Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Primary Physiology > Body Fluids > Flashcards

Body Fluids Flashcards

1
Q

Proportion of body water by weight in young adult male and female
Neonate?

What causes large variation in adults?

A

60%
50%
80%

Increasing adipose tissue means less water

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Proportion of ECF to ICF of Total water and weight

A

34% vs 66% of total body water
(20% vs 40% of total body weight)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Proportions of ECF in different compartments

A

Interstitial 75% of ECF (approx 15% body weight)
Plasma 25% of ECF (approx 5% body weight)
Transcellular (approx 1% body weight)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the implication of the impermiability of the capillary membrane to proteins

A

Higher concentration of proteins in plasma so higher concentration of chloride in ISF to maintain electrical neutrality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is Transcellular fluid

A

Fluid separated from plasma by epithelial layer e.g. csf, interocular fluid, bile, gi secretions, sweat, pleural fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Method of working out total blood volume?

A

Measure plasma volume using radioisotope dilution with a isotope that remains in plasma such as radioactive albumin then derive using haematocrit.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How to measure fluid compartment volumes? Issues that cause under or over estimates?

A

Inject a known volume of a radioactive isotope which stays in the compartment to be measured directly into the compartment. Measure its concentration and derive volume (volume = mass of indicator/concentration)
Issues if it doesn’t fully distribute - underestimates size
Issues if leaves compartment - overestimates size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What isotopes can be used to measure by dilution
Total body water
ECF
Plasma

A

TBW - antipyrine D2O
ECF - radioisotopes eg of Na or Br (though enters cells so overestimates) or saccharides such as insulin or mannitol (though incompletely distribute so underestimate)
Plasma volume - albumin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How can we calculate ICF volume

A

TBW - ECF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How can we calculate interstitial fluid volume

A

ECF-plasma volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why do we use moles instead of just mass

A

Chemical reactivity is proportional to number of molecules not weight

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is one mole of a substance

A

6.022 x 10^23 molecules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define avogadros constant

A

The number of atoms in 12g of carbon12
6.022 x 10^23

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Distinguish molarity from molality

A

Molarity - number of moles of solute per litre of solution (solute + water) (mol/L)
Molality - number of moles of solute per kg of solvent (just water) (mol/kg H2O)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the gram equivalent weight of an element?

A

The weight of an element that reacts with 8.000g O2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is a normal solution in chemistry

A

1g equivalent solute per litre of solution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is an electrical equivalent weight?

A

The atomic weight of an ion divided by its valency (eg Ca2+ = 40/2 = 20)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is osmosis

A

Movement of water across a semipermeable membrane by diffusion to equalise solution concentrations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is osmotic pressure

A

The pressure required to prevent osmosis when the solution is separated from pure solvent by a semipermeable membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the universal gas constant

A

8.32 J/K/mol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the equation for osmotic pressure? Name and formula

A

Van hoff’s

Pie = RTC
Osmotic pressure (pascals) = universal gas constant (J/K/mol) x absolute temp (K) x osmolality (mOsm/kgH2O)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is an Osmole

A

Amount of solute that exerts an osmotic pressure of 1atm when placed in 22.4 litres of solution at 0 degrees Celsius

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is a rule of thumb for calculating number of osmoles

A

For a substance that does not associate or dissociate 1 osmole = 1 mole
For a solution that fully dissociates in 2 osmotically active particles (eg NaCl) 1 osmole = 1 mole/2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Define osmolarity and osmolality
Why is it Important?

A

Osmolarity - number of osmoles of solute per litre of solution (solute + water)
Osmolality - number of osmoles of solute per kg of solvent (water alone)

Osmolality is independent of temperature and independent of the volume taken up by the solute.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Which would be higher in a human, osmolality or osmolarity When is it more significant
Osmolality usually higher as protein and lipid content ‘dilute’ osmolarity More significant in gross hyperproteinaemia or hyperlipidaemia
26
Typical range for plasma osmolality Significance for rest of body?
280-295mOsm/KgH2O steady at 290 Rest of body same - water moves freely equalising all
27
Given water moves freely between compartments and osmolality is kept equal across the body what determines compartment volume
Number of osmoles
28
How is body fluid osmolality regulated?
Secretion of ADH in response to increase in osmolality or decreased total body water detected in the hypothalamus
29
How is osmolality measured
Depression of freezing point of solution compared to pure solvent Estimated by molality of major solutes: Plasma osmolality = 2 x [Na] + [glucose] + [urea]
30
When estimating plasma osmolality why is Na concentration doubled
To account for anions eg Cl and bicarb
31
What is tonicity What contributes to it in the ECF with relevance to ICF
The relative osmolality between two fluid compartments All solutes in ECF contribute to osmolality but only those which do not cross cell membrane contribute to tonicity
32
What is the characteristic of an isotonic solution with regards to cell size
No change in size when a cell suspended in an isotonic solution
33
What is oncotic pressure What other name can it have
The osmotic pressure exerted by the plasma proteins which are unable to leave the vessels. Plasma colloid osmotic pressure
34
What is the most important determinant of oncotic pressure, how much is oncotic pressure in mmHg
Albumin, around 75% of the total 25mmHg
35
What are the three main mechanisms of transport across the capillary endothelium
Filtration - hydrostatic pressure forcing fluid out of the capillaries Diffusion - passive movement of substances down concentration gradient through fenestrations and intercellular junctions. Main barrier is basement membrane Transcytosis - active transfer of substances by endo and exocytosis across endothelial cells
36
What is the Gibbs-Donnan effect
The presence of a non-diffusible solute such as a protein on one side of a membrane affects the distribution of the diffusible ions. The negative charge on the protein holds +ve ions (Na) back to preserve electroneutrality
37
What is the implication of the Gibbs Donnan effect at the capillary membrane?
Higher Na concentration in plasma vs ISF and higher Cl concentration in the ISF vs plasma Gives a small electrical potential gradient
38
How does the Gibbs donnan effect balance mathematically
Cation x anion on one side of membrane = cation x anion on the other Eg 9x4 = 6x6
39
What is the Nernst equation?
E = 60/z.log10(Ci/Ce) (mV) (mmol/L) Equilibrium potential = constant (at 37o)/valence . Log10(internal concentration of ion/external concentration of ion) Constant derived by 2.3RT/F 2.3.universal gas constant.temp(K)/faridarys constant
40
What causes the small difference in ion concentration between plasma and ISF
Gibbs donnan effect
41
Rough weight of protein in plasma?
7g per 100ml
42
Plasma vs ICF concentration of Na. Mmol/L
153 10
43
Plasma vs ICF concentration of K Mmol/L
4.3 159
44
Plasma vs ICF concentration of Ca Mmol/L
2.7 <1
45
Plasma vs ICF concentration of Mg Mmol/L
1.1 40
46
Plasma vs ICF concentration of Cl Mmol/L
112 3
47
Plasma vs ICF concentration of HCO3 Mmol/L
25.8 7
48
Plasma vs ICF concentration of Proteins Mmol/L
15.1 45
49
Functions of albumin in plasma
Transport of free fatty acids and bilirubin Oncotic pressure
50
Intravascular half life of albumin
19 days
51
Which is the heaviest immunoglobulin, why? Implication of this to its distribution
IgM It’s a pentameter in contrast to dimer IgA and monomers of IgG,IgM and IgD Confined to intravascular space
52
Rough weight in daltons of a Ig monomer? Implication for IgA and M
150,000 to 190,000 Multiply it up by number of groups x2 for IgA (400,000) and x5 for IgM (900,000)
53
Rough pH, Na, K, Cl and HCO3 of gastric juices
pH3 Na 60 K 9 Cl 84 HCO3 0
54
Rough pH, Na, K, Cl and HCO3 of bile
pH 8 Na 149 K 5 Cl 101 HCO3 45
55
Electrolyte concentrations in Hartman’s Osmolality
Na 131 K 5 Ca 4 Cl 112 HCO3 29 Osmolality 281
56
Electrolyte concentration normal saline Osmolality
Na and Cl 154 308
57
Osmolality of 5% glucose
278
58
Electrolyte composition of 4% glucose 0.18% NaCl Osmolality
Na and Cl 31 Osmolality 284
59
Daily water and key electrolyte requirements for an adult
Water 35ml/kg Na/K 1 mmol/kg
60
Why does Hyperchloraemic acidosis occur on excessive fluid resus with normal saline
Excess Cl leads to renal HCO3 secretion
61
Causes of hypovolaemia hypernatraemia Treatment
Loss of free water eg Diabetes insipidus Osmotic diuresis Vomiting Replace free water - orally if possible, slow correction of volume deficits with normal saline then further water deficit with hypotonic fluids.
62
How can urine measurements be used to classify hypernatraemia?
High urine osmolality and low urine output indicates normal ADH function suggesting hypernatraemia from external loss or inadequate intake Huigh urine osmolality with high urine output suggests osmotic diuresis
63
Cause of hypervolaemic hypernatraemia
Iatrogenic fluid replacement
64
How can you estimate water deficit in a hypernatraemic patient
Water deficit = ([Na] / 140xTBW) - TBW
65
Signs and symptoms of hypernatraemia
Thirst lethargy weakness confusion coma seizures
66
Signs and symptoms of hyponatraemia
Malaise, nausea, headache, irritability, confusion, weakness, coma, seizures
67
Causes of spurious hyponatraemia
Sample from drip arm High serum lipid or protein causing dilutional Marked hyperglycaemia causing dilutional (add about 4 to Na for every 10 of BM above 20)
68
Causes of hypervolaemic hyponatraemia Expected urinary sodium
Heart failure, renal failure, hepatic failure, iatrogenic Urinary sodium <20mmol/L
69
Causes of euvolaemic hyponatraemia Tests to differentiate?
Urinary osmolality >100 and Na >20 - SIADH Urine osmolality <100 - water overload, severe hypothyroid, low glucocorticoids
70
Causes of siadh
Tumour (lung - small cell, pancreas, prostate, thymus, lymphoma) Cerebral abscess, stroke, haemorrhage, sle Tb, pneumonia, lung abscess Opiates, ssris, cytotoxic, psychotropics Trauma, hiv, abdominal surgery
71
Causes of hypovolaemia hyponatraemia and differentiating factor between them
Urinary Na >20 - loss from kidneys - addisons, renal failure, diuretics, osmolarity diuresis (e.g. high glucose or urea) Urinary Na <20 - loss elsewhere - d+v, fistula, burns, SBO, trauma, cystic fibrosis, heat exposure
72
Treatment of symptomatic hyponatraemia
Cautious rehydration with normal saline, max rise 15mmol/L per day if chronic or 1mmol/hr if acute In emergency hypertonic saline
73
Treatment of asymptomatic hyponatraemia
Fluid restriction Consider demeclocycline (ADH antagonist) Treatment of underlying disorder
74
How to calculate amount of Na needed to raise serum Na in hyponatraemia
Na required (mmol/L) = (desired Na - measured Na) x TBW
75
Features of hyperkalaemia Causes
Arrhythmia, weakness, numbness, confusion Renal failure, addisons, iatrogenic
76
Features of hypokalaemia Causes
Tachycardia, pvcs, weakness, hypotonia, muscle paralysis, alkalosis Insulin, diet insufficiency, malbsorption, Cushing, hyperaldosteronism, diarrhoea, vomiting,
77
Max rate of k administration Why
0.5 mmol/kg/hr To allow equilibrium between intra and extracellular compartments.
78
Roughly what deficit of total body potassium is present with a 1 mmol decrease in plasma value?
100mmol
79
Where is most calcium stored in the body?
Bone 99%
80
Features and causes of hypocalcaemia
Tetany, convulsions, ectopic calcification if CNS Hypoparathyroidism, thyridecomy, Vit D deficiency, renal failure, hyperventilation
81
Features and causes of hyperkalaemia
Stones, moans and psychic groans (renal stone, personality change, weakness, atrophy, abdominal pain) Hyperparathyroidism, malignancy, sarcoidosis, multiple myeloma, vit d toxicity,
82
Where is most body magnesium
Bones and teeth >50%
83
Body role of mg
Cofactor in many reactions (all kinases)
84
Features and causes of hypomagnesaemia
Tetany, weakness, depression, irritability, convulsions Diarrhoea, malabsorption hyperaldosteronism
85
Features and causes of hypermagnaesemia
Prolonged AV and IV conduction Iatrogenic, renal failure
86
What is the anion gap Normal value
Difference between measured cations and anions in plasma 12-18mmol/L
87
Causes of metabolic acidosis with normal anion gap
Loss of bicarb replaced with chloride p
88
Causes of metabolic acidosis with raised anion gap
Overproduction or injection of acid e.g. salicylates, dka
89
How permiable is the lymphatic system. Why? Q
A series of blind ended tubules with endothelium similar to capillaries but no basement membrane or intracellular gaps. Pinocytosis makes it very permiable to proteins
90
Function of lymph nodes
Encapsulated collections of phagocytic cells that engulf bacteria keeping distal lymph sterile normally.
91
Where does lymph drain to? Through what?
Right lymphatic duct and thoracic duct drain into subclavian veins.
92
24 hr volume of production of lymph
2-4 litres
93
What promotes flow of lymph
Low resistance valves vessels High resistance of returning interstitial space Adjacent arteriolar pulsetations Thoracic pressure driving forward flow
94
Functions of lymph
Immunological Drainage of fluid Transport of nutrients
95
How does lymph protein and electrolyte content compare to plasma, what does it contain
Lower than plasma Contains coagulation factors, antibodies, lymphocytes Electrolyte content similar
96
How much csf exists at any one time
150ml
97
How much csf is produced in 24 hrs
600ml
98
Where is csf produced
Choroid plexuses and endothelium of cerebral capillaries (30%)
99
Where are choroid plexuses located
3rd and lateral ventricles
100
Route of flow of csf
Lateral ventricles Third ventricle Fourth ventricle Foramen of luschka and magendie Circulates around brain stem, brain and spinal cord Re absorbed by subarachnoid villi in Venous sinus
101
What is normal csf outflow pressure What happens if it drops low to help
11.2 mmgh Reabsorption stops
102
Composition of csf
Ultrafiltrate Low protein 0.3 g/L Bicarb and na slightly low K and glucose around half plasma Ph 7.32 Osmolality 290 PCo2 slightly higher than plasma
103
What is the function of the blood brain barrier
Provides tight control over CNS ions Protects brain from transient changes in glucose Protects brain from toxins Prevents neurotransmitters entering systemic circulation
104
Relationship between csf and brain interstitial fluid
They equilibriate but slowly
105
Where are the chemoreceptors responsible for resp control located What do they sense
Ventral surface of medulla and floor of fourth ventricle H+
106
What is the bbb permeability to co2 and h / HCO3 Implication for resp control
Permiable to co2 but much less so to others Co2 diffuses into csf and brain interstitial fluid equilibriating with arterial pO2
107
What is the implication of the low protein state of the csf on co2
Less buffering activity so pH changes for a given Co2 are greater
108
Features of aqueous humour
Plasma dialysate with hourly turnover Produced by ciliary body Drains by canal of schlemm Metabolic and respiratory substrate for anterior chamber
109
Normal interocular pressure
15-18mmhg
110
What is the composition of vitreous humour
Gelatin like protein vitrein
111
How is pleural fluid created? Why is there so little?
Ultrafiltration of plasma in capilaries on parietal and visceral pleura These capillaries have low hydrostatic pressure and high colloid pressure so most is reabsorbed
112
What might happen to UO on administration of NaCl to a hypovolaemic hyponatraemic Why Risk Solution?
Sudden increase Hypovolaemia resolved so brain ceases release of ADH and rebound UO Sudden over correction due to concentration Administration of 2mcg IV desmopressin (DDAVP)
113
Which hyponatraemics is desmopressin to control UO contraindicated
Hypervolaemic (eg heart failure) Uncontrolled free water intake (eg psychogenic polydipsia)
114
How much should Na be corrected in hyponatraemia
Max 0.5mmol/hr 12mmol/day
115
Equation for predicting change in serum Na concentration with administration of 1L of infusate Name and formulae Issue
Adrogue-Madias formulae Change in Na = ([na in infusate] - [serum Na]) / TBW + 1 Can underestimate increase as doesn’t account for renal handling of Na
116
What drugs aim to increase water excretion to manage hyponatraemia Example Function Why not used
Vaptans (tolvaptan) Antagonist at V2 vasopressin receptor Not used as rapidly can overcorrect

Primary Physiology (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions