L24: Renal System II

Question 1

urinary excretion of a substance depends on

Answer 1

its filtration, reabsorption, secretion

Question 2

glomerular filtration

Answer 2

from glomerulus to Bowman’s capsule

Question 3

reabsorption

Answer 3

from tubules to peritubular capillaries

Question 4

secretion

Answer 4

from peritubular capillaries to tubules

Question 5

excretion

Answer 5

from tubules out of the body

Question 6

filtered quantities of a substance are generally

Answer 6

larger than the amounts of the substances in the body

Question 7

reabsorption of waste products

Answer 7

is relatively incomplete, large fractions are excreted

Question 8

reabsorption of most useful plasma components

Answer 8

is complete

Question 9

reabsorbed substance must move

Answer 9

across two barriers: the tubule epithelium and the capillary endothelium

Question 10

primary barrier to reabsorption

Answer 10

epithelial cells lining the renal tubules

Question 11

___ limit the passage of substances between cells

Answer 11

tight junctions between the renal tubule epithelial cells

Question 12

transport can be

Answer 12

active or passive

Question 13

barrier for secretion are

Answer 13

the same as for reabsorption

Question 14

substances such as ___ move from the peritubular capillaries into the tubular lumen

Answer 14

hydrogen ion, potassium, organic anions

Question 15

tubular secretion is an important mechanism for

Answer 15

disposing of drugs and drug metabolites, eliminating undesired substances that have reabsorbed by passive processes, removing excess K+, controlling blood pH

Question 16

glomerular filtration is driven by

Answer 16

hydrostatic pressure in the glomerular capillaries

Question 17

glomerular filtration is opposed by

Answer 17

hydrostatic pressure in Bowman’s space and the osmotic force due to the proteins in the glomerular capillary plasma

Question 18

under normal conditions,

Answer 18

losses of salt and water equal gains

Question 19

urinary loss regulation

Answer 19

matching of losses and gains of salt and water

Question 20

Na+ reabsorption

Answer 20

an active process occurring in all tubular segments except the descending limb of the loop of Henle

Question 21

water reabsorption

Answer 21

is by osmosis and is depended upon Na+ reabsorption

Question 22

Na+ is actively transported

Answer 22

across the basolateral membrane of renal tubule cells establishing an osmotic gradient for water reabsorption

Question 23

active transport of Na+ out of renal tubule cell keeps

Answer 23

intracellular Na+ lower than the renal tubular fluid Na+

Question 24

active transport of Na+ out of tubule cell forms a concentration gradient and favors

Answer 24

the movement of Na+ from the lumen of the renal tubule into the renal tubule cell

Question 25

Na+ moves from the tubular fluid into the tubular epithelial cell

Answer 25

through Na+ channels or via cotransport with other molecules such as glucose

Question 26

active reabsorption of sodium and other solutes in the proximal tubule creates

Answer 26

an osmotic gradient

Question 27

because of the osmotic gradient

Answer 27

water follows the solutes

Question 28

reabsorption of water creates a concentration gradient for permeating solutes

Answer 28

such as urea to move from tubular fluid to the peritubular capillaries

Question 29

water permeability

Answer 29

varies from segment to segment and depends largely on the presence of water channels, called aquaporins

Question 30

water channels

Answer 30

aquaporins (AQP)

Question 31

aquaporins are highly expressed

Answer 31

in the proximal tubule resulting in a high water permeability

Question 32

cortical and medullary collecting ducts

Answer 32

are the only tubular segments in which water permeability is under physiological control

Question 33

___ stimulates the insertion of aquaporin (AQP2) water channels

Answer 33

vasopressin (ADH)

Question 34

AQP2 channel pathways is present

Answer 34

in a PKA-dependent manner

Question 35

AQP2 are absent in the collecting duct apical membranes unless

Answer 35

ADH is active

Question 36

___ is not secreted

Answer 36

Na+

Question 37

__ is freely filterable at the glomerulus

Answer 37

Na+

Question 38

__ entry into the cell from tubular lumen is

Answer 38

always passive either through channels or contransport

Question 39

__ increases water permeability

Answer 39

ADH

Question 40

___ is a major determinant of the ability to survive with limited water intake

Answer 40

the ability of kidneys to produce hyper osmotic urine

Question 41

a maximal osmolarity that kidneys can produce

Answer 41

1400 mOsmol

Question 42

normal osmolarity of blood

Answer 42

300 mOsmol

Question 43

urinary concentration takes place

Answer 43

as tubular fluid flows through the medullary collecting ducts

Question 44

the interstitial fluid surrounding these ducts

Answer 44

very hyperosmotic

Question 45

in the presence of ADH

Answer 45

water diffused out of the ducts into the interstitial fluid to return to the capillaries

Question 46

the descending limb of the loop of Henle

Answer 46

is permeable to water, impermeable to solutes

Question 47

the ascending limb of the loop of Henle

Answer 47

is impermeable to water, permeable to solutes

Question 48

differences in the transport of water and solutes establish

Answer 48

osmotic gradient in the medullary interstitial fluid

Question 49

osmolarity differences

Answer 49

exist at each horizontal level and are multiplied as the fluid goes deeper into the medulla

Question 50

the loop of Henle is

Answer 50

a countercurrent multiplier system

Question 51

osmoreceptors in the hypothalamus

Answer 51

monitor the osmolarity of extracellular fluid

Question 52

osmolarity increases,

Answer 52

ADH secretion is stimulated and increases water reabsorption

Question 53

osmolarity decreases

Answer 53

ADH secretion is inhibited, which decreases water reabsorption and increases water excretion

Question 54

__ also influence ADH secretion

Answer 54

baroreceptors that detect blood volume and blood pressure

Question 55

baroreceptors in atria

Answer 55

detect and respond to changes in blood volume

Question 56

baroreceptors in carotid sinus

Answer 56

respond to changes in blood pressure

Question 57

blood volume and pressure decreases,

Answer 57

the frequency of action potentials in baroreceptors decreases, ADH secretion increases, water reabsorption increases, blood volume and pressure increases

Question 58

blood volume and/or pressure increases

Answer 58

ADH secretion decreases, water reabsorption decreases, blood volume and pressure decreases