Module 5 - Fluid Balance - Lecture 1

Question 1

Why is a homeostatic balance of water crucial?

Answer 1

Because water affects the concentration of everything else in the body

Question 2

What is the average daily water balance in an adult male in a thermoneutral environment? (state the values of the gains: drinking, eating and metabolic)

Answer 2

The total mls/24 hours is 2550
Drinking - 1200mls
Eating - 1000mls
Metabolic - 350mls

Question 3

What is metabolic water?

Answer 3

Oxidative phosphorylation produces carbon dioxide and water as end products

Question 4

State the average losses

Answer 4

The total mls/24 hours is 2550
Insensible loss from skin and lungs - 900mls
Sweat - 50mls
Faeces - 100mls
Urine - 1500mls

Question 5

Input and output regulation

Answer 5

Input is regulated by the thirst mechanism

The output is regulated by the urinary losses

Question 6

Internal Environment

Answer 6

The overall effect of activity by all the organ systems is to create within the body the optimum environment for all cells to function

Question 7

What is ECF?

Answer 7

Extracellular fluid, the fluid which bathes each of the body’s cells

Question 8

What is ICF?

Answer 8

Intracellular fluid, the fluid inside all of the cells in the body

Question 9

How is the total body water distributed between?

Answer 9

Both ICF and ECF

Question 10

What are the two compartments in ECF?

Answer 10

80% is interstitial fluid (ISF) and 20% constitutes the fluid portion of the blood = plasma

Question 11

What is plasma?

Answer 11

Continuously circulated to all parts of the body by the action of the heart = dynamic component of the ECF

Continuously refreshes the cells bringing fresh oxygen and nutrients and removing carbon dioxide and wastes

Plasma exchanges nutrients and waste with the ISF

Question 12

Exchange

Answer 12

Oxygen and carbon dioxide exchange is primarily the role of the red blood cells

Exchange only occurs as blood passes through the capillaries of the body

Question 13

Movement

Answer 13

There’s free movement across capillary walls except for plasma proteins which are too large and are restricted to the plasma. So ECF is effectively homogenous with one exception; the body can survive only as long as the ECF is maintained in a state compatible with the survival of its individual cells, i.e. constancy of the ECF is very important

Question 14

What is the major component of the body?

Answer 14

Water - 60% of body weight, 42 litres in the average man

Question 15

What is the body fluid compartments?

Answer 15

Made up of two bags of fluid:

1. ECF: Plasma and Interstitial fluid
2. Intracellular Fluid (ICF) fluid within the cell

Question 16

What must ECF be?

Answer 16

Must be maintained a constant, composition of the ICF differs markedly from the ECF, particularly ions

Essential to regulate ECF potassium ions (K+) (Kidney sorts it out)

Question 17

What does disease state?

Answer 17

Illness is associated with perturbation and even breakdown of homeostatic control mechanism