Anatomy Nervous System

tract

Bundle of nerve processes inside the CNS

neurotransmitters

Chemicals released by neurons that stimulate other neurons, muscles, or glands

ganglion

Collection of nerve cell bodies found outside the CNS

efferent neuron

Neuron that conducts impulses away from the CNS to muscles and glands

afferent neuron

Neuron that conducts impulses toward the CNS from the body periphery

proprioceptors

Sensory receptors found in muscle and tendons that detect their degree of stretch

cutaneous sense organs

Sensory receptors found in the skin, which are specialized to detect temperature, pressure changes, and pain

schwann cells

Specialized cells that myelinate the fibers of neurons found in the PNS

neurilemma

a layer of cells that covers the axons of peripheral neurons; concerned with nerve regeneration

central nervous system (CNS)

a major subdivision of the nervous system that interprets incoming information and issues orders

peripheral nervous system (PNS)

a major subdivision of the nervous system that serves as communication lines, linking all parts of the body to the CNS

sensory nerves

also described as afferent nerves

motor nerves

also described as efferent nerves

stimuli

changes, occurring within or outside the body, that affect nervous system functioning

ganglia

clusters of cell bodies located in the peripheral nervous system

nuclei

clusters of cell bodies located within the CNS

dendrite

conducts electrical currents toward the cell body

nodes of ranvier

gaps in the myelin sheath

axon

generally conducts impulses away from the cell body

microglia

glial cells that engage in phagocytosis of pathogens and damaged tissue

schwann cells

glial cells that form the myelin sheath in the peripheral nervous system

myelin sheath

increases the speed of impulse transmission

depolarization

inside of the neuron becomes positively charged

synapse

junction or point of close contact between neurons

cell body

location of the nucleus

myelin sheath

makes white matter

neurons

nerve cells that transmit information as electrical signals

neuroglia (glia)

nerve tissue that is called nerve glue; composed of astrocytes, microgla, oligodendrocytes, and ependymal cells

motor nerves

nerves that carry out the plans made by the CNS

sensory nerves

nerves that gather information from the environment and carry it to the CNS

central nervous system (CNS)

nervous system subdivision that is composed of the brain and spinal cord

peripheral nervous system (PNS)

nervous system subdivision that is composed of the cranial and spinal nerves

association neuron (or interneuron)

neuron, serving as part of the conduction pathway between sensory and motor neurons

axon terminal

part of the axon where the neurotransmitters are stored

cell body

part of the neuron that contains the nucleus; dendrites bring information to this structure , and the axon carries information away from this structure

axon

part of the neuron that transmits information away from the cell body

axon terminal

releases neurotransmitters

nodes of Ranvier

short segments of the axonal membrane that are not covered by the myelin sheath; allows for salutatory conduction of the nerve impulse

somatic nervous system

subdivision of the PNS that controls voluntary activities such as the activation of skeletal muscles

autonomic nervous system

subdivision of the PNS that regulates the activity of the heart and smooth muscle, and of glands, it is also called involuntary nervous system

action potential

the changes in electrical charge across the membrane during depolarization and repolarization also called the nerve impulse

repolarization

the depolarized cell returns to the resting state

depolarization

the fist phase of the action potential caused by an inward movement of sodium (Na+)

refractory period

the inability of a depolarized neuron to accept a stimulus until it has repolarized

resting membrane potential (RMP)

the inside of the unstimulated neuron is negative this electrical charge is caused by the outward leak of potassium

peripheral nervous system

the part of the nervous system consisting of nerves that connect the brain and the spinal cord with the rest of the body

central nervous system (CNS)

the part of the nervous system that contains the brain and spinal cord

integrative function

the process and interpretation of information by the cells of the CNS; the decision-making capability

repolarization

the second phase of the action potential that is caused by the outward movement of potassium (K+)

astrocyte

this common type of glial cell supports and protects the neurons; the cell helps form the blood-brain barrier

dendrites

tree-like part of the neuron that receives information from another neuron and transmits that information toward the cell body

ependymal cell

type of glial cell that lines internal cavities of the brain and produces cerebrospinal fluid

myelin sheath

white, fatty material that surrounds the axon; it increases the rate at which the electrical signal travels along the axon