ch.23 urinary Flashcards
What are the functions of the urinary system?
filter blood
regulate blood volume which alter bp
vitamin D and RBC synthesis
regulate pH
What are the organs of the urinary system?
2 kidneys
2 ureters
bladder
urethra
hilium
where the renal artery and nerves enter and where renal veins and ureter exist
What is the functional unit of the kidney?
nephron
What 2 structures make up the nephron?
renal corpuscle and renal tubule
glomerulus
filtrates and collects in capsular space then flows into the renal tubule
What are the two types of nephrons?
juxtamedullary and cortical
cortical nephron
have short loops of henle
juxtamedullary nephron
longer loops of Henle
concentrates urine
loop of henle
conducts urine w/in each nephron
What does the nephron empty into?
collecting duct
afferent arteriole
supplies blood to the glomerulus
efferent arteriole
drains the glomerulus
juxtaglomerular apparatus
site of renin production
kidney circulation
glomerulus–> efferent arteriole–> peritubular capillaries–> vasa recta–> interlobar v.–> arcuate v.–> renal veins
What are the 3 steps of urine formation?
-glomerulus filtration
-tubular reabsorption/secretion
-water conservation
glomerulus filtration
creates a plasmalike filtrate of the blood
tubular reabsorption
removes useful solutes from the filtrate, returns them to the blood
tubular secretion
removes additional wastes from the blood and adds them to the filtrate
water conservation
removes water from the urine and returns it to the blood and concentrates wastes
filtration
movement of fluid across the filtration membrane
What can pass through the filtration membrane?
water, small molecules, ions but proteins can’t
renal fraction
part of the total cardiac output that passes through the kidneys
What is the renal blood flow rate?
1176 mL/min
glomerular filtration rate
same amount of filtrate produced each minute
What 3 components make up the filtration membrane?
-fenestrated endothelium
-basement membrane
-filtration slits
glomerular capillary pressure
BP inside the capillary moves fluid out of the capillary into bowman’s capsule
-50 mmHg
What is glomerular capillary pressure responsible for?
filtration
What is the cause of high glomerular pressure?
low resistance to blood flow in afferent arterioles and glomerular capillaries
What occurs when afferent arterioles are dilated?
increases pressure
What occurs when afferent arterioles are consricted?
pressure decreases
What occurs when efferent arterioles are constricted?
increase pressure
capsule pressure
the pressure of filtrate already in the lumen of capsule
What is capsule pressure responsible for?
reabsorption
blood colloid osmotic pressure
osmotic pressure caused by proteins in blood, favors fluid into the capillary
What occurs if blood colloid osmotic pressure is increased?
reabsorption increases
What occurs if the GFR increased?
urine output rises causes dehydration and electrolyte depletion
What occurs if the GFR is decreased?
wastes reabsorbed
azotemia occurs
azotemia
buildup of wastes
myogenic mechanism
-kind of autoregulation that occurs when BP increases and it constricts the afferent arterioles to lower BP
tubuloglomerular feedback
occurs on the macula densa and it monitors the tubular fluid, it signals the juxtaglomerular cells to constrict the afferent arterioles to lower GFR
sympathetic control
decreases urine output which constricts afferent arterioles
renin angiotensin system
angiotensin II has widespread vasoconstriction to constrict afferent to lower BP
macula densa
cells of the distal convoluted tubule in contact w/ afferent arterioles
wastes
any substance that is useless to the body or present in excess of the bodys needs
What is the main waste?
urea
urea
formed by breakdown of proteins
uric acid
formed by breakdown of nucleic acid
proximal convoluted tubule
reabsorbs 65% of GF to peritubular capillaries
-major site of reabsorption
What are the two routes for reabsorption?
transcellular and paracellular
transcellular route
through epithelial cells
paracellular route
between cells
transport maximum
limit to the amount of solute that the renal tubules can reabsorb
What occurs if all transporters are occupied?
excess solutes appear in urine
secretion
waste removal of urea, uric, ammonia
nephron loop
important for water conservation
