Chapter 7:6

The Nervous System

Key Terms

• Autonomic Nervous System• Brain• Central Nervous System• Cerebellum• Cerebrospinal Fluid• Cerebrum• Diencephalon• Hypothalamus• Medulla Oblongata• Meninges• Midbrain• Nerves

• Nervous System• Neuron• Parasympathetic• Peripheral Nervous System• Pons• Somatic Nervous System• Spinal Cord• Sympathetic• Thalamus• Ventricles

The Nervous System

• Neuron (nerve cell) – the basic structural unit of the nervous system

• Consists of:• Cell body (soma) – contains the nucleus• Dendrites – nerve fibers (carries impulses towards the

cell body)• Axon – single nerve fiber (carries impulses away from

the cell body)

The Nervous System (Axons)

• Many axons have a lipid covering called a myelin sheath• Increases the rate of impulse

transmission• Insulates and maintains the axon

• The axon of one neuron lies close to the dendrites of other neurons

• Synapses – the spaces between one neuron and the dendrites of another• Impulses “jump” the synapses to

reach the next dendrite• Neurotransmitters (a special chemical)

are located at the end of each axon

Draw and Label Your Own Neuron

To Label:

AxonCell Body (Soma)DendritesMyelin SheathTerminal Branches

Central Nervous System (brain and spinal cord)

• Main Structures of the brain:• Cerebrum – the largest and highest section of the

brain• Responsible for reasoning, thought, memory,

judgment, speech, sensation, sight, smell, hearing, and voluntary body movements

• Cerebellum – section below the back of the cerebrum• Responsible for muscle coordination, balance,

posture, and muscle tone

Central Nervous System(brain and spinal cord)

• Main Structures of the brain:• Diencephalon – section located between the

cerebrum and midbrain, contains the thalamus and hypothalamus• Thalamus – allows conscious recognition of pain

and temperature• Hypothalamus – regulates and controls the ANS,

temperature, appetite, water balance, sleep, and blood vessel dilation and constriction. Also involved in emotions.

Central Nervous System(brain and spinal cord)

• Main parts of the brain:• Midbrain – located below the cerebrum at the top of the

brainstem• Conducts impulses for certain eye and auditory reflexes

• Pons – located below the midbrain and in the brainstem• Responsible for certain reflex actions such as chewing,

tasting, and saliva production; also helps with respiration

• Medulla Oblongata – lowest part of the brainstem• Responsible for regulating heartbeat, respiration,

swallowing, coughing, and blood pressure

Draw and Label Your Own Brain

To Label:

CerebellumCerebrumFrontal LobeMedulla OblongataMidbrainOccipital LobeParietal LobePonsTemporal Lobe

Central Nervous System(brain and spinal cord)

• Spinal Cord• Continues down from the medulla oblongata and ends

at the first or second lumbar vertebrae• Meninges – cover and protect the brain and spinal

cord• Dura Mater – thick, tough, outer layer• Arachnoid Membrane – middle layer that is

delicate and weblike• Subarachnoid Space – contains cerebrospinal fluid• Pia Mater – innermost layer that is closely attached

to the brain and spinal cord – provides nourishment to the nerve tissue

Peripheral Nervous System

Consists of:

1. Somatic Nervous System: • 12 pairs of cranial nerves

• Some cranial nerves are responsible for special senses

• Other cranial nerves receive general sensations such as touch, pressure, pain, and temperature

• 31 pairs of spinal nerves• Carry messages to and from the spinal cord• Each nerve goes directly to a particular part of the body

Peripheral Nervous System

Consists of:

2. Autonomic Nervous System• Helps to maintain a balance in the involuntary

functions of the body• Allows the body to react in times of emergency

• 1. Sympathetic Nervous System• Fight or flight response (increasing heart rate,

respiration, and blood pressure, slow the digestive system

• 2. Parasympathetic Nervous System• After the emergency, it returns the body to

normal