Physiology (1-5) Flashcards Preview

Year 2 - Renal (DP) > Physiology (1-5) > Flashcards

Flashcards in Physiology (1-5) Deck (126)
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1

What is osmolarity?

Concentration of osmotically active particles in a solution

2

What is the approximate osmolarity of the body's fluids?

~300mosmol/L

3

How can the osmolarity of a solution be calculated?

If the following are known:
- Molar concentration
- Number of particles present

4

What is the osmolarity of a 100mM solution of magnesium chloride?

Molar concentration = 100mM
Number of particles present = 3
Osmorality = 100 x 3 = 300mosmol/L

5

What are the units of osmolality?

osmol/kg of water

6

When are osmolarity and osmolality bascially interchangeable?

Weak solutions
Body fluids

7

What is tonicity?

Effect a solution has on cell volume

8

What effect does a hypotonic solution have on cells?

Cell lysis

9

What effect does a hypertonic solution have on cells?

Cell shrinkage

10

What does tonicity take into account?

Solute's ability to cross cell membranes

11

How much of the total body water is made up of ICF?

67%

12

How much of the total body water is made up of ECF?

33%

13

What forms the ECF?

Plasma (20%)
ISF (80%)
Lympha and transcellular fliud (Negligible)

14

What tracer can we use to calculate total body water?

³H₂O

15

What tracer can we use to calculate ECF?

Inulin

16

What tracer can we use to calculate plasma volume?

Labelled albumin

17

How can we calculate ICF?

TBW = ECF + ICF
(We know TBW and ECF from ³H₂O and Inulin respectively)

18

How can we calculate the volume of distribution?

1. Add a does of tracer (D) to an unknown volume of water (V)
2. Allow tracer to mix evenly
3. Take a small sample and measure [Tracer] (C)
4. Calculate V as follows:
V(litres) = Does (D)/[Sample](C)
Where [Sample] = Mass/Volume in mg/L

19

Calculate the volume of distribution for the following values:
- Dose given = 42mg
- Sample volume is 5ml
- Sample tracer mass is 0.01mg

[Tracer] in sample = 0.01/0.005 = 2mg/L
V = 42/2 = 21L

20

Which of the following are sensible water losses and which are insensible:
- Sweat
- Faeces
- Skin
- Urine
- Lungs

Sensible:
- Sweat
- Faeces
- Urine
Insensible:
- Skin
- Lungs

21

What sources of water loss are increased and decreased in hot weather?

Increased:
- Sweat
Decreased:
- Lungs
- Urine

22

What sources of water loss are increased and decreased during prolonged heavy exercise?

Increased:
- Lungs
- Sweat
Decreased:
- Urine

23

What is the main method of maintaining water balance?

Increasing water intake

24

What is the ionic composition of ICF in regards to the following ions:
- Na+
- K+
- Cl-
- Bicarbonate

Sodium -> 10mM
Potassium -> 140mM
Cloride -> 7mM
Bicarbonate -> 10mM

25

What is the ionic composition of ECF in regards to the following ions:
- Na+
- K+
- Cl-
- Bicarbonate

Sodium -> 140mM
Potassium -> 4.5mM
Cloride -> 115mM
Bicarbonate -> 28mM

26

What are the main ions in the ICF?

Na+
Cl-
Bicarbonate

27

What are the main ions in the ICF?

K+
Mg²⁺
Negatively charged proteins

28

What causes water movement between the ICF and ECF?

Osmotic gradient

29

What results when there is a gain or loss of H₂O in regards to fluid osmolarity and ICF/ECF volumes?

Change in fluid osmolarity
Similar change in ICF and ECF volumes

30

What results when there is a gain or loss of NaCl in regards to fluid osmolarity and ICF/ECF volumes?

Change in fluid osmolarity
Increased ECF NaCl:
- Increased ECF volume
- Decreased ICF volume
Decreased ECF NaCl:
- Decreased ECF volume
- Increased ICF volume