Homeostasis

Question 1

Define homeostasis?

Answer 1

A set of processes by which the body tries to maintain a relatively constant internal environment.

Question 2

What is homeostasis concerned with?

Answer 2

Keeping the levels of factors in the internal environment within narrow limits.

Question 3

What does homeostasis mainly involve?

Answer 3

Regulation of the fluid that surrounds cells (extracellular fluid).

Question 4

What are the 2 major elements of extracellular fluid?

Answer 4

1) . Interstitial fluid (tissue fluid) =
- fluid that leaves blood capillaries.
2) . Blood plasma =
- fluid that surrounds blood cells.

Question 5

How much interstitial fluid leaves blood capillaries?

Answer 5

Approx. 12 litres.

Question 6

How much blood plasma surrounds blood cells?

Answer 6

Approx. 3 litres.

Question 7

List factors in the internal environment that are regulated within set limits?

Answer 7

• Core body temperature.
• Blood pressure.
• Blood gases.
• pH.
• Glucose.
• Calcium ions.
• Blood volume.
• Sodium ions.

Question 8

What happens when the environment surrounding the cells is subjected to changes?

Answer 8

The cells take in (from internal environment) =

• CO2.
• Glucose.
• Amino acids.
• Vitamins.
• Minerals.

Question 9

What happens to cellular waste products in the internal environment?

Answer 9

Raised levels (such as CO2 and ammonia).

Question 10

How is the temperature of the internal environment changed?

Answer 10

Heat gained from muscle contraction and metabolism changes the temp.

Question 11

Why do cells survive these challenges?

Answer 11

The composition of the internal environment is stabilised by;

• homeostatic regulation.

Question 12

Why is it important to keep the surrounding cells within these narrow limits?

Answer 12

Chemicals within the cells may become subject to altered activity.

Question 13

What are the homeostatic mechanisms in the body based around?

Answer 13

Feedback loop.

Question 14

What are self-adjusting mechanisms?

Answer 14

Control process is built into the system =

• form a loop/cycle.
• usually reacts to change automatically.

Question 15

What are the 3 factors of a feedback loop?

Answer 15

1). Receptor =

• stimulus received.
• converted into a signal.

2) . Controller =
- interprets signal.
3) . Effector =
- produce response.

Question 16

What systems control the homeostatic mechanisms?

Answer 16

• Nervous system.

- Endocrine system.

Question 17

What is negative feedback?

Answer 17

Reverses any shift from the equilibrium.

• stops deviating from the norm.

Question 18

When does negative feedback kick in?

Answer 18

When any slight deviation from the norm occurs.

Question 19

Explain what negative feedback is?

Answer 19

• Automatic response to a change in the internal environment.
• Involves corrective mechanisms (of change).
• Reverses the original change and brings internal environment back to normal.

Question 20

Give an example of negative feedback?

Answer 20

Stress =

• change is detected by receptor.
• corrective measures are activated.
• corrective measures counteract the change back toward set point (back to normal).