Mrs. Degl 1

Nervous SystemRegulation in humans involve the interaction of both nervous and endocrine systems.

•They are similar in that they both secrete chemicals and both play a role in the maintenance of homeostasis.•They differ in that the responses of the nervous system are more rapid and of shorter duration than the endocrine.

The nervous system is made up of nerve cells/neurons. These transmit impulses. There are 3 types:

1. Sensory neurons2. Motor neurons3. Interneurons

Mrs. Degl 2

Sensory neurons transmit impulses from the sense organs (receptors) to the brain and spinal cord. Receptors include eyes, ears, tongue, nose and shin.

Motor neurons transmit impulses from the brain and spinal cord to the effectors. Effectors include muscles and glands.

Interneurons are found in the spinal cord and brain. These transmit nerve impulses from the sensory neurons to motor neurons.

Mrs. Degl 3

Nerves

Nerve cells are bundled together to create a nerve.

There are 3 types of nerves:

1. Sensory nerves (contain only sensory neurons)2. Motor nerves (contain only motor neurons)3. Mixed nerves (contain both)

There a 2 parts to the Human Nervous System

1. Central Nervous System (brain & spinal cord)2. Peripheral Nervous System (all nerves outside the

central nervous system

Mrs. Degl 4

Mrs. Degl 5

The Brain (part of the central nerves)

Medulla

Mrs. Degl 6

The Brain (central nerves)The brain is a large mass of nerve cells located in the cranial cavity and it is surrounded and protected by the skull bones.

3 Major Brain Areas:1. Cerebrum

• Largest• Center for thought, memory, and learning• Initiates voluntary or conscious movements

2. Cerebellum• Below and behind the cerebrum• Maintains body’s balance• Coordinates motor activities

3. Medulla• Connects the brain to the spinal cord at the base of brain• Controls involuntary activities

Mrs. Degl 7

The Spinal Cord (central nerves)

•The spinal cord is connected to the medulla (bottom of the brain).•It is surrounded by vertebrae (backbone) or spinal column.•It coordinates activities between the brain and rest of body.•Impulses from the brain are carried by motor neurons through the spinal cord to the rest of the body.

Mrs. Degl 8

Peripheral Nervous System•This includes all of the neurons outside the central nervous system.•These nerve cells carry impulses between the central nervous system and the rest of the body.•There are 2 main divisions of the Peripheral Nervous System. They are the Somatic and the Autonomic Nervous Systems.

The Somatic Nervous System controls all voluntary muscles.

The Autonomic Nervous System controls the involuntary activities of smooth muscles (heart and glands). These activities regulate heartbeat, circulation, respiration and peristalsis.

Mrs. Degl 9

Nervous System Behavior

Behaviors help us maintain homeostasis. Some behaviors are inborn while others are learned.

Habits are learned behaviors that become automatic through repetition. The repetition establishes pathways for quick responses.

Reflexes are autonomic inborn responses to a particular stimulus. Here impulses follow a set pathway called a reflex arc. Reflexes are generally protective in nature and cause a quick response to a dangerous situation.

Mrs. Degl 10

Disorders of the Nervous System

•Cerebral Palsy is a group of diseases caused by damage to pasts of the brain that control voluntary movement. This damage occurs during embryonic development.•Meningitis is an inflammation of the membranes that surround the brain and spinal cord. This can be caused by viral or bacterial infections. •A stoke is a disorder in which the brain is damaged by a broken blood vessel or blood clot (hemorrhage).•Polio is a disease that affects the central nervous system and can result in paralysis. This is caused by a virus that most people are vaccinated for today.•Alzheimer’s is a degenerative disease in which neurons in the brain are gradually destroyed. This fatal illness usually strikes older people.