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A&P II > packet 24 > Flashcards

packet 24 Flashcards

1
Q

Nephrons and collecting ducts perform 3 basic processes

micro essay

A
  1. glomerular filtration
  2. tubular reapbsorption
  3. tubular secretion
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2
Q

a portion of the blood plasma is filtered into the kidney

–happens one time

A

glomerular filtration

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3
Q

water & useful substances are reabsorbed into the blood

–happens over and over

A

tubular reabsorption

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4
Q

wastes are removed from the blood & secreted into urine

–happens over and over

A

tubular secretion

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5
Q

rate of secretion =

A

filtration + secretion - reabsorption

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6
Q

Blood pressure produces ____
Filtration fraction is 20% of plasma
48 Gallons/dayfiltrate reabsorbedto 1-2 qt. urine

A

glomerular filtration

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7
Q

glomerular Filtering capacityenhanced by:

maybe micro essay

A
  1. thinness of membrane & large surface area of glomerular capillaries
  2. glomerular capillary BP is high due to small size of efferent arteriole
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8
Q

Filtration membrane does what 3 things?

***micro essay?

A 
#1 Stops all cells and platelets
#2 Stops large plasma proteins
#3 Stops medium-sized proteins, not small ones
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9
Q

endothelial fenestration stops…

A

all cells and platelets

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10
Q

basal lamina stops…

A

large plasma proteins

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11
Q

slit membrane stops…

A

medium-sized proteins, not small ones

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12
Q

total pressure that promotes filtration

= 10mm Hg

A

net filtration pressure

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13
Q

BP increases to above 70 =

BP that decreases to lower than 40 =

A

increase filtration

decrease filtration

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14
Q

low BP and low filtration =

A

no filtration

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15
Q

Amount of filtrate formed in all renal corpuscles of both kidneys / minute
–average adult male rate
is 125 mL/min

A

Glomerular Filtration Rate

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16
Q

Homeostasis requires GFR that is constant

–if too high…

A

substances are lost due to the speed of fluid passage through nephron

17
Q

Homeostasis requires GFR that is constant

–if too low…

A

waste products may not be removed from the body

18
Q

Changes in net filtration pressure affects GFR by

A 
--filtration stops if GBHP 
   drops to 45mm Hg
--functions normally with 
   mean arterial 
   pressures 80-180
19
Q

Mechanisms that maintain a constant GFR despite changes in arterial BP
—myogenic mechanism
—tubuloglomerular
feedback

A

Renal Autoregulation of GFR

20
Q
  1. systemic increases in BP, stretch the afferent arteriole

2. smooth muscle contraction reduces the diameter of the arteriole returning the GFR to its previous level in seconds

A

myogenic mechanism

21
Q
  1. elevated systemic BP raises the GFR so that fluid flows too rapidly through the renal tubule & Na+, Cl- and water are not reabsorbed
  2. macula densa detects that difference & releases a vasoconstrictor from the juxtaglomerular apparatus
  3. afferent arterioles constrict & reduce GFR
A

tubuloglomerular feedback

22
Q

Blood vessels of the kidney are supplied by sympathetic fibers that cause vasoconstriction of afferent arterioles

At rest, renal BV are maximally dilated because sympathetic activity is minimal
–renal autoregulation
prevails

With moderate sympathetic stimulation, both afferent & efferent arterioles constrict equally
—decreasing GFR equally

With extreme sympathetic stimulation (exercise or hemorrhage), vasoconstriction of afferent arterioles reduces GFR
—lowers urine output &
permits blood flow to
other tissues

A

neural regulation of GFR

23
Q

hormonal regulation of GFR

A
  1. atrial natriuretic peptide (ANP)

2. Angiotensin II

24
Q 
increases GFR
---stretching of the atria 
    that occurs with an    
    increase in blood 
    volume causes 
    hormonal release
       --relaxes glomerular 
          mesangial cells 
         increasing capillary 
          surface area and 
          increasing GFR
A

atrial natriurectic peptide

ANP

25
Q

reduces GFR

potent vasoconstrictor that narrows both afferent & efferent arterioles reducing GFR

A

Angiotensin II

26
Q

Normal GFR is so high that volume of filtrate in capsular space in half an hour is greater than the total plasma volume

Nephron must reabsorb 99% of the filtrate

  • -PCT with their microvilli do most of work with rest of nephron doing just the fine-tuning
    • -solutes reabsorbed by active & passive processes
    • -water follows by osmosis
    • -small proteins by pinocytosis
A

tubular reabsorption and secretion

27
Q

Important function of nephron is tubular secretion

A

transfer of materials from blood into tubular fluid

  • –helps control blood pH because of secretion of H+
  • –helps eliminate certain substances (NH4+, creatinine, K+)
28
Q

reabsorption routes

A

paracellular

transcellular

29
Q

50% of reabsorbed materialmoves between cells bydiffusion in some parts oftubule

A

Paracellular reabsorption

30
Q

material moves throughboth the apical and basalmembranes of the tubulecell by active transport

A

Transcellular reabsorption

31
Q

water is only reabsorbed by

water follows salt

A

osmosis

32
Q

Reabsorption of Na+ is important because

A
  1. several transport systems exist to reabsorb Na+

2. Na+/K+ ATPase pumps sodium from tubule cell cytosol through the basolateral membrane only

33
Q

Renal symporters can not reabsorb glucose fast enough if blood glucose level is above 200 mg/mL
—some glucose remains in the urine

-Common cause is diabetes mellitis because insulin activity is deficient and blood sugar is too high

A

glucosuria

34
Q

–Na+ symporters help reabsorb materials from the tubular filtrate

–Glucose, amino acids, lactic acid, water-soluble vitamins and other nutrients are completely reabsorbed in the first half

–Intracellular sodium levels are kept low due to Na+/K+ pump

A

Reabsorption in the Prox. Con. Tubule

A&P II (30 decks)

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