The nervous system

The nervous system

Nervous and endocrine systemsThe nervous and endocrine glands sys-

tems interact to control and coordi-nate the body’s

-responses to change in its environ-ment

-growth & development-reproduction

A. Nervous system: Nervous con-trol depends mainly on the func-tioning of neurons (nerve cells).

1. Stimulus: a change in the external or internal environment which initi-ates and impulse.

examples: vision, smell, taste, pres-sure, temperature, pain, equilibrium.

• A demonstration

2. Impulse: an electro-chemical charge generated along a neuron.

• Electro-inside neuron• Chemical: between neurons

http://en.wikipedia.org/wiki/Action_potential

http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/Casey_Adamson/Personal%20Web%20Page.htm

3. Receptors: structures specialized to detect certain stimuli

4. Response: a reaction to a stimulus

http://meredithbond.com/blog/stimulus-and-response/

5. Neuron: the basic cellular unit of the nervous system (specially designed for the transmission of impulses.) Our brain has millions of neurons.

Neuron

Neurona. Terminal branches: ends of axons

that secrete neurotransmitters.b. Synapse: gap between adjacent

neurons (terminal branches of one neuron and the dendrites of the next) or the gap between neuron and ef -fector.

6. neurotransmitter• Neurotransmitter: chemical sub-

stance which starts the transmission of the nervous impulse (Acetyl-choline degraded by cholinesterase)

Neurotransmitter con’t• Acetylcholine is the most common

neurotransmitter. • Dopamine is another neurotransmit-

ter that brings pleasure.

http://www.muscular-dystrophy.org/research/news/3262_study_compares_two_treatments_for_myasthenia_gravis

Why do you think the nervous sys-tem is important?

How do neurotransmitters work to trans-mit the nervous impulse in humans?

1. Nervous impulse travels down an axon to the tips of a terminal branch.

2. The terminal branch secretes neuro-transmitter into the synapse gap.

3. The neurotransmitter travels to the next neuron and causes depolarization of that neuron-thus a new nervous im-pulse is started in the next neuron.

videoSynapse Structure and Function• http://www.youtube.com/watch?v=r

Wrnz-CiM7A

• Neurons may release chemicals to stimulate each other. An example of a muscle being stimulated by a neu-ron appears after the reflex path pic-tured in number four in the diagram.

• More complex animals have a central nervous system which includes a brain and a nerve cord (spinal cord).

• Brain: a large mass of neurons lo-cated in the cranial cavity—contains three major divisions.

• Cerebrum: center for voluntary activity; in-terprets sensory impulses, initiates some motor activities, and responsible for mem-ory, thinking, and reasoning.

• Cerebellum: coordinates motor activities and aids in maintaining balance.

• Medulla: controls involuntary activities such as breathing, heartbeat, blood pres-sure and peristalsis ( is part of the brain stem),

Video The nervous systemhttp://www.youtube.com/watch?v=sjyI4CmBOA0

Spinal cord: lies within, and is pro-tected by, the vertebrae of the spinal column.

http://www.quantumday.com/2012/06/walking-again-after-spinal-cord-injury.html

-- is continuous with the brain coordi-nates activities between the brain and other body structures (bridge be-tween the brain and the peripheral nervous system)

-- it is also a center for reflex actions.

Peripheral nervous system-- is located outside the central ner-

vous system and consists of the nerves extending throughout the body.

http://www.umm.edu/imagepages/8679.htm

Peripheral nervous system1) somatic: voluntary control2) automatic: involuntary