Phsl: Renal Week 2

Front 1

what is the percent of filtered water reabsorbed in the proximal tubule?

Back 1

67% - more than other part of the nephron

Front 2

what is the percent of filtered water reabsorbed in the thin descending limb of loop of henle?

Back 2

13%

Front 3

the distal tubule and collecting duct are only permeable to H2O when?

Back 3

when AVP (ADH) is present (transcellular transport)

Front 4

are the thin and thick ascending limbs of the loop of henle permeable to H2O?

Back 4

no

Front 5

what percent of the water is excreted?

Back 5

<1%

Front 6

what percent of the filtered water is reabsorbed in the distal convoluted tubule?

Back 6

10%

Front 7

what percent of the filtered water is reabsorbed in the collecting duct?

Back 7

9%

Front 8

the renal tubule is formed by what?

Back 8

a single layer of epithelial cells

Front 9

functions along the tubule vary b/c different segments have different what?

Back 9

1. permeabilities
2. transcellular potential differences
3. transport mechanisms

Front 10

when is K+ balance achieved?

Back 10

when urinary excretion of K+ exactly equals intake of K+ in the diet

Front 11

the distal tubule and collecting duct have what type of charge?

Back 11

very negative - this helps w/ secretion

Front 12

what type of charge does the thick ascending limb of the loop of henle have?

Back 12

very positive - helps w/ reabsorption

Front 13

what type of charge does the thick decending limb of the loop of henle have?

Back 13

slightly negative - drives ions in

Front 14

what type of charge does the proximal tubule have?

Back 14

slightly positive - helps to drive ions out

Front 15

nutrients like sugars and AAs along w/ other nutrients are reabsorbed by the what?

Back 15

proximal tubule

Front 16

about _____ of the total volume of filtrate is resorbed by the proximal tubule but nearly _____ of filtered AAs and glucose are rearbsorbed.

Back 16

2/3 ; 100%

Front 17

Interstitial fluid (ISF) = ?
Extracellular fluid (ECF) = ?

Back 17

interstitial fluid is equal to the fluid in between the cell; extracellular fluid is equal to the ISF + plasma

Front 18

1. in the proximal tubule, how are Glucose, AA, and other substances transported from the lumen into the proximal tubule cell?
2. how do Glucose, AAs, and other substances leave the proximal tubule cell and enter the ISF?

Back 18

1. symport active transport w/ Na+
2. by passive transport

Front 19

What are SGLT2 and SGLT1?

Back 19

SGLT2 is a weak high volume symporter in the early proximal tubule and SGLT1 is a strong symporter in the later half of the proximal tubule

Front 20

reabsorption of nutrients primarily occurs along what part of the proximal tubule?

Back 20

first 1/2

Front 21

secretion of organic acids and bases primarily occurs along what part of the proximal tubule?

Back 21

2nd half

Front 22

what is inulin?

Back 22

a sugar not normally found in the body, the amount remains constant

Front 23

is creatinine secreted?

Back 23

slightly secreted in the last 1/3 of the proximal tubule

Front 24

when the conc. of glucose w/i the proximal tubule exceed's it's transport max (amount that can be reabsorbed/min), what happens?

Back 24

glucose is excreted in the urine

Front 25

the max amount of glucose that can be reabsorbed is about what?

Back 25

300 mg/ml ( look at pg. 40 in notes)

Front 26

where does NaCl reabsorption occur?

Back 26

all along the tubule and collecting duct - different transport mechanisms are used in the different segments

Front 27

1. how is Na+ reabsorbed in the early proximal tubule?
2. late proximal tubule?

Back 27

1. - symport w/ nutrients
- antiport w/ H+
2. - transported w/ Cl-
- paracellular movement of NaCl
(leaves proximal tubule to enter ISF through symport transport w/ HCO3- and primary active transport w/ K+; Cl- passively exits the late proximal tubule to the ISF)

Front 28

how is Na+ reabsorbed in the thick ascending loop?

Back 28

- 1Na/2Cl/K cotransport
- Na/H antiporter

Front 29

how is Na+ reabsorbed in the distal tubule?

Back 29

Na/Cl symporter (it leaves the early distal tubule to enter the ISF through primary active transport w/ K+, Cl- enters ISF through channels)

Front 30

how is Na+ reabsorbed in the late distal tubule and collecting duct?

Back 30

Na+ channels controlled by aldosterone - leaves by primary active transport w/ K+

Front 31

distinguish the difference in the roles of ADH and aldosterone

Back 31

aldosterone controlls Na+ and K+ channels, ADH controls aquaporins and regulates H2O reabsorption

Front 32

1. How is Na+ reabsorbed in the loop of Henle (TAL)?
2. How does it leave TAL and enter the ISF?

Back 32

1. - w/ 2 Cl- and K+
- exchanged for H+
2. primary active transport (3Na+ leave and 2K+ enter), Cl- leaves through channels

Front 33

how does water move through membranes?

Back 33

passively, down an osmotic gradient

Front 34

how does H2O move transcellularly and paracellularly?

Back 34

transcellularly through aquaporins and paracellularly through leaky junctions

Front 35

arginine vasopressin (AVP) controls what in the late distal tubule and collecting duct?

Back 35

the # of apical membrane aquaporines

Front 36

where does paracellular transport occur in the nephron?

Back 36

proximal tubule and desceding loop of henle

Front 37

what is the most important buffer in the ECF?

Back 37

HCO3-

Front 38

how is HCO3- destroyed?

Back 38

continually destroyed in ECF by:
- buffering of metabolic acids
- filtration into the renal filtrate

Front 39

1. what is responsible for making HCO3- to replace what is destroyed?
2. explain the process

Back 39

1. the kidney
2.- tubular cells make H2CO3 which ionizes to form H+ and HCO3-
- HCO3- is reabsorbed into the ECF
- H+ is secreted into the filtrate
- to prevent the filtrate from becoming too acidic, the secreted H+ must be buffered

Front 40

H+ secreted into the filtrate are buffered by what?

Back 40

1. filtered HCO3-
2. filtered phosphates
3. other buffers (sulfates, creatinine)

Front 41

secretion of what else is also very important in the synthesis of HCO3-?

Back 41

NH4+

Front 42

differentiate between what happens to a substance if it is released into the lumen of the tubule and the ISF surrounding the tubule?

Back 42

if it is released into the lumen it is secreted, if it is released into the ISF it is reabsorbed

Front 43

what does carbonic anhydrase (CA) do in the lumen and in the proximal tubule?

Back 43

- in the lumen HCO3- combines w/ H+ to form H2CO3, CA then converts H2CO3 to H2O and CO2
- in the proximal tubule CA converts CO2 and H2O to H2CO3, H2CO3 then dissociates to form H+ and HCO3-, H+ is secreted into the lumen and HCO3- is rearbsorbed into the ISF

Front 44

the secretion of H+ and the reabsorption of HCO3- is upregulated by what and down regulated by what?

Back 44

upregulated by high CO2 (acidosis) and down regulated by alkalosis

Front 45

when is the phosphate buffer a much better buffer?

Back 45

due to its pK, it is a much better buffer as the pH of the filtrate becomes more acidic in the collecting duct

Front 46

how does a phosphate buffer act?

Back 46

it is filtered into the lumen as Na+HPO4-2 and combines w/ H+ to form Na+H2PO4- which is excreted

Front 47

where are H+ and HCO3- made in the late distal tubule and cortical collecting duct?

Back 47

intercalated cells:
- alpha intercalated cells secrete hydrogen ions and reabsorb bicarbonate ions (when plasma pH is low)
- beta intercalated cells secrete bicarbonate ions and reabsorb hydrogen ions (when plasma pH is high)

Front 48

what do alpha cells do?

Back 48

secrete hydrogen ions into the lumen and add bicarbonate to the ECF. these are strong H+ pumps that can acidify the urine down to a pH of about 4.5 - help to raise the plasma pH

Front 49

what do beta cells do?

Back 49

secrete HCO3- and add H+ to the ECF - help lower the plasma pH

Front 50

what hormone increases renal H+ secretion?

Back 50

aldosterone

Front 51

for every NH4+ excreted, one new ______ enters the blood

Back 51

HCO3-

Front 52

in which tubule is NH4+ synthesized?

Back 52

proximal tubule mostly

Front 53

what is NH4+ synthesized from?

Back 53

glutamine (from liver) is broken down to 2NH4+, 2HCO3-, and 1/2 a glucose

Front 54

1. what percent of amino groups are excreted by the kidneys as urea?
2. what percent of amino groups are converted to glutamine?

Back 54

1. 95%; 50% of this group starts out as NH4+ which produces 1 H+ in its conversion to urea and the other 1/2 start out as aspartate which produces 1 HCO3- in its conversion to urea
2. 5%; NH4+ combines w/ glutamate to form glutamine which travels in the blood to the kidney

Front 55

from 1 glutamine what is excreted and what is absorbed?

Back 55

2 NH4+ are excreted and 2 HCO3- are absorbed (rate increases w/ acidosis)

Front 56

from 1 glutamine what is excreted and what is absorbed?

Back 56

2 NH4+ are excreted and 2 HCO3- are absorbed (rate increases w/ acidosis)

Front 57

why does ammonia enter the medulla ISF?

Back 57

most bypass the distal tubule to prevent reabsorption from distal tubule and re-enter into the collecting duct to be excreted

Front 58

what percent of new HCO3- formed involves NH4 formation?

Back 58

60%, the other 40% involves titrable buffers like phosphates

Front 59

what happens to the pH as you move from the proximal tubule to the collecting duct?

Back 59

it decreases - it is 6.8 in the proximal tubule, 6.0 in the thick loop, and 4.4 by the time you get to the end of the collecting duct (lose buffering action)

Front 60

compare how much new and filtered HCO3- is found in the proximal tubule through the collecting duct to excretion

Back 60

1. proximal = 80% F 78% N
2. thick loop = 10% F 0% N
3. distal = 6% F 7% N
4. collecting = 4% F 15% N
5. exretion = 0% of either

Front 61

normal plasma bicarbonate is about what?

Back 61

24 meq/L

Front 62

1. what happens when the plasma [HCO3-] increases above normal?
2. what happens when the plasma [HCO3-] decreases below normal?

Back 62

1. the excess HCO3- is excreted and less is formed by the tubular cell
2. all of the filtered HCO3- is replaced and the tubular cells increase new HCO3- formation

Front 63

what effect on H+ secretion and HCO3- reabsorption does increased PCO2 or decreased ECF pH have?

Back 63

they both increase H+ secretion and HCO3- reabsorption

Front 64

what effect does increased ECF K+ have on H+ secretion and HCO3- reabsorption?

Back 64

it decreases H+ secretion and HCO3- reabsorption

Front 65

what effect do increased aldosterone or glucocorticoids have on H+ secretion and HCO3- reabsorption?

Back 65

increases them both

Front 66

how is plasma pH controlled?

Back 66

1. lungs - controls plasma [CO2]
2. kidneys - control plasma [HCO3-]

Front 67

what are the 4 respiratory pH problems?

Back 67

1. acute respiratory acidosis - renal compensation has not yet occured
2. chronic respiratory acidosis - renal compensation has occured
3. acute respiratory alkalosis - renal compensation has not yet occured
4. chronic respiratory alkalosis - renal compensation has occured

Front 68

Metabolic acidosis
1. primary disturbance
2. compensation

Back 68

1. decreased [HCO3-]
2. decreased PCO2 through hyperventilation (respiratory compensation)

Front 69

metabolic alkalosis
1. primary disturbance
2. compensation

Back 69

1. increased [HCO3-]
2. increased PCO2 through hypoventilation (respiratory compensation)

Front 70

respiratory alkalosis
1. primary disturbance
2. compensation

Back 70

1. lowered PCO2
2. lower [HCO3-] reabsorption and decrease H+ excretion (renal compensation)

Front 71

respiratory acidosis
1. primary disturbance
2. compensation

Back 71

1. increased PCO2
2. increased [HCO3-] reabsorption and increased H+ excretion (renal compensation)

Front 72

name 4 metabolic pH problems

Back 72

1. acute metabolic acidosis - respiratory compensation has not yet occurred
2. chronic metabolic acidosis - respiratory compensation has occurred
3. acute metabolic alkalosis - respiratory compensation has not yet occured
4. chronic metabolic acidosis - respiratory compensation has occurred

Front 73

what is the normal plasma pH range?

Back 73

7.38-7.44

Front 74

what is the normal PCO2 range in the plasma?

Back 74

33 - 42

Front 75

what is the normal HCO3 range in the plasma?

Back 75

22-28

Front 76

1. what causes respiratory acidosis?
2. what causes respiratory alkalosis?

Back 76

1. hypoventilation
2. hyperventilation

Front 77

1. what causes metabolic acidosis?
2. what causes metabolic alkalosis?

Back 77

1. exercise and acidic food
2. basic food

Front 78

1. how do the kidneys compensate for respiratory acidosis and alkalosis?
2. what initiates this compensation by the kidneys?

Back 78

1. by making more or less HCO3-
2. effect on enzymes by pH

Front 79

are Ca++, Mg++, and Pi controlled together or separately? why?

Back 79

together b/c:
1. the majority of these ions are in bone
2. many of these ions when in the plasma are bound to plasma proteins in inorganic anions
3. only free (or complexed w/ small anions) Ca++, Mg++, and Pi ions are filtered
4. parathyroid hormone (PTH) along w/ dietary intake and vit. D, control the free ion plasma concentrations

Front 80

how much calcium is reabsorbed in the:
1. proximal tubule
2. thick ascending loop
3. distal tubule
4. collecting duct

Back 80

1. 65% - mostly by paracellular transport which is passive and cannot be controlled
2. 25% - 50% by paracellular and 50% by transcellular (transcellular stimulated by PTH and D3)
3. 8% - 50% by paracellular and 50% by transcellular (transcellular stimulated by PTH and D3)
4. 1%

Front 81

what percentage of the Ca++ is excreted in the urine?

Back 81

1%

Front 82

how much Pi is reabsorbed by the:
1. proximal tubule
2. thick ascending loop
3. distal tubule
4. collecting duct

Back 82

1. 80% - inhibited by PTH
2. <1%
3. 10%
3. <1%

Front 83

how much Pi is excreted in urine?

Back 83

10%

Front 84

how much Mg++ is reabsorbed by the:
1. proximal tubule
2. thick ascending loop
3. distal tubule
4. collecting duct

Back 84

1. 15% - transcellular, stimulated by PTH
2. 70% - transcellular (stimulated by PTH) and paracellular
3 and 4. 10%

Front 85

how much Mg++ is excreted in the urine?

Back 85

5%

Front 86

the transcellular transport of Mg2+ and Ca2+ are affected by what?

Back 86

changes in concentration and electrical gradients

Front 87

where is vit. D formed?

Back 87

starts in skin, liver puts on 25 group, and the kidney puts on the 1 making 1, 25D3 which is the active form allowing the intestine to absorb Ca++ and Pi

Front 88

if Ca++ decreases in the ISF what hormone increases?

Back 88

PTH

Front 89

what effect does PTH have on Mg++, Ca++, and Pi reabsorption?

Back 89

PTH causes production of cAMP and PLC which stimulates the reabsorption of Mg2+ (in proximal tubule) and Ca++ (in thick ascending loop and distal tubule) and inhibits contransport of Pi w/ Na+ (in proximal tubule)

Front 90

what do PLC and Pi do to vit. D?

Back 90

they cause 25D3 to be converted to 1,25D3 (the active form) so it can cause absorption of Ca++ and PI in the intestine

Front 91

what happens if the filtered proteins or peptides increase much over normal?

Back 91

some will be excreted

Front 92

small filtered proteins and peptides are reabsorbed by what 3 processes in the proximal tubule?

Back 92

1. oligopeptides (n=2 to 4) are cotransported w/ H+
2. most peptides are digested by brush border peptidases and reabsorbed as AAs
3. small filtered proteins undergo endocytosis, digested by lysosomal enzymes, and returned to the blood as AAs

Front 93

1. what does hypokalemia do to cells of the body?
2. what does hyperkalemia do to cells of the body?

Back 93

1. hyperpolarizes cells of the body (including cardiac myocytes)
2. hypopolarizes cells of the body (including cardiac myocytes)

Front 94

hypokalemia or hyperkalemia can cause what in the heart?

Back 94

cardiac arrest and arrythmias

Front 95

how is the resting membrane potential created?

Back 95

mostly by K+ leaking out down it's concentration gradient

Front 96

how is the resting membrane changed when extracellular [K+] changes?

Back 96

the gradient changes

Front 97

1. increased plasma [K+] = ?
2. decreased plasma [K+] = ?

Back 97

1. hypopolarized
2. hyperpolarized

Front 98

is most K+ extracellular or intracellular?

Back 98

intracellular (98%)

Front 99

dietary K+ changes while ECF [K+] _______

Back 99

remain rather constant

Front 100

what 3 processes keep ECF [K+] rather constant?

Back 100

1. shifting of K+ in and out of cells (fast)
2. renal excretion of excess K+ (slow)
3. renal reabsorption of K+ when ECF [K+] is low

Front 101

our diet causes ECF [K+] to increase which stimulates what?

Back 101

an increase in epinephrine, insulin, and aldosterone which causes K+ to be actively pumped into the body cells (3Na+ out for 2K+ in). increased ECF [K+] also stimulates K+ to be exchanged for H+ inside the body cells

Front 102

alkalosis (decreased osmolarity) has what effect on the K+/H+ exchange?

Back 102

it stimulates the exchange and promotes the release of H+ from the body cells and the uptake of K+ by the body cells

Front 103

what effect does acidosis (?osmolarity) have on the K+/H+ exchange?

Back 103

it inhibits it

Front 104

1. most filtered K+ is reabsorbed by the what?
2. ECF K+ is primarily regulated by controlling what?

Back 104

1. proximal tubule and thick ascending tubule (some K+ is also reabsorbed by the thick loop)
2. secretion of K+ (sometimes reabsorption) into the distal tubule and collecting duct

Front 105

1. is K+ reabsorbed passively or actively in the proximal and distal tubule?

Back 105

passively in the proximal tubule; active in the distal tubule

Front 106

how is K+ moved in the distal tubule and collecting duct?

Back 106

usually secreted; controlled by regulating the K+ channels through aldosterone

Front 107

why does K+ not move paracellularly in the distal tubule and collecting duct?

Back 107

b/c they have tight junctions

Front 108

why is there a greater secretion of K+ in the late distal tubule and collecting duct?

Back 108

1. large conc. gradient
2. large electrical gradient

Front 109

how does the % of K reabsorption compare to eachother in the proximal tubule during hypokalemia, hyperkalemia, and normal states?

Back 109

it remains constant - 67%

Front 110

how does the % of K reabsorption compare to eachother in the thick loop during hypokalemia, hyperkalemia, and normal states?

Back 110

it remains constant - 20%

Front 111

compare the amount of K+ that is secreted or reabsorbed in the distal tubule during hypokalemia, normal state, and hyperkalemia?

Back 111

1. hypokalemia - 3% R
2. normal - 10% S
3. hyperkalemia - 50% S

Front 112

compare the amount of K+ that is secreted or reabsorbed in the collecting duct during hypokalemia, normal state, and hyperkalemia?

Back 112

1. hypokalemia - 9% R
2. normal - 5% S
3. hyperkalemia - 30% S

Front 113

reabsorption of K+ occurs in the distal tubule and collecting ducts during states of hypokalemia by the what?

Back 113

active transporters in alpha intercalated cells (H+ is secreted and K+ is reabsorbed)

Front 114

what are some things that increase K+ secretion?

Back 114

1. increased ECF K+
2. increased rate of tubular flow (increased GFR)
3. increase in aldosterone (there is also a decrease in ECF K+)
4. increased neg. tubular charge (pulls K+ out into filtrate)

Front 115

what effect does acidosis and increased H+ secretion have on K+ secretion?

Back 115

it decreases it b/c H+ is competing w/ K+

Front 116

increased K+ secretion decreases H+ secretion causing what?

Back 116

increased [H+] in the ECF (acidosis)

Front 117

why does increased tubular flow increase K+ secretion?

Back 117

it washes out the secreted K+ which increases the K+ gradient leading to increased K+ secretion

Front 118

what channels compete in the distal tubule and collecting duct?

Back 118

(all on lumen side)
1. passive K+ channel
2. primary active exchange channels w/ H+
3. primary active H+ channel
4. passive Cl- channel leading to inside tubule cells

Front 119

increased excretion of large anions and delivery of NaCl to the distal tubule and collecting duct causes what?

Back 119

increases tubular charge and causes an increase in K+ secretion (increased neg. charge in lumen increases the electrical gradient)

Front 120

the last 1/3 of the proximal tubule has a variety of transporters (mostly antiporters and symporters) that do what?

Back 120

secrete organic acids and bases

Front 121

organic anions and cations are are weak acids and bases meaning they ionize how?

Back 121

only partially ionize - pH of solution affects their degree of ionization

Front 122

after secretion, the pH of the filtrate will have what affect on the organic acids and bases?

Back 122

will affect the ionization and passive reabsorption of the organic acids and bases

Front 123

a more acidic filtrate increases excretion of what?
a more basic filtrate increases excretion of what?

Back 123

1. weak bases
2. weak acids

Front 124

if there is too much acid it will be secreted into the proximal tubule, why does it get trapped and excreted?

Back 124

b/c the filtrate in the proximal tubule has a higher pH and the acid dissociates becoming ionized and trapped inside b/c it is lipid insoluble

Front 125

adult males and females are approximately what % water?

Back 125

males - 60% H2O
females - 50% H2O (b/c of a little more fat)

Front 126

acute body weight changes usually indicate changes in what?

Back 126

body water content (retaining more Na+ - salt)

Front 127

what 2 mechanisms is body water regulated by?

Back 127

1. water intake (thirst)
2. changes in renal reabsorption and excretion of water

Front 128

what is the water input from:
1. drinks
2. food
3. oxidation

Back 128

1. 1000 ml
2. 1200 ml
3. 300 ml
(2500 ml total)

Front 129

what is the output of water in the:
1. skin and lungs
2. feces
3. kidneys (urine)

Back 129

1. 900 ml
2. 100 ml
3. 1500 ml
(2500 ml total)

Front 130

what is highly regulated to maintain normal osmolarity of the body?

Back 130

only thirst and renal reabsorption

Front 131

during heavy exercise, water loss through the skin can increase to what?

Back 131

several L/hr

Front 132

intracellular volume (ICV) and ECV make up what fraction of the fluid of the body?

Back 132

ICV = 2/3
ECV = 1/3

Front 133

how is plasma volume different from ISF?

Back 133

similar but has more proteins

Front 134

1. is the K+ free ion concentration greater in the ICF or the ECF?
2. Na+?
3. Cl-?
4. protein ?

Back 134

1. K+ greater in ICF
2. Na+ greater in ISF
3. Cl- is greater in the ISF
4. protein is greater in ICF
(HCO3- and Ca+ are about equal and ICF contains organic phosphates while the ISF does not)

Front 135

what is the composition of body fluids (plasma)?

Back 135

-a lot of Na+
-a little K+
-little Ca+
-a lot of Cl-
-fair amount of proteins
-fair amount of HCO3-

Front 136

what does the anion gap estimate?

Back 136

the anions in the plasma not measured during standard blood analysis

Front 137

what is the normal anion gap?

Back 137

8-12 MEq/L which is mostly due to neg. charged plasma proteins

Front 138

an increased anion gap is often due to what?

Back 138

metabolic acidosis

Front 139

in the ECF the major pos. ionis what? and the major neg. ions are what?

Back 139

pos. = Na+
neg. = Cl- and HCO3-

Front 140

how do you determine the anion gap (equation)?

Back 140

you know:
pos. ions in plasma = neg. ions
therefore:
[Na+] = [Cl-] + [HCO3-] + [Anion Gap Ions-]
So:
anion gap= [Na+] - [Cl-] - [HCO3-]

Front 141

how is osmolarity determined?

Back 141

by the conc. of impermeable particles in a solution not by the total mass of solutes

Front 142

normal body fluid osmolarity is about what?

Back 142

285 mOsm/kg

Front 143

an osmotic pressure difference of 1 mOsm/kg is equivalent to what?

Back 143

a hydrostatic pressure of 20 mmHg

Front 144

normal oncotic pressure is about what?

Back 144

25 mmHg

Front 145

increased ECF = increased # of _____

Back 145

particles

Front 146

vol. of any fluid compartment is regulated by what?

Back 146

increasing or decreasig the # of particles w/i the compartment

Front 147

higher conc. of impermeable particles inside a membrane creates what?

Back 147

an osmotic gradient causing H2O to move into the compartment until the conc. of particles is equal on both sides of the membrane

Front 148

what are osmotically active substances?

Back 148

substances that remain w/i a compartment creating an osmotic gradient

Front 149

compared to the normal osmolarity of body fluids, solutions may be
1. isotonic
2. hypertonic
3. hypotonic

Back 149

1. same
2. greater
3. less

Front 150

what are non-osmotically active substances?

Back 150

substances permeable to cell membranes that enter all compartments so that they do not produce a gradient (don't stimulate osmotic receptors)
examples: urea, glycerol

Front 151

what are 6 disturbances of volume and osmolarity?

Back 151

1. hypotonic expansion (increased H2O)
2. isotonic expansion (increased H2O and NaCl)
3. hypertonic expansion (increased NaCl)
4. hypotonic contraction (loss of NaCl)
5. isotonic contraction (loss of NaCl and H2O)
6. hypertonic contraction (loss of H2O)

Front 152

Na+ regulates fluid _____ and H2O regulates fluid _____

Back 152

vol.; osmolarity

Front 153

and increase in vol. = an increase in ______

Back 153

pressure

Front 154

ECF volume is primarily regulated by what?

Back 154

renal reabsorption of NaCl (measure ECF w/ NaCl)

Front 155

osmolarity of body fluids is primarily regulated by what?

Back 155

renal reabsorption of H2O and thirst regulation of water intake

Front 156

where are the osmoreceptors?

Back 156

in the hypothalamus (cause release of ADH)

Front 157

Na+ regulates fluid _____ and H2O regulates fluid _____

Back 157

vol.; osmolarity

Front 158

and increase in vol. = an increase in ______

Back 158

pressure

Front 159

ECF volume is primarily regulated by what?

Back 159

renal reabsorption of NaCl (measure ECF w/ NaCl)

Front 160

osmolarity of body fluids is primarily regulated by what?

Back 160

renal reabsorption of H2O and thirst regulation of water intake

Front 161

where are the osmoreceptors?

Back 161

in the hypothalamus (cause release of ADH)

Front 162

hyponatremia

Back 162

too much water = NaCl diluted

Front 163

hypernatremia

Back 163

too little water = NaCl concentrated

Front 164

ECF vol. increase results in what?

Back 164

edema (abnormal heart) or hypertension (normal heart), caused by too much sodium

Front 165

hypotension

Back 165

ECF volum depletion, caused by too little sodium

Front 166

stretch receptors

Back 166

in walls of carotid and aortic sinuses , left atrium, intrathoracic veins, and renal arteries - measures blood pressure

Front 167

if the stretch receptors measure blood pressure, how do they measure effective blood volume?

Back 167

b/c of the direct relationship between blood pressure and blood volume

Front 168

effective arterial blood volume

Back 168

blood volume that normally allows the circulatory system to produce a normal blood pressure

Front 169

decreased blood pressure in the carotid and aortic sinuses stimulates what type of activity?

Back 169

sympathetic activity which has renal and systemic effects

Front 170

high blood pressure stimulates receptors in the left atrium which results in what?

Back 170

ANP release which increases filtration rate

Front 171

if the pressure receptors in the kidney sense low blood volume, what do they do?

Back 171

1. release renin which converts angiotensinogen to angiotensin I
2. stimulate the brain to release ADH (causing water reabsorption) and increase thirst

Front 172

blood pressure to the kidney directly affects ______ reabsorption?

Back 172

Na+

Front 173

how is ECF volume measured?

Back 173

by measuring blood pressure w/ pressure receptors

Front 174

pressure receptors make changes to adjust the pressure in what ways?

Back 174

1. renin-angiotensin II - aldosterone system
2. sympathetic n. activity to the kidney
3. atrial natriuretic peptide
4. arginine vasopressin (non-osmotic control)

Front 175

1. how do you quickly increase blood pressure?
2. how do you slowly increase blood pressure?
3. how do you increase blood pressure in an emergency?

Back 175

1. blood vessels - vasoconstriction
2. adrenal cortex release aldosterone which causes the kidneys to reabsorb NaCl
3. low effective arterial blood volume stimualtes pressure receptors which stimulates the brain to release ADH causing the kidney to reabsorb water and increase thirst

Front 176

the sympathetic system regulates effective blood volume by doing what?

Back 176

1. directly increasing vascular resistance
2. increasing renin-angiotensin I - angiotensin II - aldosterone
3. directly increasing tubular reabsorption of Na+

Front 177

how does the sympathetic system:
1. reduce vascular volume?
2. increase ECF volume?

Back 177

1. by vascular constriction
2. by retaining Na+

Front 178

atrial cells release ANP in response to _______

Back 178

stretch (increased atrial BP)

Front 179

how does ANP get rid of Na+?

Back 179

by increasing RBF and GFR causing Na+ excretion and by inhibiting Na+ reabsorption by tubular cells

Front 180

ANP decreases ______ volume

Back 180

ECF

Front 181

ADH is released from the ______ in response to _______

Back 181

ADH is released from the posterior pituitary in response to increased osmotic pressure. ADH is also released w/ large decreases in effective blood volume (a 10% decrease in blood volume will cause ADH to help increase ECF volume. under these conditions body osmolarity can decrease below normal)

Front 182

ADH increases water reabsorption by what tubules?

Back 182

primarily the distal tubule and collecting duct, but also increases Na+ reabsorption by the thick ascending tubule of henle's loops

Front 183

what wrong when you have congestive heart failure?

Back 183

heart is failing - not pumping enough blood or producing enough pressure. receptors that measure blood pressure won't be stimulated so they'll increase blood volume which helps a little at first but ultimately produces edema - given diuretics to help relieve the swelling

Front 184

increased renal blood pressure causes what?

Back 184

1. increased GFR = increased tubular flow and Na+ excretion
2. increased RBF which causes:
- partial washout of medullary gradient and decreases Na+ reabsorption by thin descending loop
-decreases oncotic pressure in peritubular capillaries which decreases Na+ reabsorption

Front 185

what things stimulate Na+ reabsorption?

Back 185

1. sympathetic stimulation
2. angiotensin II
3. aldosterone
4. ADH

Front 186

what inhibits Na+ reabsorption?

Back 186

1. dopamine
2. ANP
3. urodilatin

Front 187

NaCl reabsorption increases when ECF volume ______ and decreases when ECF volume is ________

Back 187

decreases; high

Front 188

what is the range of the kidney's ability for Na+ excretion?

Back 188

10 meq/day to 1000 meq/day

Front 189

plasma volume is affected by what 4 things?

Back 189

1. ECV
2. plasma proteins
3. blood pressure
4. tissue pressure

Front 190

estrogens and glucocorticoids increase ______ reabsorption?

Back 190

NaCl

Front 191

increased excretion of ________ decreases NaCl reabsorption

Back 191

sulfates and phosphates

Front 192

diuretics decrease ______ reabsorption

Back 192

NaCl

Front 193

cell volume is controlled by what?

Back 193

1. transport processes that determine the conc. of impermeable particles inside the cell
2. synthesis of impermeable molecules inside the cell

Front 194

causes of edema (increased ISF volume)

Back 194

1. chronically decreased effective arterial blood volume
2. decreased plasma proteins - not eating enough to produce plasma proteins
3. increased capillary permeability - lose oncotic pressure (can be caused by histamine)
4. dilation of arterioles
5. decreased renal blood pressure - kidney acts as though you have no vol. and builds up Na+
6. lymph blockage

Front 195

normal osmolarity of body fluids is what?

Back 195

285 mOsm/kg

Front 196

osmolarity is regulated by what?

Back 196

thirst control and renal reabsorption of water

Front 197

renal reabsorption is regulated primarily by what?

Back 197

ADH hormone

Front 198

increased osmolarity (1%) and decreased effective blood volume (10%) stimulates what?

Back 198

osmoreceptors in the hypothalamus which causes the pituitary to release ADH. ADH increases the H2O permeability in the distal tubule and collecting duct

Front 199

aquaporins are controlled by what in the late distal tubular and collecting duct cells?

Back 199

AVP which is equal to ADH

Front 200

what causes ADH to increase H2O reabsorption in the distal tubular and collecting duct cells?

Back 200

it binds to a V2 receptor in the ISF which causes cAMP to be produced. cAMP makes aquaporins