Urinary system Flashcards
sources of heat gain during exercise
convection, conduction, thermal radiation, solar radiation, metabolic heat production
heat loss during exercise
convection, respiratory evaporation, radiation, sweat evaporation, conduction
main role of kidneys
conserve body water and electrolytes during periods of increased loss
they process the plasma portion of the blood by removing and adding substances from it
roles of kidney
removes waste products, eg urea and foreign chemicals
Regulate total body water, salts and acid base balance . excrete just enough water and salts to maintain homeostasis
* Involved in gluconeogenesis (e.g. during fasting, the kidneys
produce glucose from amino acids that is released into the blood)
* Release hormones that regulate blood pressure (e.g. renin) and
EPO (increases number of red cells)
* Produce an active from of Vitamin D that influences calcium
balance and promotes strong, healthy bone
what are the 2 types of nephron
Juxtamedullary
cortical
cortical nephron
primarily in renal cortex
These represent the majority of the kidney nephrons
Corpuscle located in outer cortex
Henle’s loops do not plunge deep into the medullar
Juxtamedullary nephron
spans renal cortex and medulla
fewer
Renal corpuscle close to cortical-medullary junction
Henle’s loops plunge deep into the medullar
Generate osmotic gradient for water reabsorption
2 main components of nephron
renal corpuscle (glomerulus and bowmans capsule)
tubule
sequence through the nephron
afferent arteriole–>renal corpuscle–>efferent arteriole–>proximal convoluted tubule–>proximal straight tubule–>descending limb of loop of henle–>thin segment of ascending limb–>thick segment–>distal convoluted tubule–>cortical collecting duct–>medullary collecting duct–>renal pelvis
components of glomerulus
glomerular capillaries surrounded by visceral layer of bowmans capsule (podocytes)
components of podocytes
filtration slits
fenestrae
extensions
Blood in the glomerular is separated from fluid in Bowman’s space by a filtration
barrier consisting of three layers
Single cell lining of the capillary endothelium
Non-cellular protein-rich layer of basement membrane
Single cell lining of the Bowman’s capsule
peritubular capillaries
supply nephron with its own blood
form veins for blood to leave kidney
macular densa
component of distal convoluted tubule
contains sensors that detect changes in blood composition at renal corpuscle
Juxtaglomerular cells
in afferent arteriole they function as baroreceptors
component of distal convoluted tubule
secrete renin which influences the formation of ANGIOTENSIN 2 which is a hormone that controls blood pressure (vasoconstriction and sodium/water retention)
renal control of blood pressure (increase)
stimuli to kidney to release renin
liver produces angiotensinogen
renin (enzyme) converts angiotensinogen into angiotensin 1 and angiotensin converting enzyme converts this inactive form into angiotensin 2
which causes vasoconstriction and causes release of aldosterone which causes Na+ and H2O retention, both leading to an increase in blood pressure
3 distinct
inputs to juxtaglomerular cells
that increase renin secretion
Renal sympathetic nerves (increase activity when low plasma volume)
intrarenal baroreceptors (decrease in pressure)
Macula densa (decrease in glomerular filtration rate, decrease NaCl delivery to macula densa)
hypotonic solution
lower concentration of non-penetrating solute compared to normal extracellular fluid
hypertonic solution
have a higher
concentration of nonpenetrating
solutes compared to normal
extracellular fluid.
osmotic regulation with vasopressin, eg excess water ingested
decrease in body fluid osmolarity, decrease in firing my hypothalamic osmoreceptors, decrease in vasopressin secretion, decrease in plasma vasopressin, decrease in tubular permeability of collecting ducts to water, decrease in water reabsorption, increase in water excretion
volume regulation with vasopressin, eg decrease in plasma volume
decrease in pressure (of arteries, veins, atrius), increase in vasopressin secretion
glomerular filtration
filtration of
plasma from glomerular capillaries into the
Bowman’s space
glomerular filtrate)
The filtrate is cell free and, except for
large proteins, contains all the substance
in virtually the same concentrations as in
plasma – “ultra-filtrate”
forces involved in glomerular filtration
glomerular capillary blood pressure (favours)
fluid pressure in bowmans space (oppose)
osmotic force due to proteins in plasma (oppose)
decrease GFR
dilate efferent arteriole
or
constrict afferent arteriole
(controlled by neural and hormonal input)
