Nervous system Flashcards
What does the nervous system do
receives and processes information, sends the signal out to muscles and glands to get a response
what is nervous tissue responsible for
responsible for communication between cells of the body by forming a system of electrical impulses that communicate rapidly
What is CNS
central nervous system
sends and receives signals from peripheral nervous system
What structures are within CNS
brain and spinal cord
In CNS cell bodies are called
nuclei
In CNS nerve axons are called
tracts
What is PNS
Peripheral nervous system
includes all nerves not in brain or spinal cord
What structures are in PNS
brainstem
cranial nerves
spinal nerves
What makes up the brainstem
midbrain
pons
medulla
What are cell bodies called in PNS
ganglia
What are axons called in PNS
nerves
Where do cranial nerves innervate
face, neck and head
Where do spinal nerves innervate
rest of the body
What are 2 division within PNS and CNS
Sensory( afferent)- receives info via sensory organ via afferent division
Motor( efferent)- replay impulse from CNS to muscle, glands via motor
How is efferent division further divided
somatic and autonomic
What is the somatic system nerves
is conscious voluntary control:
controls skeletal muscles, skin and joints
What is autonomic system
unconscious control
controls glands and smooth muscles of internal organs
What are the 2 divisions of autonomic system
sympathetic and parasympathetic
What does sympathetic part of autonomic system do
activate and prepare bod for muscle activity, stress and emergency
What does parasympathetic part of autonomic system do
operates during normal situation, aids in digestion and conserves energy
what is a neuron
nerve cell that conducts electrical impulses and relays information into the body
What are 3 basic parts of a neuron
dendrite, cell body and axon
What are 2 unique qualities of neurons
do not undergo mitosis
survive a lifetime
if die due to brain damage-> can’t be replaced
what does a nerve cell body structure and function
synthesize al nerve cell products
has large nucleus with surrounding cytoplasm contain normal organelles
info received and sent in same direction within the neuron
What is the structure and function of a dendrite
it is the receiving end of the neuron
numerous short extension emanate from cell body
receive information from other neuron and conduct impulse toward body
What is structure and function of an axon
conduct nerve impulse away from cell body to axon terminal
vary in length, composed of material like cell body
depends on cell body to send necessary protein down length of axon
What are neurotransmitters
chemicals stored inside secretary vesicles at end of axon terminal
Who manufactures neurotransmitters
cell body
What happens when neurotransmitters is released
transmits nerve impulse from neuron to another
What is a synapse
gap between 2 neurons
What is pre-synaptic and post-synaptic neuron
refers to either before or after the synapse
pulse->presynaptic->synapse->postsynaptic
How are neurons classified -3 ways
classified by # of extensions
unipolar, bipolar, multipolar
What is a multipolar neuron
3 or more extension from cell body, 1 axon and many dendrites
typically a motor neuron
What is a bipolar neuron
2 extension from cell body
special receptors in visual and olfactory system
What is unipolar neuron
1 extension off cell body: has 2 branches
central process running to CNS
peripheral process-> sensory->PNS
What are the functions a sensory neuron
afferent, unipolar-> carry info from PNS to CNS
ex. skin/internal organ->CNS
What is function of interneuron
association neuron-> only in CNS
multipolar transmit impulses with different parts of CNS
What is function of motor neuron
efferent->multipolar
sends impulse from CNS to PNS
What is definition of nerve
consists of many axons wrapped in connective tissue
What is definition of ganglia
part of single nerve-> cell bodies of neurons grouped together in masses
What are neuroglial cells
highly important for neuron function
support cells for neurons to survive and conduct electrical impulses efficiently in environment
What are schwann cells
cells found in PNS
coat peripheral nerve axon
is a type of neurological cell composed of myelin sheath
myelin sheath is rolled around axon, insulates nerve fibers increase speed of nerve impulses
What is unmyelinated fibers
gray matter-> schwann cells don’t wrap around and are loosely associated w/ax
Are schwann cell sections continous
no
What are the gaps in Schwann cells called
Nodes of Ranvier
What is saltatory connection
nerve impulse forced to next node when previously exposed
increases nerve impulse transmission axon axon
What are satellite cells
surround cell bodies of peripheral neuron
help to regulate cell body environment
What is axonal regeneration
process of axon regrowth for peripheral nerves
if peripheral nerve axon is injured, schwann cells grow ahead of axon and create a path for axon to follow as it grows
What are the 4 main types of cells in CNS
ependymal
oligodendrocyte
astorcyte
microglial
What are ependymal cells structure and function
circulate cerebrospinal fluid and allow fluid exchange between brain, spinal cord and CSF
What is cerebral spinal fluid
clear fluid in brain and spinal cord
What are oligodendrocytes function
act as insulation for CNS axon
What are function of astrocyte
control chemical environment of neurons by wrapping around blood capillaries
What is the blood brain barrier
barrier hat allows passage of certain substances into CNS
What are microglial cells
cells that protect CNS by picking up dead cells and infectious organisms
Define action potential
neurons perform and specialized to conduct electrical impulses
rapid change in polarity because axon stimulated to conduct a nerve impulse
What is a nerve impulse
electrochemical charge moving along an axon created by movement of unequally distributed ions on either side of axon plasma membrane
What does it mean when neurons are “polarized”
at rest plasma membrane has one side that has a different charge than the other
What is resting potential
axon not conducting an impulse-> different in electrical charge is -70mV
charge is - because charge on inside of axon cell membrane is -70mV
maintained by sodium-potassium pump-> use active transport to carry ion across plasma membrane
Describe sodium potassium pump
integral protein: for every 3 Na+ ion go out 2 K+ion come in
must keep in constant operation because Na+ and K+ naturally diffuse back to starting point
plasma membrane more permeable to K+ diffusion gout, more Na+ pumped out than K+ pumped in, a relative (+) charge develops and maintain on outside of membrane
What are the 4 steps of action potential
resting potential, membrane depolarization, repolarization, after polarization
How does resting potential become active
if membrane is depolarized
once occurs: impulse travels entire length of axon
What is depolarization
impulse on membrane so that potential becomes more positive
indicates inside of membrane is now more positive than outside
What is repolarization
when potential of membrane returns to normal indicate axon is (-)
Describe complete phases of action potential
- resting potential: both Na+ and K+ are closed
- Depolarization->Na+ gate open, Na+ rsh into axon, voltage travels to zero then up to +40mV
- Repolarization-> Na+ gate closes, K+ gate open allow K+ to rush out of axon-> return (-) volt to inside of axon
- Afterpolarization-> hyper polarization->K+ gates slow to close, undershoot of potential volts drop below -70mV then return to -70mV as resting state begins
What is self-propagating
ion channels open whenever membrane potential decreases
T/F action potential is all or nothing
T
How is intensity of pain measured
by sensation of # of neurons stimulated and frequency of the stimulus
what is electrochemical mean with action potential
transmission of nerve impulses as chemical-> neurotransmitters
What does electrochemical allow for and what is functional
allow signal to jump synaptic gap
signal moves from electrical( through neurons) to chemical ( in synapses) back to electrical when reaches next neuron
How is Ca+ involved in action potential
nerve reaches end of axon, Ca2+ channel open
Ca2+ comes in causes vesicle to fuse w/plasma membrane and release neurotransmitters
as neurotransmitter is released it binds w/receptr on next neuron, Na+ in dendrites open
Depolarization occurs in next neuron, impulses is propagated forward to next neuron or target organ-> always in one direction
What is acetylcholinesterase
neurotransmitter that breaks down actylcholine
what is inhibition in terms of action potential
prevention of continuous stimulation
T/F once neurotransmitter is released only a short time for it to act
T
Where are norepinephrine and epinephrine produced
adrenal glands
What is dopamine and what is function
brain neurotransmitter that regulates emotional response and tone
What is acetylcholine and where is it found
neurotransmitter found at Neuromuscular junction in PNS
What is the neuromuscular junction and where is it located
located where motor neuron ends on a muscle instead of another neuron
for muscles to contract it must work w/nerves and muscular system
What are the steps for the NMJ to work with muscular system to enable muscle contraction
- nerve impulse sent to muscle by presynaptic neuron
- nerve impulse reaches muscle fiber, at NMJ, actylochonline released into synapse
- Acytlcholine binds to receptors on muscle fiber cause Na+ channel to open
- Na+ rush out of muscle cell which trigger action potential reaches sarcoplasmic reticulum
- Ca2+ released from sarcoplasmic reticulum causes muscle to contract
What is sarcoplasmic reticulum
specialized smooth ER found in striated muscle tissue
What are reflexes
automatic, instantaneous, involuntary motor responses within nervous system
start from stimuli occur in/out of body
subconscious regulate blood sugar by hormone
involuntary: pull hand away from hot object
blinking: involve brain stem
What is the reflex arc
neural pathway that nerve impulse travels
certain reflexes tested to examine function of nervous system as reflex arc pass through CNS
How does sensory info travel with spinal cord
sensory info travel into spinal cord via dorsal root
How does motor info travel with spinal cord
motor info travel out of spinal cord via ventral root
What is gray matter
contains cell body of neuron, neuron synapse with other neuron
what is white matter
contains axon of neuron
white surrounds grey
What is interneuron and where is it located
located in CNS and designed to connect neuron to each other
What is dorsal root ganglian
contain cell body of sensory neuron
Where does sensory neuron synapse on cells in grey matter
Posterior horn
Where is motor neuron cell located in grey matter
anterior horn
what is a spinal nerve
contains both sensory and motor neuron from ventral to dorsal roots
What is a spinal reflex and why is it faster
reflex that goes from stimulus to brain stem and back
goes a shorter distance then going to CNS
What are 2 examples of spinal reflexes
stretch reflex and flexor-withdraws reflex
What are 5 steps of reflex arc to neural pathway
- receptor @ end of sensory neuron reacts to stimulus
- sensory neuron conduct impulse along afferent path to CNS
- integration center consist of 1 or more synapse in CNS
4 motor neuron conduct nerve impulse from efferent path to effector - effector responds to efferent impulse by contract( muscle) or secrete a product( gland)
What is the stretch reflex
muscle reflex protects muscle against increase in length that may damage fibers
What is a muscle spindle
specialized muscle cell that constantly monitors amount of stretch in muscle
What is an example of stretch reflex
patellar tendon
How does patellar tendon stretch reflex work
knee-jerk tests reflex of quadricep femurs-> prevents overstretch of quad
What is the detailed process of stretch reflex
muscle spindle detects stretch-> sends signal along afferent neuron-> through the dorsal root ganglian-> to spinal cord via dorsal root
afferent synapse in grey matter of spinal cord directly onto efferent neuron in grey matter( anterior horn)
efferent neuron travel out of ventral root and through the nerve to synapse on some muscle
What is flexor-withdraw reflex
reflex that designed to flex the bicep and withdraw the hand so not to injure the nerves and tissues of the hand
What is the process for the flexor-withdraw reflex
hot object touched-> pain receptor generate impulse
impulse move along dendrite of sensory neuron toward cell body + CNS
from cell body impulse travel along axon of sensory nerve synapse on many interneuron in grey matter of spinal cord
excitatory nerve synapse on bicep causing it to contract which draws it back
at same time as excitatory the inhibitory neuron synapse on tricep making it to not contract and does not stay extended
whole process happens instantaneously
What is excitatory interneuron
send excitatory signal to motor neuron causing muscle contract
What is inhibitory neuron
send inhibitory signal to prevent muscular contract
