Urinary System Anatomy Flashcards
Describe the general locations of the kidneys within the body.
R kidney lower (liver)
retroperitoneal
superior lumbar region between T12 and L5
3 layers supportive tissue of kidneys
superficial to deep - renal fascia, perirenal fat capsule, fibrous capsule
Describe the anatomy of a nephron
renal corpuscle = Bowman’s capsule + glomerulus, proximal convoluted tubule, nephron loop, distal convoluted tubule, collecting duct
Trace the blood supply through the kidney, beginning with the ab aorta and ending with the IVC
ab aorta, renal a, segmental a, interlobar a, arcuate a, cortical radiate a, afferent arteriole, glomerulus, efferent arteriole, peritubular capillary/vasa recta, cortical radiate v, arcuate v, interlobar v, renal v, IVC
List the three cell populations found in the juxtaglomerular apparatus.
macula densa of ascending nephron loop, granular cells in afferent arteriole, extraglomerular mesangial cells
Describe the structure of the filtration membrane as it relates to its function in the kidney.
between blood and interior of glomerular capsule. Porous to allow water and solutes < plasma proteins, disallows larger than 5nm to maintain colloid osmotic pressure of blood to prevent loss of all water, 3 layers: fenestrated endothelium of glomerular capillaries, basement membrane, foot processes of podocytes of glomerular capsule
Describe the general location, structure, and function of the ureters
bring urine from kidneys to bladder, begin at L2 as continuation of renal pelvis, goes down behind peritoneum and runs obliquely through posterior bladder wall to prevent backflow, mucosa + muscularis (inner longitudinal and outer circular) + adventitia, actively propels urine, peristalsis adjusted to rate of urine formation, smooth muscle responds to stretch
Define urinary tract infection
bacteria enters through external urethral orifice and travel length of urethra
Describe the histological structure of the nephron as it relates to its function.
proximal convoluted tubule cells are cuboidal with brush border for reabsorption and secretion, have lots of mitochondria for ATP for active transport, thin descending limb of nephron loop has simple squamous ep with aquaporins for water permeability, thick limb lets salts through but not water, distal convoluted tubule cells are cuboidal with sparse microvilli because more secretion and less absorption, collecting duct cells are either principal for salt-water balance or intercalated for acid-base balance
explain why urinary tract infections are more common in females than males.
3-4 cm urethra in women, 19-20 cm in men, so bacteria has to travel much further to take up residence and ejaculate washes bacteria out after intercourse, whereas women have to urinate to get that benefit
Describe the general location, structure, and function of the urinary bladder
retroperitoneal on pelvic floor posterior to pubic symphysis, trigone is area formed by the 3 interior openings, mucosa with transitional ep for distention + muscular layer with inner and outer longitudinal and middle circular + fibrous adventitia, superior surface covered by peritoneum
Describe the general location, structure, and function of the urethra.
thin-walled muscular tube that drains urine to convey it out of body, mostly pseudostratified columnar ep, some transitional ep near bladder, 3-4 cm long in women, 19-20 in men, prostatic urethra, membranous, spongy
internal gross anatomy of kidneys
superficial grainy light renal cortex, dark renal medulla with renal pyramids with base and papilla, one minor calyx for each pyramid, major calyx when minors converge, renal pelvis in middle
lobe of kidney
one pyramid and half renal column on either side
trace filtrate/urine path
renal pyramids > minor calyx > major calyx > renal pelvis > ureter > urinary bladder > urethra > out
tissue type of parietal layer of Bowman’s capsule
simple sqamous ep
filtration membrane components
glomerular endothelium and podocyte foot processes with basement membrane in between (aka visceral layer of Bowman’s capsule)
cortical nephrons
85% of nephrons in kidneys, shorter nephron loop, closer to fibrous capsule, more superficial and almost all in cortex
juxtamedullary nephron
closer to renal pyramids, longer nephron loop,
medullary gradient
nephron loops + vasa recta, essential for making concentrated urine to avoid losing too much water
granular cells physiology
in juxtaglomerular complex, wall of afferent arterioles, act as mechanoreceptors that sense stretch, have secretory granules packed with renin which is released in response to increased stretch
macula densa cells
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ascending limb of nephron loop facing afferent and efferent arterioles, have chemoreceptors to sense salt concentration, monitor [NaCl], effectively measuring blood pressure, what does it do with that information?
extraglomerular mesangial cells
interconnected with gap junctions, thought to be communicating across other two cell types (granular and macula densa)
glomerular mesangial cells
contractile to control some of the function of glomerulus
If you see renal corpuscles on a kidney histology slide, is it the cortex or medulla?
renal cortex, because never find corpuscles in medulla
histology of ureter
transitional ep with umbrella cells that allow for distention, round when ureter collapsed and no fluid, cells transition to squamous when ureter filled with fluid
muscularis has two layers of smooth muscle - outer circular & inner longitudinal for peristaltic waves to propel urine
adventitia dense CT because retroperitoneal
In which of the following renal areas would you find the majority of nephron loops (loops of Henle)?
renal pyramid (medulla)
indicate the correct flow of filtrate through the nephron.
Fluid is Pulled from the Blood
Bowman’s space
proximal convoluted tubule
loop of Henle (descending limb)
loop of Henle (ascending limb)
distal convoluted tubule
collecting duct
Urine Drains from Renal Papillae
indicate the flow of urine through the kidney.
Urine Drains from Renal Papillae
minor calyx
major calyx
renal pelvis
ureter
urinary bladder
urethra
Urine Exits the Body
which has a larger diameter, the afferent arteriole or the efferent arteriole?
An afferent arteriole supplies blood to a glomerulus and has a larger diameter than the efferent arteriole which drains blood from the glomerulus
Compare cortical nephrons to juxtamedullary nephrons
Compared to cortical nephrons, juxtamedullary nephrons have long nephron loops that deeply invade the medulla, the ascending limb has both thick and thin segments, and the glomerulus is closer to the cortex-medulla junction.
granular cells
Granular cells are specialized mechanoreceptors.
Granular cells [also called juxtaglomerular (JG) cells] are in the arteriolar walls. They are enlarged smooth muscle cells with prominent secretory granules containing the enzyme renin. Granular cells act as mechanoreceptors that sense the blood pressure in the afferent arteriole.
