Urinary System Flashcards
How many liters does the kidney filter
200 liters
What is removed from the body as urine
toxins, metabolic waste, and excess ions
what happens when the kidney stops functioning
the body’s fluids become contaminated
major organs
- kidneys
- ureters
- urinary bladder
- urethra
kidneys
major excretory organs, create urine
ureters
transport urine from kidneys to bladder
urinary bladder
temporarily stores urine
urethra
transports urine out of the body
functions of the kidney
- regulating total water volume and total solute concentration
- regulating ion concentration in extracellular fluid (ECF)
…
renal hilum
point of entrance/exit for ureters, blood vessels, lymphatics, nerves
3 surrounding layers
- renal fascia
- perirenal fat capsule
- fibrous/renal capsule
renal fascia
anchoring outer layer of dense fibrous connective tissue
perirenal fat capsule
fatty cushion
fibrous/renal capsule
transparent capsule – prevents spread of infection to the kidneys
renal trauma
the inferior portions of the kidneys are unprotected, especially the right kidney – the renal artery is susceptible to laceration
renal ptosis
condition in which 1 or both kidneys drop to a lower position
- caused by loss of surrounding fatty tissue - likely with emaciation for rapid weight loss
- can lead to a kink in the ureter and the back up of the urine into the kidney
hydronephrosis
backup of urine into the kidney because or ureteral obstruction or infection
- can cause kidney damage, tissue death, renal failure
hematuria
presence of blood in the urine
dialysis
process of removing waste and extra fluid from the body when the kidneys are unable to
internal anatomy of kidney (3 distinct regions)
- renal cortex
- renal medulla
- renal pelvis
renal cortex
lighter color, granular appearance
renal medulla
darker color, contains cone-shaped masses called Rena pyramids
- papilla
- renal column
papilla
the apex of each pyramid
renal column
projections from the renal cortex that divide the renal pyramids
renal pelvis
tunnel-shaped tube, continuous with the ureter
- major calyces
- minor calyces
major calyces
branching extensions of the pelvis
minor calyces
subdivisions of the major calyces, enclose the papillae
where is urine created
in the nephrons
where does urine drain
continuously through the renal papillae
path of urine flow
- renal pyramid
- minor calyx
- major calyx
- renal pelvis
- ureter
pyelonephritis
inflammation or infection of the kidney
- extension of UTI
what is UTI caused by
spread of fecal bacteria, less often by blood-borne bacteria
what happens to the kidney in severe pylonephritis
the kidney swells, abscesses form, and the pelvis fills with pus
what type of blood supply does kidneys have
rich blood supply
how much does the renal artery deliver to the kidneys each minute
1/4th of cardiac output
Arterial flow
aorta -> renal artery -> segmental -> interlobar -> arcuate -> cortical radiate
venous flow
cortical radiate -> arcuate -> interlobar -> renal vein -> IVC
nephron
the structural + functional unit of the kidney, forms urine
what do nephrons make
cell-free and protein-free filtrate from blood
each nephron consists of what
- renal corpuscle
- renal tubule
2 main parts of renal corpuscle
- glomerulus
- glomerular/bowman’s capsule
glomerulus
tuft of capillaries composed of fernestrated endothelium - highly porous, allows for efficient formation of filtrate
glomerular/bowman’s capsule
cup-shaped, hollow structure that surrounds the glomerulus, continuous with the renal tubule
parietal layer
simple squamous epithelium
visceral layer
clings to the glomerular capillaries, contains branching epithelial called called podocytes
podocytes
terminate in foot processes
filtration slits
clefts/openings between foot processes. filtrate passes through these sites and into the capsular space
renal tubule
about 3 cm long, consists of a single layer of epithelial cells + basement membrane, each region has a unique histology and function
3 major parts of nephron
- proximal convoluted tubule (PCT)
- nephron loop (Loop of Henle)
- distal convoluted tubule (DCT)
proximal convoluted tubule (PCT)
closest to the renal corpuscle
- cuboidal cells with dense microvilli that form brush border
- increased surface area
- large mitochondria
Functions of proximal convoluted tubule (PCT)
reabsorption of water + solutes and secretion of substances
- confined to renal cortex
nephron loop
u-shaped, a hairpin turn; has ascending and descending limbs
Descending Limb (nephron loop)
proximal part is continuous with PCT; distal part is the descending thin limb (simple squamous epithelium)
Ascending limb (nephron loop)
typically, thicker, cuboidal + columnar cells
distal convoluted tubule
furthest from the renal corpuscle, drains into the collecting duct
- cuboidal cells with few mircovilli
functions of distal convoluted tubule
more in secretion, less reabsorption
- confined to renal cortex
collecting ducts
runs side-by-side through the medullary pyramids and receive filtrate from many different nephrons
- collecting ducts fuse together to deliver urine through the renal papillae to the minor calyces
2 cell types for collecting ducts
- principal cells
- intercalated cells
principal cells
more plentiful, sparse, short microvilli, maintain the body’s water/Na+ balance
intercalated cells
cuboidal cells with abundant microvilli; exist in type A and B - both help maintain the acid-base balance of blood
2 categories of nephrons
- cortical nephrons
- juxtamedullary nephrons
cortical nephrons
(85%)
- almost entirely in the cortex
juxtamedullary nephrons
(15%)
- originate near the cortex-medulla junction
- have long nephron loops that deeply invade the renal medulla
- important for the production of concentrated urine
2 capillary beds of nephrons
- glomerulus
- peritubular capillaries (vasa recta)
glomerulus
produces fltrate
peritubular capillaries (vasa recta)
reclaim/reabsorb most of that filtrate
glomerulus (slide 25)
peritubular capillaries (slide 26)
vasa recta
arise from the efferent arterioles serving juxtamedullary nephrons
- long, thin-walled vessels running parallel to the juxtamedullary nephrons long nephron loops
- supply O2 and nutrients into the renal medulla
- function in formation of concentrated urine
juxtaglomerular complex (JGC)
region where the most distal portion of the ascending limb of the nephron loop lies against the afferent arteriole feeding the glomerulus
- important role in regulating the rate of filtrate formation and systemic blood pressure
how many juxtaglomerular complex does each nephron have
1
3 cell populations of (JGC)
- macula densa
- granular cells (juxtaglomerular cells)
- extraglomerular mesangial cells
macula densa
- tall, closely packed cells in the ascending limb of the nephron loop
- chemoreceptors that sense the NaCl content of filtrate entering the DCT
Granular cells (juxtaglomerular cells)
- enlarged, smooth muscle cells in the afferent arteriole wall
- act as mechanoreceptors to sense blood pressure in the afferent arteriole
- contain secretory granules for the enzyme renin
extraglomerular mesangial cells
- located between the arteriole and tubule cells
- interconnected by gap junctions
- may pass regulatory signals between macula densa and granular cells
