1. Introduction to Anatomy & Physiology

Calcium levels in Mr. Gallariani's blood are dropping to dangerously low levels. The hormone PTH is released and soon blood calcium levels begin to rise. Shortly after, PTH release slows. Is this an example of a positive or negative feedback mechanism? What is the initial stimulus? What is the result?

A gradient exists:

a. When heat is concentrated in one area of the body

b. When more of a substance is located in one place than in another

c. When there is higher pressure in one place than in another

d. All of the above are correct

e. None of the above are correct

The baroreceptor reflex causes blood pressure to drop when it rises dangerously high. Predict whether this is a positive or negative feedback loop. Explain your reasoning.

Compare and contrast the operation of negative and positive feedback mechanisms in maintaining homeostasis. Provide two examples of variables controlled by negative feedback mechanisms and one example of a process regulated by a positive feedback mechanism.

Which example below describes a system that is NOT able to maintain homeostasis?

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Cell-cell communication is required to coordinate the activities of the whole body.

Define homeostasis.

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Positive feedback loops are triggered by a deviation from the set point of a regulated variable and are shut down when conditions return to the set point.

Which example most clearly describes a system maintained by homeostasis?

Mark the following statements as true or false. If a statement is false, correct it to make a true statement.

Homeostasis is the condition of having a dynamic equilibrium of the internal environment.