The Adrenal Gland

HideShow resource information
What is the adrenal cortex responsible for?
Release of corticosteroids, regulation of metabolic processes, regulation of Na+ and K+ blood levels and control of volume of extracellular fluid
1 of 55
What is the adrenal medulla responsible for?
Release of adrenaline and noradrenaline, responsiveness to stressors and regulation of metabolic processes
2 of 55
What layers make up the adrenal cortex?
Glomerulosa, fasciculata and reticularis
3 of 55
What type of hormones does the glomerulosa layer secrete?
Mineralocorticoid
4 of 55
What type of hormone does the fasciculata layer secrete?
Glucocorticoids
5 of 55
What type of hormone does the reticularis layer secrete?
Androgens
6 of 55
Which layer in the cortex stores cholesterol in lipid droplets as a precursor to hormones?
Fasciculata
7 of 55
Give an examples of glucocorticoids
Cortisol and corticosterone
8 of 55
Give an example of mineralocorticoids
Aldosterone
9 of 55
What are androgens?
Gonadal steroids however they are in small amount and are insufficient to replace loss of gonadal steroids
10 of 55
What can cholesterol be derived from?
Synthesised from acetate or absorbed from the GI tract (carried in the form of LDL)
11 of 55
How is cholersterol turned into the desired hormone?
It goes under several enzymatic processes
12 of 55
Steroids are ______ stored in the cortical cells
Not
13 of 55
How is cholesterol stored in the cells?
As cholesterol esters
14 of 55
How do hormones circulate?
They attach to plasma proteins which are synthesised from the liver
15 of 55
How do steroids work on their target cell?
Steroids are lipophilic so can diffuse through the membrane. They attach to cytoplasmic receptors and then translocates to the nucleus upon binding and then modulates the transcription of genes.
16 of 55
How is the release of cortisol/corticosterone controlled?
By the secretion of corticotrophin releasing hormone from the hypothalmus to the anterior pituitary gland that releases adrenocorticotrophic hormone that acts on the adrenal cortex fasciculata cells which in turn release cortisol to peripheral tissue
17 of 55
What factors stimulate the hypothalmus to release adrenocorticotrophic hormone?
Acute long term stress or the hypothalmic circadian rhythm generator
18 of 55
How are levels of cortisol monitored?
Cortisol concentration negatively feedback to the hypothalmus and the anterior pituitary gland and adrenocorticotrophic hormone negatively feedsback to the hypothalmus
19 of 55
Which hormone, cortisol or corticosterone, is more potent?
Neither both have equal potency
20 of 55
Where are cortisol/corticosterone released from?
Fasciculata
21 of 55
Do all species have daily cortisol rhythms?
No eg cat and dog
22 of 55
When do nocturnal animals have higher cortisol levels?
At the onset of darkness
23 of 55
When do day animals have higher cortisol levels?
In the morning
24 of 55
Can stess-induced secretion of corticotrophin releasing hormone override circadian rhythm?
Yes as stress induced secretion of CRH can cause up to 20x increase in glucocorticoids
25 of 55
What metabolic effects can glucocorticoids have?
They stimulate gluconeogenesis, they inhibit the effects of insulin therefore decreasing tissue uptake of glucose, they stimulate catabolism of proteins (gluconeogenesis) and there is an increase in lipolysis (using fatty acids as fuel)
26 of 55
What state can the body be in if the metabolic effects of glucocorticoids remain high?
Hyperglycaemia
27 of 55
What effect can glucocorticoids have on cardiac, skeletal and vascular smooth muscle?
If there is too little glucocorticoids there is muscle fatigue meaning potential cardiac failure, loss of vasomotor tone and general muscle weakness
28 of 55
What effect can glucocorticoids have on the nervous system?
If there is too little it causes lethargy, apathy and inability to concentrate. But if there is too much it causes hyperactivity, insomnia, euphoria and an increase in sensory acuity
29 of 55
What effect can glucocorticoids have on inflammatory and immune responses?
Anti-inflammatory, immuno-suppressive, inhibition of: cytokines secretion, proliferation of immune cells, antibody synthesis. Increase susceptibility to infection.
30 of 55
How long is the half life of a mineralocorticoids?
15-30 mins
31 of 55
What is the release of mineralocorticoids regulated by?
renin/angiotensin or Na+K+ concentration
32 of 55
What is the purpose of mineralocorticoids?
To regulate concentration of Na+ and K+ in extracellular fluid
33 of 55
What is the most important stimuli for mineralocorticoids?
Changes in electrolyte levels and water balance
34 of 55
What do mineralocorticoids target?
Epithelial cells of the collecting tubules of the kidney where they activate Na+K+ pumps therefore allowing reabsorption of Na+ and excretion of K+ and the restoration of blood Na+K+ balance, blood volume and pressure
35 of 55
How is aldosterone (mineralocorticoid) released?
The liver secretes angiotensinogen which reacts with renin to form angiotensin 1 which reacts with angiotensin converting enzyme in the lungs to form angiotensin 2 which stimulates the glomerulosa cells to release aldosterone
36 of 55
What dysfunctions of the adrenal cortex are there?
Hyperadrenocorticism (cushing's disease- oversecretion of glucocorticoids) and Hypoadrenocorticism (addison's disease- undersecretion of glucocorticoids and mineralocorticoids)
37 of 55
What is cushing's disease?
Overproduction of glucocorticoids and is observed in cats, dogs and horses
38 of 55
What causes primary hypercorticism?
Adenomas of the adrenal cortex
39 of 55
What causes secondary hypercorticism?
Adrenocorticotropic hormone producing neoplasms of the anterior or intermeadiate pituitary
40 of 55
What causes latrogenic hypercorticism?
Widespread use of synthetic glucocorticoids
41 of 55
What symptoms are there for Cushing's disease?
Alopecia, muscle wasting and hirsutism
42 of 55
What causes primary hypocorticism?
Atrophy of adrenal cortex
43 of 55
What causes latrogenic hypocorticism?
Abrupt withdrawal of steroid therapy
44 of 55
What symptoms does addison's disease have?
Muscle weakness, poor cardiovascular function and low blood pressure
45 of 55
What can glucocorticoids be used for therapeutically?
Anti-inflammatory and anti-allergic effects and immunosupressant in autoimmune disorders
46 of 55
Which cells in the adrenal medulla secrete adrenaline and noradrenaline and how are they stored?
Chromaffin cells and in catecholamine storage granules
47 of 55
Where can adrenergic receptors be found?
Adipose, cardiovascular, muscular and pancreatic tissue and CNS (response of cells is related to nature of adrenergic receptors)
48 of 55
What is adrenalin synthesised from?
Tyrosine (from the diet) to DOPA to dopamine to noradrenaline to adrenaline by a series of enzymatic reactions
49 of 55
Where can noradrenaline be synthesised?
Chromaffin cells and noradrenergic neurones
50 of 55
How does noradrenaline/adrenaline get secreted?
Depolarisation of neurone, calcium influx, granules fuse with chromaffin cell membrane, exocytosis amd catecholamine release
51 of 55
How are adrenergic receptors regulated?
Hormone binding properties, receptor concentration and receptor signalling
52 of 55
What effects does adrenaline have on the body?
Vasoconstriction in viscera and skin, dilation of coronary arteries and vessels in skeletal muscle, contraction of pilomotor muscles to raise the hair and liberation of nutrients
53 of 55
What effects does vasoconstriction in viscera and skin cause?
Increase force and rate of constriction of the heart and to shunt blood flow to the heart and muscles
54 of 55
What can cause hyperfunction of the adrenal medulla?
Pheochromocytomas (tumours arising from chromaffin cells) causing large quantities of catecholamines to be secreted meaning an elevated blood pressure and increased heart rate
55 of 55

Other cards in this set

Card 2

Front

What is the adrenal medulla responsible for?

Back

Release of adrenaline and noradrenaline, responsiveness to stressors and regulation of metabolic processes

Card 3

Front

What layers make up the adrenal cortex?

Back

Preview of the front of card 3

Card 4

Front

What type of hormones does the glomerulosa layer secrete?

Back

Preview of the front of card 4

Card 5

Front

What type of hormone does the fasciculata layer secrete?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Other resources:

See all Other resources »See all Physiology resources »