Adrenal medulla & adrenaline Flashcards
what is the stress response?
process that is initiated by events that threaten/harm/challenge an organism, there are two types of response.
What are the two types of responses of the stress axis?
Acute (Rapid response) and Chronic (long term)
Describe the Acute (rapid response)
- sympathetic nervous system mediated release of adrenaline and noradrenaline from the adrenal medulla
Describe the Chronic (long term response)
-hypothalamic-pituitary-adrenal Axis (HPA) mediated release of steroid (predominantly glucocorticoids)
Describe the adrenal glands:
small glands 4-6g in mass triangular positioned bilaterally positioned on the superior poles of the kidney two main areas: inner - MEDULLA outer - CORTEX
Describe the glomerulosa
lies under fibrous capsule
5-10% of cortex
cells closely packed in clumps
Describe the fasciculata
Lies under ZG
75% of cortex volume
larger cells than ZG arranged radially in cords separated by cortical capillaries
Describe the reticularis
network of interdigitating capillaries
What cells is the adrenal medulla composed of?
chromaffin cells
Describe the chromaffin cells of adrenal medulla
electron dense granules store molecules secreted by the cell
What is synthesised and released by chromaffin cells?
Catecholamines, adrenaline and noradrenaline
also produce opioid peptides
Whats the blood supply like to the adrenal glands>
from superior, inferior and middle adrenal arteries
medulla is what of origin?
neurodermal
the cortex is what of origin?
Mesodermal
What % is adrenaline of the total catecholamines produced?
80%
What % is noradrenaline of the total catecholamines produced?
20%
what is each chromatin cell innervated by?
pre-ganglionic sympathetic neurone T5-11
fibers in cortex interface mainly with what?
blood vessels, no secretomotor innervation
The synthesis of noradrenaline and adrenaline is regulated by what?
negative feedback; tyrosine hydroxyls is -vely regulated by dopamine and noradrenaline
why are the short term effects of epinephrine and norepinephrine?
- glycogen broken down into glucose
- Increased blood pressure
- Increased breathing rate
- Increased metabolic rate
- Change in blood flow patterns, leading to increased alertness and decreased digestive and kidney activity
what are the long term effects of mineralocorticoids?
- Retention of sodium ions and water by kidneys
2. Increased blood volume and blood pressure
What are the long term effects of glucocorticoids?
- Proteins and fats broken down and converted to glucose, leading to increased blood glucose
- Immune system maybe suppressed
what is a Pheochromocytoma?
tumour of adrenal medulla
What are the symptoms of pheochromocytoma?
episodic hypertension due to excessive secretion of adrenaline and noradrenaline
What is the treatment of pheochromocytoma?
alpha and beta adrenoreceptor blockers
tumour removal
