Homeostasis

Question 1

Define Homeostasis, and its importance in the body.

Answer 1

Homeostasis is the balance of the equation of life within the body. It is vital that this balance is maintained, as any disturbance can cause difficulty or harm in the survival of the organism. What is used in the body must be replenished.

Question 2

Define Physiology.

Answer 2

Physiology (physio meaning exercise in Latin) is the state and maintainence of Homeostasis (a constant internal environment).

Question 3

Define Pathology.

Answer 3

Pathology (pathos meaning suffering in Latin) is the failure to maintain Homeostasis (a constant internal environment). This is caused by anything that imbalances the internal environment to a point that it is not adequately corrected by the body.

Question 4

What does Homeostasis require in order to be maintained, in terms of the organ systems?

Answer 4

Homeostasis requires the integration of organ systems. This is the interaction and coordination of all organ systems (the Nervous and Endocrine Systems co-ordinate and control all other organ systems).

Question 5

What does Homeostasis require in order to be maintained, in terms of the equation of life?

Answer 5

Homeostasis requires constant input to equate constant output. It has a range in which it can tolerate change, but the overall input of nutrients and oxygen must equal the output of energy and waste.

Question 6

Why is Homeostasis important?

Answer 6

Without it, we would simply die. Homeostatic control allows the body to maintain temperature, pH, etc. If it could not do this, our temperatures would rise/lower and denature proteins, etc.

Question 7

What are the main mechanisms of maintaining Homeostasis?

Answer 7

1. Negative Feedback (the most important and common one)
2. Feedforward
3. Positive Feedback

Question 8

Describe Negative Feedback.

Answer 8

• a homeostatically regulated condition (like temperature) shifts from the normal range
• a signal (usually Nervous or Endocrine) is sent to produce a response (like shivering or sweating) to rectify the disturbance
• the homeostatically regulated condition returns to normal range

Question 9

Why is Negative Feedback “negative”?

Answer 9

Negative Feedback is named as such as it “switches off” or “removes” the disturbance. It gets rid of it - think of it “subtracting” the bad thing away from the good Homeostatic whole.

Question 10

How big is the size of the response in Negative Feedback?

Answer 10

The size of the response in Negative Feedback is proportional to the size of the disturbance. Consider; if there is only a slight chill, there will only be mild shivering. If it is very cold, the shivering will be more intense.

Question 11

What kind of response is the following example? Why?
- Person works outside on hot dry day
- Loses body water by evaporation
- Body fluids become more concentrated
- Internal receptors sense disturbance to homeostatically controlled condition (body fluid concentration)
- Thirst pathways stimulated
- Person seeks out and drinks water
- Water added to body fluids decreases body fluid concentration

Answer 11

Negative Feedback. This is because it is a self-limiting response - it removes the trigger or the “disturbance” that caused the response, which then stops the response once the trigger or “disturbance” is removed.

Question 12

What are the characteristics of Negative Feedback Systems?

Answer 12

1. There is oscillation around the set point.
2. Restores the regulated condition AFTER its initial disturbance, but cannot prevent the disturbance from happening.

Question 13

Describe Feed-Forward Systems.

Answer 13

a