Ch. 12 Nervous System a
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What is the central nervous system?
Consists of the brain and spinal cord. Communicates with all divisions of the peripheral nervous system
What is the peripheral nervous system?
Consists of all other nervous tissue. Carries stimuli to the CNS and carries responses to appropriate areas
What are the two major divisions of the PNS and what is their primary function?
Sensory (afferent) division: Carries signals of stimuli to CNS
Motor (efferent) division: carries signals of stimuli from CNS to execute appropriate body response
What are the two divisions of the sensory (afferent) division of the PNS and their major functions?
Somatic sensory: carries signals from structures such as skin, muscles, bones, and joints
Visceral sensory: carries signals from cavities of thorocic and abdominal cavities. (heart, lungs, stomach, and bladder
What are the two divisions of the motor (efferent) division of the PNS and their major functions?
Somatic motor:carries signals to skeletal muscles and produces muscular contraction
Visceral motor: carries signals to glands, cardiac muscle, and smooth muscle.
What are the 2 subdivisions of the Visceral motor division?
Sympathetic: arouses body for action (speeding up heart rate)
Parasympatheic: calms down (slows heart rate) but also stimulates digestive and urinary systems
What is a reflex arc?
Sensory receptor recieves a stimuli (pain from touching something hot), causing a signal (pain) to go along the afferent neuron to the CNS. The CNS processes the signal, sends a new one down an efferent neuron to the responding body (skeletal muscle to take your hand off the hot object).
What is a neuron?
Transmits impulses across the body. About 1 trillion in nervous system
What is a neuroglial cell? What four are unique to the CNS?
Support/caretaking cells of the neurons. Also creates fast and accurate signal transmission. Outnumber neurons about 50:1
- Ependymal cells
Oligodendrocyte. Up to 15 arms wrap around axons in CNS to form myelin sheaths, same as schwann cells in PNS.
Ependymal cells. secretes cerebrospinal fluid, circulates it with its cilia, and absorbs CSF
Microglia cell. Immune cell for nervous tissue. Its branches poke into nervous tissue and clean up (phagocytize) any cellular debris.
Astrocyte. Most abundant glial cell in CNS. Creates blood-brain barrier on capillaries, limiting what can get to the brain cells. its arms also provide physical support to the neurons.
Schwann cells. ½ in PNS. Forms myelin sheath around axons in PNS
Satellite cells 2/2 in PNS. Surrounds cells body around neurons in PNS. Unknown function, although believed to provide electrical insulation around the soma
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