Fluid in the body

Question 1

What % of body content is water?

Answer 1

60%

Question 2

How does body fat affect the bodies water content?

Answer 2

Obese person = 40% body is water

Lean person = 80% body is water

Question 3

What three things manage body water content?

Answer 3

Hormonal mechanisms
Circulatory mechanisms
Renal Mechanisms

Question 4

What is body water balance?

Answer 4

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

Question 5

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

Answer 5

The Intracellular fluid = 2/3 of body water

The Extracellular fluid = 1/3 of body water

Question 6

How is the ECF divided and what are the breakdowns?

Answer 6

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

Question 7

What are the volumes of these breakdowns?

Answer 7

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

Question 8

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

Answer 8

Cell membranes

Question 9

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

Answer 9

Blood capillary walls

Question 10

Describe water intake

Answer 10

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)

Question 11

Describe water loss

Answer 11

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)

Question 12

Describe the ionic makeup of plasm and interstitial fluid?

Answer 12

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.

Question 13

What is Colloid Osmotic Pressure?

Answer 13

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

Question 14

Describe how oedema occurs.

Answer 14

• 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

Question 15

What is CSF?

Answer 15

Cerebrospinal Fluid

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

Question 16

How much CSF is there and what is its composition?

Answer 16

150 ml.

No cells present, lower protein content and slightly different ionic content

Question 17

What does CSF do?

Answer 17

Supports, protects and supplies nutrients

Question 18

What is the blood-brain barrier?

Answer 18

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