Nervous system Flashcards
CNS
Central Nervous System
what two organs make up CNS
Brain and spinal cord
Functions of the CNS
Integrate, porcess and coordinate sonsory data and motor commands
PNS
peripheral nerve system
Two types of Peripheral nefves
cranial and spinal
Mixed nerves
nerves that contain both sensory and motor nerve fibes (most nerves are mixed)
Motor Nerves
nerves that carry impulses to muscles or glands
sensory nerves
nerves that carry out impulses into the brain or spinal cord
Two divisions of spinal nerves
Afferent and Efferent
afferent
brings sensory information from receptors (PNS) to the CNS
efferent
Carries motor commands from CNS to muscles
somatic nerves
Muscles with voluntary control
autonomic nerves
Muscles with involuntary control
sympathetic
fight or flight
parasympathetic
Rest and digest/ feed and breed
3 general nervous system functions
sensory, integrative and motor
Sensory Functions
receptors detect changes in body conditions
Integrative function
Taxes sensory info and makes decisions that are acted upon with motor function
Motor Functions
make use of effectors that respond when they are stimulated by motor impulses
Convergence
a single neuron recives impulses from several incoming fibers, having an additve effect
Divergence
Impulse from one neuron may stimulate two, those two may stimulate 2 more.
what does divergence allow for
an impules to be amplified and spread out between neurons
Functions of the CNS
Integrate, porcess and coordinate sonsory data and motor commands
3 general nervous system functions
sensory, integrative and motor
2 principle kinds of cells in neural tissue
Neurons and Neuroglial (Glial) cells
Neurons
structural and functional unit of neural tissue
neuron function
process and relay information
Glial cells function
supporting cells that give structural support to nervous tissue, serve as phagocytes, regulate interstitial fluid and assist in metabolism.
T/F there are more neurons thatn glial cells
False
primary difference between CNS and PNS
number and types of glial cells they contain
what four types of glial cells are found in CNS
Ependymal, astrocytes, oligodendrocytes and Microglia
Ependymal
line the central canal of spinal cord and brain ventricles; some secrete cerebrospinal fluid, others assit in circulation of the fluid
Astrocytes
Maintai blood-brain barrier, provide structural framework for neurons, perform repairs to tissue and direct the growth of develepoping neurons in the womb
Oligodendrocytes
Tie axon clusters together and improve neuron performince
Microglia
clean up crew that engulfs celular waste products, increase in number with injury
2 types of glial cells found in the PNS
Satellite cells and Schwann cells
sattelite cells
surround neuron cell bodies
Ganglia
special masses of nervous tissue that occuer outside of the spinal cord
schwann cells
covr peripheral axons to myelenate them
Mylenation
a layer of mylen surronds nerve cell and makes it transmit faster
how many axons in a nerve
one
axon
long process that carries impulses away from the cell body
fine extensions at the end of an Axon
terminal filaments
whats found on the end of terminal filaments
synaptic knobs
synaptic knobs
contain neurotransmitters that facilitate movement of impulses across a synapse
Neurilemma
surronds myelin sheaths
what part of brain matter do mylenated nerves make up
white matter
nodes of ranvier
gaps found along the axon between myelin sheaths
Perikaryon (soma)
the cell body of a nerve cell-contains cytoplasm, nucleus etc.
What makes up gray matter
Nissl bodies (free ribosomes seen in nerve bodies)
how do neuron cells divide
they don’t (no centrioles)
how many Dendrites does a neuron have
many
Dendrites
Short and branching; extend from the cell body; sends info to cell body
Unipolar neurons
1 process that extends from body that divides into a peripheral process( dendrite) and a central process
What type of neurons are unipolar
PNS sensoy neurons
Multipola Neurons
Many process on cell body, one axon, the rest are dendrites
types of neurons that are multipolar
Most neurons in brain or spinal cord and motor neurons
Bipolar Neuron
Nonmyelinated; have 1 dendrite and 1 axon, with cell body in the middle,
where can bipolar neurons be found
they are relatively rare but are found in retna, inner ear and nose
Sensory Neyrons
collect data about internal and external environment, which is sent to brain or spinal cord
types of sensory receptors
extroceptors, proprioceptors and introceptors
exteroceptors
external environment
Proprioceptors
position and movement of skeletal muscles and joints
interoceptors
internal environment
somatic motor neurons
stimulate voluntary muscle activity
visceral motor neurons
elicit response from all other peripheral structures (not muscle); involuntary
Interneurons
connector neurons that link other neurons
excitability
able to change in their environment
conductivity
ENABLES THEM TO SEND ELECTRICAL IMPULSES
Inttegration
Allows incoming impulses to be sorted out and interpreted
Inttegration
Allows incoming impulses to be sorted out and interpreted
What is the outer charge of a resting nerve cell
Positive
Resting cell has sodium or potassium
High concentration of potassium inside the cell
action potential
a nerve impulse
depoloraxation
neuron becomes more positive
refractory period
time required to restore the resting potential
Excitaory synapses
trigger a nerve impulse
Inhibitory synapses
reduce the ability of a neuron to depolarize
