Histology: Urinary Flashcards
1
Q
Kidney Structure
A
Renal Cortex
Renal Medulla
- Contains pyramids
- Extensions of cortex are renal columns
8-18 Lobes
- Renal pyramid, minor calyx and surrounding column
- Minor calyces combine to form major calyces and finally renal pelvis
2
Q
Nephron Organization
A
Nephron is functional unit
-
Renal Corpuscle
- Glomerulus (tuft of capillaries)
- Glomerular Capsule
- Proximal Convoluted Tubule
- Nephron Loop (loop of Henle)
- Distal Convoluted Tubule
- Collecting Ducts
3
Q
Renal Cortex
A
- Renal Corpuscles
- Convoluted Tubules
4
Q
Renal Medulla
A
- Straight Tubules
- Nephron Loops
- Collecting Ducts
5
Q
Types of Nephrons
A
Cortical Nephrons
-
Short loop nephrons
- Loop of Henle into _outer_ medulla
Juxtamedullary Nephrons
-
Long loop nephrons
- Loop of Henle into _inner_ medulla
6
Q
Blood Circulation in Kidney
A
Receive 25% cardiac output
- Renal artery –> Segmental Arteries –> Interlobar arteries –> Arcuate arteries (arching over top of pyramids) –> Interlobular/Cortical Radial arteries –> Afferent arteriole –> Glomerulus –> Efferent arterioles –>
- Peritubular capillaries (surrounding convoluted tubules)
- OR vasa recta (follow loop of henle)
- Interlobular veins –> Arcuate veins –> Interlobar veins –> Renal veins
7
Q
Arterioles
A
8
Q
Renal Capillaries
A
Which pathway?
-
Peritubular Capillaries
- Arise from cortical glomeruli
- Reabsorb water/solutes in tubules
-
Vasa Recta
- Arise from juxtamedullary glomeruli
- Along lopp of henle
- Countercurrent exchange of water/solutes
9
Q
Renal Corpuscle
A
Glomerulus
- Fenestrated capillaries
Glomerular Capsule
- Visceral layer made of podocytes
- Parietal layer (simple squamous epithelium)
- Capsular/urinary space in b/w
Vascular Pole
- Where arterioles enter/exit
Tubular/Urinary Pole
- opens into PCT
10
Q
Glomerular Filtration
A
- Water and solutes leave vascular space, enter capsular space (called filtrate)
-
Glomerular Filtrate
- Similar to blood plasma, LITTLE protein
- Glomerular Filtration Rate
- 125 mL/min –> 180 L/day
-
Glomerular Filtrate
11
Q
Glomerular Filtration Barrier
A
-
Endothelium of glomerular capillaries (fenestrated)
- Prevents filtration of blood/platelets
-
Glomerular basement membrane (basal lamina of endothelium and podocytes)
- Prevents filtration of proteins/anions
-
Pedicels of Podocytes
- Form filtration slits
12
Q
Podocytes
A
- Processes surround glomerular capillaries
-
Pedicels form filtration slits
- Joined by modified tight junctions
13
Q
Mesangium
A
- Enclosed within glomerular basement membrane
- contains mesangial cells and ECM
-
Resemble vasulr pericytes
- Provide structural support
- Phagocytosis
- Immune defense and injury repair
-
Resemble vasulr pericytes
(MM) is mesangial matrix on image
14
Q
Proximal Convoluted Tubule
A
- Simple cuboidal epithelium
- Star-shaped lumen
- Appears occluded due to microvilli
- Indisctinct cell boundaries
-
Primary site of reabsorption (2/3 of filtrate)
- Glucose, amino acids, small polypeptides
- Microvilli with glycocalyx
- Tight junctions/zonula adherens
-
Basal striations with mitochondria (power Na+/K+ pumps to establish Na+ gradient to absorb water)
- Also, aquaporin-1 channels in lateral PM
- Secretes anions/cations
15
Q
Nephron Loop
A
Proximal Straight Tubule (thick descending limb)
- Recovers remaining Glucose
- Resembles PCT (simple cuboidal epithelium, brush border, star-shaped)
Thin Segment (simple squamous epithelium)
- Thin Descending Limb
- Permeable to water, concentrates fluid
- Thin Ascending Limb
- Permeable to ions (not water)
- fluid becomes dilute
Distal Straight Tubule
- Reabsorbs NaCl
- Resembles DCT (simple cuboidal epithelium, smaller lumen than PCT, round, few microvilli)