EXAM III Renal Histology Flashcards by Erin O

What are the two components of the urinary system?

Two kidneys and ureters

Urinary bladder and urethra

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What components are within a nephron?

Renal corpuscle = Bowman’s capsule

Renal tubule = continuation of Bowman’s capsule

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What are the two types of nephrons? What are their characteristics?

Cortical Nephrons (cortex region) - have short LOHs w/ no capillaries

Glomeruli empty into peritubular capillary networks that surround PCT and DCT

Juxtramedullary Nephrons (deeper in cortex)

Glomeruli empty into vasa recta near LOHs and collecting ducts, long LOHs in deep medulla

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List the vascular supply to the kidneys

Interlobar A.

Arcuate A.

Interlobular A.

Afferent A.

Glomeruli

Efferent A.

Interlobular vein

Arcuate vein

Interlobar vein

Renal vein

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What two locations can the efferent arterioles feed into?

Vasa recta of juxtamedullary nephrons (capillary loop)

Peritubular capillaries of cortical nephrons (capillary network)

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What makes up the renal corpuscle? What is its function?

Glomerulus

Bowman’s capsule

Involved in producing a filtrate for blood

The remainder of the nephron functions as to modify the filtrate

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What are the 3 processes that are involved in forming urine?

Filtration (renal corpuscle)

Reabsorption (renal tubule)

Secretion (renal tubule)

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What are the components of the glomerulus? What type of cells are involved in the afferent arteriole? What do they secrete?

Afferent Arteriole

Juxtaglomerular cells - secrete renin, circular smooth muscle cells at vascular pole

Glomerular capillaries

Efferent Arteriole

Mesangium - mesangial cells

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What is the Bowman’s capsule made up of? What type of cells are in the layers?

Double-layered, cup-shaped dilation of the nephron

Parietal layer - outer layer = simple squamous, continuous w/ simple cuboidal epi. of PCT

Visceral layer - inner layer = podocytes in contact w endothelium of glomerular capillaries (the actual filtration layer)

Bowman’s Space - b/w the parietal & visceral layers; continuous w/ lumen of PCT

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What are the 2 types of mesangial cells?

Intraglomerular mesangial cells

b/w nearby capillaries in golmerulus and cover endothelium not covered by podocytes

Extraglomerular mesangial cells

b/w afferent & efferent arterioles at vascular pole, associated w/ juxtaglomerular apparatus

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What are the characteristics and functions of mesangial cells?

Contractile = modify blood flow thru glomerular capillaries

Phagocytic - recycles worn out glomerular basal lamina, phagocytose immunoglobulins trapped in basal lamina

Proliferative

Synthesize matrix & collagen

Secrete prostaglandins and endothelins

Respond to angiotensin II

Provide mechanical support & regulate blood flow

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Which cells help modify blood flow through the glomerular capillaries?

Mesangial cells

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What are the components of the juxtaglomerular apparatus?

Macula densa

Extraglomerular mesangial cells

Juxtaglomerular cells

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What are the functions of the macula densa?

Responds to changes in [Na+] and [Cl-] in urine or hypotensin

Signals renin release from juxtraglomerular cells

Involved in regulation of fluid-electrolyte balance and blood pressure regulation

Reversed polarity of cells; formed by elongated, densely packed cells in wall of convoluted tubule

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What are the characteristics of the juxtaglomerular cells? What are they made up of?

Modified smooth muscle cells associated w/ macula densa and afferent arteriole

Secrete renin into blood; stimulated by mascula densa

Innervated by sympathetic nerve endings w/ increase renin release

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What are the components of the renal tubule? (5)

PCT

Descending LOH

LOH

Ascending LOH

DCT - continuous w/ collecting duct

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What are the components of the renal filtration barrier?

Fenestrated endothelium of glomerular capillaries

Fused basal laminae of endothelial cells & podocytes

Filtration slits

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What are the filtration slits of the renal filtration barrier made up of? Basal lamina?

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Fenestrated endothelium of capillaries

Basal lamina = Type IV collagen, fibronectin, laminin, heparin sulfate

Filtration slits created by adjacent pedicels of podocytes; pedicels are attached to basal lamina via alpha-3-beta-1 integrins

What creates the filtration slits of the renal filtration barrier?

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Pedicels of the podocytes

Where does the PCT begin and end?

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Extends from the urinary pole of the renal corpuscle to the beginning of the LOH

What are the characteristics of the PCT? What type of epithelium? Cytoplasm? Nuclei?

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Simple cuboidal made up of truncated pyramidal cells

Apical - tight juncts & brush border

Basolateral infoldings & interdigitations

Basal striations w/ abundant mitochondria

large, pale-staining nuclei

Eosinophilic cytoplasm

What are the functions of the PCT?

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Reabsorbs majority of filtrate including H2o, glucose, and amino acids, Na+ and Cl-

Characterized by a complex set of transporters, co-transporters, channels, and exchangers

What type of cells make up the thick segments (thick ascending LOH) of the LOH?

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Simple low cuboidal epithelium

No brush border, more basal vertical striations

Impermeable to water

What type of epithelium makes up the thin LOH (thin descending and ascending LOH)

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Simple squamous epithelium

What are the functions of the thin descending LOH?

Permeable to water, Na+, Cl- ions Makes medulla less salty **Hyperosmotic** Helps to establish a countercurrent exchange system

What is the counter-current exchange system?

Creates the osmotic conditions that are necessary to **pull water out of the DCT and collecting duct in the presence of ADH**

What is the function of the thin ascending LOH?

**Impermeable to water** **Makes medulla salty by actively pumping Cl- ions out, with Na+ following**

What type of cells make up the DCT? PCT?

DCT - **simple cuboidal with smaller nuclei** PCT - **simple cuboidal with LARGE nuclei**

What are the 3 distinguishable characteristics of the PCT and DCT?

DCT has a **larger lumen than PCT** (think veins) **A less eosiniphilic cytoplasm** **Smaller cells**/nuclei **Impermeable to water except when in the presence of ADH/vasopressin** (via posterior pituitary)

What type of epithelium makes up the collecting duct?

**Simple cuboidal epithelium**

What two specialized cells are involved with the collecting duct? What are their functions?

**_Principal cells_** Reabsorb Na+ and H2o, **Secrete K+** via ATPase **_Intercalated cells_** Secrete either hydrogen or bicarbonate ion, **Reabsorb K+**

What are the 4 layers of the renal pelvis, ureter, and urinary bladder?

**Mucosa** **Submucosa** (not clearly demarcated) **Muscularis** **Adventitia** (FECT external to muscularis)

What type of epithelium make up the mucosa of the renal pelvis, ureter, and urinary bladder? What are the other characteristics?

**Transitional/Urothelium epithelium** Basement membrane Lamina propria of FECT Some loose lymphoid tissue Few smooth muscle cells

What are the features of the muscularis layer of the renal pelvis, ureter, and urinary bladder?

Inner = **longitudinal smooth muscle coat** Outer = **circular smooth muscle coat** Lower 3rd of ureter has a 3rd external longitudinal coat Smooth muscle layers of bladder = detruser muscle

What are the 4 components of the male urethra? Type of epithelium in each?

**MGCP - M**ale's **G**row **C**olorful **P**enises **Membranous Urethra -** tall pseudostratified columnar, variable **Glands** **Cavernous Urethra -** pseudostratified epithelium w/ patches of stratified squamous **Prostatic urethra -** mucosa lined w/ transitional/urothelium

What are the characteristics of the prostatic urethra of the male urethra?

**Mucosa lined with transitional/urothelium epithelium** Section of urethra passing thru prostate gland Highly vascularized w/ veins and abundant elastic tissue

What are the characteristics of the membranous urethra of the male urethra?

**Tall pseudostratified columnar cells, variable** Extends thru urogenital diaphragm and receives straiated muscle cells = external sphincter of bladder

What are the 2 types of glands of the male urethra?

**Lacunae of Morgagni** invaginations of mucous membrane w/ single/groups of intraepithelial mucous cells **Gland of Littre** Branched tubulara glands opening into lacunae of Morgagni

Which portions of the female urethra are not discernible? (2)

Leave a female **AS** IS! **Adventitia** **Submucosa**

What type of epithelium is the mucosa of female urethra?

**Stratified or Pseudostratified columnar epithelium w/ intraepithelial nests of mucous glands**

Characteristics of the lamina propria and muscularis of the female urethra?

Lamina Propira - highly vascularized w/ veins and abundant elastic tissue Muscularis - inner longitudinal and outer circular layer of smooth muscle cells but not well defined

What is the function of renin?

**Converts protein Angiotensinogen to Angiotensin I**

What is the function of ACE in the Renin-Angiotensin-Aldosterone system?

**Converts Angiotensin I to Angiotensin II**

What is the function of Angiotensin II?

**Stimulates secretion of aldosterone from adrenal cortex -** acts on principal cells and collecting ducts, thick ascending LOH ## Footnote **Increases reabsorption of Na+ and Water = increases BP** **Stimulates ADH release**

EXAM III Renal Histology Flashcards

(44 cards)