Exam 3 - Renal Histology

Question 1

What is the basic stucture of the renal corpuscle including vascular supply?

Answer 1

• Glomerulus
  
  • afferent and efferent arteriole
• Bowmans capsule
  
  • is a double layered, cup shaped dilation of the nephron; it consists of an inner and outer layer
  • bowmans space is located between the parieta land viscera layers and is continuous with the lumen of the prximal convoluted tubule
• Involved in producing a filtrate of blood
• the rest of the nephron used in modifying the filtration
• 3 processes
  
  • filtration - occuring in the renal corpuscle
  • reabsorption occuring in the renal tubule
  • Secretion occuring in the renal tubule
• What ever is filitered and secreted but not reabsorbed forms the excretory product of the kidneys

Question 2

What is the bowmans capsule?

Answer 2

• is a double layered, cup shaped dilation of the nephron; it consists of an inner and outer layer
  
  • Parietal Layer
    
    • this is an oute layer of simple squamous epithelium
    • the squamous epithelium is continuous with the simple cuboidal epitheloum of the proximal convoluted tubule
  • Visceral layer
    
    • this is the inner layer of podocytes in contact the endothelium of the glomerular capillaries
• bowmans space is located between the parieta land viscera layers and is continuous with the lumen of the prximal convoluted tubule

Question 3

What is the glomerulus

Answer 3

• afferent arteriole
  
  • juxtaglomerular cells
  • circular smooth muscle cells at the vascular pole
  • secrete renin (hypertensive factor)
• Glomerular formation of capillaries
• Efferent arteriole

Question 4

What is the structure of the extraglomerular and intraglomerular mesangium?

Answer 4

• Intraglomercular mesangial cells are located between nearby capillaries in the glomerulus and cover endothelium not covered by podocytes
• Extraglomerular mesangial cells located between the afferent and efferent aterioles at the vascular pole and are associated with the juxtaglomerular appartus

Question 5

What are the funtions of the mesangium

Answer 5

• Contractile: utilize cytoskeltal contractile proteins to modify blood flow through the glomerular capillaries
• phagocytic: take up worn out glomerular basal lamina for recycling and also phagocytose immunoglobins trapped in the basal lamina
• proliferative
• synthesize matrix and collagen
• secrete prostaglandins and endothelins
• respond to angiotensin II
• Provide mechanical support and regulate blood flow

Question 6

What the componets of the juxtaglomerular appartus?

Answer 6

• macula densa
• extraglomerular mesangual cells
• juxtaglomerular cells

Question 7

What is the histology of the macula densa

Answer 7

Formed by elongated densely packed cells in the wall of the convoluted tubule. the polarity of these cells is reversed

Question 8

What is the function of the macula densa

Answer 8

• responds to chagnes in sodium and chloride concentration in the urine or hypotensis
• signals renin to release from juxtaglomerular cells
• involved in regulation of fluid eletrolyte balance and blood pressure regulation

Question 9

What is the structure of the juxtaglomerular cells and where are they found?

Answer 9

MOdified smooth muscle cells associated with macula densa and afferent arteriole

Question 10

What are the components of the renal tubule?

Answer 10

Secrete renin into the blood when stumulated by the macula densa

innervated by sympathetic nerve endings which increase renin release

Question 11

What is the histology of the components of the renal fitration barrier

Answer 11

• Components
  
  • fenestrated endothelium of glomerular acpillaries
  • fused basal laminae of endothelial cell and podocytes
  • filtration barrier components
    
    • fenestrated endothelium of capillaries
    • basal almine
      
      • type 4 collagen, fibronectin, lamin, herparin sulfate
    • Filtration slits created by adjacent pedicels of podocytes
      
      • covered by filtration slit diagragm
      • pedicels are attached to basal lamina via alpha₃beta₁ integrins
• Selectivity
  
  • water, glucose, and most ions pass through filter into bowmans space
  • proteins are typically excluded from passing across the filiter
  • molecules with large negative charge are exclded
    
    • like albumnin ( a small protein with negative charge)

Question 12

What is the selectivity of the renal filtration barrier?

Answer 12

• Water, glucose, and most ions pass through filter into bowmans space
• proteins are typialled from passing across the filter
• molecules with a large negative charge excluded

Question 13

What histology of the proximal convoluted tuble

Answer 13

• Extends from the urinary pole of the renal corpuscle to beginning of the loop of nele
• Characteristics
  
  • simple cubodial epithelium made up truncated pyrimidle cells
  • apical (facing lumen of tubule) tight junctions and brush border
  • basolateral infoldings and interdigitations
  • basal striations with abundant mitochondria (for active transport across basal membrane )
  • Large, pale- staining nuclei
  • Eosinophillic Cytoplasm

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Question 24

what are the characteristics of the loop of henle?

Answer 24

• Extends from the proximal to distal convoluted tubules
• made up of descending limb and ascending limb
• Each limb has a thin and thick pub
  
  • Thick segments of the loop of henle are composed simple low cubodial epithelium
  • Thin segments of the loop of henle are composed of simple squamous epithelium
  • Cells of Thick scending limb have no brush border and more basal vertical striations
• Thicks ascending limb is impermeable to water

Question 25

what are the functions of loop of henle ?

Answer 25

• descending thin limb is permeable to water sodium and chloride and ions
• ascending thin limb is impearmeable to water and acetively pumps chloride ion out of the tubule alowing sodium ions to follow
• The major function of the loop of henle is to establish the counter-current exchange system which creates the osmotic conditions necessary to pull water iut of the distal convulted tubule and collecting duct in the presence of ADH

Question 26

what are the characteristics of Distal Convoluted Tubles ?

Answer 26

• Lined with simple cubodial epithelium with smaller cells than those of the proximal convoluted
• THe lumen is larger than that of the proximal convoluted tubule and there is no brush border
• The cytoplams is less esoinophilic than that of tje proximal convoluted tubule
• The distal convoluted tubule is imperable to water except in the persence of ADH
  
  • Antiduretic Hormone (A.K.A vasopressin)
    
    • derived from the posterior Pituitary
      
      • to reduce water loss

Question 27

what are the characteristics of the collecting duct?

Answer 27

• The collecting duct has a different embryological origin than that of the nephron
• Its walls consists of somple cubiodal epithelium
• Principal Cells
  
  • Reabsorbs sodium ions and water and secrete potassium via ATPase pump
• Intercalated Cells
  
  • secrete eithers hydrogen ion or bicarbonate ion

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Question 35

What are the layers of the excertory passages ( Renal pelvis, ureter, and urinary bladder)?

Answer 35

• Layers
  
  • mucosa
  • submucosa
  • Muscularis
  • Adventitia (fect external to muscularis; serosa over superior surface surface of bladder)

Question 36

What is the mucosa?

Answer 36

• transitional epithelium (urothelium), basement membrane, lamina propria of FECT; soome loose lymphoid tissue and a few smooth muscle cells

Question 37

What is muscularis ?

Answer 37

• Inner longitdinal and outer circular smooth muscle coat in ureter
• lower third of ureter has external longitudinal coat
• layers of smooth muscle in urinary bladder form detrusor muscle

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Question 46

WHat are different layers of the male urethra

Answer 46

• PRostatic urethra
  
  • section of urethra passing through prostate gland
  • mucosa lined with transitional epithelium
  • Highly vascularized with veins with abundant elastic tissue
• Membranous Urethra
  
  • Tall pseudostratified columnar cells but variable
  • extends through urogentital diaphragm and recieves squamous epithelium
• Cavernous urethra
  
  • lined with pseuduostratified epithelium with patches of stratified squamous epithelium
• glands
  
  • lacunae of morgagni are invaginations of mucous membrane containing single or groups of intraepithelial mucous cells
  • glands of littre are rbanched tublar glands opening into the lacuna of morgagni

Question 47

What are teh differnt Layers of the female urethra ?

Answer 47

• Mucosa is lined primarily with stratified or pseudostratified columnar epithelium with intraepitelial nests of mucous glands
• Lamina Propria is highly vascularized with veins with an abundance of elastic tissue
• Submucosa is not discernible
• muscularis has an inner longitudinal and an outer circular layer of smooth muscle cell but is not well defined
• adventitia is not discernible