Glomerular Filtration

Question 1

glomerular filtration creates

Answer 1

a plasma like filtrate of blood

Question 2

glomerular filtrate description of formation

Answer 2

water and substances that are dissolved in blood plasma get forced out of the glomerular capillaries into Bowman’s capsule and form glomerular filtrate

Question 3

composition of glomerular filtrate

Answer 3

consists of water, electrolytes, glucose, fatty acids, amino acids, vitamins, and nitrogenous wastes

Question 4

are formed elements and proteins in the filtrate?

Answer 4

no, they are too big to leave the blood vessels.

Question 5

how is the filtration membrane formed

Answer 5

endothelial cells in glomerular capillaries join podocytes to form a filtration membrane that filters water and small solutes, but not plasma proteins or formed elements

Question 6

glomerular endothelial cells

Answer 6

have large fenestrations through which solutes pass

Question 7

basement membrane

Answer 7

restricts passage of particles due to their size and their electronegativity

Question 8

large plasma proteins

Answer 8

like albumins, are too big to pass through the membrane; glomerular filtrate is only 0.3% protein while blood plasma is 7% protein

Question 9

pedicels

Answer 9

foot-like extensions from podocytes that wrap around glomerular capillaries to form filtration slits that can block passage of negative ions

Question 10

kidney infection or kidney trauma

Answer 10

can damage the filtration membrane and allow plasma proteins and/or formed elements to enter the filtrate causing proteinuria and hematuria

Question 11

what principles does glomerular filtration follow

Answer 11

the same principals that govern capillary bulk flow, but glomerular filtration involves much more fluid

Question 12

glomerular capillaries

Answer 12

long and provide large surface area for filtration

Question 13

filtration membrane

Answer 13

thin and porous

Question 14

blood pressure in glomerular capillaries

Answer 14

is high

Question 15

glomerular blood hydrostatic pressure

Answer 15

GBHP- the main force responsible for moving water and solutes out of blood plasma through the filtration membrane

Question 16

capsular hydrostatic pressure

Answer 16

CHP- opposes additional filtration because there is a high rate of filtration and because fluid is already present in the renal tubule

Question 17

blood colloid osmotic pressure

Answer 17

BCOP- also opposes filtration because of the plasma proteins that are present in blood plasma

Question 18

net filtration pressure promotes

Answer 18

filtration out of the glomerular capillaries

Question 19

NFP=

Answer 19

GBHP - (CHP + BCOP)

Question 20

glomerular filtration rate

Answer 20

GFR- refers to the amount of filtrate that is formed per minute in all of the renal corpuscles of both kidneys

Question 21

GFR for males

Answer 21

125 mL/min; which produces 180L of filtrate per day

Question 22

GFR for females

Answer 22

105 mL/min; which produces 150L of filtrate per day

Question 23

GFR relationship to NFP

Answer 23

GFR is directly proportional to NFP, so changes in GBHP, CHP, or BCOP will affect GFR

Question 24

if the GFR is too high

Answer 24

filtrate will flow through the renal tubules too quickly for them to reabsorb water and solutes

Question 25

urinary output (if GFR is too high)

Answer 25

rises and creates a risk for becoming dehydrated

Question 26

if the GFR is too low

Answer 26

filtrate will flow through the renal tubules too slowly and wastes will get reabsorbed

Question 27

risk of GFR being too low

Answer 27

creates a risk for developing azotemia

Question 28

renal autoregulation

Answer 28

the ability of the kidneys to maintain constant renal blood flow and glomerular filtration despite changes in arterial blood pressure

Question 29

myogenic mechanism

Answer 29

occurs when arterial blood pressure changes, which affects smooth muscle cells in walls of afferent arterioles

Question 30

when blood pressure rises

Answer 30

smooth muscle fibers contract and constrict afferent arteriole, which decreases blood flow into glomerulus to reduce GFR

Question 31

when blood pressure drops

Answer 31

smooth muscle fibers relax and dilate afferent arteriole, which increases blood flow into glomerulus to raise GFR

Question 32

tubuloglomerular feedback involves the

Answer 32

juxtaglomerular apparatus

Question 33

when GFR is elevated

Answer 33

filtrate flows through renal tubule too fast to reabsorb enough NaCl

Question 34

macula densa cells

Answer 34

release vasoconstrictor that reduces flow of blood from afferent arteriole into glomerulus to reduce GFR

Question 35

when GFR falls

Answer 35

flow of blood from afferent arteriole into glomerulus is increased

Question 36

autoregulation and changes in GFR

Answer 36

autoregulation does not completely block changes in GFR, but it allows for fluctuations within narrow limits

Question 37

autoregulation and variations in blood pressure

Answer 37

autoregulation cannot compensate for extreme variations in blood pressure but it will prevent large changes in water and solute excretion

Question 38

neural regulation

Answer 38

uses sympathetic nerve fibers to send signals to afferent arterioles that constrict them and decrease the flow of blood into the glomerular capillaries in order to reduce GFR and maintain systemic blood pressure

Question 39

the renin-angiotensin mechanism

Answer 39

is activated by a drop in blood pressure

Question 40

juxtaglomerular cells

Answer 40

secrete renin (an enzyme), which triggers conversion of angiotensinogen to angiotensin II

Question 41

angiotensin II constricts

Answer 41

both afferent and efferent arterioles to reduce GFR

Question 42

angiotensin II stimulates adrenal cortex to

Answer 42

secrete aldosterone to promote water retention and sodium retention

Question 43

angiotensin II stimulates pituitary gland to

Answer 43

secrete ADH to increase water absorption