Homeostasis

Question 1

What is homeostasis

Answer 1

Relatively constant internal environment in which all processes work optimally

Question 2

What is a negative feedback reaction

Answer 2

Homeostatic range shifted from the normal range.
Signal generated to produce a response.
Corrects original disturbance brings back to normal range.

Question 3

What is an example of a negative feedback reaction

Answer 3

Question 4

What is a feed forward reaction

Answer 4

Body’s additional receptors anticipate change and activate earlier response

Question 5

Example of feed forward system

Answer 5

Glucose receptors in the GI tract increase insulin secretion before raised blood glucose

Question 6

What is positive feedback system

Answer 6

Examples best way to explain:
An initial triggers causes influx of charged Na+ to enter nerve cell
Charge inside cell becomes more positive
Na+ permeability increases
SELF AMPLIFICATION

Question 7

What % of humans body weight is water

Answer 7

60%

Question 8

What 3 bodily compartments is water in

Answer 8

1. Intracellular fluid
2. Interstitial fluid
3. Plasma

Question 9

What is the dilution principle

Answer 9

Question 10

What compartments can be measured directly using Dilution Principle

Answer 10

1. Plasma Volume:- radioactive labels/dyes
2. ECF:- substance that freely crosses capillary but not cell membrane
3. TBW:- Heavy water

Question 11

Example question for vol. of ECF

Answer 11

Question 12

Why must we maintain body temperature within a narrow range?

Answer 12

Inability to maintain body temperature (a monitored variable) within narrow range around 37oC disrupts all biochemical reactions inside cells,
Therefore we’re unable to generate energy to power cellular function.

Question 13

Answer 13

You should have said B – Causes a return to a set point
Negative feedback is the most common type of homeostatic feedback. It aims to reduce the disturbance of a monitored variable – think about the example of getting dehydrated when working outside on a hot day. The threat to water balance in the body is countered by an increased thirst, driving the individual to seek water.
Negative feedback is a key aspect of maintaining homeostasis

Question 14

Answer 14

You should have said C - Amplifies the response
Positive feedback is uncommon in normal homeostasis although it does occur and is vitally important when it does. Remember the example of the sodium based action potential in nerves. Review this if necessary to understand how it amplifies the response (of sodium entry to the nerve cell). Without this positive feedback nerves would cease to function.
Positive feedback cannot predict and prevent disruption before it happens. That is the role of Feedforward mechanisms.