Final: Lecture 21 Flashcards
0
Q
Nephron
A
- Functional unit of the Kidney, approx 1 million
- Each nephron consists of: renal corpuscle composed of Bowman’s capsule and glomerulus, and renal tubule that is continuation of Bowman’s
- Empty into collecting ducts, which then empty into renal pelvis
1
Q
Sagittal section of the kidney reveals the following areas:
A
- Outer capsule surrounding the entire kidney except the hilum
- Outer cortical area beneath capsule which has cuplike form with open side of cup facing hilum
- Juxtamedullary cortex deeper
- Medullary area made up of triangular-shaped renal pyramids and divided into outer deep to jux, inner deep to outer
- Renal pelvis into which empty the renal pyramids
2
Q
Cortical Nephrons
A
- Located in the cortex
- Their glomeruli empty into peritubular capillary networks that surround proximal and distal convoluted tubules
- Have short loops of Henle that don’t extend deeply into medulla
3
Q
Juxtamedullary nephrons
A
- Renal corpuscles of these located in the cortex next to cortical-medullary junction
- Glomeruli empty into vasa recta consisting of long, straight arterioles and venuels that run parallel to the loops of Henle and collecting ducts
- Long loops of Henle that extend deeply into medulla
4
Q
Vascular supply to the Kidney
A
•Branches of the renal artery within kidney organized into the following sequene:
- Interlobar arteries
- Arcuate arteries
- Interlobular arteries
- Afferent arterioles–>Glomeruli–>Efferent arterioles
- Vasa recta or peritubular capillaries
- Interlobular veins
- Arcuate veins
- Interlobar veins
- Renal vein
5
Q
Glomerulus
A
- Afferent arteriole: juxtaglomerular cells (circular smooth muscle at vascular pole, secrete renin (hypertensive factor))
- Glomerular formation of capillaries
- Efferent arteriole
6
Q
Bowman’s capsule
A
- Double-layered, cup-shaped dilation of nephron, consists of inner and outer layer
- Parietal layer: outer layer of simple squamous epithelium, continuous with simple cuboidal epithelium of the proximal convoluted tubule
- Visceral layers: inner layer of podocytes in contact with endothelium of glomerular capillaries
- Bowman’s located between parietal and visceral layers and is continuous with the lumen of proximal convoluted tubule
7
Q
Renal Corpuscle
A
- Involved in producing a filtrate of blood
- Rest of the nephron, including convoluted portions of LOH, as well as collecting ducts involved in Modifying the filtrate
- Formation of urine involves: Filtration (in renal corpuscle), Reabsorption (in renal tubules), and Secretion (in renal tubule)
8
Q
Mesangium
A
- Part of the glomerulus
- Formed by mesangial cells embedded in a mesangial matrix
- Intraglomerular mesangial cells located between nearby capillaries in the glomerulus and cover endothelium not covered by Podocytes
- Extraglomerular located between the afferent and efferent arterioles at the vascular pole and ass. with juxtaglomerular apparatus.
9
Q
Characteristics of Mesangium cells
A
- Contractile: utilize cytoskeletal contractile proteins to modify blood flow through glomerular capillaries
- Phagocytic: take up worn out glomerular basal lamina for recycling and phagocytose immunoglobulins trapped in basal lamina
- Proliferative, synthesize matrix and collagen
- Secrete prostaglandins and endothelins*
- Respond to angiotensin II*
- Provide mechanical support and regulate blood flow
10
Q
An increase in sympathetic activity _______ renin secretion.
A
•Stimulates
11
Q
Juxtaglomerular apparatus
A
•Components of: macula densa, extraglomerular mesangial cells, and juxtaglomerular cells
12
Q
Macula densa
A
- Formed by elongated, densely packed cells in the wall of Proximal convoluted tubule. Polarity of these cells is reversed.
- Responds to changes in Na and Cl in urine or hypotensin
- Signals renin release from jux cells**
- Involved in regulation of fluid-electrolyte balance and blood pressure regulation**
13
Q
Juxtaglomerular Cells
A
- Modified smooth muscle cells ass. with macula densa and afferent arteriole
- Secrete renin into the blood when stimulated by the macula densa
- Innervated by sympathetic nerve endings with increase renin release
14
Q
Uriniferous (Renal) Tubule
A
- Simple squamous epithelium of Bowman’s Capsule becomes contiunous with simple cuboidal of proximal
- Parts of the renal tubule: proximal, descending limb of Henle (think and thin portions), LOH, Ascending limb of Henle (think and thin), distal convoluted tubule (continuous with collecting ducts)
15
Q
Proximal Convoluted Tubule characteristics
A
- Extends from the urinary pole of renal corpuscle to beginning of LOH
- Simple cuboidal made up of truncated pyramidal cells
- Apical (facing the lumen) tight junctions and brush border
- Basolateral infoldings and interdigitations
- Basal striations with abundant mitochondria
- Large, pale-staining nuclei, Eosinophilic cyto
16
Q
Loop of Henle
A
- Extends from proximal to distal convoluted tubules
- Descending and ascending limbs
- Think segments of LOH are composed of simple low cuboidal, no brush border and more basal vertical striations
- Thin segments are simple squamous epithelium, impermeable to water
17
Q
Distal Convoluted Tubule
A
- Simple cuboidal epithelium with smaller cells than those of proximal
- Larger lumen than proximal, no brush border
- Cytoplasm less eosinophilic
- Impermeable to water except in presence of ADH (antidiuretic hormone, (AKA: vasopressin) derived from posterior pituitary, functions to reduce water loss)
18
Q
Collecting Duct
A
- Different embryological origin than that of nephron
- Walls consists of simple cuboidal epithelium
- Two major specialized cells:
- Principal cells: reabsorb Na ions and water and secrete K+ via ATPase pump
- Intercalated cells: secrete either H+ ion or bicarbonate ion
19
Q
Excretory Passages
A
- Renal pelvis, ureter, and urinary bladder
- Mucosa: Transitional epithelium (urothelium) basement membrane, lamina propria of FECT, some loose lymphoid tissue and a few smooth muscles
- Muscularis: Inner longitudinal and outer circular smooth muscle coat ureter, lower thirst of ureter has third external longitudinal coat, layers of smooth muscle in urinary bladder from detrusor muscle.
- Adventitia (FECT external to muscularis, serosa over superior surface of bladder)
20
Q
Prostatic urethra (males)
A
- Section of urethra passing through prostrate gland
- Mucosa lined with transitional epithelium
- Highly vascularized with veins with abundant elastic tissue
21
Q
Membranous urethra (males)
A
- Tall pseudostratified columnar cells but variable
* Extends through urogenital diaphragm and receives striated muscle cells forming the external sphincter of bladder
22
Q
Cavenous urethra (males)
A
•Lined with pseuduostratified epithelium with patches of stratified squamous
23
Q
Glands of Male urethra
A
- Lucanae of Morgagni are invaginations of mucous membrane containing single or group of intraepithelial mucous cells
- Glands of Littre are branched tubulara glands opening into the lacunae of Morgagni
24
Q
Female Urethra
A
- Mucosa line with stratified or pseudostratified columnar epithelium with intraepithelial 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 cells but not well defined
- Adventitia not discernible
25
Q
Renal filtration barrie
A
- Function: separates blood in glomerular capillaries from filtrate in Bowman’s space
- Components: fenestrated endothelium of capillaries,
- basal lamina contains type IV collagen, fibronectin, laminin, heparin sulfate
- Filtration slits created by pedicles of podocytes: covered by filtration slit diaphragm, pedicels are attached to basal lamina via ab integrins
26
Q
Angiotensin II
A
- Stimulates secretion of aldosterone from adrenal cortex
- Aldosterone acts on the principal cells of the collecting ducts and the thick ascending limbs of Henle
- Increases reabsorption of Na and water which increases blood pressure
- Stimulates release of ADH
27
Q
Renin-Angiotensin-Aldosterone system:
A
•Angiogtensinogen (circulating blood protein from liver)–(Renin)–>Angiotensin I (primarily produced in lungs)–(ACE angiotensin-converting factor from pulmonary and renal endothelium)–>Angiotensin II
