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Histo: Urinary System

Terms in this set (47)

afferent arteriole --> glomerulus --> efferent arteriole --> (w/in efferent arteriole) peritubular capillaries associated w/ convoluted tubules OR vasa recta associated w/ nephron loop
important section/order of blood supply through the kidney:s
the cortical nephrons and proximal/distal convoluted tubules
review: where do the peritubular capillaries supply blood to?
the juxtamedullary nephrons, structures in the medulla, and then loop back to supply the cortex/medullary boundary

(long loops of Henli, gradient for water to get absorbed)
review: where do the vasa recta supply blood to?
1) Glomerulus
2) Bowman's capsule
3) Urinary space
3 things a renal corpuscle consists of:
a tuft of capillaries
what is a glomerulus composed of?
container that surrounds the glomerulus, has a visceral and parietal layer
what is the bowman's capsule?
the space between the 2 layers of the Bowman's capsule (where urine collects)
what is the urinary space?
vascular and urinary poles

- blood comes in the vascular pole
- urine goes out of the urinary pole
what are the two 'poles' of the glomerulus and what goes in/out of them?
- podocytes
- glomerular capillaries
- mesangial cells
important histological parts in the glomerulus:
a main cell bodies lining the surface of the glomerular capillaries (part of the visceral epithelium of the renal corpuscle)
- helps filter blood
- has a central body with primary/secondary processes branching off of it
what is a podocyte?
pedicles (foot processes)
- embrace the glomerular capillaries
another name for the secondary processes
interdigitate, filtration slit
foot process from different podocytes ___ (or cross over each other), and the spaces between them are called ___ ____
capillary lumen, endothelium, basement membrane, foot processes (podocytes), visceral epithelium, and parietal epithelium
describe the glomerular capillaries:
a structure w/in the corpuscle that holds the capillary loops together (physical support)
- phagocytosis of proteins and other debris from the glomerular basal lamina
** secretion of cytokines and other substances for immune defense and repair
what is a mesangial cell?
renal corpuscle, tubules (proximal/convoluted tubule, loop of Henle, distal convoluted tubule)
parts of a nephron
- fenestrated endothelial cells of the glomerular capillaries
- glomerular basal lamina
- filtration slits between foot processes (the podocytes of the visceral epithelium), covered with a diaphragm
3 things that comprise the filter of the nephron:
endothelial cells and podocytes (fused together to make up the basal laminae)
what makes up the glomerular basal lamina?
the lamina densa and lamina rara
what is the basal laminae split into?
the lamina densa is the physical barrier (particles large than 10nm can't easily cross) and the lamina rara is a charge barrier (negatively charged particles with a molecular weight greater than albumin can't easily cross)
difference between the lamina densa and the lamina rara
hydrostatic pressure

(provisional urine= could be secreted into urine or could be resorped back into the body)
what forces pushes the blood through the filter into the urinary space in Bowman's capsule to be provisional urine?
small (smaller than 10nm), + charged particles
so what kinds of molecules can cross?
whether or not it gets absorbed in the nephron (resportion= moved from the provisional urine back into the blood)
what determines whether or not it will be excreted as urine?
resorption= moving from provisional urine into blood (back into blood in body)
secretion= moving from blood into urine to be secreted
review: difference between resorption and secretion
proximal convoluted tubule --> proximal straight tubules (thick part of descending limb) --> thin segment of loop of Henle --> thick segment of loop of Henle/distal straight tubule --> distal convoluted tubule
order that travel through the tubules goes after the glomerulus:
- tons of mitochondria
- a brush border (microvilli) on its basal plasma membrane (so the lumen looks fuzzy)
- deep invaginations in the basal plasma membrane
what does the proximal convoluted tubule have a lot of in it?
resorption of water, NaCl, glucose, and amino acids
**main job of proximal convoluted tubule
suggests the cells are involved in active ion transport
what does it suggest when a basal membrane has invaginations and there are tons mitochondria?
the medulla
which part of the nephron are the loops of Henle located?
thick and thin descending limbs and thick and thin ascending limbs
parts of the loop of Henle
actively pulls ions out of the urine, creating high osmotic pressure, thereby allowing water to passively leave the urine and go through the medulla back into the blood stream (creating a concentrated urine and preventing dehydration)
job of the loop of henle:
juxtamedullary nephrons and cortical nephrons

- juxtamedullary nephrons have very long loops of Henle (function in making concentrated urine)
- cortical nephrons have very short loops of Henle
what are the 2 different types of nephrons and what is the difference between them?
- has capillaries surrounding it (VASA RECTA) and simple SQUAMOUS epithelium

- brush border "pretty much ends"
after the proximal tubule, the thin segment of the loop of Henle has what and doesn't have what?
- has simple CUBOIDAL epithelium
** has JUXTOGLOMERULAR APPARATUS CELLS

- brush border gone
after the thin segment of the loop of Henle, the distal straight tubule/thick ascending limb has what and doesn't have what?
make the hormone renin, which helps control blood pressure. also makes macula densa (function unknown)
function of juxtaglomerular apparatus cells:
aldosterone!
after the distal straight tubule/thick ascending limb, the distal convoluted tubule releases what important component?
increases sodium resorption by the distal convoluted tubular cells. water follows, making the urine become even more concentrated
function of aldosterone:
- simple CUBOIDAL epithelium
- sensitive to ADH
after the distal convoluted tubule, the urine goes through the collecting tubules which has what kind of epithelium and what hormone acting in it?
makes special aquaporin channels open up and allow water to pass through the cells and makes urine more concentrated
function of ADH
aldosterone in the distal convoluted tubule and ADH in the collecting tubule
review of hormones in the tubules:
minor calyx --> major calyx --> renal pelvis --> ureter
where does urine go after it flows through the collecting ducts? (urine that will leave the body)
transitional epithelium
what type of epithelium are the minor and major calyces, renal pelvis, ureter, and bladder ALL lined by?
it is impermeable to water and ions
what is unique about transitional epithelium?
infoldings
the mucosa/transitional epithelium in the ureters has lots of what?
4! transitional epithelium, lamina propria, musculares externa, and adventitia
the ureters and bladder are both composed of how many layers?
umbrella cells
other random kind of cells in the ureter and bladder
3!
how many layers of muscular externa does the bladder have?
it varies from stratified psuedostratified columnar to stratified squamous (more squamosal towards the outside world)

- all the epithelium is transitional until the urethra! then it changes to be more squamosal!!
what is important about the epithelium of the urethra? (last little tube to go out)
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