Nervous System 6.1

divisions of the nervous system

divisions of the nervous system

central and peripheral

central nervous system

brain, spinal cord

afferent nerves

Nerves that transmit impulses from the sensory receptors in the skin, muscles, and joints to the CNS (towards)

efferent nerves

Nerves that carry impulses from the CNS out to the muscles and glands (away)

somatic nervous system

stimulates our skeletal muscles, causing them to develop tension (voluntary)

autonomic nervous system

controls the cardiac muscle of the heart and the smooth muscles of the internal organs (involuntary)

sympathetic

parasympathetic

neuroglia/glial cells

astrocytes, microglia, ependymal, oligodendrocytes, Schwann cells, satellite cells

Astrocytes

link capillaries to neurons and control the chemical environment to protect neurons

Microglia

absorb and dispose of dead cells and bacteria

Ependymal

form a protective covering around the spinal cord and central cavities within the brain

Oligodendrocytes

wrap around nerve fibers and produce a fatty insulating material called myelin

Schwann cells

form the fatty myelin sheaths around nerve fibers in the PNS

Satellite cells

serve as cushioning support cells

dendrites

collect stimuli and transport them to the cell body

axons

transmit impulses away from the cell body

myelin sheaths

insulate axon fibers, which increases the rate of conduction

neurilemma

the external covering of the Schwann cell, outside the myelin sheath

Nodes of Ranvier

uninsulated gaps, where the axon is exposed between the myelin sheaths

synapse

axon terminals are separated by a microscopic intersection called