Chapter 29 - Urinary System
Excretory passages - share similar basic structural features (5)
Calyces Pelvis Ureter Urinary bladder Urethra
The epithelial cells of the smaller collecting tubules are
cuboidal
Only ___ cells are present in collecting ducts - deeper in the medulla
Light/principal cells
Int he cortex and in the outer zone of the medulla contain cells (2)
Light/principal cells Dark/intercalated cells
Is a special region of the DCT in which the cells are thickened and narrower
Macula densa (Juxtaglomerular complex)
Is located close to the afferent and efferent arterioles, at vascular pole of renal corpuscle
Macula densa (Juxtaglomerular complex)
Juxtaglomerular Complex (2)
Macula densa Juxtaglomerular cells
Extend into the cortex and alternate with regions of convoluted tubules and renal corpuscles in the cortex
Medullary rays
The parallel bundles of straight tubules are the
Medullary rays
Also play a role in modulating blood flow by contracting in response to angiotensin stimulation (thereby decreasing blood flow)
Mesangial cells
May unclog and recondition the glomerular basement membrane by phagocytosing and removing accumulated filtration residues
Mesangial cells
Provide further support for renal corpuscle
Mesangial cells
Compression of capillaries
Mesangial glomerulonephritis
Deposition of immune complexes in the mesangium
Mesangial glomerulonephritis
Proliferation of mesangial cells
Mesangial glomerulonephritis
Vascular pole of the renal corpuscle
Mesangium
Urine first empties from the renal papilla into the
Minor calyces
Continuous with visceral layer, which is composed of highly specialized epithelial cells called podocytes
Parietal layer (Renal Corpuscle)
Is a simple squamous epithelium
Parietal layer (Renal Corpuscle)
Also adhere closely to the basal lamina that separates the visceral layer of the glomerular capsule from the endothelial layer of the fenestrated glomerular capillaries
Pedicels (of neighboring podocytes) (Renal Corpuscle)
Interdigitate forming slit-like pores between them
Pedicels (of neighboring podocytes) (Renal Corpuscle)
Common cause of nephrotic syndrome in children
Podocyte abnormalities
Loss of foot process
Podocyte abnormalities
Loss of polyanionic charge
Podocyte abnormalities
Form cellular extensions that branch into foot like processes called pedicles
Podocytes (Renal Corpuscle)
Made up of nephrons and collecting tubules (2)
Renal cortex Renal medulla
Contains connecting and collecting tubules and collecting ducts
Renal medulla
Each medullary ray is located at the center of a lobule, flanked by regions of convoluted tubules and renal corpuscles
Renal medulla
contains blood vessels
Renal medulla
contains thin ascending and descending limbs of henle
Renal medulla
Excretory Passages include (5)
Calyces Pelvis Ureter Urinary bladder Urethra
Water enters and exits the PCT cells through ___ located in the apical and basolateral plasma membrane
Aquaporins
Distal convoluted tubule connect to ___, which empty into ___
Arched collecting tubules Straight collecting tubules
Interlobar arteries between pyramids dichotomize into ___
Arcuate arteries
Muscularis propria - The lower 1/3 of the ureter contains
(Additional) Outermost longitudinal layer
Nephrons ___ in each kidney
1.3 million
The apex of each papilla is perforated by openings of ___ in the region called the area cribosa
10-25 collecting ducts (Ducts of Bellini)
Collectively, the cortex receives over ___ blood than the medulla
10x more
Renal medulla ___ renal pyramids
12-15
Renal medulla apex of ___ renal pyramids form a renal papilla
2-3
Mucosa Transitional epithelium ___ layers in the calyces ___ layers in the ureter ___ layers in the bladder
2-3 4-5 6-8
Each minor calyx drains into ____, which in turn drain into the ___
2-3 major calyces Renal pelvis
Renal sinus contains ___ minor calyces and ___ major calyces
7-13 2-3
Obliteration of capillary lumens in
Acute glomerulonephritis
Acute inflammation of the glomerulus
Acute nephritic syndrome
Leads to constriction of blood flow through the kidney
Acute nephritic syndrome
Leads to decrease glomerular filtration rate
Acute nephritic syndrome
Leads to elevated BUN
Acute nephritic syndrome
Leads to hematuria, albuminuria and edema
Acute nephritic syndrome
Leads to increased BP
Acute nephritic syndrome
Leads to leakage of red cells and some protein into urine
Acute nephritic syndrome
Leads to swelling of the endothelium
Acute nephritic syndrome
Loosely arranged CT, with many blood vessels
Adventitia (Excretory Passages)
In the ureter and bladder, the outer layer is ___ in some regions and ___ in other regions
Adventitia Serosa
___ arterioles have a larger diameter than the ___ arteriole
Afferent Efferent
Divide to form a tuft of capillaries, the glomerulus, closely associated with the renal (Bowman's) capsule
Afferent arterioles
Pass through Mesangium (2)
Afferent glomerular arterioles Efferent glomerular arterioles
Mutations in type IV collagen compromise the structure of the basal lamina
Alport syndrome (Renal Corpuscle)
Renal failure is a consequence, because of the abnormal filtration function of the glomerular basal lamina
Alport syndrome (Renal Corpuscle)
Functions as a size and charge (due to heparin sulfate proteoglycans) barrier
Basal lamina (Renal Corpuscle)
Is composed of a network of type IV collagen and laminin, with associated heparin sulfate proteoglycans
Basal lamina (Renal Corpuscle)
Is the critical barrier between the endothelium and the capsular space
Basal lamina (Renal Corpuscle)
Connecting tubule merge to form
Collecting ducts
open into the cribriform area at the apex of the medulla
Collecting ducts
Positioning of the Distal tubule close to the renal corpuscle creates an opportunity for
Communication
Between structures affecting the initial stage of fluid processing and structures at nephron end positions
Communication (Distal Tubule)
From several nephrons merge to form
Connecting tubule
Short segment linking the nephron to the collecting ducts
Connecting tubule
Extend between the pyramids
Cortical columns
Basal plasma membrane forms inholdings that contain the Na+/K+ ATPase
Cuboidal PCT cells
Have a prominent apical brush border formed by the long microvilli that greatly increase the surface area active in reabsorption
Cuboidal PCT cells
Have many mitochondria which reflects the energy requirements of the active transport
Cuboidal PCT cells
Have numerous endocytic vesicles at the bases of apical microvilli, organized in apical canaliculi, which endocytose the small amount of protein remaining in the ultrafiltrate
Cuboidal PCT cells
Lysosomes digest the endocytose proteins
Cuboidal PCT cells
Regulate acid-base balances through the active transport of hydrogen ions
Dark/intercalated cells
Basement membrane is thickened 3-5 times
Diabetes mellitus
Demarcation of lamina lost
Diabetes mellitus
Endstage renal disease: glomerular tuft -> acellular hylanized mass
Diabetes mellitus
Kimmesteil-Wilson nodules
Diabetes mellitus
Mesangial cells produce excess amounts of extracellular matrix
Diabetes mellitus
Histologically very similar (2)
Distal Tubule Distal Convoluted Tubule
Inholdings of the basolateral surfaces (2)
Distal Tubule Distal Convoluted Tubule
Nuclei protrude toward apical lumen (2)
Distal Tubule Distal Convoluted Tubule
Numerous mitochondria, mostly basally located (2)
Distal Tubule Distal Convoluted Tubule
Some cells have irregular microvilli, while others are smooth-surfaced (2)
Distal Tubule Distal Convoluted Tubule
Distal/ascending thin limb of the loop of Henle continues in the cortex as the
Distal convoluted tubule
Thick straight part ascending from the loop of Henle back into the cortex
Distal tubule
Transitional epithelium ___ state - surface cells become squamous to low to cuboidal in shape
Distended (Stretched) (Excretory Passages)
Blood leaves the glomerular capillaries via
Efferent arterioles
Break up into the peritubular capillary plexus networks that surround and supply their own uriniferous tubules
Efferent arterioles (of the cortical nephrons)
The thickness of the three layers of the wall gradually increases down the urinary tract
Excretory Passage
Move urine from the kidney to the outside
Excretory Passages
Mucosa of the urinary bladder forms folds
Excretory Passages
Excretory Passages Mucosa - Lamina propria
FIbroelastic CT
Renal Corpuscle - Form the filtration membrane barrier (3)
Fenestrated capillary endothelium Glomerular basal lamina Slit diaphragm (between pedicles)
Renal corpuscle (2)
Glomerulus Glomerular capsule
Renal corpuscle comprises (2)
Glomerulus Glomerular capsule
Kidneys (2)
Hilum Renal sinus
Is a convex depression in its medial border
Hilum of the kidney
Where branches of the renal artery and nerves enter into the renal sinus
Hilum of the kidney
Where renal vein, lymph vessels and renal pelvis leave the kidney
Hilum of the kidney
Involved in water reabsorption
Light/principal cells
Muscularis Propria in the top 2/3 of the ureter (2)
Inner longitudinal layer Outer circular layer
Afferent glomerular arterioles
Interlobular arteries
Arcuate arteries go into ___
Interlobular arteries
Run in the cortex
Interlobular arteries
Some terminal branches -> Perforating radiate arteries which supply the renal capsule
Interlobular arteries
Drain into arcuate veins
Interlobular veins
Joined by venous ends of peritubular capillary plexus and spending vasa recta
Interlobular veins
Mesangial cells (2)
Intraglomerular Extraglomerular
Are located between the endothelial cells of the glomerular capillaries and cover the capillary surfaces not covered by podocyte processes
Intraglomerular mesangial cells
In contact with the basal portion of the macula dense cells of the DCT, and with the intimal of the arteriole suggesting cellular communication here
Juxtaglomerular cells (Juxtaglomerular complex)
Modified smooth muscle cells in the wall of the afferent arteriole that produce and secrete renin
Juxtaglomerular cells (Juxtaglomerular complex)
the ___ nephrons have longer thin limbs than the ___ nephrons
Juxtamedullary (15%) Cortical
Are bean-shaped organs covered by a thin, fibrous CT capsule
Kidneys
In the calyces and pelvis is a thin and predominantly arranged in a circular manner
Muscularis Propria (Excretory passages)
Smooth muscle arranged in bundles separated by fibroblast if CT
Muscularis Propria (Excretory passages)
Thicker and stronger in the bladder
Muscularis Propria (Excretory passages)
Dense bundles of circular smooth muscle forms the internal urethral sphincter around the neck of the bladder
Muscularis Propria (Bladder)
Middle layer is generally thickest
Muscularis Propria (Bladder)
Thicker and stronger
Muscularis Propria (Bladder)
Three layers are poorly distinguished
Muscularis Propria (Bladder)
Causes structural and functional abnormality of basement membrane
Nephrotic syndrome
Deposition of antigen-antibody complexes on basement membrane
Nephrotic syndrome
Lipids are increased in serum and pass into urine
Nephrotic syndrome
Membranous nephropathy
Nephrotic syndrome
Proteinuria, hypoalbuminemia, edema
Nephrotic syndrome
Usually no red cells or decreased GFR
Nephrotic syndrome
Leaky Basement membrane (3)
Nephrotic syndrome Diabetes mellitus Podocyte abnormalities
Excretory Passages Submucosa
None
Renal Corpuscle layers (2)
Parietal layer Visceral layer
Continuous with proximal convoluted tubule at urinary pole, roughly opposite to the vascular pole
Parietal layer (Renal Corpuscle)
In the adult, it forms a continuous smooth outer zone
Renal cortex
Although the nephron provides a continuous, tubular path, the epithelial lining changes abruptly for each segment
Proximal convoluted tubule
Are the longest segment of the nephrons in the cortex and fill most of the cortex
Proximal convoluted tubule
Can be distinguished as the microvillar debris remains in the lumen
Proximal convoluted tubule
Microvilli of the apical brush border are often destroyed as a result of post mortem degeneration
Proximal convoluted tubule
The simple squamous lining of the parietal layer of Bowman's capsule quickly transitions at the proximal convoluted tubule to a cuboidal epithelium with an extensive apical brush border
Proximal convoluted tubule
Renal tubules (6)
Proximal convoluted tubule Proximal straight tubule Loop of Henle Distal straight tubule Distal convoluted tubule Connecting tubule
Have a shorter straight part that enters the renal medulla
Proximal convoluted tubules
In medullary rays have prominent apical microvilli brush border
Proximal straight tubules
The ultra filtrate flows from the ___ in the medullary ray into the medulla
Proximal straight tubules
The ultra filtrate passes from the PCT into the ___ in medullary rays, in the cortex
Proximal straight tubules
Transitional epithelium ___ state - surface cells are dome shaped and balloon into the lumen of the organ
Relaxed (Excretory Passages)
Also contains mesangial cells
Renal Corpuscle
Bowman's capsule is a double-walled epithelial cup
Renal Corpuscle
Fluid under pressure moves from the circulation and across the filtration membrane barrier to enter the capsular space
Renal Corpuscle
Has a vascular pole and tubular (urinary) pole
Renal Corpuscle
A funnel-shaped, expanded part of the ureter
Renal Pelvis
Each nephron comprises (2)
Renal corpuscle Renal tubules
Renal cortex contain (7)
Renal corpuscles Proximal convoluted tubules Distal convoluted tubules Distal tubule Cortical connecting tubules Cortical collecting tubules Blood vessels
Between the renal capsule and the renal medulla
Renal cortex
Forms projections called cortical columns
Renal cortex
Contains infrarenal part of renal pelvis
Renal sinus
Contains perirenal fat
Renal sinus
Contains segmental and lobar branches of the renal artery
Renal sinus
Is lined by the renal fibrous capsule which is continuous with the adventitia of minor renal calyces
Renal sinus
Arcuate veins -> Interlobar veins united to form ___ -> ___
Renal veins IVC
Are modified and specialized tight junctions composed of nephrins, glycoproteins and proteoglycans
Slit diaphragms (Renal Corpuscle)
Span adjacent pedicles and bridge the slit-like pores
Slit diaphragms (Renal Corpuscle)
Collect blood from the fibrous renal capsule
Stellate veins
Collect blood from the most superficial zone of renal cortex
Stellate veins
Drain into interlobular veins
Stellate veins
Are initially in medullar rays in the cortex
Straight collecting tubules
Continue down through the medulla, ending in the large, straight, papillary ducts that open at the apex of the renal papilla in the area cribosa
Straight collecting tubules
Has a simple squamous epithelium that is thin, but not as thin as a capillary wall
Thin limb of loop of Henle
Apical cytoplasm contains an abundant micro filaments and reserve membrane in vesicles
Transitional epithelium (Excretory Passages)
Appear to have four to six layers in the contracted or relaxed state
Transitional epithelium (Excretory Passages)
When distended, the reserve membrane is used to expand the apical surface as the cells flatten
Transitional epithelium (Excretory Passages)
Urinary system includes (4)
Two Kidneys Two Ureters One bladder One urethra
Control of acid-base balance
Urinary System (Functions)
Control of blood volume and blood pressure
Urinary System (Functions)
Elimination of foreign substances and their breakdown products
Urinary System (Functions)
Excretion of waste products of metabolism
Urinary System (Functions)
Maintenance of extracellular fluid volume
Urinary System (Functions)
Metabolism of vitamin D
Urinary System (Functions)
Production of renin
Urinary System (Functions)
Regulates the volume and composition of body fluids
Urinary System (Functions)
Regulation of body water
Urinary System (Functions)
Regulation of erythropoisis
Urinary System (Functions)
Regulation of salts, retained or excreted
Urinary System (Functions)
In the absence of ADH, collecting ducts are impermeable to water, causing the excreted urine to be dilute, or hypotonic
Water permeability
The collecting tubules are involved in the concentration of urine, and are responsive to antidiuretic hormone
Water permeability
The permeability barrier continues in the distal thick limb
Water permeability
The permeability properties reflect the presence or absence of water channels/aquaporins
Water permeability
The thin ascending limb is impermeable to water, although salts can move across the tubule membranes
Water permeability
Water and salts move freely across the membranes of thin descending limb
Water permeability
Efferent arterioles from juxtamedullary nephrons branch into thin blood vessels, the ___
descending vasa recta
At some point after descending the proximal thin limb loops and continues back up as the ___ of the ___
distal (ascending) thin limb loop of Henle
Consequently, the ___ offers greater resistance and contributes to maintaining high blood pressure in the glomerular capillary bed
efferent arteriole
Lobar arteries divides into 2 ___
interlobar arteries
___ of the thin loop directly correlated with the ability to concentrate and produce hypertonic urine
length
Segmental arteries go to the ___
lobar arteries
In the medulla vasa recta are structured into bundles in close association with the ___ and ___
loops of Henle Collecting ducts
Descending vasa recta branch into ___, and then return as ___
peritubular capillary networks ascending vasa recta
The ultra filtrate passes from the proximal straight tubules in medullary rays, in the cortex into ___ down though the outer stripe of the outer medulla
proximal thick, descending limb
Blood enters each kidney through the ___ and goes to ___
renal artery segmental arteries
Each renal pyramid capped by cortical tissue forms a
renal lobe
As the straight collecting tubules process toward the deeper parts of the medulla and the papilla, they become increasingly ___ cells
taller columnar
varies considerably in length
thin limb
The thick limb changes abruptly to the ___ of the ___ at the inner stripe of the outer medulla
thin limb loop of Henle
The ___ draining the kidney shave no segmental organization like the ___
veins arteries