Neuroendocrinology (recap) Flashcards
Describe how the nervous system works
Nervous system uses neurotransmitters to relay messages from one nerve to another or from a nerve to a tissue
Describe how the endocrine system works
Endocrine system releases hormones into blood to circulate to
tissues
What do endocrine glands do?
Release hormones directly into the blood (ductless)
What is the effect of hormones on a tissue determined by?
The effect of a hormone on a tissue is determined by the plasma concentration and the number of active receptors
What is plasma hormone concentration determined by?
- Rate of secretion of hormone from endocrine gland
- Rate of metabolism or excretion of hormone
- Quantity of transport proteins
- Changes in plasma volume
What does the magnitude of hormone effect depend on?
- Concentration of the hormone
- Number of target receptors on the cell
- Affinity of the receptor for the hormone
What is ‘downregulation’?
Decrease in receptor number in response to high concentration of hormone (e.g., age & -receptors).
What is ‘upregulation’?
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.
* Steroid hormones. - Activating ‘second messengers’ in the cell via G protein.
- Altering membrane transport.
* Insulin via tyrosine kinase.
What are the ‘second messengers’ in the cell?
- Cyclic AMP.
- Ca2+.
- Inositol triphosphate.
- Diacylglycerol.
What is the relationship between the hypothalamus and the pituitary gland?
Hypothalamus controls secretions from pituitary gland
Where is ADH secreted from and what does it do?
- Secreted from the posterior pituitary gland.
- Reduces water loss from the body to maintain plasma volume.
- Favours reabsorption of water from kidney tubules to capillaries.
What is ADH release stimulated by?
1) high plasma osmolality
2) low plasma volume
* Due to sweat loss without water replacement
How does ADH concentration change during exercise?
Increases during
exercise >60% VO2
max to maintain plasma
volume.
Where is aldosterone secreted from and what does it do?
- Secreted from the adrenal cortex
- Control of Na+ reabsorption and K+ secretion
- Na+/H2O balance
- Regulation of blood volume and blood pressure