Homeostasis and Regulation

Question 1

What are the mechanisms used by homeostatic control systems?

Answer 1

Negative and Positive feedback loops

Question 2

What is a negative feedback loop?

Answer 2

Response removed or negates the stimulus back towards the set point.

(ex. Normal homeostatic temperature of the body is disturbed. STIMULUS: Body temperature increases. RECEPTORS: temperature sensors in skin and hypothalamus detect change. Information is sent and processed in the control center of the brain, which sends commands to the EFFECTORS; sweat glands in skin increase in secretion and blood vessels dilate to decrease temperature. Negative feedback loop stops when normal temperature is restored).

Question 3

What is a positive feedback loop?

Answer 3

Positive feedback loops are relatively rare and exaggerate or reinforce the original stimulus.

(ex. a break in blood vessel wall causes bleeding which results in the damaged cells releasing chemicals, beginning the clotting process. Additional chemicals are then released which accelerates the clotting process until the bleeding stops)

Question 4

How does homeostasis regulation occur?

Answer 4

Homeostasis requires:

1. Receptor: that is sensitive to a particular environmental stimulus (temperature sensors in skin)
2. Control center: receives and process information
   (hypothalamus; heat regulating center in the brain)
3. Effector: Responds to the control center, whose activity either opposes or reinforces the stimulus (sweat glands increase sweat production)

Question 5

What are receptors?

Answer 5

Receptors detect change/disruption to body’s homeostatic equilibrium

ex. detects the stimulus of body temperature rising
(temperature sensors in skin and hypothalamus)

Question 6

What is a stimulus?

Answer 6

A change/disruption to the body’s internal balancing conditions

ex. when the temperature of a body increases past its ideal homeostatic temperature of 37 degrees

Question 7

What does the control center do?

Answer 7

Sends commands to the body’s effectors in attempts to reduce the homeostatic disruption

ex. hypothalamus commands sweat glands in skin to increase sweat secretion to help the body cool down

Question 8

What is an effector?

Answer 8

An organ or cell that acts in response to a stimulus. it provides the means for the control center’s response to the stimulus.

ex. sweat glands increase secretion to cool body, blood vessels dilate

Question 9

What is a response?

Answer 9

The body’s natural reaction to changes in optimal conditions to return to balance.

ex. increased heat loss and temperature decrease after the effectors cause sweating

Question 10

When do feedback loops stop?

Answer 10

Negative feedback loops will stop once the initial disruption to the body stabilizes and returns to homeostatic conditions

ex. when normal body temperature is achieved after the initial stimulus of body temperature rising

Positive feedback loops will stop when a response is intensified until an endpoint is reached.

ex. positive feedback loop caused by childbirth will stop once the baby is born, removing the stimulus causing contractions and hormone production