urinary histo

Question 1

intermediate mesoderm

Answer 1

gives rise to paired glands:
kidneys, adrenals and gonads

Question 2

pronephrons, mesonephrons, metanephrons

Answer 2

mesoderm along post. border attempts to diff. 3times into kidneys::

1. pronephrons (first kidneys) =
   appear at day 21
   -in segmented intermediate mesoderm in cervical reg.
   -degenerates at day 24
   -never functional
2. mesonephrons (2nd kidney) =
   -in week 4
   -in intermediate mesoderm thoracic og lumbar reg
   -urine is prod. and drains along mesonephric (wolfian) duct to cloaca/bladder.
   -in week 5, thoracic segments regress, but mesonephric kidney cont to work till week 10
3. metanephrons (3d) =
   definitive kidney appear when metanephric duct (ureteric buds) sprout from distal end mesonephric duct. Um 5 week
   -Ureteric buds induce intermediate mesoderm in sacral reg to form metanephric blastema sem form glomeruli + tubules.

Question 3

metanephrons differentiation

Answer 3

ureteric buds bifurcate many times—>
forming collecting ducts og calices
-kidney byrja prod urine 12 week
-fetal kidney not excrete, placenta do so

Question 4

ascent of kidneys

Answer 4

í 6 week, kidneys begin to ascent from sacral reg. to their upper abd. position
-As kidneys ascent they recieve new segmental arteries from aorta and lose those vessels below (climbing a ladder)
-

Question 5

kidneys

Answer 5

Renal lobulus:
-renal column + 2 interlobular arteries

Renal lobe:
-renal pyramid + adj cortex
(8-15 per kidney)

Question 6

blood supply kidney

Answer 6

-receives 1.25 l/per minute
-125 ml of filtrate/per minute

124 ml are reabsorbed

path:
renal aa to segmental aa
to interlobar aa to arcuate aa to interlobular aa to:

aff. arteriole to glomerulus
to efferent arteriole
to peritubular capillaries (cortex)
to vasa recta (medulla)

Question 7

peritubular capillaries

Answer 7

absorb 180 liters daily from interstitial spaces

-extremly porous endothelial cells
-colloidal osmotic pressure
of plasma proteins
-low capillary pressure
-proximity to uriniferous tubules

Question 8

nephrons - functional unit

Answer 8

consists of:
-renal corpuscle (glomerulus og gl. capsule//bowmans)

-prox. conv. tubule
-loop of henle (asc og desc)
-distal conv. tubule

-i baðum kidney ca 2.5 milljon nephrons

Question 9

nephrons

Answer 9

1. cortical nephrons:
   -near peripheral edge of cortex
   -short nephron loops
   -w. peritubular capillaries
2. juxtamedullary nephrons
   -near corticomedullary border
   -long nephron loops
   -have vasa recta

Question 10

renal corpuscle

Answer 10

-vascular pole:
aff + eff. arterioles

-tubular//urinary pole:
con. to PCT

-glomerulus:
capillary bed
high pressure
fenestrations

-glom. capsule

Question 11

renal corpuscle

Answer 11

glomerular capsule:
parietal layer w simple sq. epithelium

visceral layer w podocytes and their pedicels, filtration slits

Question 12

filtration membrane

Answer 12

1. endothelial fenestrations:
   prevent filtration of blood cells, but allows all components of plasma to go thru
2. basal lamina:
   stops large proteins
3. slit membrane milli pedicels of podocytes:
   stops medium sized proteins

Question 13

prox conv. tubule

Answer 13

begins hja tubular pole renal corpuscle

-simple cuboidal epith
-ACTIVELY resorb
almost all nutrients
electrolytes
plasma proteins

osmosis: 60% of water reabsorption

-have microvilli

..solutes and water moved into blood plasma via peritubular capillaries

Question 14

prox conv. tubule

Answer 14

brush border (inv in reabs. of proteins. 0-8 mg/dL normal)
acidoph. c.plasm
nuclei far apart
indistinct lateral cell boundaries

PCT reabs. um 70% vatn via osmosis due to the reabsorbed glucose og NaCl

across tight junctions

Question 15

nephroon loop henle

Answer 15

projects towards/into medulla

desc limb: from cortex towards/into medulla

Thick asc limb: back to cortex

reabsorb water (desc)
and NaCl (asc)

Question 16

distal conv. tubule

Answer 16

adj to afferent arteriole (important physiologically)
-juxtaglomerular apparatus

-secretion
-from plasma to filtrate
secrete K og H (acid)
-toxins drugs

-reabs. of water due to:
aldosterone og ADH

-no brush border
-c.plasm less acidophilic
-nuclei closer together
-larger lumen
-short microvilli

-symport:
enables reabs. of NaCl

Question 17

juxtaglomerular apparatus

Answer 17

specialization of glom. aff arteriole + DCT

-regulation of BP via renin-angiotensin-aldosterone

composed of:
-juxtaglomerular cells
-macula densa
-extraglomerular mesangial cells

juxtaglomerular cells (aff arteriole) synth + secrete renin.
Renin released if decrease in salt concr. (sensed via osmoreceptors in macula densa) or drop in BP (sensed via mechano/barorec in afferent arteriole)

binding of angiotensin 2 to receptors—>
stimulates mesangial cells to contract (can cause vasoconstriction)

Question 18

collecting ducts

Answer 18

in hydrated ppl:
transports tubular fluid into papillary duct then into minor calyx

in dehydrated ppl:
conserve water
more concentrated urine

ADH can act on CD epith
water moves from filtrate to plasma
involves vasa recta

and acid bace balance

Question 19

ureter

Answer 19

fibromuscular tubes
-t. mucosa: transitional epith. (5-6 cells thick), longitudinal folds. Supported by lamina propria of dense CT

-muscularis: inner longitudinal, outer circular (outermost longitudinal can be present)

-adventita: fibroelastic CT

Question 20

BLADDER

Answer 20

four layers:
-mucosa
-submucosa
-muscularis (called the detrusor mm)
-adventita

Question 21

urethra

Answer 21

t mucosa:
protective mucus membrane.
w clusters of mucin producing cells (urethral glands)

t muscularis:
primarly smooth muscles

2 urethral spinchters