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Kin 1AA3 > Urinary system part 2 > Flashcards

Urinary system part 2 Flashcards

1
Q

diverticulitis

A

when pressure builds up in sigmoid colon, weakened walls form out pockets called diverticula = diverticulosis

  • when things get stuck and the diverticula get inflamed, it results in diverticulitis
  • fistula can form = a canal b/w 2 organs
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2
Q

treatment of mild diverticulitis

A

antibiotics to treat infection
high fiber diet
fluid diet until healed

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3
Q

treatment of severe diverticulitis

A

colonoscopy: 2 parts
1. surgically remove part of inflamed colon, take healthy part and attach it to a hole in the abdominal wall called a stoma and put a bag on it
2. once colon has healed, reattach colon to rectum again

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4
Q

true vs false diverticula

A

true are made up of all layers of large intestine

false are only pockets that consist of serosa

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5
Q

3 processes in urine production

A
  1. glomerular filtration
  2. tubular reabsorption
  3. tubular secretion
    results in fully filtered blood and production of urine
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6
Q

glomerular filtration

A

occurs in renal corpuscle,

where water and solutes move into Bowman’s capsule

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7
Q

renal bloodflow

A

20-25% of CO goes to kidneys at rest

this is about 1.2 L/min

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8
Q

renal plasma flow rate

A

55% of renal blood flow
is about 650 mL
- this is the amount of fluid that COULD be filtered

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9
Q

filtration fraction/ somewhat lumped with glomerular filtration rate

A

16-20% of the plasma flow rate

is about 125 mL/min OR 150-180 L/day

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10
Q

contributors to net filtration pressure (NFP)

A
  1. glomerular blood hydrostatic pressure
  2. capsular hydrostatic pressure
  3. blood colloid osmotic pressure
    - the last 2 both work against GBHP
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11
Q

glomerular blood hydrostatic pressure (GBHP or GCP)

A

55mmHg

  • the driving pressure in the afferent arteriole that works towards producing filtrate
  • same as regular BP bc pressure in efferent arteriole is less which gives driving pressure
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12
Q

capsular hydrostatic pressure (CHP)

A

15mmHg

  • pressure in capsular space due to the constant presence of some amount of glomerular filtrate
  • works against producing filtrate
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13
Q

blood colloid osmotic pressure (BCOP)

A

30mmHg

  • because filtration membrane doesn’t allow proteins to leave the glomerulus, the proteins on the inside are attracting the water outside to their area of higher concentration inside the glomerular capillaries
  • works against producing filtrate
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14
Q

how is net filtration pressure calculated and what is it?

A

NFP = GBHP - CHP - BCOP
= 55 - 15 - 30
= 10 mmHg

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15
Q

glomerular filtration rate

A

the amount of filtrate formed in all renal corpuscles in both kidneys per minute
- average rate for women is 105 mL/min,
for men is 125 mL/min
- filtration stops if GCP (GBHP) drops to 45mmHg bc NFP becomes 0 then

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16
Q

what happens when GFR is too high

A

we may not be able to absorb things quickly enough and things that we want could be leaving the body

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17
Q

what happens when GFR is too low

A

filtrate may spend too much time in renal tubules and things we don’t want might be reabsorbed

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18
Q

ways GFR is regulated

A

2 ways:

  1. adjusting blood flow (by decreasing BF, we decrease the amount of filtrate produced)
  2. altering glomerular capillary surface area (less SA means less filtrate produced)
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19
Q

mechanisms of GFR control

A
  1. renal autoregulation
  2. neural regulation
  3. hormonal regulation
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20
Q

renal autoregulation of GFR

A

keeps rate relatively constant despite changes in BP, etc

incl: myogenic mechanism and tubulogomerular feedback

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21
Q

myogenic mechanism

A

a mechanism of renal autoregulation

  • fast response to BP changes
  • an increase in BP causes afferent arteriole walls to stretch causing smooth muscles to contract and decrease blood flow to glomerulus, thus GFR returns to normal
  • prevents high BP from affecting GFR too much
  • also works in response to a decrease in BP
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22
Q

tubuloglomerular feedback

A

a mechanism of renal autoregulation

  • slower because have to wait for fluid to move through tubules and back to juxtaglomerular apparatus to know if adjustments need to be made or not
  • GFR increases when Na+, Cl- and water are not reabsorbed, leaving more stuff in tubules
    • this is detected by macula densa and inhibits release of nitric oxide (a vasodilator) from juxtaglomerular apparatus, causing afferent arterioles to constrict, decreasing blood flow to glomerulus and decreasing GFR
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23
Q

neural regulation of GFR

A

sympathetic ANS innervation
not a lot at rest
not a lot when moderate sympathetic stimulation
- larger sympathetic stimulation ex. exercise: vasoconstriction of afferent arterioles causes a decrease in blood flow and GFR, lowering urine output and allows blood flow to other tissues

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24
Q

hormonal regulation of GFR

A

2 methods:

  • atrial natriuretic peptide
  • angiotensin II
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25
Q

atrial natriuretic peptide (hormonal regulation of GFR)

A

increases GFR

  • stretching of atria occurring bc of increase in blood volume causes ANP to be released from cells near atria
  • relaxes glomerular mesangial cells which increases capillary SA, producing more filtrate, urine and decreasing blood volume to get back to norm
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26
Q

angiotensin II (hormonal regulation of GFR)

A

reduces GFR

- a vasoconstrictor that narrows afferent AND efferent arterioles therefore decreasing blood flow and GFR

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27
Q

tubular reabsorption

A
  • nephron reabsorbs 99% of filtrate
  • most reabsorption occurs in PCT
    • water, solutes, glucose, AA, urea, ions (Na, Cl, Ca2+, bicarbonate, phosphate) and small proteins
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28
Q

tubular secretion

A

transferring materials from blood into glomerular filtrate/tubular fluid

  • controls blood pH (H+ secretion)
  • eliminates substances (ammonia, creatinine, K+, some drugs)
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29
Q

primary active transport

A

ATP dependant transport used to move ions against their concentration gradients
ex. Na+/K+ pump

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30
Q

secondary active transport

A

driven by ion’s electrochemical gradient via symporters and antiporters

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31
Q

symporter

A

bring substances in same direction (towards cell)
ex. Na brings glucose with in into the cell and we need active transport to create a low concentration of Na+ inside the cell, keeping the electrochemical gradient

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32
Q

antiporter

A

move substances in opposite directions

ex. Na+-H+: for every Na+ that enters, a H+ leaves the cell, levels of Na+ inside stay low because of Na+/K+ ATPase

33
Q

methods of water reabsorption

A

obligatory water reabsorption

facultative water reabsorption

34
Q

obligatory water reabsorption

A

90% of water
water follows the solutes absorbed via osmosis
aquaporin-1: a protein water channel found in apical and basolateral membranes of PCT and descending limb of nephron loop
- facilitates water transport and helps water movement

35
Q

facultative water reabsorption

A

10% of water

  • water reabsorbed based on need regulated by ADH
  • primarily occurring in collecting ducts and end of DCT
36
Q

overall reabsorption in the PCT

A

65% of water, all glucose and AAs reabsorbed here
sodium symporters and antiporters
passive reabsorption of ions later in PCT

37
Q

Na+ symporters reabsorption in PCT

A
  • help reabsorb glucose, AAs, lactic acid, water-soluble vitamins, other nutrients in first half of PCT
38
Q

Na+ antiporters reabsorption in PCT

A

help reabsorb Na+ while H+ secreted into PCT aides in bicarbonate reabsorption

39
Q

reabsorption in 2nd half of PCT

A

passive reabsorption of Cl-, K+, Ca2+, Mg2+, urea, by diffusion, and water by osmosis
- osmolarity in this region is the same as in the blood bc water is constantly following movement of solutes in this region

40
Q

reabsorption in descending limb of nephron loop

A

simple squamous cells here

  • 15% of water reabsorbed and small diffusion of solutes back into tubule drives out more water
  • concentration of solutes gets greater as loop of Henle dips further into medulla and os more water is reabsorbed through simple squamous cells
41
Q

reabsorption in ascending limb of nephron loop

A

cells impermeable to water here so water is not absorbed, but ions are

thin: simple diffusion out
thick: active transport of K+, Na+, Cl- out

42
Q

reabsorption in DCT

A

PTH controls Ca2+ reabsorption here
10-15% water reabsorbed
Na+ and Cl- are reabsorbed by symporters

43
Q

principal cells

A

reabsorb Na+ and secrete K+ into end of DCT and collecting duct
- controlled by ADH and aldosterone

44
Q

intercalated cells

A

reabsorb K+ and bicarbonate ions and secrete H+ into end of DCT and collecting duct
- helps maintain blood pH

45
Q

osmolarity

A

the number of solutes in a given amount of fluid

ex high osmolarity means a high amount of solutes

46
Q

hormonal regulation of tubular reabsorption and secretion

A 
5 hormones regulate Na+, Cl-, Ca2+, and water reabsorption along with K+ secretion in renal tubules
angiontensin II
aldosterone
antidiuretic hormone
atrial narurietic peptide
parathyriod hormone
47
Q

renin-angiotensin system

A

the steps needed to produce the active form of angiotensin II triggered by a decrease in blood volume and/or blood pressure:

  1. less stretch in afferent arterioles (and increases in SNS)
  2. juxtaglomerular cells secrete renin into blood
  3. renin concerts angiotensinogen into angiotensin I
  4. angiotensin converting enzyme (ACE) converts angiotensin I into angiotensin II
48
Q

renin

A

acts like an enzyme, released from the kidneys into the blood
- meeds to find its substrate (angiotensinogen) to have action

49
Q

angiontensinogen

A
  • released from the liver

- renin cleaves off some AAs to create angiontensin I

50
Q

ACE

A

angiotensin converting enzyme

  • made in lungs
  • cleaves off a few more AAs and converts angiotensin I into angiotensin II
51
Q

angiotensin II

A
  • decreases GFR by vasoconstriction of afferent arterioles to prevent loss of too much fluid
  • increases Na+, Cl+ and therefore water reabsorption in PCT by stimulating Na+/H+ antiporters (Na takes Cl bc of charge and ion movement brings water w it)
  • causes adrenal CORTEX cells to secret aldosterone: principal cells in collecting duct reabsorb Na+, Cl- and water and secrete K+
52
Q

antidiuretic hormone (ADH)

A

key to making concentrated or dilute urine, works when BP/volume are low

  • increases water permeability of principal cells by facultative water reabsorption through insertion of aquaporin-2 channels from inside the cell into the cell membrane
  • regulated by negative feedback loop, detected by osmoreceptors going to hypothalamus causing ADH to be released from posterior pituitary, when BP gets low
53
Q

atrial natriuretic peptide (ANP)

A

target: mesangial cells of glomerulus and tubules
- works when BP/volume is high
- release from heart stimulated by a large increase in blood volume
- - inhibits reabsorption of Na+ and water in PCT and collecting ducts
- - suppresses secretion of aldosterone and AND which causes more Na+ and water to be excreted and more urine to be produced

54
Q

parathyroid hormone (PTH)

A
  • released from parathyroid glands in response to low blood Ca2+
  • stimulates cells in early DCT to increase reabsorption of Ca2+
  • also inhibits phosphate reabsorption in the PCT
55
Q

production of dilute or concentrated urine

A
  • despite varying fluid uptake, we still maintain homeostasis of fluids in the body
  • kidneys regulate water loss in urine
  • ADH controls whether dilute or concentrated urine is produced—- dilute urine is the default until ADH gets released
56
Q

formation of dilute urine

A

glomerular filtrate and blood have same osmolarity of 300mOsm/Liter
- tubular osmolarity changes due to concentration gradient in medulla

57
Q

when dilute urine is formed, osmolarity in the tubule:

A
  1. increases in descending limb: water moves out freely bc of aquaporin-1
  2. decreases in ascending limb: only ions can move out, leaving more water in tubule
  3. decreases even more in collecting duct: water not freely moving, only ions move out and filtrate gets more dilute
58
Q

what does it mean for urine to be dilute

A

it has fewer solutes than plasma present

59
Q

formation of concentrated urine

A

everything is the same until the collecting duct where lots of water gets reabsorbed when ADH increases

  • compensation for low water intake or heavy perspiration
  • principal cells move water (ADH present) if interstitial fluid surrounding nephron loop has high osmolarity
    • long loop juxtamedullary nephrons create gradient by Na+/K+/Cl- symporters reabsorbing Na+ and Cl- to create osmotic gradient in medulla
60
Q

characteristics of normal urine

A
  • 1-2 L produced per day
  • yellow or amber colour, may vary with diet
  • transparent, shouldn’t be cloudy
  • pH ranges from 4.6-8, avg of about 6, but varies with diet
  • slightly aromatic
61
Q

anatomy of ureters

A

25-30 cm long, 1-10mm diameter

  • run from renal pelvis to bladder where they enter halfway down on the posterior
  • retroperitoneal
62
Q

ureter valve anatomy

A

physiological valves
when bladder is empty, valve is open and urine can flow in
when bladder is stretched, it closes the valves so the bladder doesn’t get too full

63
Q

flow through ureters results from

A
  • gravity
  • peristalsis: alternating contractions of circular and longitudinal muscle
  • hydrostatic pressure: urine moves from high to low pressure areas
64
Q

mucosa layer in ureter wall

A
  • transitional epithelium that stretches and changes shape and lamina propria holds epithelial cells together
  • goblet cells produce mucous and prevents cells from contacting the urine bc its pH can vary a lot
65
Q

muscularis layer of ureter wall

A

2 layers of smooth muscle: inner longitudinal and outer circular
- distal 1/3 has additional outer longitudinal layer which is the same organization as found in the bladder

66
Q

adventitia layer of ureter wall

A

layer of areolar CT that holds ureters in place

67
Q

urinary bladder

A
  • distensible, hollow and very muscular organ
  • holds 700-800 mL
  • located posterior to pubic symphysis
    in females is anterior to vagina and inferior to uterus
    in males is anterior to rectum
68
Q

trigone

A

mucosa layer pulled tighter here

- triangle shaped region between ureteral openings and internal urethral oriface

69
Q

detrusor muscle

A

smooth muscle that contracts to push urine into urethra, just the 3 layers that make up the muscularis layer

70
Q

internal urethral sphincter

A

smooth muscle therefore involuntarily controls opening and closing of urethra
- an extension of the muscularis layer

71
Q

external urethral sphincter

A

located in deep muscles of peritoneum, voluntarily controls opening and closing of urethra because composed of skeletal muscle
- part of muscles of pelvic floor and people with weak pelvic floor muscles have less control of opening since it wraps around the urethra to control it

72
Q

micturition reflex

A
  • urination reflex
    1. stretch receptors activated when volume is 200-400mL
    2. impulse is sent to micturition centre in sacral SC (S2 and S3) and reflex is triggered
    3. parasympathetic fibers cause detrusor muscle to contract, and external and internal sphincter muscles to relax
    • this inhibits the signal from coming to the external urethral sphincter so it stays relaxed
      4. cerebral cortex recognizes the urge to urinate so it can initiate micturition or delay it’s occurrence for a limited period of time
73
Q

male urethra

A

20 cm long
has mucosa and muscularis layers
3 regions

74
Q

regions of the male urethra

A

prostatic urethra
intermediate urethra
spongy urethra

75
Q

prostatic urethra

A

1st portion of male urethra

  • transitional epithelium becomes stratified/pseudostratified columnar
  • runs through prostate gland and seminal gland region
  • sperm and seminal fluid are added to urethra here
76
Q

intermediate (membranous) urethra

A

2nd portion of male urethra

  • stratified or pseudostratified columnar epithelium
  • passes through perineum and runs through pelvic floor muscles which control opening of urethra consciously
77
Q

spongy urethra

A

3rd portion of male urethra

  • stratified or pseudostratified columnar epithelium becomes stratified squamous near exterior
  • passes through penis
78
Q

female urethra

A

4 cm long

  • external orifice is b/w clitoris and vagina
  • transitional epithelium changes to stratified or pseudostratified columnar and then stratified squamous epithelium near orifice
  • has mucosa and muscularis layers

Kin 1AA3 (11 decks)

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