nervous system overview + nerves

nervous system functions

sensory input, integration, motor output

another term for sensory input

gathering info

what is sensory input?

monitoring changes/stimuli inside and outside body

what is integration?

processsing and interpreting sensory input, deciding if action is needed

what is motor output?

responding to integrated stimuli

what can motor output activate?

muscles, glands

CNS

central nervous system

parts of CNS

brain, spinal cord

CNS is the command center for…

integration

CNS functions

interprets incoming sensory info, issues outgoing instructions

PNS

peripheral nervous system

parts of PNS

nerves extending from brain and spinal cord

spinal nerves

carry impulses to and from spinal cord

cranial nerves

carry impulses to and from brain

nerves serve as…

communication lines among sensory organs, brain, spinal cord, glands, and muscles

another term for sensory neurons

afferent nerve

another term for motor neurons

efferent nerve

sensory/afferent

carry impulses to CNS

motor/efferent

carry impulses away from CNS

2 subdivisions of motor/efferent nerves

somatic nervous system, autonomic nervous system

soma

body

somatic nervous system is…

voluntary

somatic nervous system function

consciously controls skeletal muscle

autonomic nervous system is…

involuntary

autonomic nervous system function

automatically controls smooth muscle, cardiac muscle, and glands

autonomic nervous system is further divided into…

sympathetic and parasympathetic nervous systems

neurons

nerve cells specialized to transmit messages

neuron cell body

nucleus and metabolic center of cell

neuron cell body contains…

Nissl bodies, neurofibrils, nucleus with large nucleolus

Nissl bodies

specialized rough endoplasmic reticulum

neurofibrils

intermediate cytoskeleton, maintains cell shape

neuron processes

fibers that extend from cell body

dendrites

conduct impulses towards cell body

axons

conduct impulses away from cell body

how many dendrites can a neuron have?

hundreds

how many axons can a neuron have and where?

one, arising from cell body at axon hillock

axons end in…

axon terminals

axon terminals contain…

vesicles with neurotransmitters

what separates axon terminals from next neuron?

synaptic cleft

synaptic cleft

gap between adjacent neurons

synapse

junction between nerves

myelin sheath

whitish, fatty material covering axons

Schwann cells

produce myelin sheaths in a pumpkin roll-like fashion around axons of PNS

nodes of Ranvier

gaps in myelin sheath along axon

oligodendrocytes

produce myelin sheaths around axons of CNS

most neuron cell bodies are found in…

CNS

gray matter

cell bodies and unmyelinated fibers

nuclei

clusters of cell bodies within CNS white matter

white matter

collections of myelinated fibers

ganglia

collections of cell bodies outside CNS

tracts

bundles of nerve fibers in CNS (white matter)

nerves

bundles of nerve fibers in PNS