Introduction to homeostatic regulation

Question 1

Define: homeostasis

Answer 1

Maintenance of a constant internal environment within narrow limits.

Question 2

Define: homeostatic regulation

Answer 2

Monitoring a variable, and making adjustments if the variable moves outside of its normal range

Question 3

Define: internal environment

Answer 3

Blood plasma and extracellular fluid

Question 4

How is homeostasis achieved?

Answer 4

Through homeostatic mechanisms: functions within the body that enable homeostasis

Question 5

How can homeostatic mechanisms be summarised?

Answer 5

Using a stimulus-response model

Question 6

Name and describe the 5 components of the stimulus response model.

Answer 6

Stimulus: change in an internal or external factor
Receptor: specialised cells that detect changes and send info to control center
Modulator/message: evaluates change, sends hormonal or nerve message to effector
Effector: usually a muscle or organ, that respons
Response: the corrective action taken to achieve homeostasis

Question 7

Define: negative feedback

Answer 7

When the response counteracts the initial stimulus.

Question 8

Define: positive feedback

Answer 8

The original stimulus is amplified away from the normal value.

Question 9

Provide an example of positive feedback

Answer 9

Childbirth: oxytocin increases contractions; when baby’s head activates pressure receptors than more is produced.

Question 10

Define: hormone

Answer 10

a chemical messenger required in small quantities that is secreted by endocrine cells and travels in the bloodstream to a target organ where it effects a response.