Chapter 7 Neuron structures and functions

Central Nervous System organs?

brain and spinal cord

Central Nervous System functions?

commands center interprets incoming sensory information

Peripheral Nervous System organs?

spinal nerves and cranial nerves

Peripheral Nervous System functions?

communication line among sensory organs, the brain, spinal cord, gland, and muscle

Sensory (afferent) Division

nerve fibers that carry information to the central nervous system

Somatic sensory fibers

carries information from the skin, skeletal muscle, and joints

Visceral (organ) sensory fibers

carries information from visceral organs

Motor (efferent) Division

nerves fibers that carry impulses away from the central nervous system organs to muscle and glands

Somatic Nervous System

voluntary, consciously controls skeletal muscles

Autonomic Nervous System

controls smooth and cardiac muscles and glands

Sympatric

fight or flight

Parasympathetic

rest and repose

CNS support cells grouped together are called what?

neuroglia

General functions of support cells?

support, insulate, protect neurons

CNS-Astrocytes

• abundant, star-shaped cells

• protect neurons from harmful substances in blood

• control the chemical environment of the brain

CNS-Microglia

• spiderlike phagocytes

• Monitor health of nearby neurons

• dispose of debris

CNS-Ependymal cells

• lines cavities of the brain and spinal cord

• cilia assists with circulation of cerebrospinal fluid

CNS-Oligodendrocytes

• wraps around nerve fibers in the central nervous system

• produce myelin sheaths

PNS-Schwann cells

• forms myelin sheath around nerve fibers in the Peripheral nervous system

PNS-Satellite cells

protects and cushions neuron cell bodies

Myelin?

white fatty material covering axons of a neuron to protect and insulate fibers as a way to speed up nerve impulse transmissions

sensory neurons?

from Peripheral NS to Central NS

interneuron neurons?

links sensory and motor

motor neurons?

from Central NS to Peripheral NS to muscle and glands

Unipolar neurons?

1 cell process extending from cell body

bipolar neurons?

2 cell processes extending from cell body

multipolar neurons?

many cell process extending from cell body

nerve impulse 1st step

resting membrane potential is polarized; inside has more negative and outside is positive

nerve impulse 2nd step

local stimulus opens Na+(sodium) gates

nerve impulse 3rd step

all or none response activates the action potential

nerve impulse 4th step

depolarization - Na+ rushes in; inside of cell becomes positive and outside negative

nerve impulse 5th step

repolarization - Na+ gates close

nerve impulse 6th step

return to resting state by the activity of the Na+/K+ pump

transmission of a signal at synapses 1st step

action potential reaches the axon terminals, Ca² + channels open (presynaptic cell)

transmission of a signal at synapses 2nd step

vesicles to fuse with the axon membrane

transmission of a signal at synapses 3rd step

neurotransmitters are released into the synaptic cleft

transmission of a signal at synapses 4th step

neurotransmitters diffuse across and bind to receptor proteins on post synaptic cell

transmission of a signal at synapses 5th step

Na+ ion channels open; action potential

transmission of a signal at synapses 6th step

ion channels close neurotransmitter is removed from the synapse

multiple sclerosis

a disease that gradually destroys the myelin sheath around CNS fibers converting them to hardened sheaths called scleroses (an autoimmune diseases = mistakenly attack healthy body cells)