Histology: Urinary System

Front 1

Kidney: Function

Back 1

1. regulation of body fluid compostion and V: filtration, wastes, metabolites
2. secretion of renin: hormone which regulates BP
3. production of hemopoeitin: regulates RBC production

Front 2

outside of kidney

Back 2

1. embedded in deposits of fat
2. CT capsule: may contain smooth m fibers

Front 3

parenchyma of kidney

Back 3

1. outer cortex: dark red
2. inner medulla: light colored

Front 4

types of kidneys

Back 4

1. multilobular/ multipyramidal: bovines and pigs
2. unilobular or unipyramidal: cats, dogs, horses, sheep and goats

Front 5

hilus of kidney

Back 5

-single indentation
- blood vessels, nerves and ureters pass through here

Front 6

nephron components

Back 6

1. renal corpuscles: glomerulus and glomerular (Bowman's) capsule
2. proximal and distal straight tubules
3. proximal and distal convoluted tubules
4. thin tubule: descending and ascending parts

Front 7

collecting duct system

Back 7

1. arched collecting duct: connecting tubules
2. collecting duct: straight collecting tubules:
a. cortical
b. medullary
c. papillary duct

Front 8

uriniferous (renal) tubule

Back 8

nephron + collecting duct system

Front 9

renal corpuscles

Back 9

glomerulus + glomerular (Bowman's) capsule
- vascular pole: where arterioles enter/ leave
- urinary pole: where proximal convoluted tubule begins

Front 10

glomerulus blood vessels

Back 10

- several loops of branching and anastomosing capillaries connecting the afferent and efferent arterioles
- lined by porous endothelial cells

Front 11

mesengial/ intercapillary cells of glomerulus

Back 11

-located between capillaries
- stellate
- synthesize the extracellular martix which supports the capillary walls
- similar to pericytes

Front 12

glomerular basement membrane

Back 12

-basal lamina separating the endothelial cells of the glomerular capillaries from the mesengial cells

Front 13

layers of glomerular (Bowman's) capsule

Back 13

-surrounds glomerulus
- parietal and visceral layers
- urinary space: between layers

Front 14

parietal (capsular) layer of glomerular capsule

Back 14

-simple squamous epithelium
- overlying a thick basal lamina

Front 15

visceral (glomerular) layer of glomerular capsule

Back 15

-envelops the capillaries of glomerulus
- composed of podocytes cells: octopus-like cells

Front 16

basement membrane of glomerular capsule

Back 16

separates the endothelial cells of glomerular capillaries and podocytes

Front 17

podocytes

Back 17

-primary processes give rise to secondary processes= pedicles
- pedicles of adjacent cells interdigitate around capillaries of glomerulus
- filtration slits: narrow space between pedicles bridged by thin e- dense layer called the slit diaphragm

Front 18

filtration barrier

Back 18

glomerular:
1. endothelium: porous
2. basement membrane
3. epithelium: visceral layer of Bowman's capsule

Front 19

proximal convoluted and straight tubule structure

Back 19

-lined by simple cuboidal or columnar
-acidiophilic cytoplasm
- apex: microvilli from a brush border
- basal striations: infolding of membrane and alignment of mitochondria

Front 20

Relationship between proximal convoluted and straight tubules

Back 20

-convoluted continue into straight (descending thick limb)
- proximal straight tubules have less distinct brush borders

Front 21

thin tubules

Back 21

-forms the thin descending limb and thin ascending limb of the loop of Henle
-lined by simple squamous
- nuclei are somewhat flattened and protrude into the lumen

Front 22

distal straight vs convoluted tubules

Back 22

-DCT are shorter than PCT, therefore fewer profiles of DCT are seen in the cortex
- DCT and ST: simple cuboidal
-lumen of DT larger, cells smaller and flatter, lacking brush borders

Front 23

components of juxtaglomerular apparatus

Back 23

1. macula densa
2. juxtaglomerular cells
3. extraglomerular mesangial cells

Front 24

macula densa

Back 24

-modified segment of the DT that established contact with the vascular pole of the renal corpuscles
- closely packed columnar cells
- cells sensitive to [Cl] of tubular fluid:
produces molecular signals that constrict the afferent arteriole= regulates GFR

Front 25

juxtaglomerular cells structure

Back 25

-modified smooth m cells of the tunica media of the afferent arteriole, adjacent to macula densa
- ellipsoid nuclei, secretory granules in cytoplasm

Front 26

juxtaglomerular cells fx

Back 26

reduced BP--> renin--> angiotensin (plasma protein) --> angiotensin I --ACE (lungs) --> angiotension II:
vasoconstriction of arterioles which raises BP

Front 27

extraglomerular mesangial cells

Back 27

- present between the macula densa and arterioles
-continuous
-fx uncertain

Front 28

arched collecting ducts

Back 28

connects the DCT to a collecting duct
-simple cuboidal epithelium
-not easily distinguished

Front 29

smaller collecting ducts

Back 29

-simple cuboidal epithelium
- borders between cells are easily distinguished because of relatively straight lateral cell membrane

Front 30

larger collecting ducts

Back 30

simple columnar epithelium

Front 31

papillary ducts

Back 31

epithelium two layered
-becomes transitional towards opening

Front 32

collecting ducts gen

Back 32

major component of urine-concentrating mechanism

Front 33

kidney vasculature

Back 33

1. renal a --> interlobar aa --> arcuate aa --> interlobular aa
2. afferent arteriole --> glomerulus --> efferent arteriole --> descending vasa recta --> peritubular capillary network --> ascending vasa recta (venules)
3. interlobular v --> arcuate v --> interlobar v --> renal v

Front 34

interstitium of the kidney

Back 34

=stroma, present between renal tubules and vessels
- sparse in cortex, plentiful in medulla
- collagen fibrils, some fibroblasts
- interstitial cells: lipid laden, prominent in inner medulla, fx uncertain

Front 35

urinary passages

Back 35

1. calyces and renal pelvis
2. ureter
3. urinary bladder

Front 36

calyces and renal pelvis

Back 36

-transitional epithelium
-underlying loose CT layer
-horses: mucous (simple branched tubuloalveolar) glands under epithelium, mucous in urine

Front 37

t. mucosa of ureter

Back 37

-folded, transitional epithelium
- no lamina muscularis
- horses: tubuloalveolar mucous glands in propria-submucosa

Front 38

t. muscularis of ureter

Back 38

-3 ill-defined layers:
1. inner londitudinal
2. middle circular
3. outer longitudinal

Front 39

t. adventitia/ serosa of ureter

Back 39

loose CT with blood vessels and nerves

Front 40

urinary bladders

Back 40

-same layer patterns as urethra
- transitional epithelium flattens as filled
- l. muscularis: present in all but cats
- detrustor mm: smooth m of t. muscularis, irregularly shaped interweaving bundles (not well layered)