Homeostasis Control Mechanisms

BIOL 2010: Anatomy and Physiology I

Case Study 1: Homeostatic Control Mechanisms

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

1. Variable: it’s the condition being maintained such as blood pressure, blood sugar, etc

2. Receptor: structure that detects that body conditions are out of the normal range

3. Set Point: the normal range

4. Control Center: receives signal from the receptor

5. Effector: structure that carries out the response from the brain

6. Response: what the effector does to get/ effort that changes the controlled condition

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: exercise

Receptor: increase in respiratory rate

Set point: 35-45

Control center: brain

Effector: controls the activity of the respiratory muscles

Response: the excess co2 is exhaled

2. Blood calcium (which is normally between 9.0 and 10.5 mg/dl) is controlled by a hormonal control system. Calvin was on a high protein diet that led to a loss of calcium and blood calcium levels of 6.5mg/dl. Calvin’s parathyroid gland detected this lowered level and released parathyroid hormone...