1. Assignment # Nervous Regulation and Reflex Arcs
Biology
Mrs. McCarthy
Monday, August 27, 2018

2. I. Regulation – all the activities that help to maintain homeostasis
Changes take place both inside and outside an organism
To stay alive, an organism must respond to these changes
Responses must be regulated and coordinated
Irritability – ability to respond to the environment

3. II. Mechanisms of Nervous Regulation
Impulses – messages carried by neurons
Neuron – nerve cell

4. C. Receptors – sense organs sensitive to certain changes
1. Examples:
a. physical forces – pressure, temperature
b. chemicals inside and outside the body
c. sight, hearing, touch, taste, smell

5. Effector –responds to the nervous system
1. Examples are glands and muscles

6. E. Stimulus – anything that causes a nerve impulse

7. How will your body respond to the hot stove?
Example – you walk into your kitchen where your mother has just finished boiling some water. You did not know she was doing this, and so you touch the hot stove. Identify the following parts of the scenario:
What is the stimulus?
What is the receptor?
What is the effector?
How will your body respond to the hot stove?

9. III. Structure of a neuron
Three basic parts
1. Cell body contains the nucleus and organelles
2. Dendrites – short, highly branched fibers that receive impulses
3. Axon – long, thin fiber that extends from the cell body. It carries the impulse to other neurons.

10. Neuron Diagram

11. Reflex – involuntary, automatic response to a stimulus
IV. The reflex arc
Reflex – involuntary, automatic response to a stimulus
Reflex arc – pathway of impulses for a reflex

12. Receptor in the skin is stimulated by the heat
Example – when your hand touches a hot object, it actually pulls away before you feel the sensation of heat or pain
Receptor in the skin is stimulated by the heat
The receptor starts an impulse in a sensory neuron, which carries it to the spinal cord
In the spinal cord, the sensory neuron sends the impulse to an interneuron
The interneuron sends the impulse to a motor neuron
The motor neuron sends the impulse to the effector
The effector is a muscle, which moves away the hand