Urinary Microanatomy 1 and 2

Question 1

what makes up the outer and inner layer of the kidney?

Answer 1

outer: fibroblasts and collagen fibers

inner: myofibroblasts

Question 2

what role does the outer layer of the kidney do?

Answer 2

protection

Question 3

what role does the inner layer of the kidney do?

Answer 3

contractibility may aid in resisting volume and pressure variations

Question 4

what makes up the parenchyma

Answer 4

cortex and medulla

Question 5

what makes up the renal lobe

Answer 5

renal pyramid + adjacent renal cortex and column tissue

Question 6

what makes up the renal papilla

Answer 6

pyramid protection into the minor calyx

Question 7

what makes up the area cribosa

Answer 7

surface of papilla w/openings of papillary ducts

Question 8

describe the path of urine

Answer 8

minor calyx –> major calyx –> renal pelvis –> ureter

Question 9

what is the uriniferous tubule

Answer 9

nephron + collecting duct

Question 10

describe the parts of the glomerular capsule

Answer 10

parietal layer: simple squamous epithelium
visceral layer: layer of podocytes that covers the glomerulus

pedicels: secondary processes that interdigitate
–> gaps between = filtration slits

Question 11

what are mesangial cells?

Answer 11

-modified smooth muscle cells
-secrete ECM for support
-regulate glomerular distension (contraction)
-keep the glomerular filtration apparatus clean from filtration residues (phagocytosis)

Question 12

what are glomerular endothelium

Answer 12

fenestrated capillaries with no diaphragms

Question 13

what are glomerular basement membranes

Answer 13

thick basal lamina

collagen type 4, laminin, fibronectin, entacin

Question 14

what are podocyte filtration slits

Answer 14

filtration slit diaphragm (zipper like frame of nephrin and adhesion proteins)

Question 15

what type of filter are the fenestrations

Answer 15

size-selective filter

Question 16

what type of filter are basal lamina

Answer 16

physical barrier and ion-selective filter

Question 17

what type of filter are filtration slit diaphragm

Answer 17

size-selective filter

Question 18

describe the proximal tubule

Answer 18

-reabsorption of ions and fluid and secretion of calcitriol

Question 19

what does calcitriol do

Answer 19

increases the uptake of calcium and its concentration in the blood

Question 20

describe what you can see on histology for the proximal tubule

Answer 20

-simple cuboidal epithelium
-microvilli (brush border) –> irregular lumen
-lateral and basal folds –> no clear cell borders
-high concentration of mitochondria, vesicles, and lysosomes at the basal surface

Question 21

what does the thin loop of henle (TLH) do?

Answer 21

-absorption of fluid by countercurrent exchange with vasa recta
-concentration of urine
-simple squamous epithelium –> facilitates countercurrent exchange
-few short microvilli

Question 22

what does the countercurrent exchange do?

Answer 22

-gradient-dependent transport of fluid into blood
-lower osmolarity in ultrafiltrate and higher osmolarity in blood plasma = fluid transport into blood

Question 23

describe the distal tubule (DT)?

Answer 23

-selective secretion and absorption of ions (osmoregulation)
-juxtaglomerular apparatus (for sodium)

Question 24

describe the histology for DT

Answer 24

-simple cuboidal epithelium
-few short microvilli (smaller and more regular borders than the one of PT)
-lateral and basal folds (no clear cell borders)
-abundant mitochondria

Question 25

describe the osmoregulation in DT

Answer 25

-SECRETION to the ultrafiltrate if there is a HIGH concentration of ions in the blood -ABSORPTION to the ultrafiltrate if there is a LOW concentration of ions in the blood

Question 26

describe the blood flow in the afferent arteriole in the kidney

Answer 26

from renal artery to the glomerular capillaries

Question 27

describe the blood flow in the efferent arteriole in the kidney

Answer 27

from glomerular capillaries to cortical and medullar capillaries

Question 28

what are efferent arterioles?

Answer 28

-nourish cortical and medullary tissue -peritubular cortical capillary network --> reabsorption of ultrafiltrate in cortex --> endothelium secretes EPO -peritubular medullary capillary network --> vasa recta for countercurrent exchange (in TLH)

Question 29

what is EPO

Answer 29

increases the rate of production of RBC's in response to falling levels of oxygen in the tissues

Question 30

what makes up the juxtaglomerular apparatus and what does it do?

Answer 30

-macula densa + juxtaglomerular cells -sensor that helps maintain sodium homeostasis and regulates BP

Question 31

what are macula densa

Answer 31

narrower and taller cells than those typical of the distal straight tubule monitor sodium concentration in ultrafiltrate secrete ATP, adenosine, NO and PGE2 to stimulate JGC

Question 32

what are juxtaglomerular cells

Answer 32

specialized smooth muscle cells of the afferent arteriole wall monitor sodium concentration in blood; secrete renin

Question 33

what does renin do?

Answer 33

increases the reabsorption of sodium and BP by a higher transfer of fluid from tissues into blood, leading to a greater blood volume

Question 34

what do the collecting ducts do

Answer 34

conduct urine into minor calices

Question 35

describe the cortical and medullary collecting ducts

Answer 35

-cuboidal epithelium, large and regular lumen with distinct cell borders -light cells --> stimulated by ADH to provide water permeability (PREDOMINANT TYPE) -dark cells --> involved in acid-base balance --> too basic: secretes carbonate --> too acidic: secrete H+

Question 36

describe the papillary ducts

Answer 36

columnar epithelium

Question 37

what are the two types of nephrons and what do they do?

Answer 37

juxtamedullary nephron: long-looped, performs most urine concentration cortical nephron: short-looped, performs most filtration/absorption (85%)

Question 38

describe the general aspects of the urinary passages

Answer 38

-mucosa: transitional epithelium -lamina propria: fibroelastic CT -muscularis: smooth muscle, peristalsis -adventitia: peritoneum or loose CT

Question 39

describe the transitional epithelium in the bladder

Answer 39

stratified number of layers increases proximal-distal -surface cells --> secrete lipids -intermediate cells -basal cells

Question 40

what do urothelial plaques do

Answer 40

lipid layer on the surface of superficial cells

Question 41

describe the urinary bladder

Answer 41

-highly distensible; rugae -thicker mucosa -muscularis (detrusor muscle, multidirectional) -serosa adjacent to peritoneal reflections

Question 42

what epithelium is found in the prostatic urethra

Answer 42

transitional epithelium

Question 43

what type of epithelium is found in the penile urethra

Answer 43

stratified squamous epithelium (non-keratinized)

Question 44

what type of epithelium is found in the pelvic urethra

Answer 44

stratified/pseudostratified columnar epithelium

Question 45

where can paraurethral mucous glands be found

Answer 45

near urethra lined by simple cuboidal epithelium