Week 11 - The Adrenal Glands Flashcards
where are the adrenal glands located
- sit on top of the kidneys
what do the adrenal glands consist of
2 endocrine glands in one:
- an outer adrenal cortex
- an inner adrenal medulla
what does the adrenal cortex secrete
- steroid hormones synthesized from cholestrol
= corticosteroids
what does the adrenal medulla secrete
- epi and norepi (catecholamines)
list 3 steroid hormones released from the adrenal cortex
- aldo
- androgens
- cortisol
what steroid hormones are mineralcorticoids? which are glucocorticoids
- mineral = aldo and androgens
- gluco = cortisol
how is aldosterone regulated
- via the RAAS system
what is the fnxn of aldo
- acts on the kidney and colon to reabsorb water & Na, and release K+ and H+
where is aldo secereted from
- zona glomerulosa
where is cortisol secreted from
- zona fasciiculata
- reticularis
what is cortisol involved in
- catabolic & involved in body’s response to stress
what is the fnxn of cortisol (7)
- protein catabolism
- lipid catobolism
- increased hepatic glucose output
- suppressed lymphocytes & immune response
- inhibits inflammation
- sensitizes organs to catecholamines
what does lack of cortisol cause for most mammals
- die of circulatory collapse when exposed to stress
what does excess cortisol cause
- can activate aldo receptors and mimic its physiological effects
what is the fnxn of androgens (4)
- similar effects to testosterone, but less effect on reproductive function
- stimulate pubic & axillary hair growth
- sex drive in females
- produced in small but significnat amts
what are the adrenal glands controlled by
- hypothalamus and anterior pituiatry
describe the regulation of adrenal gland secretion
- hypothalamus releases corticotropin releasing hormone which stimulates the anteruir pituitary
- anterior pituitary releases adrenocorticotropic hormone (ACTH) which stimulates the adrenals
- ACTH acts as a cortisol growth factors & causes the adrenals to produce corticosteroids
- cortisol inhibits further CRH and ACTH in a negative feedback mechanism
what stimulates the hypothalamus to release CRH
- physical or emotional stress
what does ACTH at higher concentrations cause
- will also increase aldo & androgen secretion
- increase melanin production = increased skin pigmentation
in addition to the negative feedback mechanism, ACTH secretions follows….
- a diurnal circadian rhythmn = peaks before waking & noon
what are some stressors that increase ACTH production
- changes in light-dark cycle
- starvation
- hypoglycemia
- illness
- infection
- trauma
- surgery
- psychological stress
- anxiety
- depression
- alcoholism
what is meant by a physiological vs pharmacologic effect of corticosteroids
- physiologic = occur at low dosing (dosing similar to what the body produces)
- pharmacologic = occur at high doses & for inflammation
