Body Fluids And Oedema

Question 1

Define homeostasis

Answer 1

A dynamic equilibrium whereby cells, tissues and organisms maintain the status quo

Question 2

Describe the homeostatic mechanism steps

Answer 2

Variable > Sensor > Control Centre > Effector

Question 3

Name 3 bodily systems that rely on homeostasis

Answer 3

• Temperature
• Acid-base balance
• Fluid balance

Question 4

What is the difference between a positive and negative feedback loop?

Answer 4

Negative feedback stops when the effector ceases

Positive feedback enhances or exaggerates the original stimulus and stops when the initiator ceases

Question 5

What can causes blood acidosis?

Answer 5

• Increased production of metabolic acids (metabolic)

- Increased CO2 from hypoventilation (respiratory)

Question 6

What can reverse blood acidosis?

Answer 6

Bicarbonate solution or mechanical ventilation

Question 7

What is the pH limit of tissue survival?

Answer 7

6.8-7.8

Question 8

What two systems control blood pH?

Answer 8

• Lung-respiratory balance

- Kidney-metabolic balance

Question 9

What is the [H+] concentration in pH 7.0 and 7.4?

Answer 9

pH 7.0 = 100

pH 7.4 = 40

Question 10

What composes circulating blood volume and what are the amounts?

Answer 10

5L of blood:

• 3L plasma
• 2L RBC

Question 11

What are the percentage of water volume in an adult male, adult female and child?

Answer 11

Male - 60% water
Female - 50% water
Child - 70% water

Question 12

What are the concentrations of fluid composites?

Answer 12

2/3 intracellular fluid

1/3 extra cellular fluid > 80% interstitial fluid and 20% plasma

Question 13

What happens to a person in terms of fluid balance when they are dehydrated?

Answer 13

• Osmolarity increases
• Cells absorb interstitial fluid
• Aquaporin proteins allow bulk water flow by osmosis

Question 14

What happens in the body when water toxicity occurs?

Answer 14

• High osmotic pressure

- Cells swell and burst

Question 15

What is osmolality?

Answer 15

Measure of number of dissolved particles in a fluid in terms of mass

Question 16

What is one mechanism of oedema?

Answer 16

• Hydrostatic pressure > osmotic pressure

- Water is driven into the extracellular space

Question 17

What is the difference between osmolarity and osmolality?

Answer 17

Osmolarity - Measure of the concentration of osmotically active solutes in a solution (mOsm/kg)
Osmolality- Measured in mOsm/L

Question 18

How do you calculate osmolality?

Answer 18

• Sum of osmotically active ions (Na+, K+, Cl-)
• Na+ + K+ + 2(Cl-)
• Charges must balance

Question 19

What are the 4 main causes of oedema?

Answer 19

• Raised hydrostatic pressure (Heart Failure)
• Decreased oncotic pressure (Liver Disease)
• Increased interstitial oncotic pressure (Inflammation)
• Impaired lymphatic drainage (Lymphodema)