Neuroendocrinology W2 Flashcards
What makes up the neuroendocrine system?
Nervous system
Endocrine system
What does the nervous system do in the neuroendocrine system?
Uses transmitters to relay messages from one nerve to another or from a nerve to a tissue
What does the endocrine system do in the neuroendocrine system?
Releases hormones into blood to circulate to tissues
What does the endocrine gland do?
Release hormones directly into the blood (ductless)
What are the 2 classes of hormones?
Amino acids derivates
Peptides/protein
What are amino acid derivate hormones?
Thyroid hormones
Catecholamines
What are peptides/protein hormones?
ACTN
ADH
What is the effect of hormone on a tissue determined by?
Plasma concentration
Number of active receptors
What is plasma concentration determined? (4)
1) Rate of secretion of hormone from endocrine gland
2) Rate of metabolism or excretion of hormone
3) Quantity of transport proteins
4) Changes in plasma volume
How does rate of secretion of hormone from endocrine gland effect plasma concentration?
Magnitude of stimulatory input
Stimulatory versus inhibitory input
What is greater, stimulatory or inhibitory input?
Stimulatory
What are 3 factors that the magnitude of a hormone-receptor effect depends on?
Concentration of the hormone
Number of target receptors on the cell
Affinity of the receptor for the hormone
What is downregulation of a hormone receptor?
Decrease in receptor number in response to high concentration of hormone
What is upregulation of a hormone receptor?
Increase in receptor number in response to low concentration of hormone
What are the mechanisms of hormone action?
Activation of genes to alter protein synthesis
Activating “second messengers”
Altering membrane transport
What second messengers are activated during hormone action?
Cyclic AMP
Ca++
Inositol triphosphate
Diacylglycerol
What is the mechanisms of steroid hormone action?
1) Hormone passes through plasma membrane
2) Inside target cell the hormone binds to a receptor protein in the cytoplasm or nucleus
3) Hormone-receptor complex binds to hormone response element on DNA, regulating gene transcription
4) Protein synthesis
5) Change in protein synthesis is cellular response
What are the membrane transport mechanisms?
1) Insulin binds to the extracellular domain of the alpha-subunit of the insulin receptor
2) The beta-subunit of one insulin receptor phosphorylates the other, allowing the insulin response proteins to be activated
3) Phosphorylated insulin response proteins activate glycogen synthase
4) Glycogen synthase converts glucose into glycogen
What is the hypothalamus?
Controls secretions from pituitary gland
What hormones are in the anterior pituitary gland?
ACTH
FSH
LH
MSH
TSH
GH
Prolactin
What hormones are in the posterior pituitary gland?
ADH
Oxytocin
What does Antidiuretic Hormone (ADH) do?
Reduces water loss from the body to maintain plasma volume (favours reabsorption of water from kidney tubules to capillaries)
What is Antidiuretic Hormone (ADH) stimulated by?
High plasma osmolality
Low plasma volume
(due to sweat loss without water replacement)
What is aldosterone secreted from?
Adrenal cortex
What is aldosterone release stimulated by?
Increased plasma K+ concentration (negative feedback loop
Decreased plasma volume
What does aldosterone do?
Control of Na+ reabsorption and K+ secretion
Regulation of blood volume and blood pressure
What happens to renin, angiotensin II and aldosterone during exercise?
They increase
How long does renin, angiotensin II and aldosterone effects take to occur?
Takes >45min
Major effect is post-exercise
