Urinary system Flashcards
(43 cards)
List the 3 endocrine functions of kidneys
- produces renin
- produces erythropoietin
- hydroxylates vit D to active corm (calcitriol)
What makes up a renal lobe? What makes up a renal lobule?
renal lobe = renal pyramid + cortical tissue overlying its base and covering its sides
renal lobule = medullary ray + associated cortical tissue
What are renal columns?
inward extensions of cortical tissue
What are renal papillae?
projections of pyramids (make up medulla) into minor calyces
Renal pelvis = expansion of upper end of ureter –> ______ –> ______ which makes contact with renal papillae
Renal pelvix –> major calyces –> minor calyces which make contact with renal papillae (projections of pyramids into minor calyces)
What is a medullary ray?What 3 parts of the nephron do medullary rays contain?
it is medullary tissue that projects up into cortex. Medullary rays contain collecting tubules, parts of PCT, and parts of distal tubules
Which parts of nephron aid in formation of urine and which parts play a big role in concentration of urine?
- Bowman’s capsule, PCT, loop of henle and DCT –> formation of urine
- collecting tubule & ducts –> concentration of urine
The Bowman’s capsule is polarized having a vascular pole and an urinary pole. It is an expansion at proximal end of each neprhone. What does the visceral layer cover and what is it composed of? What is the parietal layer composed of? What is the name of the space that exists btw visceral and parietal layers which receives the ultrafltrate?
The visceral layer is made of PODOCYTES & covers glomerular capillaries
The parietal layer is simple squamous epithelium
The space that exists btw visceral and parietal layers is called urinary space or capsular space, which receives the glomerular filtrate.
What are the 3 components that form the filtration barrier at the glomerulus?
- capillary endothelium aka glomerular capillaries -UNIQUE in that they’re fenestrated WITH NO diaphragms
- basement membrane fromed by both endothelium & podocytes
- filtration slits which are btw secondary processes of podocytes
What forms the renal corpuscle?
Bowman’s capsule + glomerulus
From which pole of the bowman’s capsule does the PCT begin?
urinary pole
The PCT is composed of convoluted and straight portions. Where are they?
Convoluted PCT is close to renal corpuscle of origin
Straight enters a medullary ray (medulla that is in the cortex)
The PCT is lined by?
simple cuboidal epithelium with a conspicuous brush border
Can you see discrete cell boundaries in PCT?
No discrete cell boundaries
The loop of henle is mostily in the medulla. What are the 3 parts of the loop of henle?
- descending straight proximal
- thin segment
- ascending straight distal
The thin segments often look like capillaries and venules so be careful!
The distal tubule has an ascending straight portion (part of loop of henle), portion adjacent to renal corpuscle and convoluted part. It is mainly located in cortex. Compare cells, epithelium found here to those found in PCT>
- PCT - simple cuboidal epithelium with brush border
- DT - simple cuboidal WITHOUT brush border
- cells found in DT are smaller than in PCT
- apical nuclei in DT vs spherical/central nuclei in PCT
- precipitate in lumen of PCT vs no precipitate in DT
Where do you find collecting tubules? What about collecting ducts?
collecting tubules - cortex
collecting ducts - medulla
How does the epithelium change from collecting tubules to collecting ducts?
epithelium goes from cuboidal in tubules to columnar in ducts.
The largest collecting ducts aka papillary ducts communicate with the minor calyx at which area?
area of cribrosa
Are intercellular boundaries clearly visible in PCT, DT and collecting tubules?
indistinct in PCT and DT
Clearly visble in collecting tubules
There are 3 types of nephrons that are characterized based on position of their renal corpuscles in the cortex. Explain
1) superficial (cortical) nephrons)
- SHORT loops of henle
- extend a short distance into medulla
2) juxtamedullary neprhons
- LONG loops of henle
- penetrate deep into medulla (most impt in production of hypertonic urine)
3) intermediate (midcortical) nephrons
There is a tripartheid structure known as the juxtaglomerular apparatus that is reponsible for production of renin. What are the 3 components of this apparatus?
1) macula densa (cells of distal tubule that are super close to afferent arteriole) -sensor (reads ionic comp & volume to signal juxtagomerular cells
2) juxtaglomerular cells - modified smooth muscle cells in tunica media of afferent arteriole; will produce renin
3) extraglomerular mesangial cells aka lacis cells are pale-staining cells located in the angle btw afferent and efferent arterioles and play supportive role and provide integrative signals
Briefly summarize the renin-angiotensin system
- renin secreted by JG cells in kidneys will cleave angiotensinogen (produced by liver) into angiotensin I (decapeptide).
- then ACE (lungs) converts I to angiotensin II (octapeptide)
- angiotensin II stimulates zona glomerulosa of adrenal cortex to produce aldosterone
- aldosterone acts on distal tubule to REABSORB SODIUM and water
macula densa senses changes in NaCl concentration in distal tubule. What are effects of high and low NaCl on renin secretion
high NaCl - inhibits renin secretion
low NaCl - stimulates renin secretion by JG cells
