bi205- nervous tissue

characteristics of the nervous system

• controls and adjusts the activity of the body

• provides swift but brief responses

associated with the brain and spinal cord

central nervous system (CNS)

associated with the tissue outside of the CNS

peripheral nervous system (PNS)

functions of the CNS

• responsible for integrating, processing, and coordinating sensory input

• responsible for integrating, processing, and coordinating motor output

• it is the seat of intelligence, memory, learning, and emotion

function of PNS

provides sensory information to the CNS and carries motor commands away from the CNS

brings sensory information to the CNS, begins at the receptors

afferent division

carries motor commands to muscles and glands, ends at the effectors

efferent divisions

nerve cells that are responsible for the transfer and processing of information in the nervous system

neurons

what are the components of a neuron

soma (cell body), axon, dendrites, perikaryon, dendritic spines, and axon terminals

supporting cells that protect the neuron

neuroglia

largest and most numerous type of neuroglia, make up the blood brain barrier (BBB)

astrocytes

form myelin sheaths, form internodes and myelin sheath gaps

oligodendrocytes

areas with mostly myelinated axons that are called…

white matter

areas devoid of myelinated axons are called_____ also composed of cell bodies and dendrites

gray matter

phagocytic neuroglia cells

microglia

involved in cerebrospinal fluid (CSF) production, make up a cellular lining called the ependyma

ependymal cells

the neuroglia of the PNS are clustered in _____

ganglia

axons bundled together to form…

peripheral nerves

neuroglia of the PNS that surround cell bodies

satellite cells

neuroglia of the PNS that surround axons, consist of axolemma and neurolemma and are also called neurolemmocytes

schwann cells

neuron cytoplasm

perikaryon

make up the neuron cytoskeleton

neurofilaments/ neurotubules

clusters of free ribosomes

nissl bodies

area where initial segment connects to the cell body

axon hillock

cytoplasm of the axon

axoplasm

branches off the axon

collaterals

ends of the axon and collaterals

telodendria

ends of the telodendrias

axon terminals

the movement of material between the cell body and the axons

axoplasmic transport

has many processes but cannot differentiate between axons and dendrites, found only in the CNS

anaxonic

the cell body is between the dendrite and axon, axons are not myelinated

bipolar

the cell body is off to one side of the axon

pseudounipolar

typically has a single axon and multiple dendrites, most common type in the CNS

multipolar

the axons are afferent fibers, send information from the PNS to the CNS

sensory neurons

sensory neurons that monitor internal organ activity

interoceptors

sensory neurons that provide information about the external environment

exteroceptors

sensory neurons that monitor position and movement

proprioceptors

the axons are efferent fibers, send information from the CNS to the PNS

motor neuron

consist of somatic motor neurons

somatic nervous system (SNS)

consists of visceral motor neurons, preganglionic fibers and postganglionic fibers

autonomic nervous system (ANS)

located entirely in the CNS, situated between the motor and sensory neurons, analyze sensory input and coordinate motor inputs, can be excitatory or inhibitory

interneurons

the ability to conduct an impulse

excitability

a nerve impulse is known as the _____ of a nerve

action potential

the uneven distribution of positive and negative ions across the plasma membrane

membrane potential

the level of stimuli to cause a change in membrane permeability

threshold stimulus

the impulse will _____ the length of the axon

propagate

presence of a myelin sheath will create a ____ impulse

fast

lack of a myelin sheath will create a ____ impulse

slow

the junction between a neuron and another cell

synapse

vesicular synapse

chemical synapse

nonvesicular synapse

electrical synapse

where does a neurotransmitter diffuse across

synapse

what does the neurotransmitter bind to

postsynaptic membrane

what does the binding action of a neurotransmitter and postsynaptic membrane cause

change in permeability

the change in permeability in the synaptic communication results in an _____ of the next neuron

action potential

neurons can be organized into smaller organized groups called…

neural pools

the spread of information from one neuron to several neurons, permits broad distribution of a specific input, information enters the CNS and then spreads to the brain and spinal cord at the same time

divergence

information going from several neurons to single neuron, ex: rods in the retina of an eye

convergence

information going from one neuron to the next sequence, information going to one part of the brain, then to another part, and then to another part, etc.

serial processing

several neurons are processing the information at the same time, if you step on a nail, you typically move your foot, shout “ouch” and dance a bit, all at the same time

parallel processing

collateral axons extend back toward the origin of the impulse to cause an enhancement or a continuation of the impulse

reverberation

neurons in the PNS consist of…

ganglia

neurons in the ONS axons are bundled together in…

nerves

neurons in the CNS, collection of cell bodies celled a…

center

if the center of neurons in the CNS has distinct boundary that is called…

nucleus

white matter in the CNS consists of neurons consists of axons in bundles called…

tracts and columns