Endocrine System: Adrenal Gland
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- Created by: Bhickling
- Created on: 21-04-21 12:07
Where are the adrenal glands found?
- paired glands
- lie beneath the peritoneum
- cranio-medial to the corresponding kidney
- lie beneath the peritoneum
- cranio-medial to the corresponding kidney
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Describe the make up of the adrenal gland
- inner medulla = sympathetic neuroendocrine cells (adrenaline/ noradrenaline)
- surrounded by cortex (3 zones each responsible for the production of 1 type of hormone (inside to outside):
1. zona reticularis = androgens
2. zona fasciculata = glucocortico
- surrounded by cortex (3 zones each responsible for the production of 1 type of hormone (inside to outside):
1. zona reticularis = androgens
2. zona fasciculata = glucocortico
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What are corticoids?
lipid-soluble steroid hormones formed from the cholesterol molecule
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What is the first step in the conversion of cholesterol into steroid hormones?
- first step is the conversion of cholesterol into pregnenalone - rate limiting step
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Is there a steroid hormone store?
No, they are produced on demand
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Name the 3 types of adrenocortical hormones
- mineralocorticoids
- glucocorticoids
- androgens
- glucocorticoids
- androgens
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What do mineralocorticoids do?
- regulate concentrations of Na+ and K+ in the blood
- main hormone = aldosterone
- main hormone = aldosterone
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What do glucocorticoids do?
- affect CHO, lipid and protein metabolism
- help animals resist the effects of stress
- main hormone = cortisol
- help animals resist the effects of stress
- main hormone = cortisol
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Describe mineralocorticoids
- bound to corticosteroid binding globulin (CBG) and albumin in blood
- short half life (20 mins)
- inactivated in the liver
- short half life (20 mins)
- inactivated in the liver
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What does aldosterone do?
- causes a rapid increase in Na+ reabsorption and K+ secretion in principle cells of DCT + collecting duct
- increases Na+ reabsorption in salivary glands + large intestine
- increased Na+ reabsorption = increased water reabsorption = increased volume of
- increases Na+ reabsorption in salivary glands + large intestine
- increased Na+ reabsorption = increased water reabsorption = increased volume of
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How is aldosterone regulated?
Two major regulators:
1. RAAS renin- increases when atrial blood pressure falls
2. Plasma K - directly affects aldosterone producing cells, increased K= increased aldosterone
Minor regulators:
1. ACTH
2. Na ECF - decrease in Na = aldosterone secretion
1. RAAS renin- increases when atrial blood pressure falls
2. Plasma K - directly affects aldosterone producing cells, increased K= increased aldosterone
Minor regulators:
1. ACTH
2. Na ECF - decrease in Na = aldosterone secretion
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Describe glucocorticoids
- essential for cells
- all nucleated cells have receptors
- released in response to sustained + high levels of stress
- cortisol = main hormone
- bound to CBG and albumin in blood
- half life = 70 mins
- inactivated in liver
- all nucleated cells have receptors
- released in response to sustained + high levels of stress
- cortisol = main hormone
- bound to CBG and albumin in blood
- half life = 70 mins
- inactivated in liver
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Why does glucocorticoids have a longer half life than mineralocorticoids?
glucocorticoids are more tightly protein bound
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How do glucocorticoids regulate metabolism?
- promote gluconeogenesis in liver + reduce uptake of glucose by tissues (not brain)
- stimulates degradation of fat + protein- allow oxidation of fatty acids and amino acids for energy use to preserve cell glucose
- stimulates degradation of fat + protein- allow oxidation of fatty acids and amino acids for energy use to preserve cell glucose
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What role do glucocorticoids play in the immune system?
- maintain low level anti-inflammatory tone
- high cortisol level can reduce/ reverse inflammatory + allergic reactions
- high cortisol level can reduce/ reverse inflammatory + allergic reactions
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How are glucocorticoids regulated?
- negative feedback mechanism consisting of the hypothalamus, anterior pituitary and adrenal glands
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What is the role of ACTH?
- Required for the rate limiting step in the conversion of cholesterol to steroid hormones
- required for all hormones produced in the adrenal glands
- regulates glucocorticoid + androgen production
- required for all hormones produced in the adrenal glands
- regulates glucocorticoid + androgen production
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What group of hormones do adrenaline, noradrenaline + dopamine belong to?
catecholamines
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What are catecholamines?
Water- soluble hormones produced in the adrenal medulla and derived from the amino acid tyrosine
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What is the regulation of catecholamines controlled by?
pre-ganglionic sympathetic nerve fibres
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What are the major functions of catecholamines?
- increase CO
- redistribution of blood to skeletal muscles
- increase plasma glucose concentration
- increase breakdown of triglycerides = increase in plasma fatty acids
- redistribution of blood to skeletal muscles
- increase plasma glucose concentration
- increase breakdown of triglycerides = increase in plasma fatty acids
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Describe prolactin
- secreted by the anterior pituitary
- water-soluble hormone
- similar structure to GH
- tyrosine kinase receptor
- water-soluble hormone
- similar structure to GH
- tyrosine kinase receptor
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What does prolactin do?
- stimulates growth + differentiation of mammary tissue
- stimulates milk production after parturition
- important in maternal behaviour
- stimulates milk production after parturition
- important in maternal behaviour
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How is prolactin regulated?
- stimulating + inhibitory hormones from the hypothalamus- TRH stimulates, dopamine inhibits
- oestradiol directly directly effects prolactin producing cells in anterior pituitary = stimulates prolactin secretion
- suckling inhibits dopamine secretion = i
- oestradiol directly directly effects prolactin producing cells in anterior pituitary = stimulates prolactin secretion
- suckling inhibits dopamine secretion = i
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What does the pineal gland secrete?
melatonin
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How is melatonin secretion regulated?
- affected by light exposure to the eyes
- more melatonin is produced in the dark
- more melatonin is produced in the dark
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Other cards in this set
Card 2
Front
Describe the make up of the adrenal gland
Back
- inner medulla = sympathetic neuroendocrine cells (adrenaline/ noradrenaline)
- surrounded by cortex (3 zones each responsible for the production of 1 type of hormone (inside to outside):
1. zona reticularis = androgens
2. zona fasciculata = glucocortico
- surrounded by cortex (3 zones each responsible for the production of 1 type of hormone (inside to outside):
1. zona reticularis = androgens
2. zona fasciculata = glucocortico
Card 3
Front
What are corticoids?
Back
Card 4
Front
What is the first step in the conversion of cholesterol into steroid hormones?
Back
Card 5
Front
Is there a steroid hormone store?
Back
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