Flashcards in ENDOCRINE GLANDS Deck (188)
what is the location of the adrenal glands?
sit on supramedial aspect of kidneys
it is a retroperitoneal organ
what is the arterial supply of the adrenal glands?
superior adrenal artery - inferior phrenic
middle adrenal artery - abdominal aorta
inferior adrenal artery - renal artery
what is the venous drainage of the adrenal glands?
right kidney = IVC
left kidney = left renal vein then into IVC
what is the nerve supply of the adrenal glands?
what are the different parts of the adrenal cortex?
what does the zona glomerulosa produce?
the main one is aldosterone
what is the role of the zona glomerulosa?
the mineralocorticoids are used in the regulation of the body's electrolytes via aldosterone
what triggers secretion of mineralocorticoids in the zona glomerulosa of the adrenal gland?
secretion is triggered by renin from the juxtaglomerular cells of the kidney
what are the effects of mineralocorticoid secretion by the zona glomerulosa of the adrenal gland?
- salt balance in the kidneys, colon, pancreas, salivary glands and sweat glands
- in the kidney it has it's effect in the DCT
- it increases ENaC expression apically
- increases Na/K ATPase expression basolaterally
what controls pre-receptor regulation of mineralocorticoids?
what is the effect of inhibiting 11B-HSD2 on mineralocorticoids?
it increases the effects of corticoids in mineralocorticoid receptors
what does the zona fasciculata produce?
cortisol and corticosterone
what is the role of the zona fasciculata of the adrenal glands?
it produces cortisol and corticosterone
this facilitates response to stress and regulation of immune system
what is stress?
it is a real/perceived threat to homeostasis
what is the process of cortisol production?
1. hypothalamus releases CRH which acts on anterior pituitary
2. anterior pituitary releases ACTH which is carried systemically to the zona fasciculata
3. this binds to GPCRs
4. protein kinase A (PKA) stimulates production of cholesterol - this is converted to pregnenolone in mitochondria
5. it undergoes further processing in endoplasmic reticulum
6. final conversion to cortisol takes place in mitochondria
how is cortisol found in blood?
90% is bound to cortisosteroid-binding globulin (CBG)
5% bound to albumin
5% is free
what is the effect of stress on cortisol in blood?
it promotes the release of cortisol from CBG in blood
this means more is free and can be utilised
what are the effects of cortisol produced by the zona fasciculata?
- increased energy mobilisation
- increased amino acid generation (muscle catabolism)
- vascular tone - promotes shunt to periphery
- salt and water balance
- immune suppression
- inhibits growth and reproduction
what is a permissive effect?
allows another action to take place
eg. vasoconstriction via catecholamines
what type of feedback is used in cortisol production?
cortisol acts on hypothalamus and pituitary
when are cortisol levels at their highest?
high levels in morning and early afternoon - diurnal rhythm
what does the zona reticularis produce?
it produces androgens
the main ones are DHEA and androstenedione
it also produces some glucocorticoids
what is the role of androstenedione?
it is 1/10th the strength of testosterone but it is a major source of androgens in women
it is converted to testosterone in peripheral tissues
how do androgens act?
they act similar to testosterone
how is androgen production regulated?
through ACTH from the anterior pituitary
how is glucocorticoid production regulated?
through negative feedback - cortisol acts on hypothalamus and pituitary
what does the adrenal medulla produce?
it produces catecholamines
adrenaline = 80% (epinephrine)
noradrenaline = 20% (norepinephrine)
what is catecholamine synthesis dependent on?
dependent on cortisol levels (permissive effect)
what is the structure of the adrenal medulla?
it is part of the autonomic nervous system - specialised ganglia which are supplied by sympathetic preganglionic fibres
use ACh as a neurotransmitter