Physiology 1 - Fluid Compartments and Homeostasis Flashcards
What is meant by the term osmolarity?
The concentration of osmotically active particles within a solution
What are the units of osmolarity for body fluids?
mosmol/l
What is the osmolarity of most body fluids?
300mosmol/l
What effect does an isotonic solution have on cell volume?
No effect
What effect does a hypotonic solution have on cell volume?
Increase
What effect does a hypertonic solution have on cell volume?
Decrease
What percentage of a male’s body weight is made up of water?
60%
What percentage of a female’s body weight is made up of water?
50%
Why do females have less total body water than males?
They have more fat cells
Which body fluid compartment makes up 67% of total body water?
Intracellular fluid (ICF)
Which body fluid compartment makes up 33% of total body water?
Extracellular fluid (ECF)
What are the two major components of the extracellular fluid volume?
Interstitial fluid and plasma
Which component makes up 80% of the extracellular fluid volume?
Interstitial fluid
Which component makes up 20% of the extracellular fluid volume?
Plasma
What tracer can be used to measure total body water?
Tritiated water
What tracer can be used to measure extracellular fluid volume?
Inulin
What tracer can be used to measure plasma volume?
Labelled albumin
What are the three main examples of sensible losses of water from the body?
Sweat, faeces, urine
What is meant by the term insensible losses of water?
There are no regulatory mechanisms to prevent these losses
How much water does the average person lose as urine each day?
1500ml
If an individual is in hot weather or does prolonged heavy exercise, what is the only way to maintain water homeostasis?
Increase water ingestion
Which ion(s) is/are found in higher concentrations in the ECF compared with the ICF?
Sodium, chloride, bicarbonate
Which ion(s) is/are found in higher concentrations in the ICF compared with the ECF?
Potassium
If the osmolarity of the ECF increases, what happens to the volume of the ECF and ICF?
ECF volume will increase, ICF volume will decrease
If the osmolarity of the ECF decreases, what happens to the volume of the ECF and ICF?
ECF volume will decrease, ICF volume will increase
Why can minor fluctuations in plasma potassium levels have detrimental consequences?
Potassium plays a major role in establishing the membrane potential
What are some potential consequences of increased ECF potassium?
Paralysis and cardiac arrhythmias
