Physiology Flashcards
1
Q
osmolarity =
A
concentration of osmotically active particles in a solution
2
Q
units for osmolarity in body fluids
A
mosmol/l
3
Q
osmolality =
for weak salt solutions like body fluids is interchangeable with __
A
osmol/kg water
osmolarity
4
Q
tonicity is related to osmolarity but also considers
A
the ability of a solute to cross the cell membrane
5
Q
total body water = __% of body wt in M + F
A
60% males
50% females - more adipose tissue
6
Q
ICF = ___% of total body water
A
67
7
Q
ECF = +++
A
plasma (20%)
interstitial fluid (80%)
lymph and transcellular fluid (negligible)
8
Q
tracers to measure volume of fluid compartments
total body water =
ECF =
plasma =
A
TBW = water ECF = inulin plasma = labelled albumin
9
Q
equation for using a tracer to measure the volume of a fluid compartment
A
initial dose of tracer (mol) / sample concn (mmol/l) = volume (l)
10
Q
insensible and sensible fluid losses
A
insensible = skin and lungs sensible = sweat, faeces, urine
11
Q
in hot temperature and exercise lung loss of fluid __
A
hot = decreases exercise = increases
12
Q
Na K Cl and HCO3 are higher or lower in ICF compared to ECF
A
in ICF - Na and Cl and HCO3 = lower
K = higher
13
Q
main ions in ECF
A
Na Cl HCO3
14
Q
main ions in ICF
A
K
Mg
-vely charged proteins
15
Q
osmotic concns of ICF and ECF are __ at around __
A
equal
300mosmol/l
16
Q
if gain NaCl ICF and ECF volumes __
A
ICF decreases
ECF increases
17
Q
if gain isotonic fluid there is no __ change
ICF and ECF volumes __
A
osmolarity
ECF increase
ICF stays the same
18
Q
> 90% of osmotic concn of ECF is from
A
Na salts = main determinant of ECF volume
19
Q
> 95% of body __ is in ICF
so minor fluctuations in its __ concn => __+__
A
K+
plasma
paralysis + cardiac arrest
20
Q
juxtaglomerular apparatus lies between __+__ in nephron
A
afferent and efferent arteriole
21
Q
in cortical nephrons efferent arteriole > ___ > venules
A
peritubular capillaries
22
Q
20% of nephrons =
80% =
A
20% = juxtamedullary nephrons 80% = cortical
23
Q
key differences of juxtamedullary nephrons compared to cortical nephrons
A
juxta = longer loop of Henle
make more concn urine
single vasa recta that follows loop of Henle (rather that peritubular capillaries)
24
Q
equation for rate of filtration of a substance
A
concn of X in plasma x GFR
25
normal GFR=
120-125ml/min
26
rate of excretion of a substance equation =
concn of X in urine x rate of urine production
27
rate of reabsorption of a substance equation =
rate of filtration - rate of excretion
28
rate of secretion of a substance equation =
rate of excretion - rate of filtration
29
glomerular membrane = _+_+_
glomerular capillary endothelium
basal lamina
slit processes of podocytes - glomerular epithelium
30
the glomerular capillary endothelium in the glomerular membrane is a barrier to ___ filtration
RBC
31
the basal lamina in the glomerular membrane is a barrier to ___ filtration because it is __ due to _+_
-ve plasma proteins
-vely charged
collagen and glycoproteins
32
forces that favour filtration that make up part of net filtration P
glomerular capillary bp (BPgc = 55mmHg)
| Bowman's capsule oncotic P (COPbc = 0)
33
forces that are against filtration that make up part of net filtration P
Bowmans capsule hydrostatic P (HPbc = 15mmHg)
| capillary oncotic P (COPgc =30)
34
net filtration P = __mmHg
10
35
Starling forces are the balance of _+_
hydrostatic and osmotic forces
36
GFR definition
rate at which protein free plasma is filtered from glomeruli into bowmans capsule per unit time
37
GFR = ___ x ___
Kf (filtration coefficient "holiness")
| net filtration P
38
main determinant of GFR
| stays constant along length of glomerular capillary due to ___
glomerular capillary bp
| change in capillary diameter
39
extrinsic control of GFR is due to __
| where decreased blood volume causes increased ___ => vaso__ and decreased ____+__
baroreceptor reflex
sympathetic activity
constriction
glomerular capillary bp and GFR
40
autoregulation/intrinsic control of GFR = __+__
myogenic response
| tubuloglomerular feedback
41
bowmans capsule hydrostatic P increases if ___
| causes GFR to
there is an obstruction => fluid build up in kidneys
| decreases
42
capillary oncotic pressure increases if ___
| causes GFR to
dehydrated
| decrease
43
bowmans capillary oncotic pressure decreases if ___
| causes GFR to __
burned => decreased plasma proteins
| increases
44
plasma clearance definition
volume of plasma completely cleared of a particular substance per min = ml/min
45
plasma clearance = (__x__)/___
[X] in urine x volume of urine
| [X] in plasma
46
clearance of __ = GFR
inulin
47
why is inulin a good measurement of GFR?
```
freely filtered at glomerulus
not absorbed or secreted in nephron
not metabolised by kidney
not toxic
easily measured in urine and blood
```
48
___ clearance is a close approximation of GFR
however some of it is ___
but it is ___ and so easier to measure than inulin
creatinine
secreted in nephron
endogenous
49
filtered, completely reabsorbed in prox tubule and not secreted
glucose
50
urea clearance is greater/less than GFR? because ?
```
less
partly reabs (50%)
```
51
H+ clearance is greater/less than GFR?
| because?
more
| filtered, secreted from peritubular plasma + not reabsorbed
52
RPF (renal plasma flow) is calculated using __
PAH (para-amino hippuric acid)
53
exogenous organic anion used to measure RPF clinically =
PAH (para-amino hippuric acid)
54
PAH features that make it a good indicator of RPF
freely filtered at glomeruli
completely secreted into tubule
not reabsorbed
ie. completely cleared from plasma
55
filtration fraction = __/__ = __%
GFR/RPF
| 20% (125/650)
56
RBF = __ x __/__
RPF
| 1/1-haematocrit
57
RPF normally = ___ ml/min
650
58
__% of fluid and slat is reabs in kidney
99%
59
in proximal tubule ions and solutes are at ___ concn but there are no __/__
plasma
| RBC/large proteins
60
__ml/min is reabs in proximal tubule so __ml/min is goes on to enter loop of Henle
80
| 45
61
in proximal tubule the reabsorbed fluid is ___ with the filtrate therefore there is no change in ___ as you go along the tubule
iso-osmotic
| osmolarity
62
5 things reabs in proximal tubule
```
lactate
glucose
AAs
sulfate
phosphate
```
63
6 things secreted in proximal tubule
```
H+
toxins
drugs eg. morphine
uric acid
bile pigments
hippurates
```
64
NaKATPase is found at the ___ membrane in proximal tubule and increases ___ levels of K+ and __ levels of Na+
basolateral
intracellular K+
interstitial Na+
65
transporters at the luminal surface of proximal tubule for Na reabs
Na glucose
Na AA
Na H+ countertransporter
66
Na+ reabs in proximal tubule sets up an ___ gradient for Cl- to enter interstitial fluid ___ => ___ pull
electrical
paracellularly
osmotic
67
___ of peritubular plasma proteins causes H2O and Cl- reabs in proximal tubule
oncotic drag
68
transporters involved in glucose reabs at proximal tubule
luminal Na glucose cotransporter
| basolateral glucose facilitated diffusion
69
__+___ systems in kidney are saturable and so once Tm is reached clearance is not __
reabsorption and secretory
| constant
70
Tm (transport maximum) of glucose =
| renal threshold therefore for plasma glucose =
2mmol/min
| 10-12mmol/l
71
__% of salt and water, __% of glucose and AAs are reabs in proximal tubule
67 salt and h2o
| 100 glucose and AA
72
loop of henle generates a ___ concn gradient to allow for production of ____
cortico-medullary solute
| hypertonic urine
73
in loop of henle the medullary interstitial fluid is hypo/hypertonic
hypertonic
74
descending limb of loop of henle is highly permeable to ___ but no ___ reabs
H2O
| no salt
75
in ascending limb of loop of Henle __+__ reabs
by __ in thick upper part and __ in thin lower part
is relatively impermeable to __
Na and Cl
active transport in thick
passively in thin
H2O
76
in thick ascending limb of loop of Henle there is the ___ cotransporter = blocked by ___
```
TALH triple (Na K +2Cl)
loop diuretics
```
77
in thick ascending limb of loop of henle interstitial fluids osmolarity ____ => __ cant enter descending limb and H2O leaves it by osmosis => fluid in descending limb is __ and so salt __ => cycle repeats (countercurrent multiplier)
increases
interstitial solutes
concentrated
leaves into interstitium
78
___ fluid leaves loop of henle
hypoosmotic
79
50% of cortico-medullary gradient is contributed to by ___
urea cycle
| other 50% = salt
80
urea cycle for loop of Henle:
| urea ___ into loop > adds solute to ___ > distal tubule is not ___ to urea > collecting ducts ___ 50%(__ promotes this )
```
diffuses passively
interstitium
permeable
reabs
ADH
```
81
blood in vasa recta ___ with interstitial fluid across leaky endothelium
equilibriates
82
3 features of vasa recta that mean salt and urea arent washed away from loop of Henle =
hairpin
freely permeable to NaCl and H2O
blood flow to it is low
83
as vas recta goes down blood osmolarity __ and as it rises the osmolarity ___
increases
| decreases
84
4 hormones that control Na reabs in distal tubule/collecting duct =
aldosterone
ANP
ADH
PTH
85
at resting state the distal tubule has low permeability to _+_ and so ___ is concentrated in tubular fluid
urea and H2O
| urea
86
process that occurs in early distal tubule =
NaCl reabs by NaK2Cl cotransporter
87
processes in late distal tubule and early collecting duct =
Ca2+ reabs
H+ secretion
Na + K reabs (in basal state)
88
the late collecting duct has ___ ion permeability and _+_ permeability are influenced by ADH
low
| urea and H2O
89
octrapeptide synthesised by supraoptic and paraventricular nuclei in hypothalamus =
ADH
90
type 2 ADH receptors are on ____ and ATP>cAMP => more ___
basolateral membrane of tubular cells
| aquaporins inserted on luminal membrane
91
type 1 ADH receptors cause __
SM in arterioles to constrict
92
high concn of ADH in collecting duct => ___ H2O perm and ___ urine as ___ equilibriates with ___
low
hypertonic, small vol
tubular fluid with interstitium
93
most important stimulus of hypothalamus to release ADH =
hypothalamic osmoreceptors sense increased osmolarity
94
__ sitmulates ADH release and __+__ inhibit it (toxic substances)
nicotine increases
| alcohol and ecstasy
95
aldosterone is secreted if __ increases/__ decreases in blood or __ is activated
K+ increases
Na decreases
RAAS
96
increased K+ directly stimulates adrenal cortex to release ___ which causes __
aldosterone
| K+ secretion
97
decreased Na+ indirectly stimulates ___ release through __ causing RAAS activation
Aldosterone
| juxtaglomerular apparatus
98
renin release = ___ sense low __ in distal tubule => increased __ to ___ cells and released
macula densa
sodium
sympathetic activity
granular cells
99
ATII effects =
aldosterone release
thirst
vasoconstriction of arterioles
100
aldosterone acts on luminal ___ and basolateral __
Na+
| NaKATPase
101
__ is activated in HF due to low _+_
causes worsening of HF by __
Rx =
```
RAAS
lbp and low CO
retention
low salt diet
ACEI
loops
```
102
ANP is produced by __ and stored in ___
heart
| atrial muscle cells
103
ANP is released when ___ due to increased ___
atrial muscle cells are stretched
| plasma volume
104
ANP => _+_ increased, ___ decreased and afferent arteriolar vaso___ => increased GFR => _+_ increased filtration and decreased ___ causing decreased CO and TPR
```
Na excretion and diuresis increased
RAAS decreased
dilatation
Na and H2O filtration
decreased sympathetics
```
105
blood pH 6.8 - &.35 =
acidotic
106
blood pH 7.45 - 8 =
alkalosis
107
3 ways in which H+ is constantly added to body fluids
```
carbonic acid formation
inorganic acids (nutrient breakdown)
organic acids (metabolism)
```
108
H2CO3 concn is dependent on ___ controlled by __
and HCO3- by __
therefore pH = __/___ function
PPCO2 - lungs
kidneys
kidneys/lungs
109
kidney - variable reabs of HCO3- and addition of HCO3- to blood depends on ___
H+ secretion into tubule
110
HCO3- reabs -
___ drives H+ secretion into tubule by ___ > + HCO3- > H2CO3 > _+_ enter the cell > ____ > H2CO3 > H+ (secreted) + HCO3- -> ___ and enters interstitium
```
CO2
Na/H exchanger
CO2 and H2O
carbonic anhydrase
basolateral Na/HCO3 cotransporter
```
111
when HCO3 in tubular fluid is low H+ combines with __
| as H+ is still secreted this causes a net gain of ___
phosphate
| HCO3 from cleavage intracellularly from H2CO3
112
titratable acid measures ___ largely as __ in urine
H+ excreted
| H2PO4-
113
titratable acid = the amount of __ added to circulation as a result of its formation
bicarbonate
114
if severely acidotic tubular cells break down ___ from liver by ___ to form ___ which combines with H+ to form __ which is secreted in urine
glutamine
glutaminase
ammonia
ammonium
115
amount of ammonium secreted in urine is the same as ___ added to the blood as a result
bicarbonate
116
H+ excretion = _+_ excretion = new __ generated
Titratable acid and ammonium
| bicarbonate
117
normal bicarb plasma concns
22-26
118
normal PCO2 =
35-45mmHg
| 4.7-6kPa
119
compensation of AB balance =
restoration of pH irrespective of bicarb and PCO2
120
correction of AB balance =
restoration of pH and bicarb and PCO2
121
pH is directly proportional to __/___
[HCO3] / [CO2]
122
causes of resp acidosis =
COPD
| airway restriction, opioids, chest trauma
123
in resp acidosis:
| increased CO2 causes increased __+__ (proportionally more __)
H+ and bicarb
| more H+
124
uncompensated resp acidosis pH and PCO2 =
pH <7.35
| PCO2 > 45 mmHg
125
compensation by kidneys in resp acidosis
PCO2 drives H+ secretion and HCO3- reabs and formation
| H+ is excreted as titratable acid and ammonium
126
causes of resp alkalosis =
```
low PO2 at altitude
hyperventilation
fever
CNS damage
anxiety
```
127
uncompensated resp alkalosis =
pH >7.45
| PCO2 <35mmHg
128
renal compensation of resp alkalosis =
decreased CO2 causes decreased H+ secretion => decreased HCO3- reabs and none new formed - so lose bicarc
129
metabolic acidosis causes =
ingest acids
H+ production - lactic acid/ketones
diarrhoea
130
uncompensated metabolic acidosis =
pH <7.35
| [HCO3-]plasma <22
131
compensation of metabolic acidosis by resp system
peripheral chemoreceptors stimulated by plasma pH
| increase ventilation and decrease CO2
132
renal correction of metabolic acidosis =
decreased CO2 causes HCO3- reabs and fromation with H+ secretion
133
causes of metabolic alkalosis
vomit
ingest alkali
aldosterone hypersecretion
134
uncompensated metabolic alkalosis
pH >7.45
| HCO3- concn plasma >26
135
compensation by resp system in metabolic alkalosis =
peripheral chemoreceptors see increased pH and decrease ventilation
136
correction by kidneys in metabolic alkalosis
not all bicarb is reabs and so decreased H+ secretion
| urine is alkaline
