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Water balance Flashcards

1
Q

what does the kidney maintain within the body

A

maintains:

  • water balance in body
  • plasma volume (blood pressure)
  • acid-base balance (pH)
  • osmolarity (solute concentration)
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2
Q

what waste products does the kidney regulate

A

urea
uric acid
creatinine

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3
Q

what does the kidney regulate within the body

A

extracellular fluid ion concentration

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4
Q

what does the kidney excrete

A

excretion of:

  • waste products of body metabolism
  • foreign compounds
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5
Q

what foreign compounds may the kidney excrete

A

food additives
drugs
pesticides

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6
Q

what does the kidney secrete and what are the secretions used for

A

erythropoietin (red blood cell production)

renin (hormone regulation salt conservation)

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7
Q

how does the kidney link to vitamin D

A

converts it to an active form

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8
Q

what is the main excretory product produced by the kidney

what is it produced by

A

urine

  • filtration of plasma
  • reabsorption from filtrate
  • secretion directly into filtrate
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9
Q

how many nephrons are there per kidney

A

1 million

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10
Q

what makes up the vascular component of the kidney and what is its function

A

glomerulus - ball of capillaries

water and solutes filtered out here from the blood

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11
Q

what is the function of the tubular component of the kidney

A

fluid passes into tubular after vascular

fluid is modified

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12
Q

what makes up the afferent arterioles

A

large amount of small vessels

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13
Q

how many arterioles supply a nephron

A

one

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14
Q

what does the afferent arteriole do

A

deliver blood to glomerular capillaries

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15
Q

what makes up the efferent arterioles

A

formed by re-joining glomerular capillaries

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16
Q

what are the efferent arterioles divided into

A

peritubular capillaries

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17
Q

where does the efferent arteriole provide blood to

A

carry blood that was not filtered into tubules

supply renal tissue with blood

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18
Q

what is the tube in the tubular component made up of

A

hollow tube formed from single layer epithelial cells

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19
Q

what does the tubular component consist of

A 
hollow tube
bowmans capsule
proximal tubule in cortex
loop of henle 
distal tubule
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20
Q

what is the bowmans capsule

A

cups around the glomerulus to collect fluid

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21
Q

what is the function of the loop of henle

A

establishes an osmotic gradient essential for concentrating urine

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22
Q

what is the distal tubule

A

highly coiled

lies in cortex and empties into collecting duct

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23
Q

is the glomerular membrane permeable

A

100x more permeable than other capillaries

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24
Q

what does glomerular filtration depend on

A

hydrostatic pressure

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25
how does colloid osmotic pressure form
in plasma contains proteins, if these are not passed into the filtrate - their concentrated in the unfiltered plasma increases = exert resistance to further filtration of fluid
26
what is GFR
glomerular filtration rate
27
how is GFR reduced
afferent arteriole - vasoconstriction decreases blood flow into glomerulus - decrease glomerular capillary blood pressure - decrease net filtration pressure - decrease GFR
28
how is GFR increased
afferent arteriole - vasodilation increases blood flow into glomerulus - increases glomerular capillary blood pressure - increases net filtration pressure - increases GFR
29
what prevents fluctuations in GFR
auto regulation of arteriole diameters
30
what type of mechanism is auto regulation
myogenic mechanism - afferent arteriole contracts in response to stretching from increased blood flow
31
what happens if the afferent arteriole contracts
decrease blood flow into glomerulus
32
what is the feedback mechanism involved in auto regulation
tubuloglomerular feedback mechanism - local vasoconstrictor/vasodilator release
33
what is a neural mechanism
extrinsic control from sympathetic nervous system
34
what are the characteristics of tubular reabsorption
occurs at very high rate highly selective highly variable
35
how does a diabetics urine differ
higher glucose concentration as they have higher glucose concentration in blood, kidneys cannot reabsorb all of it
36
what must a substance do to be reabsorbed
- cross luminal membrane of tubular cell - pass through tubular cell cytosol - cross tubular cell basolateral membrane to enter interstitial fluid - diffuse through interstitial fluid - penetrate capillary wall to enter blood plasma
37
what does the extracellular fluid osmolarity depend on
relative amount of water to solute
38
what makes up 2/3rds of bodys water
intra cellular fluid (within cells)
39
what makes up the extracellular fluid
``` plasma interstitial fluid (spaces between cells) ```
40
if the water balance is normal what is the ECF
isotonic
41
if the water balance is too much water what is the ECF
hypotonic
42
if the water balance is too little water what is the ECF
hypertonic
43
what are the concentrations that urine can be excreted between
100-1200 mosm/l
44
what is the vertical osmotic gradient
in the renal medulla intracellular fluid all of the cortex is ~ 300 mosm/l descend into medulla intracellular fluid more concentrated ~ 1200 mosm/l
45
what causes the medulla intracellular fluid concentration to be so high
sodium and chloride ions ~ 300 mosm each | urea contribute to rest concentration
46
what is the counter current multiplication
as fluid flows down water diffuses out down osmotic gradient so concentration increases fluid flows back salt is actively pumped out so concentration decreases
47
where does the counter current multiplication occur
loop of henle
48
how is the proximal convoluted tubule specialised
luminal border microvilli increase surface area
49
what occurs in the descending limb
ONLY permeable to water | water diffuses out of descending limb down conc gradient
50
what occurs in the thin ascending limb
not permeable to water high permeability to sodium and chloride ions NaCl diffuse out limb down conc gradient
51
what occurs in the thick ascending limb
ACTIVELY pumps out sodium and chloride | does do efficiently only concentrated by urea
52
what does the distal convoluted tubule transport into the lumen
transport into lumen: - potassium ions - hydrogen protons - ammonia
53
what does the distal convoluted tubule transport out of the lumen
- sodium ions - chloride ions - bicarbonate ions as salt pumped out water follows
54
what happens at the collecting duct
permeable to water water flow from dilute urine to more concentrated interstitial fluid of renal medulla - back to ~300 msom as reach CD reabsorbs NaCl by active transport high permeability to urea at bottom
55
when are the distal and collecting tubules not permeable to water
when vasopressin (anti-diuretic hormone) not present
56
where is the vasopressin made
hypothalamus
57
where is the vasopressin stored
posterior pituitary gland
58
when is the release of vasopressin stimulated
water deficit
59
what happens for water channels to be inserted in DCT and CD
vasopressin binds to the receptor on the DCT basolateral membrane once activated, receptor cyclises ATP to cyclic AMP - causes water channels to be inserted
60
what triggers release of vasopressin and thirst | where are they located
hypothalamic osmoreceptors | - neat vasopressin secreting cells and thirst centre
61
what happens when increased osmolarity in surrounding fluid
vasopressin release | thirst triggered
62
what happens when decreased osmolarity in surrounding fluid
inhibition of vasopressin release | suppression of thirst
63
what else regulates vasopressin
volume receptors | - monitor blood pressure
64
which fluid can be directly acted on to regulate volume and composition
plasma
65
how id fluid balance regulated
through ECF volume and osmolarity
66
what regulates the ECF osmolarity
maintenance of water balance
67
what regulates the ECF volume
maintenance of salt balance
68
what uses most of the kidneys energy
sodium reabsorption 80%
69
how much of the filtered sodium is reabsorbed | and where
99.5% 67% PCT 25% loop of henle 8% DCT
70
how is sodium concentration reflected in ECF volume
high sodium load = extra water in ECF and volume increases | low sodium load = less water held in ECF and volume decreases
71
what does the ECF volume effect
blood pressure
72
what is angiotensinogen
precursor constantly secreted into circulatory system
73
what happens in the renin-angiotensisn-aldosterone system when e.g. atrial blood pressure drops/ ECF drops/ decrease in NaCl
kidney detects change and releases renin renin cleaves apart angiotensinogen = angiotensin I pass through lungs where angiotensin-converting enzyme cleaves more of angiotensin I = angiotensin II (active hormone) angiotensin II pass to adrenal cortex = release of aldosterone aldosterone causes increase in sodium reabsorption in kidney tubule angiotensin II then helps correct
74
what does angiotensin II do to help correct in the renin-angiotensisn-aldosterone system
angiotensin II causes: - facilitated release of vasopressin - retain fluid - thirst to drink more - as blood pressure lower - need to maintain certain pressure, causes arteriolar vasoconstriction
75
what does aldosterone do
increases sodium reabsorption in DCT and CD - insert additional sodium ion channels into luminal membranes - insert additional sodium potassium ATPase carrier into basolateral membranes
76
if no aldosterone is present how much salt is secreted
up to 20g a day
77
if aldosterone is present how much salt is secreted
non

Food + Physiology (17 decks)

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