Adrenal gland Flashcards
Characteristics of adrenal gland
Weighs between 8-10 g
Sits above the kidneys
What is the function of the adrenal glands?
To help our bodies respond well to environmental changes
Can control many fight or flight responses in response to stress
What are the two areas of the adrenal gland?
Medulla
Cortex
What is the function of the medulla in the fight or flight response?
Dilation of airways
Improved gas exchange
Increase cardiac output
What is the funciton of the cortex in the fight or flight response?
Prevent losing extracellular fluid
Mental preparation -> if not able to mentally prepare = not able to cope
Suppress pain and inflammation
What do both the medulla and the cortex do in response to stress?
Keep blood glucose high
Characteristics of the arenal medulla
Made of chromaffin cells
Produces catecholamines
Extension of the sympathetic nervous system - nerves synapse with neuroendocrine cells in the medulla
What are chromaffin cells?
Neuroendocrine cells in the medulla
Synthesise and store epinephrine and norepinephrine
What are catecholamines?
Any structure with a catechol ring and an amine
What is a catechol ring?
Phenol ring with 2 OH
Process of catecholamine synthesis
- Main precursor = tyrosine
- Addition of -OH makes DOPA => catalysed by tyrosine hydroxylase
- DOPA -> dopamine by removing carboxyl group => catalysed by DOPA decarboxylase
- Dopamine -> norepinephrine by adding -OH => catalysed by dopamine oxidase
- Norephinephrine -> epinephrine by adding CH3
What is the main hormone in the adrenal medulla?
Epinephrine
What 3 layers make up the cortex?
Zona reticularis - inner
Zona fasciculata
Zona glomerulosa - outer
What are the differences between the layers that make up the adrenal medulla?
Their shape and the hormones they produce
What hormones does the zona glomerulosa produce?
Mineralocorticoids -> aldosterone
What hormones does the zona fasciculata produce?
Glucocorticoids -> cortisol
What hormones does the zona glomerulosa produce?
DHEA
What is DHEA?
Sex hormone precursor of estrogen/ progesterone
What does DHEA stand for?
Dehydropiandrosterone
What is common between all the hormones produced in the adrenal cortex?
They are all cholesterol derivatives
When is cortisol released?
In response to stress
Can ve either internal or external stress
Information is sent to the CNS
CNS signals to the hypothalamus
What is the process by which cortisol is released?
- Hypothalamus releases cortisol releasing hormone
- This activates the pituitary gland which in turn releases ACTH
- ACTH stimulates the adrenal gland
- Activates the zona fasciculata to make glucocorticoids
What mechanism ensures the level of cortisol in the body is optimal?
Negative feedback mechanism
Cortisol suppresses:
Pituitary from releasing ACTH
Hypothalamus from releasing CTH
What are the functions of cortisol?
Has two functions:
- Metabolic effect - affects glucose metabolism. Increases plasma glucose by increasing lipolysis, gluconeogenesis and increases mobilization of amino acids.
- Stress response - anti-inflammatory action: inhibits immune-mediated tissue damage. Creates a feeling or state of excitement
