Homeostatic Controls

BIOL 2010, Anatomy and Physiology I

Homeostatic Control Mechanisms, Part I

Group Members:_______________

Part I:

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) and then diagram this mechanism using Fig 1-3 as a general guide. Note: fig. 1-3 does not properly separate effector from response, but you have to.

Variable:

Receptor:

Set point:

Control center:

Effector:

Response:

BIOL 2010, Anatomy and Physiology I

Homeostatic Control Mechanisms, Part II

Part II:

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 (PTH). PTH caused an increase in the rate of calcium absorption by the digestive tract and reduced the rate of calcium loss by the kidneys.

Identify all parts of this homeostatic mechanism (variable, receptor, set point, control center, effector, response) and then diagram this mechanism using Fig 1-3 as a guide.

Note: this system has 2 effectors and thus 2 responses.

Variable:

Receptor:

Set point:

Control center:

Effector:

Response: