Chapter 6 - Detecting & Regulating Change

Question 1

What is homeostasis?

Answer 1

Homeostasis is the process of keeping the body’s internal environment fairly constant, within limits.

Question 2

What is a reflex?

Answer 2

• a rapid, automatic response to a change in the internal or external environment.

Question 3

What are the characteristics of a reflex?

Answer 3

• a stimulus is required to trigger a reflex - a reflex is not spontaneous
• a reflex is involuntary - it occurs without any conscious thought
• a reflex response is rapid - only a small number of neurons are involves
• a reflex response is stereotyped - it occurs the same way each time

Question 3

What is a reflex arc?

Answer 3

The pathway an impulse follows in travelling from a receptor to an effector

Question 4

What is the first stage of a reflex arc?

Answer 4

The receptor is either the ending of a sensory neuron or a specialised cell associated with the end of a sensory neuron. The receptor reacts to a change in the internal or external environment by initiating a nerve impulse in the sensory neuron.

Question 5

What is the second stage of a reflex arc?

Answer 5

A sensory neuron carries the nerve impulse from the receptor to the CNS.

Question 6

What is the third stage of a reflex arc?

Answer 6

There is at least on synapse. The nerve impulse may be passed directly to a motor neuron or there may be one or more interneurons, which direct the impulse to the correct motor neuron.

Question 7

What is the fourth stage of a reflex arc?

Answer 7

A moron neuron carries the nerve impulse from the CNS to the effector.

Question 8

What is the fifth stage of a reflex arc?

Answer 8

An effector receives the nerve impulse and carries out the appropriate response. Effectors are muscle cells or secretory cells.