Ch 14. Final Osmoregulatory Organs (Book) Flashcards Preview

Animal Physiology > Ch 14. Final Osmoregulatory Organs (Book) > Flashcards

Flashcards in Ch 14. Final Osmoregulatory Organs (Book) Deck (79):
1

apical surface of an epithelial cell

continuous with the external world (ex. sea, gut lumen, kidney tubule lumen)

aka. mucosal or laminal surface

2

basal surface

faces an internal compartment with extracellular fluid

aka. serosal surface

3

Na/K ATPase

3 Na+ out

2 K+ in

maintain -70mV, uses ATP

basolateral surface...type of P-ATPase

4

3 classes of ion-motive ATPase pumps

F-ATP synthase

V-ATPase

P-ATPase

5

F-ATP synthase

drive ATP synthesis in mitochondria

6

V-ATPase

vacuolar type

hydrolyze ATP to make an electrochemical gradient

7

P-ATPase

include Na/K

Ca pump of muscle contraction

H+/K+ pump in the stomach

8

net movement of chloride across the cell membrane generates a ______________ membrane potential that can...

transepithelial

move sodium against its gradient paracellularly (btw cells)

9

can Na/K and proton ATPases be modified by hormones?

yes

ex. both increased activity by aldosterone

10

kidney anatomy

outer cortex and inner medulla

renal pelvis turns into the ureter --> bladder

11

urine contains water and other by-products of _________, like...

metabolism

urea, NaCl, KCl, phosphates

12

the function of the kidneys is to maintain...

more or less constant body composition

ex. composition of urine reflects water taken in and composition of food ingested

13

actual volume of urine produced is made of...

water ingested plus water made through metabolism

minus evaporative water loss and sweating and pooping

14

how is sensation of fullness via bladder produced

as bladder is stretched by filling, stretch receptors in the wall generate nerve impulses carried by sensory neurons

15

functional unit of the kidney is the ______ which empty into the __________ _____

nephron, collecting ducts

16

nephron structure

long tube structure closed and widened at the beginning (Bowman's capsule) and opened at the distal end --> collecting duct

17

bowman's capsule

contains a cluster of capillaries called the glomerulus where urine formation begins

18

3 regions of a nephron

proximal nephron

loop of Henle

distal nephron

19

proximal nephron

contains Bowman's capsule and proximal tubule

20

loop of Henle structure

has a descending limb and ascending limb

21

distal nephron

a distal tubule that enters into a collecting duct

22

two types of nephron

juxtamedullary

cortical

23

juxtamedullary nephron

has glomeruli in the inner cortex

long loops of Henle plunge far into the medulla

24

cortical nephrons

glomeruli in the outer cortex

short loops of Henle that extend a short distance into the medulla

25

without a loop of Henle you can't make

concentrated urine

26

path of blood from renal artery

renal artery --> afferent arteriole --> glomerular capillaries of bowman's capsule --> efferent arteriole --> vasa recta around loops of Henle

27

3 main processes that contribute to urine composition

filtering blood plasma into an ultrafiltrate in the lumen of Bowman's capsule

tubular reabsorption of 99% of water and salts form ultrafiltrate (leaves behind waste products like urea)

tubular secretion of substances via active transport

28

what does glomerular filtrate contain

all parts of blood except RBC

nearly all blood proteins

29

the process of ultrafiltration in the glomerulus depends on what

net pressure gradient (passive)

from hydrostatic pressure difference across 2 compartments

and colloid osmotic pressure

30

fenestrated capillaries in glomerulus

pores that are 100x more permeable than normal ones

31

pedicles extending from podocytes have filtration slits between them

help glomerular filtration

32

to ensure that changes in bp and co have little effect on normally high glomerular filtration rate...

many regulatory processes involving paracrine and endocrine secretions and neuronal control

33

how does an increase in bp affect glomerular filtration rate

not much

afferent arteriole constricts so increased pressure isn't transmitted

34

what can specialized cells of the juxtaglomerular apparatus do to help modulate renal blood flow

special distal-tubule cells (macula densa) monitor osmolarity and flow

modified-smc called granular cells in the afferent arteriole secrete renin, which affects bp

35

macula densa cells release..

paracrine substances that cause vasoconstriction or vasodilation

36

neuronal control

sympathetic activation causes vasoconstriction of afferent arteriole and less glomerular filtration -- when bp drops sharply

37

can sympathetic activation cause contractions of cells in the glomerulus?

yes... reduces area available for filtration

38

renin release causes what

increased angiotensin II in the blood

causes arteriole constriction to raise bp and increase rate of filtration

stim release of aldosterone and vasopressin to promote tubular reabsorption of salts and water

39

renal clearance of a substance

measure of how much it is reabsorbed or secreted

40

micropuncture technique to discover how urine moves through the nephron

micropipette inserted and oil injected until proximal tubule

perfusion fluid injected in oil column to force a droplet the the end of the tubule

after 20 min, 2nd fluid forces a second oil droplet forward and perfusion fluid is collected

tubule ability to reabsorb is determined by comparing perfusate composition b4 and after

41

the proximal tubule begins the process of concentrating _________ filtrate, is the most important tubule segment in the active reabsorption of _______

glomerular, salts (70% and a nearly proportional amount of water and other solutes like Cl-)

42

in the proximal tubule, _____ is the major solute reabsorbed proximally, and ______ is the major solute reabsorbed distally

NaHCO3, NaCl

43

brush border in proximal tubule

tons of microvilli to increase absorptive surface area of apical membrane

44

do the descending limb and ascending limb of the loop of Henle exhibit active salt transport?

no, fairly impermeable to NaCl and urea, but permeable to water (descending limb only)

opposite for ascending limb

45

thick medullary ascending limb of loop of Henle

actively transports NaCl our to the interstitial space

low water permeability

46

collecting duct highly water permeable

moves from dilute urine in the duct to the concentrated interstitial fluid

final concentration of urine

controllable by ADH

47

aldosterone

steroid hormone that causes an increase in sodium reabsorption

48

3 proposed methods of sodium reabsorption

Na/K pump activity increases

ATP production increases to power Na/K pump

premeability of membrane to Na increases

49

ADH

increases water permeability of distal tubule and collecting duct to promote water reabsorption

uses cAMP amplification to insert more aquaporins in apical memb of collecting duct

50

atrial natriuretic peptide (ANP)

released by atrial heart cells to promote urine production and sodium excretion

51

renin-angiotensin system

renin cleaves angiotensinogen into angiotensin I and angiotensin converting enzyme (ACE) turns angiotensin I into angiotensin II which stimulates secretion of aldosterone and ADH

52

tubular secretion occurs from where to where

plasma into tubular lumen

53

substances that may be secreted across proximal tubule

K+, H+, NH3

molecules get conjugated to move them across

54

most K+ ions filtered at the glomerulus are reabsorbed from filtrate in the proximal tubule and loop of Henle because of what transporters

Na/2Cl/K cotransporter in apical memb

Na/K pump in basolateral memb

55

can the distal tubule and collecting duct secrete K into the lumen

yes, balances reabsorption

Basolat - Na/K pump brings K from blood into cell

Apical - Na moves into cell through channels, K moves into urine by channels (both passive down gradients)

56

aldosterone leads up enhanced __ uptake and __ excretion

Na, K

57

2 factors of pH control in mammals

acid excretion by kidneys

CO2 excretion by lungs

58

during which part of the tubule is acid added to urine

entire length

urine becomes progressively more acidic

59

in proximal tubule and loop of Henle how are protons secreted

Na/H antiporter

60

A cells are found in the

distal tubule and collecting duct

61

what do A cells do

Secrete acid into urine

Carbonic anhydrase converts CO2 --> H+ + HCO3-

Apical - H+ ATPase moves H+ into urine, Na reabsorbed

Basolat - Na/K pump moves Na into blood, and HCO3-/Cl- antiport moves HCO3 into blood and Cl into cell

62

B cells are found in the

distal tubule and collecting duct

63

what do B cells do

Secretes HCO3- into urine in exchange for Cl

carbonic anhydrase

Apical - HCO3-/Cl- antiport moves Cl into cell and HCO3- into urine

Basolat - H+ ATPase pumps H+ into blood, and Cl- channels move Cl into blood

64

does acidosis increase the activity of A cells

yes

65

does alkalosis increase the activity of B cells

yes

66

what changes happen in A cells in acidosis

activity of Na/K ATPase and bicarb-chloride exchangers

67

proton secretion by renal tubular cells ______ the pH of the ultrafiltrate, which ______ the gradient against which protons are transported

decreases, increases

this is why the ultrafiltrate is buffered by bicarb, phosphate, etc

68

long term mechanism for correcting acidosis

producing ammonia ions that form ammonium ions after picking up H+ and secreting

69

concentrating urine is directly proportional to

loop of Henle length

because there is osmotic removal of water in the collecting duct

70

why is there increase in osmolarity of fluid from descending limb of loop of henle to hairpin turn

permeable to water but not nacl so water moves out

71

what happens as fluid moves up ascending limb of loop of henle

NaCl is actively moved out and some diffuses out

causes even more water to flow out

72

when is urea removed

when collecting duct enters deep inner medulla

flows out of tube and causes more water to flow out too

73

osmolarity becomes progressively ________ as you go deeper into the medulla

higher

74

countercurrent system with vasa recta

as blood enters inner medulla it picks up a lot of solute and releases water

when it moves to cortex is releases solute

75

when is ADH stimulated for release

dehydration (inc in osmolarity) --> hypothalamic neurosecretory cells impulses --> neurosecretory terminals in pituitary --> ADH

blood loss --> reduce inhibitory effect of receptors --> ADH

76

overall pathway

formation of urine begins w/ concentration of glomerular filtrate into hyperosmotic fluid in proximal tubule

75% salt and water removed through proximal tubule

in loop of Henle there is little net change of osmolarity, but a countercurrent multiplier sets up a concentration gradient

gradient drives osmotic reabsorption of water and resultant concentrated urine

77

proximal tubule and loop of Henle transporters for Na reabsorption

Na passively crosses apical memb via Na/2Cl/K and gluc/Na cotransporters

Na/K pump in basolat moves Na into blood (reabsorbs)

K and Cl into blood down their conc gradients through ion channels

78

Proximal tubule reabsorption of ultrafiltrate transporters

Apical - Na/glu cotransporter brings them into cell & Na/2Cl/K into cell

Basolat - Na/K pump moves Na into blood & K and Cl channels move them into blood

79

Proximal tubule secretion

CO2 into cell --> H+ + HCO3- by carbonic anhydrase

Apical - H+/Na antiport moves H+ into urine and Na into cell

Basolat - Na/K pump moves Na into blood & K and HCO3- move into the blood by channels