Session 1 - Homeostasis

Question 1

Define homeostasis

Answer 1

The process where cells, tissues and organisms maintain a state of internal balance

Question 2

What five things need to be maintained constant in the internal environment?

Answer 2

• concentration of oxygen, carbon dioxide, salt and other electrolytes
• concentration of nutrients and waste products
• pH of internal environment
• Temperature
• volume and pressure of fluid and cell compartments equalised

Question 3

What fundamental techniques are used to maintain homeostasis?

Answer 3

Positive and negative feedback loops

Question 4

How many litres of blood is in the standard 70 kg male?

Answer 4

5 litres

Question 5

Total body water in a 70 kg male?

Answer 5

42 kg = total body water
Intracellular Fluid Volume = 2/3 total body water
Extracellular fluid volume = 1/3 total body water

Interstitial fluid volume = 75% ECF Vol
Plasma Vol = 25% ECF Vol