Homeostasis

Case Study 4: Homeostatic Control Mechanisms

A. Identify what each part of a homeostatic mechanism is/does:

1. Variable: The variable is the condition that is being monitored.

2. Receptor: The receptor detects the change in the variable.

3. Set Point: The set point is the target value of the variable.

4. Control Center: The control center processes the change in the variable and determines how to achieve homeostasis.

5. Effector: The effector will carry out the response.

6. Response: The response is what happens in order to “fix” the variable.

B. For the next 2 scenarios, identify each part of the homeostatic mechanism described.

1. Connie is a long distance runner. Her respiratory rate is based on the amount of CO2 (Carbon Dioxide) in her blood. The normal levels of CO2 are 35-45 mmHg. Chemoreceptors in major blood vessels detect blood CO2 levels and relay that information to the respiratory center in the medulla oblongata (part of the brain stem). The respiratory center controls the activity of the respiratory muscles (diaphragm and intercostals). When Connie exercises, her CO2 levels increase and her respiratory rate increases in an attempt to exhale the excess CO2.

Identify all parts of this homeostatic mechanism (variable, receptor, set point, control center, effector, response).

Variable: The variable is Connie’s respiratory rate, the CO2 in her blood.

Receptor: The chemoreceptors in her major blood vessels detect the blood CO2

levels and sends that information to the respiratory center.

Set point: The set point is the normal level of CO2 (35-45 mmHg)

Control center: The control center is the medulla oblongata which also contains the respiratory center.

Effector: The effector is exercise.

Response: Connie’s CO2 levels increase in addition to her respiratory rate so she can exhale the...