L22: Homeostasis

Question 1

5 elements of homeostasis

Answer 1

1. Spatial
2. Temporal
3. Quantity
4. Quality
5. Dynamic

Question 2

Components of homeostasis

Answer 2

1. Sensor
2. Controller
3. Effector
4. Variable

Question 3

Hierarchy of organisation in human body

Answer 3

Cell
—> Tissue
—> Organ
—> System

Question 4

Types of signals

Answer 4

1. Chemical signals
   - Autocrine
   - Paracrine
   - Endocrine
2. Electrical signals —> Nerve impulse

Question 5

Classification and volume of body fluids

Answer 5

Total body fluids (42L, 60% body weight)

• Intracellular (28L)
• Extracellular (14L)
  —> Interstitial (3/4 = 10.5L)
  —> Plasma (1/4 = 3.5L)

Question 6

What to measure extracellular volume and plasma volume

Answer 6

Extracellular fluid volume: Inulin

Plasma volume: Albumin

Question 7

Total body stores of Na+ and K+

Answer 7

[Na+] = [K+] = 3000mmol

Question 9

How to calculate plasma osmolality

Answer 9

2x [Na+] + [K+] + [urea] + [glucose]

Question 10

How to calculate efficiency of negative feedback and examples

Answer 10

Efficiency = Correction / Error

E.g. thermoregulation
Control of parathyroid hormone

Question 11

Examples of positive feedback

Answer 11

1. Childbirth (nerve signal from cervix —> Posterior pituitary gland —> oxytocin release)
2. Blood clot
3. Estrogen on preovulatory LH surge
4. Generation of nerve impulse (sodium influx, action potential)