Fluids and electrolytes

Question 1

Functions of water:

Answer 1

• Acts as a solvent, allowing electrolytes to ionize
• Is a reagent in many chemical reactions
• Acts as a transport medium e.g blood
  -Is a lubricant, eg, synovial fluid and mucus

Question 2

Understand distribution of fluids in the body:

Answer 2

Total body water varies from 45% to 75% of total body weight

• Males of 70kg will have around 50-60%
• Females around 50%
• Infants around 75%

Question 3

Understand distribution of sources of body water gain and loss.

Answer 3

Input
- Water gained in drinks and moist food (Food and drink)
- Water gained from metabolism (Produced by cells)

Output
- Water lost in urine (kidneys as urine)
- Water lost through skin (skin by diffusion and by sweat)
- Water vapour lost through lungs (lungs with expired air)
Water lost through faeces and sweat (intestines as faeces)

Question 4

Understand the regulation of body water gain.

Answer 4

Dehydration occurs when water loss is greater than water gain, therefore there is a decrease in volume and increase in osmolarity of body fluids.
The increase of osmolarity is detected by the thirst centre in the hypothalamus which triggers the urge to drink
Dehydration stimulates the production of aldosterone via the renin-angiotensin-aldosterone (RAA) pathway
The main way to regulate body water balance is by adjusting the volume of water intake.

Question 5

How water moves between compartments

Answer 5

Intracellular and Extracellular fluid compartments.

Intracellular - intracellular fluid is INSIDE the cells (2/3 of the bodies fluid)

Extracellular - extracellular fluid OUTSIDE the cells (1/3 of the bodies fluid)

Question 6

Understand electrolyte composition of fluid compartments.

Answer 6

• Sodium most prevalent in extracellular compartments
• Potassium most prevalent in intracellular compartment
  Electrolytes - a substance which forms ions in a water solution
• Electrolytes are a tool to control the movement of fluids between the fluid compartments.
• By manipulating electrolyte concentration, we can alter the movement of bodily fluid via osmosis

Question 7

Excess water:

Answer 7

In the body causes over-hydration and the cells start to overfill, causes increased workload of the heart and SOB
Insufficient water - in the body causes dehydration, and a drop in blood volume and therefore a drop in blood pressure can decrease renal function and tissue perfusion