important functions of the kidneys
Maintain the chemical consistency of blood
Filter many liters of fluid from blood
Send toxins, metabolic wastes, and excess water out of the body
what are the 3 nitrogenous main waste products
urea, uric acid, creatinine
kidney location and protection
some protection from lower ribs
right kidney lies lower than the left due to liver crowding
are kidneys vulnerable to injury
yes
four main organs of the urinary system
kidney
ureter
urinary bladder
urethra
fribrous capsule renal
capsule of dense connective tissue surrounds the kidney
maintains shape, inhibits spread of infection
perirenal fat capsule
external to renal/fibrous capsule
renal fascia (anterior and posterior)
external to perirenal fat capsule
contains fat
kidney tissue supportive layers from outer to inner
renal fascia
perirenal fat capsule
fibrous capsule
renal cortex
more superficial; granular appearance
medulla
deep to the cortex consists of cone shaped masses called renal pyramids
renal pyramids contain
urine collecting tubules
apex of renal pyramid
papilla
renal columns
extensions of the renal cortex that separate pyramids
kidney nephron extends from the _____ into the _____-
from the pyramid to the cortex
renal sinus
large space within medial part of the kidney
contains vessels and nerves
urine carrying tubes called renal pelvis and calices
opens to the exterior via the renal hilum
general kidney blood flow
renal arteries
kidney via hilum
filter blood
exit kidney via hilum
renal veins
complex renal blood flow
aorta-renal artery-segmental artery-interlobar artery-arcuate artery-cortical radiate artery---
afferent arteriole-glomerulus-efferent arteriole-peritubular capillaries and vasa recta ---
cortical radiate vein-arcuate vein-interlobar vein-renal vein-infer
what are the nephron associated blood vessels
afferent arteriole-glomerulus-efferent arteriole-peritubular capillaries and vasa recta
nephron
structural and functional unit of the kidney
how many nephrons per kidney
more than 1 million nephrons crowded together within each kidney
glomeruli
produce filtrate that becomes urine
feb and drained by arterioles
afferent/efferent glomerular arteriole
vasa recta
continue from efferent arterioles of juxtamedullary nephrons
thin walled looping vessels
descend into the medulla
are part of the kidney's urine concentrating mechanisms
three steps in urine production
filtration
reabsorption
secretion
what produces urine
nephrons
filtration
filtrate of blood leaves kidney capillaries and enters renal tubule
reabsorption
most nutrients, water, and essential ions reclaimed from filtrate
secretion
active process of removing undesirable molecules into the renal tubule
nephron is composed of
renal tubule
renal corpuscle (filtration occurs here)
where does filtration occur
renal corpuscle
renal corpuscle consists of
glomerulus surround by Bowmans capsule
renal corpuscle is strictly within the
cortex
renal corpuscle parietal layer is made of
is made of simple squamous epithelium
renal corpuscle visceral layer
consists of branched epithelial cells called podocytes
podocytes
foot processes or little feet
interdigitate with one another as they surround the glomerular capillaries
filtration slits
filtrate passes into capsular space through thin clefts between foot processes
filtration membrane consists of three layers
1. endothelium of the capillary
2. slits between foot processes of podocytes
3. basement membrane holds back all but the smallest proteins
filtrate procedes to the renal tubules from
the glomerulus
renal tubule
proximal convoluted tubule
loop of henle (nephron loop) - descending limb, descending thin limb, ascending thin limb, thick ascending limb
distal convoluted tubule
collecting ducts
receive urine from several nephrons
play and important role in conserving fluids
dehydration
posterior pituitary secretes ADH
increases permeability of collecting ducts and DCT to water
alcohol inhibits the release of
ADH - reduces water absorption
glomeruli generate ______ liters of fluid every _____ minutes
1 liter ever 8 minutes
how much filtrate is reabsorbed by tubules
99%
how much filtrate becomes urine
1%
nephron summary
resorbs water, ions, and solutes from filtrate
selective secretion and resorption of ions
permeable simple squamous epithelium
receives urine from several nephrons
CONSERVES BODY FLUIDS
cortical nephrons
85% of nephrons
located almost entirely within the cortex (nephron loops dip a short distance into the medulla)
juxtamedullary nephrons (near medulla)
15% of nephrons
renal corpuscles lie near the cortex medulla junction
nephron loops deeply invade the medulla
contribute to kidney's ability to concentrate urine, regulates BP
exist within a juxtamedullary apparatus
juxtamedullary apparatus
area of specialized contact between the terminal end of the thick ascending limb of the nephron loop and the afferent arteriole
nephrons associate with two capillary beds
glomeruli and peritubular capillaries in cortical nephrons or vasa recta
cortical nephron
short nephron loop
glomerulus further from the cortex-medulla junction
efferent arteriole supplies peritubular capillaries
juxtamedullary nephron
long nephron loop
glomerulus closer to the cortex-medulla junction
efferent arteriole supplies vasa recta
juxtaglomerular apparatus specialized cells
granular cells
macula densa
extraglomerular mesangial cells
mesangial cells
granular cells
modified smooth muscle cells with secretory granules that contain the hormone renin
renin
kidney hormone
secreted in response to falling BP in afferent arteriole
macula densa
end of nephron loop
monitors solute concentration in the filtrate
mesangial cells
located around base of the glomerulus
regulate blood flow within the glomerulus
extraglomerular mesangial cells
interact with macula densa and granular cells
help regulate glomerular flow
urinary bladder
collapsible sac
stores and expels urine
urinary bladder is composed of three layers
mucosa - transitional epithelium
thick muscular layer - detrusor muscle
fibrous adventitia
male urethra divided into ______ regions
3
spongy
prostatic
intermediate
control of micturition
stretch receptors
integration
detrusor contracts and opens internal urethral sphincter
external urethral sphincter is inhibited and bladder is emptied