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Membranes and Action Potentials > Fluid in the body > Flashcards

Flashcards in Fluid in the body Deck (18)
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What % of body content is water?



How does body fat affect the bodies water content?

Obese person = 40% body is water
Lean person = 80% body is water


What three things manage body water content?

Hormonal mechanisms
Circulatory mechanisms
Renal Mechanisms


What is body water balance?

The relationship where the body balances the body water content by intaking the same amount as it loses


What are the two types of body water and what percentage are they?

The Intracellular fluid = 2/3 of body water
The Extracellular fluid = 1/3 of body water


How is the ECF divided and what are the breakdowns?

Interstitial fluid (fluid that surround the cells)= 80% of ECF
Plasma (fluid in circulatory system) = 20% of ECF


What are the volumes of these breakdowns?

ICF = 27 Litres
Interstitial Fluid = 11
Plasm = 3-3.5 Litres


What is the barrier between the intracellular fluid and the interstitial fluid?

Cell membranes


What is the barrier between the Interstitial fluid and the plasm?

Blood capillary walls


Describe water intake

Water intake occurs via the plasma. It occurs from metabolic reactions (around 200ml a day) and food and drink (around 1.5-2.5 L a day)


Describe water loss

Water loss occurs via the plasma. It occurs from water loss from kidneys (0.5-1.5 L a day).
Lungs (0.3-0.4 L a day)
Skin (0.2-1 L a day)
Faeces (0.1-0.2 L a day)


Describe the ionic makeup of plasm and interstitial fluid?

Similar as small ions can move across capillary walls with fluid.
Proteins are to big so the protein content of Plasma is much higher than interstitial fluid.


What is Colloid Osmotic Pressure?

Because of the higher concentrations of proteins in the plasm, there is a lower concentration of water. This creates a concentration gradient from the interstitial fluid down a concentration gradient into the plasm.
So plasma proteins help to retain water in plasma


Describe how oedema occurs.

-Starvation creates a lack of proteins in plasma
- initiates the breakdown of muscle tissue to replace plasma protein
-loss of plasm proteins removes the concentration gradient so fluid not retained in plasma
-to much water in interstitial spaces = swelling = kwashiorkor


What is CSF?

Cerebrospinal Fluid
A specialised part of the ECF, found in the cerebral ventricles, and outer portions of brain and spinal cord


How much CSF is there and what is its composition?

150 ml.
No cells present, lower protein content and slightly different ionic content


What does CSF do?

Supports, protects and supplies nutrients


What is the blood-brain barrier?

The capillary walls in the brain are much less leaky and this stops many elements of the blood from entering the brain keeping the ionic composition of CSF consistent