Homeostasis and Feedback Mechanisms

Homeostasis and Feedback Loops

Anatomy and Physiology Honors

Homeostasis = tendency of the body to maintain a stable, balanced, internal environment. “Sameness”

Feedback Loops

- how the body makes adjustments when the environment changes and maintains homeostasis

-  normal range indicates where the body can function, or what is optimal   

-  the set point is the value around which the range fluctuates        

Homeostasis = tendency of the body to maintain a stable, balanced, internal environment. “Sameness”

Multiple Choice

Which of the following describes homeostasis?

• keeps variables exactly at the set point

• organism's ability to maintain steady(stable) internal conditions

• acts to keep values outside of a desired range

• operates through positive feedback

​Components of Feedback Loops

Stimulus

• Change in environment

Receptor

• Monitors a controlled condition

Control Center (Muscles/glands)

• Determines next action

Effector (Muscles/glands action)

• Receives directions from the control center

• Produces a response that changes the controlled condition

Response

Multiple Choice

What detects change and sends a message to the control center?

• receptor

• control center

• effector

• regulation

Multiple Choice

What detects that the system is outside of homeostasis and adjustments need to be made?

• effector

• response

• control center

• stimulus

Multiple Choice

What responds to the output from the control center?

• control center

• receptor

• thermoregulation

• effector

Negative Feedback Loops

Homeostasis typically involves negative feedback loops that counteract (suppress) changes of various properties from their target values, known as set points.

Ex. a rise in a substance’s concentrations produces feedback, which causes the substance’s content to reduce.

Positive Feedback Loops

Positive feedback loops amplify their initiating stimuli, in other words, they move the system away from its starting state.

•Not seen widely in human body

•usually found in processes that need to be pushed to completion

Reorder

Organize the following into the correct order of events

• Stimulus

• Receptor

• Control Center

• Effector

• Response

1

2

3

4

5

• 1
• 2
• 3
• 4
• 5

Disruption of Feedback Loops

Homeostasis depends on negative feedback loops. So, anything that interferes with the feedback mechanisms can—and usually will!—disrupt homeostasis.

In the case of the human body, this may lead to disease.

Match

For the follow steps identify them as one of the following: Stimulus, Receptor, Control Center, Effector, Response

• Chlorine levels drop

• Test strips detect imbalance

• Pool person responds

• Chlorine is added

• Chlorine levels rise to normal

Stimulus

Receptor

Control Center

Effector

Response

• Stimulus

• Receptor

• Control Center

• Effector

• Response

Match

For the follow steps identify them as one of the following: Stimulus, Receptor, Control Center, Effector, Response

• Blood glucose levels rise

• Chemoreceptors detect imbalance

• Pancreas responds

• Insulin is produced

• Glucose levels drop to normal

Stimulus

Receptor

Control Center

Effector

Response

• Stimulus

• Receptor

• Control Center

• Effector

• Response

Match

For the follow steps, identify them as one of the following: Stimulus, Receptor, Control Center, Effector, Response

• Oxygen levels drop

• Chemoreceptors detect imbalance

• Liver and kidney respond

• More red blood cells are created

• Oxygen levels rise to normal

Stimulus

Receptor

Control Center

Effector

Response

• Stimulus

• Receptor

• Control Center

• Effector

• Response