The Nervous System

Role of the nervous system

• respiratory center• defense (ex: pain stimuli)• relay information (ex: hunger, full bladder)

Functions of the nervous system

• receives information • interprets the information• makes the body respond or react

Nerve cell

Structure and Functions –Nerve cell

• also called neuron• scattered throughout the body• born with all the neurons that you would need

(none grows or regenerates)

Parts of a neuron

• dendrites• axon• nucleus• cytoplasm• interneurons*

*HW: 1) What are interneurons? 2) What is a soma/perikaryon?

Axon

• threadlike structure• carries impulses away from the nerve cell

body• may have a myelin sheath (myelinated)

Dendrites

• looks like fibers branching out• receives impulses or stimuli

Afferent or Efferent? Sensory or Motor?

• Pick up information, sends it to CNS• From CNS, sends out orders

Structure and Functions- Neuroglia

• Also called glia• Does not transmit impulses• For protection and nourishment

Kinds of Glia

• Astrocytes –pass nutrients between blood capillaries and neurons

• Microglia – engulf foreign materials and bacteria

• Oligodendroglia, Schwann cells*- insulate axons of neurons

*HW: Are oligodendroglia and Schwann cells the same thing?

Central nervous system

• brain• spinal cord

Brain

• cerebrum• cerebellum• brain stem• diencephalon

Spinal Cord

Peripheral Nervous System

• cranial nerves• spinal nerves• peripheral nerves

Autonomic Nervous System

• Sympathetic • Parasympathetic

• (I) O• (II)* O• (III) O• (IV) T• (V) T• (VI) A• (VII) F• (VIII) A• (IX) G• (X) V• (XI) S• (XII) H

– Olfactory (I) – sensory (olfactory)– Optic (II) – not a true nerve– Oculomotor (III) – motor (extrinsic eye muscles)– Trochlear (IV) – motor (extrinsic eye muscles)– Trigeminal (V) – sensory &motor (skin of head, teeth, jaws)– Abducens (VI) – motor (extrinsic eye muscles)– Facial (VII) – sensory (taste buds) & motor (2nd hyoid arch)– Auditory (VIII) – aka octaval; sensory (inner ear)– Glossopharyngeal (IX) – sensory (taste buds, gill pouches) & motor (3rd hyoid

arch)– Vagus (X) – sensory & motor (mouth, pharynx, viscera)– Spinal Accessory (XI) – motor (mastoids, trapezius)– Hypoglossal (XII) – motor (hyoid and tongue muscles)