Chapter 25 - Renal System

200 L

how much fluid do the kidneys filter a day?

renal hilum

region of kidney where ureter, vessels, nerves, and lymphatics enter the kidney

renal fascia

dense CT anchoring the kidney to surrounding structures

perirenal fat capsule

fat mass surrounding the kidneys, cushions them from trauma

fibrous capsule

innermost thin capsule, prevents disease from spreading to the kidneys

renal cortex

outer region if kidney where filtration of blood and EPO production occurs

renal medulla

contains several renal pyramids that are packed with capillaries and urine collecting tubules

water reabsorption, electrolyte balance, waste removal

functions of the renal medulla

renal pelvis

collects urine from the calyces and allows it to drain from the kidney

minor calyces

these are found at the tip of each renal pyramid

major calyces

minor calyces combine to form these

segmental arteries

these arteries split off the renal artery

interlobar arteries

these arteries split off the segmental arteries

arcuate arteries

these arteries split off the interlobar arteries

cortical radiate arteries

these arteries split off the arcuate arteries, supplying the cortex

segmental vein

renal veins traces the arteries in reverse aside from the absence of this structure

renal plexus

autonomic nerve fibers and ganglia supplied to the kidney

blood supply

sympathetic vasomotor fibers regulate ___________ to each of the kidneys

nephron

functional unit of the kidney

renal corpuscle

this region of the nephron filters blood to form the filtrate

renal tubule

this region of the nephron reabsorbs some substances from the filtrate and secretes other substances into the filtrate

between the cortex and medulla

where is the renal tubule located?

renal cortex

where is the renal corpuscle located?

glomerulus

cluster of capillaries found in the renal corpuscle

afferent arteriole

blood enters the glomerulus via this

efferent arteriole

blood leaves the glomerulus via this

high pressure

this is required for filtrate formation, and explains why arterioles are used in the glomerulus

filtrate

filtered blood plasma, filtered to become urine

glomerular capsule

double layer structure that surround capillaries

podocytes

these catch filtrate that is formed by the capillaries

cortex, medulla, cortex

regions the renal tubule passes through

allows for concentrated urine formation

benefit of the hairpin like structure of the renal tubule

PCT

this region of the renal tubule leads right off the glomerulus

renal cortex

where is the PCT located?

large cuboidal ET cells, dense microvili

qualities of the PCT

nephron loop

this region of the renal tubule goes between the renal cortex and medulla

descending limb

this region of the nephron loop is continuous with the PCT, carrying filtrate down

ascending limb

this region of the nephron loop is continuous with the DCT, carrying filtrate upward

small cuboidal ET, skinnier, no microvili

qualities of the DCT

PCT

this part of the renal tubule is for bulk reabsorption and secretion

DCT

this part of the renal tubule is for selective/fine-tuned reabsorption and secretion

principal cells

these cells of collecting ducts maintain Na balance in the body by reabsorbing it from filtrate

type A and B intercalated cells

these cells of the collecting duct maintain acid-base balance by secreting or reabsorbing H/HCO3

multiple

each collecting duct gets the filtrate from ________ nephrons

minor calyces

collecting ducts fuse together to form these

cortical

type of nephron, located almost entirely in the cortex, 80-85% of nephrons

juxtamedullary

type of nephron, nephron loops goes deep into renal medulla

can form highly concentrated urine

what is special about juxtamedullary nephrons?

glomerulus

this maintains high pressure to increase filtrate production

peritubular capillaries

these capillaries arise from efferent arterioles, clinging to PCT/DCT of cortical nephrons allowing for water and solute reabsorption

cortical radiate veins

what do peritubular capillaries empty into?

vasa recta

this is only found on juxtamedullary nephrons, running parallel to the nephron loop and helping to form concentrated urine

juxtaglomerular complex

region of nephron where part of the DCT contacts afferent and efferent arterioles

regulate pressure and filtration rate in glomerular capillaries

function of the juxtaglomerular complex

macula densa

these chemoreceptor cells in the JGC monitor NaCl content in the filtrate of the DCT

increase

increased NaCl concentration will _________ filtrate formation

dialate

low NaCl concentration sensed by the macula densa cells will trigger the afferent arteriole to do this

granular cells

these specialized smooth MT cells are found in the walls of afferent arterioles, being activated by macula densa cells and stretch receptors

renin

granular cells secrete this in response to low filtrate formation

efferent

what arteriole does renin effect?

extraglomerular mesangial cells

these cells are packed between the tubule and arterioles, facilitating communication between the macula densa and granular cells

filtration membrane

this allows passage of water and small solutes into the glomerular capusule

filtrate free of cells and proteins

goal of glomerular filtration

foot processes (of podocytes)

these create filtration slits in the filtration membrane of the slomerular capsule

outward pressures

these promotes filtrate formation (pushing fluid out of capillaries)

HPgc

the blood pressure in the glomerular capillaries that pushes fluid out of the glomerulus

inward pressures

these oppose filtrate formation by putting fluid back in the glomerular capillaries

HPcs

filtrate in the glomerular capsule “pushes into” glomerular capillaries

OPgc

proteins that are still in capillaries will “pull” water back in

glomerular filtration rate

the total volume of filtrate formed per minute for all nephrons in the kidneys

true

true or false: filtration occurs along the entire length of a glomerular capillary

90-120 ml filtrate/min

normal GFR

HPgc

primary variable controlled to regulated GFR

decrease

when HPgc decreases, NFP and GFR ________

renal autoregulation

of GFR, kidneys adjust resistance to blood flow

80-180 mmHg

intrinsic controls can maintain blood pressures in this range

myogenic mechanism

this is activated when rising systemic BP stretches the afferent arteriole

constriction

how does the afferent arteriole respond to stretch?

tubuloglomerular feedback mechanism

this is type of renal autoregulation is activated by the macula densa

constriction

increase of NaCl in filtrate results in ___________ of the afferent arteriole

extrinsic

neural mechanisms of renal autoregulation are ________

sympathetic NS

this will override renal autoregulation when systolic BP drops too low

NE

this will be released by the neural mechanism of renal regulation to contract sm MT

renin-angiotensin-aldosterone mechanism

this is the hormonal mechanism of renal regulation, increasing BP

reabsorption

the movement of substances from the filtrate back into the blood

99

___% of filtrate is reabsorbed by the body

transcellular, active

how Na is reabsorbed

cotransported with Na

how do nutrients move through kidney tubule cells?

transcellular or paracellular

how do ions move through tubule cells?

passive

how does water move through tubule cells?

aquaporin

transmembrane protein that allows for water to cross the plasma membrane of the tubule cell

PCT

this region has a lot of aquaporins, where water is always reabsorbed

ADH

collecting ducts will have aquaporins when this hormone is present

Tm

transport maximum

transport maximum

number of binding sites on a transport protein

PCT

main site of reabsorption in the renal tubule

urea

this is absorbed in the PCT, which is odd as it is nitrogenous waste

not

Water reabsorption (is/is not) coupled to solute reabsorption here

water

only ______ can cross the wall of the descending limb

solutes

one _______ can cross the wall of the ascending limb