Unit 1 - A & P Module - Homeostasis

Question 1

__________ allows the body to predict that a change is about to occur and start the response loop in anticipation of the change.

Answer 1

Feed forward control

Question 2

What is the proper description of a set point for a homeostatically controlled variable?

Answer 2

The normal, “desired” value of the variable

Question 3

The chemoreceptors in blood vessels that sense oxygen and carbon dioxide levels in the blood are __________.

Answer 3

sensors

Question 4

Which of the following is the correct definition of positive feedback?

Answer 4

The response of the system goes in the same direction as the change that sets it in motion.

Question 5

A positive feedback mechanism is prevented from spiralling out of control by __________.

Answer 5

a factor that stops the feedback loop, a factor that removes the stimulus, a factor that limits the system’s ability to respond to the stimulus

Question 6

What does Cannon’s postulates describe for properties of homeostatic control systems?

Answer 6

1. The nervous system plays an important role in maintaining homeostasis.
2. Some parameters are under tonic control, which allows the parameter to be increased or decreased.
3. Some parameters are under antagonistic control in which, for example, one hormone increases the parameter while a second hormone decreases it.

Question 7

The drop in blood pressure that can occur when a person stands up too quickly is an ________ ________.

Answer 7

error signal

Question 8

Negative feedback __________.

Answer 8

moves a physiological variable that has deviated from the set point back toward the set point

Question 9

What is the most complicated control pathway in homeostatic systems?

Answer 9

An efferent pathway that includes a neuron, an endocrine gland functioning as an integrator, and a target tissue

Question 10

List the body’s controlled variables.

Answer 10

1. Body temperature
2. Heart rate
3. Blood pressure
4. Blood pH
5. Respiratory rate

Question 11

The term used to describe the minimum stimulus to trigger a response in a feedback loop is __________.

Answer 11

threshold

Question 12

What is the definition of a stimulus?

Answer 12

A detectable disturbance or change in the internal or external environment

Question 13

What is true with regard to negative feedback loops in the physiological control system?

Answer 13

Negative feedback loops are more common that positive feedback loops in living systems. Negative feedback loops are homeostatic; positive feedback loops are not.

Question 14

What is the correct sequence of events from the stimulus to the target tissue?

Answer 14

Stimulus, input (afferent) signal, integrating center, output (efferent) signal, target response