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NERVOUS SYSTEMBRAIN

SPINAL CORD

Nerve Cell

Nervous System:What it is & what it does.

• The control and communication network

of the body.

• 3 functions of the nervous system:

1. Detects internal & external stimuli

2. Controls responses to stimuli

3. Integrates activities of organ systems.

Neurons & Nerves• Neuron: a nerve cell that

carries information from one place to another.

• Nerve: a bundle of neuronstogether

• Types of Neurons:1. Sensory Neurons: get

information from the environment through the senses and relays the message to the brain.

2. Motor Neurons: carry information from the brain to the muscle and glands to cause action.

Parts of A Nerve Cell• Dentrites carry impulses

from the environment or other neurons toward the cell body.

• Axons carry impulses away from the cell body.

• The area where one nerve cell transfers an impulse to another is called a synapse

• Myelin Sheath insulates the axons and helps nerve cells send impulses

NeuronDendrites

Axon

Nucleus

Cell Body

Schwann Cell

Mylenated

Sheath

Two Main parts of the Nervous System

• Central Nervous System:

composed of the brain and the spinal cord.

– The brain has different parts that perform specific tasks.

– The spinal cord runs up and down the back and is surrounded by

vertebrae which provides protection. The spinal cord transmits sensory and motor information between the

body and the brain.

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Figure 48.24 Structure and functional areas of the cerebrum

Two Main parts of the Nervous System

• Peripheral Nervous System: consists of all other parts of the nervous system. It carries

nerve impulses from the brain and spinal cord to the body and transmits sensory input from the body to the brain.

• It is broken into two parts:

1. Autonomic system: controls the involuntarysystems such as glands and smooth muscles.

2. Somatic system: controls the voluntary systems like the skeletal muscles.

Figure 48.16 The nervous system of a vertebrate

Central Nervous System:

Brain & Spinal Cord

-evolved from the

embryonic dorsal nerve

cord

Peripheral Nervous System:

Cranial Nerves, Spinal

Nerves, Ganglia

Figure 48.1 Overview of a vertebrate nervous system

Senses

• Senses are the ability for us to detect what

is happening in our environment and are used for protection.

• 5 senses: smell, sight, touch, hearing, taste

5 senses

• Taste: can be used for protection, a bad taste can indicate poison or rotten food.

• Smell: assists in taste and associates memory with odor.

• Sight: allows us to see to obtain food and avoid danger.

• Touch: protects us from harming our selves physically.

• Hearing: allows us to detect danger and obtain food, the ears also maintain balance.

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Other info.

• Simpler animals have simpler system.

– Cnidarians have nerve nets that conduct

impulses from the body and cause the cells to contract.

– Flatworms have a small brain called a

ganglion. The ganglion sends messages down 2 nerve cords that run the length of

the body.

– Insects have well developed nervous systems including brains that allow the

organisms to respond to their environment.