diuretics Flashcards
what are the functions of the kidneys?
- regulation of H2O and inorganic ion balance
- removal of metabolic waste products from blood and excretion in urine
- removal of foreign chemicals in the blood and excretion in urine
- gluconeogenisis
- endocrine functions (renin, eythropoietin and aldosterone)
where are the adrenal glands found?
theyre found at the top of the kidneys
what is the role of the adrenal glands?
theyre responsible for secretion of a number of important hormones
what is each adrenal gland made up of?
theyre each comprised of two endocrine components, a medulla (the inner part) that makes up 20% of the gland and a cortex (the outer part) that makes up the other 80%
what parts make up the cortex of the adrenal gland?
zona glomerulosa
zona fasciculata
zona reticularis
what does the zona glomerulosa secrete?
mineralcorticoids (aldosterone)
Na+, K+ and water homeostasis
what does the zona fasciculata secrete?
glucocorticoids (cortisol)
glucosa homeostasis and many others
what does the reticularis secrete?
sex steroids (androgens)
what does the medulla secrete?
catecholamines such as adrenaline, noradrenaline and dopamine
where does glomerular filtrate drain?
it drains into the bowman’s space then into the proximal convoluted tubule
what do endothelium pores allow through?
it allows through small molecules
what are podocytes?
they help to form a filtration barrier with endothelial cells
what stops proteins getting through into the tubular fluid?
the negative charge of the podocytes and the masement membrane
what does GFR stand for? and what is it?
glomular filtration rate and its represents the flow of plasma from the glomerulus into Bowman’s space over a specified period and is the chief measure of kidney function
what cells are in the juxtaglomerular apparatus and what do they secrete?
it includes JG cells and they secrete renin
does the afferent arteriole run into or out of the kidney?
it goes into the kidney
what is the nephrin?
it is where the reabsorption of water occurs
what does the juxtaglomerular apparatus do?
it helps reulate renal blood flow
glomerular filtration rate
it also indiretly modulates Na+ balance and systemic BP
what are macula densa cells sensitive to?
theyre sensitive to the level of sodium present in the filtrate
what is an off target effect of beta blockers?
they indirectly inhibit the release of renin
what is glomerular filtration controlled by?
its controlled by diameters of afferent and efferent arterioles
what does autoregulation do?
it maintains blood supply and glomerular filtration rate and prevents high blood pressure surges from damaging the kidneys
what is the juxtaglomerular apparatus made up of?
the afferent and efferent arterioles and the distal convoluted apparatus
what happens at the juxtaglomerular apparatus?
- at this site, there are specialised cells in both the afferent arteriole and the macula densa
- its believed to be involved in feedback control of renal blood flow and glomerular filtration rate.
what do macula densa cells do?
they respond to changes in the rate of flow and the composition of tubule fluid and they control renin release from specialised granular renin-containing cells in the afferent arteriole
what is fluid driven by when it goes from the capillaries into the tubular capsule?
its driven by hydrodynamic force opposed by the oncogenic pressure of the plasma proteins to which the capillaries are impermeable to
where are all the low molecular weight constituents found in the JGA?
theyre found in the filtrate
what molecules are kept in the blood rather than the filtrate after the JGA?
albumin and larger proteins are retained in the blood
what is high hydrostatic pressure at glomerular capillaries due to?
its due to short, wide afferent arterioles having low resistance to the flow and long, narrow efferent arterioles having high resistance
what does a low dose of angiotensin II cause to the efferent arteriole ?
it causes constriction of the blood vessel
what things can cause the afferent arteriole to dilate?
-prostaglandins
- kinins
- dopamine (low dose)
- ANP
- NO
what causes the efferent arteriole to constrict?
- high dose of angiotensin II
- noradrenaline (sympathetic nerves)
- endothelin
- ADH
what causes an efferent arteriole dilation?
an angiotensin II blockade
what is long term blood pressure controlled by?
it controlled by controlling blood volume
what is a reduction in renal pressure due to?
intrarenal redistribution of pressure and increased absorption of salt and water
what does angiotensin II do in the kidneys?
it causes direct constriction of the renal arteries and stimulates aldosterone synthesis
what do diuretics have an effect on?
thyeve got a direct effect on blood and the levels of sodium
what happens if cells are loaded with sodium?
they become loaded with water as sodium has a high osmotic value, this causes the blood vessels to become rigid which reduces the volume within the tissue and makes the tissue tension lower as the blood vessels are more rigid
what is vascular edema and why would people be given diuretics?
