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Histology - Exam 3 > Urinary System - Part 2 > Flashcards

Urinary System - Part 2 Flashcards

1
Q

describe DCT

A
  • continuous w/ macula densa
  • similar histologically to the ascending thick limb of LOH
  • shorter cells and wider lumen than PCT
  • NO brush border
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2
Q

DCT function

A
  • resorbs Na+ ions from the filtrate and actively transports them into the renal interstitium
  • transfers K+, ammonium, H+ ions into filtrate from interstitium
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3
Q

what stimulates the DCT to actively transport sodium ions into renal interstitium?

A

aldosterone

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4
Q

where is the JG apparatus located?

A

at the renal corpuscle vascular pole

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5
Q

contents of JG apparatus

A
  • juxtaglomerular cells mainly in wall of afferent a. (some in efferent)
  • macula densa cells
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6
Q

juxtaglomerular cells description

A

-modified smooth muscle cells

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7
Q

macula densa cells description

A
  • tall, narrow, epithelial distal tubule cells

- elongated, closely packed nuclei

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8
Q

fxn of macula densa cells

A

-sense changes in [NaCl]

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9
Q

JG cell fxn

A
  • sense BP decreases

- synthesize renin stored in secretory granules

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10
Q

what stimulates secretion of renin in JG cells?

A
  • low salt levels

- norepinephrine, dopamine from adrenergic nerve fibers (sym)

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11
Q

how do macula densa cells transmit info to JG cells?

A

via gap jxns (possibly)

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12
Q

fxn of JG apparatus

A

maintain BP by stimulating JG cells to release renin

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13
Q

action of renin and describe pathway it activates

A

renin converts angiotensinogen in plasma to angiotensin I -> converted to angiotensin II in lung capillaries -> AT-II stimulates release of aldosterone in the adrenal cortex

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14
Q

fxn of aldosterone in adrenal cortex?

A

stimulates DCT epithelial cells to resorb Na and water -> raises blood volume and pressure

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15
Q

lacis cells

A

extraglomerular mesangial cells / pole cushion

-found b/w afferent and efferent glomerular arterioles

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16
Q

how are lacis cells connected to each other and JG cells?

A

gap jxns

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17
Q

what is the tubuloglomerular feedback system to maintain system BP?

A

renin-angiotensin-aldosterone system

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18
Q

what does a decrease in vascular volume cause?

A

decrease in glomerular filtration rate, decrease in amount of filtered NaCl -> sensed by macula densa -> renin secretion

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19
Q

3 factors that stimulate the renin-angiotensin-aldosterone feedback system

A
  1. decrease in extracellular fluid
  2. decrease in renal BP
  3. decrease in NaCl in macula densa
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20
Q

what does angiotensin II stimulate release of other than aldosterone?

A

vasopressin/ ADH from hypothalamus -> increases permeability of collecting tubule and DCT to water

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21
Q

5 regions of collecting duct/tubule

A
  • connecting tubule
  • cortical collecting duct
  • outer medullary collecting duct
  • inner medullary collecting duct
  • papillary duct (duct of Bellini)
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22
Q

what are cell membranes of the collecting duct rich in?

A

aquaporins

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23
Q

what portions of the kidney do collecting tubules have segments in?

A

both cortex and medulla

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24
Q

cortical collecting tubules

A
  • located mainly in medullary rays

- lined by simple epithelium w/ 2 types of cuboidal cells: principal (light) and intercalated (dark) cells

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25
principal (light) cells
- round, centrally located nucleus - single, central cilium - many basal plasma membrane infoldings
26
fxn of cilium of principal cells
mechanosensor
27
fxn of principal cells
- remove Na+ ions from filtrate | - secrete K+ ions into filtrate
28
what do principal cells respond to?
aldosterone from adrenals
29
intercalated (dark) cells
- less numerous than principal cells - many apical cytoplasmic vesicles - microplicae (folds) on surface
30
fxn of intercalated cells
- remove K+ from filtrate | - secrete H+ into it
31
medullary collecting tubules: cell types in outer and inner medulla
outer: both principal and intercalated cells inner: only principal cells
32
papillary collecting tubules
ducts of Bellini | -large collecting tubules - 200-300 um diameter
33
lining of ducts of Bellini
simple cuboidal/columnar epithelium w/ single central primary cilium (may be a sensor)
34
where do ducts of Bellini empty?
at the area cribrosa at the apex of each renal pyramid
35
how many openings does each renal pyramid have where urine flows into a minor calyx?
10-25 openings
36
why does the countercurrent multiplier and exchanger fxn?
due to the fact that different portions of the nephron vary in their permeability to NaCl, water, and urea
37
what is resorbed in PCT?
``` 2/3 of filtrate: -glucose -aa's -small proteins -80% of NaCl and water from filtrate -Ca and water absorbed in parallel to Na (no osmolarity change) ```
38
permeability of descending thick limb of LOH
- water resorbed | - NaCl NOT
39
permeability of descending thin limb of LOH
-perm to water -> ultrafiltrate equilibrates w/ renal interstitium
40
permeability of ascending thin limb of LOH
- water NOT resorbed | - NaCl resorbed
41
where does urea move into tubule?
ascending thin limb of LOH
42
permeability of DCT and part of collecting tubule
-reabsorb NaCl
43
what happens in the collecting duct?
urea moves from interstitium into duct
44
glomerulonephritis
- inflammation of the glomeruli - often have hematuria, proteinuria or both - oliguria
45
what can cause glomerulonephritis (4 things)?
- proliferation of podocytes and mesangial cells and leukocyte infiltration - streptococcal infection elsewhere in body due to deposition of immune complexes in the GBM - from immune or autoimmune disorders (lupus) - autoimmune disorder where glomerular components are targeted (anti-GBM antibodies against type 4 collagen)
46
time course of glomerulonephritis
can be acute, subacute and chronic
47
what can chronic glomerulonephritis cause?
destroys glomeruli - leads to renal failure and death
48
acute tubular necrosis
destruction of epithelial cells lining a specific area of the nephron - as cells die, they slough, forming casts that occlude the lumen
49
two types of acute tubular necrosis
- ischemic: shock, crush injuries, bacterial infection | - toxic: ingestion of renal poisons
50
what are some renal poisons?
- heavy metals (Hg) - organic solvents - antibacterial/antifungal agents/ nonsteroidals
51
what does acute tubular necrosis cause?
severe loss of kidney fxn (acute renal failure)
52
is recovery from tubular necrosis possible?
yes if damage is not too severe - if too severe-> death
53
chronic renal failure
multifactorial disease where reduced blood flow to kidneys causes decreased glomerular filtration and tubular ischemia
54
symptoms w/ chronic renal failure?
- changes to glomeruli (hyalinization) - tubular atrophy of the tubules - lack of acid/base balance -> acidosis, hyperkalemia, uremia due to inability to eliminate metabolic waste
55
what happens if chronic renal failure goes untreated?
neurologic problems, coma, death
56
some causes of chronic renal failure?
- diabetes mellitus - HTN - atherosclerosis
57
diabetes insipidus
decreased ability of kidney to concentrate urine in the collecting tubule due to reduced levels of ADH
58
what causes diabetes insipidus?
destruction of the paraventricular and supraoptic nuclei in hypothalamus (which synthesize antidiuretic hormone (ADH))
59
symptoms of diabetes insipidus
- dehydration - polydipsia - excretion of large amounts of dilute urine
60
renal calculi
kidney stones - calcium stones due to elevated urinary levels of Ca, oxalic acid, uric acid
61
what are kidney stones usually made of?
calcium oxalate
62
struvite stones
stones of Mg ammonium phosphate and calcium carbonate - usually result from UTIs
63
what is the ureter?
muscular tube that conducts urine to bladder from renal pelvis
64
innervation of ureter?
sympathetic and parasympathetic
65
epithelium of ureter?
transitional
66
smooth muscle of ureter?
- prox 2/3: 2-layered muscularis (inner longitudinal, outer circular) - distal 1/3: has an additional layer
67
how does the ureter move urine to the bladder?
peristaltic waves -> urine enters bladder in spurts
68
epithelium and lamina propria of urinary bladder
- epith: transitional - 3 layers (basal layer, 2-3 cell deep intermediate layer, superficial layer "umbrella cells") - LP: thin, made of fibroelastic CT
69
how many layers does the muscularis of the urinary bladder have?
3
70
appearance of relaxed bladder
- epithelium has rounded cells w/ scalloped contour | - umbrella cells contain plaques (thickened PM) in luminal PM and flat elliptical vesicles in cytoplasm
71
fxn of the elliptical vesicles in relaxed bladder?
reserve surface membrane
72
appearance of distended bladder
- superficial cell layer appears squamous and number of cell layers reduced - due to insertion of elliptical vesicles into the luminal plasma membrane of the surface cells
73
fxn of urethra
moves urine from bladder to outside - carries semen in males
74
muscularis of urethra
2 layers - inner longitudinal and outer circular smooth muscle
75
what allows voluntary closure of the urethra and where is it located in males?
external skeletal muscle sphincter - in membranous urethra region
76
male urethra parts
- prostatic - membranous - cavernous (penile)
77
prostatic urethra
- transitional epithelium - passes through prostate - ducts from prostate open into urethra
78
membranous urethra
-short segment of urethra in b/w prostatic and penile
79
penile urethra
- pseudostratified or stratified columnar epithelium - switches at end to stratified squamous epithelium - receives ducts of bulbourethral glands - has mucus secreting glands of Littre in lamina propria
80
female urethra lining
- starts lined by transitional epithelium - changes to pseudostratified columnar - then stratified squamous nonkeratinized epithelium - may also have glands of Littre in lamina propria

Histology - Exam 3 (12 decks)

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