packet 24

Question 1

Nephrons and collecting ducts perform 3 basic processes

micro essay

Answer 1

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

Question 2

a portion of the blood plasma is filtered into the kidney

–happens one time

Answer 2

glomerular filtration

Question 3

water & useful substances are reabsorbed into the blood

–happens over and over

Answer 3

tubular reabsorption

Question 4

wastes are removed from the blood & secreted into urine

–happens over and over

Answer 4

tubular secretion

Question 5

rate of secretion =

Answer 5

filtration + secretion - reabsorption

Question 6

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

Answer 6

glomerular filtration

Question 7

glomerular Filtering capacityenhanced by:

maybe micro essay

Answer 7

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

Question 8

Filtration membrane does what 3 things?

***micro essay?

Answer 8

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

Question 9

endothelial fenestration stops…

Answer 9

all cells and platelets

Question 10

basal lamina stops…

Answer 10

large plasma proteins

Question 11

slit membrane stops…

Answer 11

medium-sized proteins, not small ones

Question 12

total pressure that promotes filtration

= 10mm Hg

Answer 12

net filtration pressure

Question 13

BP increases to above 70 =

BP that decreases to lower than 40 =

Answer 13

increase filtration

decrease filtration

Question 14

low BP and low filtration =

Answer 14

no filtration

Question 15

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

Answer 15

Glomerular Filtration Rate

Question 16

Homeostasis requires GFR that is constant

–if too high…

Answer 16

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

Question 17

Homeostasis requires GFR that is constant

–if too low…

Answer 17

waste products may not be removed from the body

Question 18

Changes in net filtration pressure affects GFR by

Answer 18

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

Question 19

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

Answer 19

Renal Autoregulation of GFR

Question 20

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

Answer 20

myogenic mechanism

Question 21

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

Answer 21

tubuloglomerular feedback

Question 22

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

Answer 22

neural regulation of GFR

Question 23

hormonal regulation of GFR

Answer 23

1. atrial natriuretic peptide (ANP)

2. Angiotensin II

Question 24

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

Answer 24

atrial natriurectic peptide

ANP

Question 25

reduces GFR potent vasoconstrictor that narrows both afferent & efferent arterioles reducing GFR

Answer 25

Angiotensin II

Question 26

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

Answer 26

tubular reabsorption and secretion

Question 27

Important function of nephron is tubular secretion

Answer 27

transfer of materials from blood into tubular fluid - --helps control blood pH because of secretion of H+ - --helps eliminate certain substances (NH4+, creatinine, K+)

Question 28

reabsorption routes

Answer 28

paracellular transcellular

Question 29

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

Answer 29

Paracellular reabsorption

Question 30

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

Answer 30

Transcellular reabsorption

Question 31

water is only reabsorbed by | water follows salt

Answer 31

osmosis

Question 32

Reabsorption of Na+ is important because

Answer 32

1. several transport systems exist to reabsorb Na+ | 2. Na+/K+ ATPase pumps sodium from tubule cell cytosol through the basolateral membrane only

Question 33

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

Answer 33

glucosuria

Question 34

--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

Answer 34

Reabsorption in the Prox. Con. Tubule