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Flashcards in Physiology Deck (102):
1

How much of a male is water?

60%

2

How much of TBW is intracellular/extracellular?

67% = intracellular
33% = extracellular

3

What are tracers used for?

measuring sizes of fluid compartments

4

What is a good indicator for TBW?

3H20

5

What is a good indicator for plasma volume?

labelled aluminium

6

What is a good indicator for extracellular fluid volume?

inulin

7

Name 3 things which cause input of fluid throughout the day.

fluid
food
metabolism

8

Name 5 things which cause output of fluid throughout the day.

skin, lungs (insensible)
sweat, faeces, urine (sensible)

9

What are the ICF and ECF concentrations of sodium?

ICF - 10
ECF - 140

10

What are the ICF and ECF concentrations of potassium?

ICF- 140
ECF- 4.5

11

If there is a gain of water, what changes occur?

similar to both ECF and ICF

12

If there is a gain/loss of Na/Cl what changes occur?

opposite in ECF and ICF
e.g.
if NaCl ECF increases, ECF increases but ICF decreases

13

What happens if there is a gain or loss of isotonic fluid?

no change in fluid osmolarity
change in ECF only

14

Does water follow salt, or does salt follow water?

water follows SALT

15

How much of the body's potassium is intracellar?

95%

16

What two things might small leakages or increase in cellular uptake of K cause?

muscle weakness - paralysis
cardiac irregularities - cardiac arrest

17

Does cell lysis occur if a cell is hypotonic or hypertonic?

hypotonic

18

What happens if a cell is hypertonic?

cell shrinkage

19

Which, tonicity or osmolarity takes into account the ability of a solute to cross the membrane?

tonicity

20

What is the major anion of ECF?

chloride

21

Major cation of ECF?

sodium

22

Are osmotic concentrations of ECF//ICF the same or different?

identical

23

What alters composition + volume of ECF?

kidney

24

What are the two types of nephron?

juxtamedullary
corticol

25

How much of plasma entering the glomerulus is filtered?

20%

26

What calculation is used for the filtration rate?

Filtration rate = concentration of plasma X GFR

27

What calculation is used for the Excretion rate?

Excretion rate = concentration of urine X urine flow rate

28

What calculation is used for the reabsorption rate?

rate of filtration - rate of excretion

29

What calculation is used for the secretion rate?

rate of excretion - filtration

30

Approx value for glomerular capillary blood pressure?

55

31

Approx value for Bowmans capsule oncotic pressure?

0

32

Approx value for hydrostatic pressure in Bowmans capsule?

15

33

capillary oncotic pressure approx value?

30

34

What is net filtration equal to?

(55 + 0) - (15+30) = 10mmHg

35

What is GFR equal to?

Kf x net filtration pressure = 125ml/min

36

What is GFR?

rate at which protein free plasma is filtered from glomeruli at Bowman's capsule?

37

What is clearance of a substance equal to?

volume of plasma cleared for substance per minute

38

Is clearance of every substance the same?

no substance has different clearance values

39

What is used clinically to determine GFR?

inulin

40

What else can be used to determine GFR?

creatinine

41

What properties should a substance have to make it an indicator for GFR measurement?

freely filtered at glomerulus
neither absorbed nor secreted
not metabolised by kidney
not toxic
easily measured in urine and blood

42

What is the clearance for a substance which is completely reabsorbed and not secreted, and give an example of such a substance?

0
glucose

43

What is the clearance for a substance which is filtered, partly reabsorbed and not secreted, and give an example of such a substance?

more than GFR
urea

44

What is the clearance for a substance which is filtered, secreted but not reabsorbed, and give an example of such a substance?

less than GFR
H+

45

If clearance < GFR (inulin clearance) then substance is what?

reabsorbed

46

If clearance = GFR then substance is what?

neither reabsorbed or secreted

47

If clearance > GFR then substance is what?

secreted into tubule

48

What can be used to calculate RPF?

para-amino hippuric acid (PAH)

49

What happens to all the PAH in the plasma that escapes filtration?

it is secreted from the peritubular capillaries

50

What is creatinine?

Creatinine is a muscle metabolite produced at a near constant rate

51

What does measurement of inulin require?

does require constant infusion to ensure a constant [inulin]p  not very convenient

52

Describe what a GRF marker should be.

should be filtered freely; NOT secreted or reabsorbed

53

Describe what a RPF marker should be.

marker should be filtered and completely secreted

54

What is filtration fraction?

fraction of plasma flowing through the glomeruli that is filtered into the tubules - 20%

55

20% of the plasma that enters the flomerulus is filtered. What happens to the other 80%?

it is not filtered and leaves through the efferent arteriole

56

Which is more specific, reabsorption or filtration?

reabsorption

57

Fluid reabsorbed in the proximal tubule is what with filtrate?

iso-osmotic with filtrate

58

What is reabsorbed in the proximal tubule?

Sugars
Amino acids
Phosphate
Sulphate
Lactate

59

What is secreted in the proximal tubule?

H+
Hippurates
Neurotransmitters
Bile pigments
Uric acid
Drugs
Toxins

60

What type of active transport is this: Energy is directly required to operate the carrier and move the substrate against its concentration gradient

primary

61

What type of active transport is this: Passive carrier-mediated transport of a substance down its concentration gradient

facilitated diffusion

62

What type of active transport is this: The carrier molecule is transported coupled to the concentration gradient of an ion (usually Na+)

secondary

63

Normally, how much glucose is reabsorbed in the proximal tubule?

100%

64

Is clearance of reabsorbed or secreted substances is constant once Tm is reached?

NO

65

How much of all salt and water is reabsorbed in the PT?

~67%

66

What drives sodium reabsorption?

the basolateral Na+-K+-ATPase

67

How is water reabsorbed?

by osmosis

68

What is the function of the loop of henle?

Generates a cortico-medullary solute concentration gradient, enabling the formation of hypertonic urine

69

Is the ascending or descending limb permeable to water?

descending

70

Which side reabsorbs NaCl, ascending or descending ?

ascending

71

What do “Loop diuretics” block?

the triple co transporter

72

What is the purpose of countercurrent multiplication?

To concentrate the medullary interstitial fluid

73

What run alongside the long loop of Henle of juxtamedullary nephrons?

vasa recta

74

Is the residual load of NaCl after reabsorption important?

Yes very apparently

75

What are major sites for the regulation of ion and water balance?

The distal tubule and the collecting duct

76

What does Aldosterone do to regulate ion and water balance?

increases Na+ reabsorption
increases H+ / K+ secretion

77

What does Atrial natriuretic hormone do to regulate ion and water balance?

decreases Na+ reabsorption

78

What does PTH do to regulate ion and water balance?

increases Ca2+ reabsorption
decreases PO43- reabsorption

79

Does the distal tubule have high or low permeability to water and urea?

low

80

What two mechanisms control bladder emptying?

The micturation reflex
Voluntary control

81

What produces ADH and where is it stored?

hypothalamus
stored in POSTERIOR pituitary gland

82

What controls the release of ADH from the pituitary into the blood?

hypothalamus

83

WhWhat stimulates ADH secretion?

water deficit

84

When is ADH secretion stimulated and when is it inhibited?

Stimulated when hypertonic
inhibited when hypotonic

85

What are the main symptoms of diabetes insipidus?

large volumes of dilute urine
constant thirst

86

How is diabetes insipidus treated?

ADH replacement

87

ADH release is affected by activation of left atrial stretch receptors. If atrial pressure decreases, what happens to ADH release?

increases

88

How does salt imbalance manifest itself?

as changes in extracellular fluid volume

89

Is regulation of extracellular fluid volume important for short term regulation of blood pressure or also long term regulation?

also long term

90

What does sodium filtered minus sodium reabsorbed equal?

sodium excreted

91

What is aldosterone?

steroid hormone secreted by adrenal cortex

92

When is aldosterone secreted?

in response to rising potassium or falling sodium
AND
activation of Renin angiotensin system

93

WHat does aldosterone do to sodium?

stimulates reabsorption

94

WHat does italdosterone do to potassium?

stimulates secretion

95

What happens wto potassium reabsorption if aldosterone is absent?

all is reabsorbed in distal tubule, so no potassium is excreted in urine

96

What does a decrease in plasma sodium promote?

the indirect secretion of aldosterone via the juxtaglomerular apparatus

97

What are the 3 main ways of control of renin release from granular cells in the juxaglomerular apparatus?

1. reduced pressure in afferent arteriole
2. macula densa cells sense amount of NaCl in distal tubule
3. increased sympathetic activity as a result of reduced arterial BP

98

How is fluid retention associated with congestive heart failure caused by RAAS problems treated?

low salt diet
diuretics (LOOP)
ACE Is

99

What does atrial natriuretic peptide do?

is released when atrial muscle cells are stretched
promotes eexcretion of sodium and diuresis, so causes:
1.a decrease in plasma volume
2. and in BP

100

What is the difference between water diuresis and osmotic diuresis?

Both have increased urine flow, but water does NOT have an increased solute excretion, osmotic does

101

What produces erthropoitin?

kidney

102

WHat does erytropoitin do?

stimulates stem cells in bone marrow to produce RBCs which increases O2 supply to tissues (if there is not enough O2 supply to tissue, kidney makes more!)