Physiology - Kidney Structure and Function Flashcards
what is the functional unit of the kidney?
the nephron
what mechanisms allow the urine to produce urine?
filtration
reabsorption
secretion
what supplies the glomerulus with blood?
the afferent arteriole
what drains blood from the glomerulus?
the efferent arteriole
what does the efferent arteriole divide into?
a network of peritubular capillaries that surround the nephron
what does the peritubular capillary network become?
a renal venule
drain into the renal vein
what is the juxtaglomerular apparatus?
the part of the nephron where part of the distal tubule passes in between the afferent and efferent arterioles
what are the two types of nephrons?
juxtamedullary
cortical (more common)
what makes up the blood supply to a juxtamedullary nephron?
the vasa recta
what type of nephron is responsible for making concentrated urine?
juxtamedullary nephrons
what are the two specialised cells found in the juxtaglomerular apparatus?
granular cells
macula densa
what do granular cells do?
produce and secrete renin
what does the macula densa do?
detects the amount of salt in the tubular fluid in the distal tubule
signals the smooth muscle of the afferent arteriole to regulate blood flow in the glomerulus
what is urine?
a modified filtrate of blood
how much of the cardiac output do the kidneys recieved?
around 25%
what is the rate of filtration of a substance?
mass of substance filtered into the bowman’s capsule per unit time
how can you calculate the rate of filtration of a freely filtered substance?
plasma concentration x GFR
what effect does increasing plasma volume have on a substances rate of filtration?
increases rate of filtration
what is the rate of excretion of a substance?
mass of substance excreted per unit time
how do you calculate the rate of excretion of a substance X?
urine concentration x Vu
Vu = urine flow rate
when has net reabsorption of a substance occured?
rate of filtration > rate of excretion
how do you calculate rate of reabsorption of a substance?
rate of filtration - rate of excretion
when has net secretion of a substance occured?
rate of filtration < rate of excretion
how do you calculate rate of secretion of a substance?
rate of excretion - rate of filtration
