anatomy unit 6: the nervous system

sensory input

monitors changing occurring inside and outside the body

integration

processes and interprets sensory using “relay neurons” or “interneurons;” mainly occurs in brain and spinal cord

motor output

response to integrated stimuli by activating effector organs (muscles and glands)

central nervous system

integrating and command center; brain and spinal cord

peripheral nervous system

cranial nerves and spinal nerves

sympathetic nervous system

fight or flight response

parasympathetic nervous system

rest and digest response

sensory nervous system

• aka afferent

• carries signal to CNS

motor nervous system

• aka efferent

• carries information away from the CNS to muscles and glands

somatic nervous system

controls voluntary movements

autonomic nervous system

controls involuntary/subconscious movements

mechanoreceptors

sense touch

thermoreceptors

sense temperature

photoreceptors

sense light

chemoreceptors

sense taste & smell

nociceptors

sense pain

neuroglia

• support cells

• supports, insulates, and protects neurons

• do not transmit impulses

• divide continuously

neurons

• structural unit of the nervous system

• transmits electrical impulses

• cannot divide

• highly specialized

• can conduct electricity

amiotic

describes cells that cannot divide

astrocytes

• in CNS

• star-shaped

• anchor and brace neurons

• makes exchanges between capillaries & neurons

• cleans up potassium & sodium ions

microglia

• in CNS

• small ovoid cells with thorny processes

• spider-like phagocytes

• disposes of debris

ependymal cells

• line central cavities of the CNS

• cells are squamous and columnar shaped with cilia

• circulates cerebrospinal fluid

oligodenrocytes

• in CNS

• produce myelin sheath

satellite cells

• surrounds neurons in PNS

• protects and cushions neurons

Schwann cells

• in PNS

• surrounds & forms myelin sheath in PNS

• similar to oligodendrocytes

dendrites

1

soma/cell body

2

axon terminals

3

myelin sheath

4

axon

5

cell body/soma

• metabolic center

• most found in CNS

dendrites

• main input or receptive region

• receives signals from other neurons

• conducts impulses toward the cell body

axon

• each neuron only has one

• conducting region of the neuron

• some are short and some are long depending on where neurons are

myelin sheath

• covers and protects axon

• increases speed of impulse

nodes of Ranvier

• gaps in the myelin sheath

• help conduct impulse more rapidly

multipolar neurons

• three or more processes

• one axon and many dendrites

• most common neuron type

• most are in CNS

bipolar neurons

• two processes

• one axon and one dendrite

• only found in sensory organs

unipolar neurons

• short, single process leaving the cell body

• mostly found in sensory organs

sensory neurons

send signals to the CNS

motor neurons

send signals away from the CNS

interneurons

• sit in between the sensory and motor

• can also be called relay neurons

• 99% of neurons in the body

• in the brain & spinal cord

cervical

1

thoracic

2

lumbar

3

sacral

4

coccygeal

5

neck muscles

C1-C3 control ________

diaphragm

C4 controls __________

deltoid

C5 controls __________

wrists

C6 controls __________

fingers

C7-C8 control __________

hands

T1 controls __________

intercostals

T2-T12 control __________

L2 controls __________