasma volume
What processes maintains plasma glucose during fasting or exercise
Mobilisation of glucose from liver glycogen stores
Mobilisation of FFA from adipose tissue
Gluconeogenesis from amino acids, lactic acid and glycerol
Blocking the entry of glucose into cells
Explain the role of permissive and slow-acting hormones in the body
Permissive and slow-acting hormones like thyroid hormones, growth hormones, and cortisol act to allow other hormones to exert their full effects, influencing processes like amino acid uptake, protein synthesis, and maintenance of plasma glucose levels
Describe the role of catecholamine in the body during exercise
Catecholamines, such as epinephrine and norepinephrine are fast-acting hormones secreted from the adrenal medulla. They are part of the fight or flight response and bind to adrenergic receptors, with effects depending on the hormone used and receptor type
Define glycogen depletion and its relationship to exercise intensity
Glycogen depletion refers to the breakdown of glycogen stores in the body. It is related to exercise intensity with high-intensity exercise leading to greater and more rapid glycogen depletion
How does the breakdown of muscle glycogen occur under dual control
The breakdown of muscle glycogen is under dual control. Ca2+ released from the sarcoplasmic reticulum with muscle contraction floods the cell, leading to the activation of protein kinase by Ca2+ ions binding to calmodulin
Describe the roles of insulin and glucagon in the body
Insulin promotes the storage of glucose, amino acids and fats while glucagon promotes the mobilisation of fatty acids and glucose. Glucagon also stimulates gluconeogenesis in the liver
What happens to plasma insulin & glucagon during exercise
During moderate intensity exercise, insulin concentrations can drop by 50%, favouring the mobilisation of glucose from the liver and FFA from adipose tissue
What effect does catecholamines have on insulin and glucagon secretion
Catecholamines have an effect on insulin and glucagon secretion, influencing the hormonal control of substrate mobilisation
What are the reasons to decreased FFA oxidation during heavy exercise
High levels of lactic acid
Elevated H+ concentration inhibits HSL
Inadequate blood flow to adipose tissue
Insufficient albumin to transport FFA in plasma
How does endurance training impact on lactate concentration and FFA mobilisation
Endurance training decreases lactate concentration at a fixed work rate, reducing inhibition of FFA mobilisation from adipose tissue
Increases mitochondria in skeletal muscle, utilising fat more and preserving carbohydrates
Describe the renin-angiotensin-aldosterone system
- Decreased plasma volume.
- Decreased BP at the kidney or increased sympathetic nerve activity.
- Secretes renin.
- Angiotensin I.
- Angiotensin II from ACE enzyme.
- Triggers aldosterone release increase for Na reabsorption
What is the function of growth hormone
- Increases amino acids uptake and protein synthesis (Treats childhood dwarfism & Used by athletes & elderly)
- Reduces the use of plasma glucose.
- Increases gluconeogenesis.
- Mobilises fatty acids from adipose tissue
What is the function of cortisol
- Steroid hormone derived from cholesterol and secreted from the adrenal cortex.
- Stimulated by stress (ACTH) & exercise.
- Contributes to the maintenance of plasma glucose by a variety of mechanisms.
- Mobilise tissue amino acids
- Mobilise free fatty acids
- Blocking glucose uptake into tissue
- Stimulates gluconeogenesis - Concentrations peak in the morning (AM) & drop throughout the day
- Increase proportional to increase in exercise intensity.
- The direct effect of cortisol is meditate through the slow process of DNA transcription and translation to protein synthesis. Therefore changes in cortisol may be related to repair of exercise induced tissue damage rather than the mobilisation of fuel
What is the function of thyroid hormone
- Influences the number of receptors on the surface of a cell for other hormones to interact with
- The affinity of the receptor for the hormone
- Triiodothyronine enhances effect of epinephrine to mobilise free fatty acids from adipose tissue
- No real change in thyroid hormones during exercise
Hypothyroid state interferes with the ability of other hormones to mobilise fuel for exercise
What are the mechanisms of hormone action
Altering Transport proteins
Activation of genes to alter protein synthesis
Activating second messengers in the cell via g protein
