Nervous system Flashcards
(32 cards)
Nervous system
system that controls all parts of the body, allows different parts of the body to coordinate and communicate with each other
CNS (central nervous system)
the brain and the spinal cord, processes information from PNS and determines a reaction
PNS (peripheral nervous system)
a system of neurons that carries information to and from the CNS
a neuron
an individual cell of a nerve
ganglia
the cell bodies of all the neurons collected together, forming a small mass, outside of brain and spinal cord
3 interconnected functions of the nervous system
- sensory function(PNS)- a stimulus alerts sensory receptors, sensory neurons carry this info to CNS
- uses sensory neurons (afferent)
- sensory divison(PNS) - integration /CNS processing function- interpret this data and determines a response (CNS)
- uses integration neurons - motor function- carries the response from CNS to effector cells -muscles and glands
- motor neurons (efferent)
- motor division (PNS)
- automatic (involuntary (muscles/glands in the heart for example)
-somatic (voluntary- skeletal muscles)
- sympathetic (flight or fight response)
-parasympathetic (rest and digest)
neuron
dendrites: receive info from other neurons
cell body: contains nucleus and other organelles
axon: carries electrical signal to synaptic terminal
- myelin sheaths: insulting layer around axon, appears in beadlike sections, makes the electrical signal travel faster
- Schwann cell: in the myelin sheath, provide maintenance
- nodes of Ranvier : small nodes in between myelin sheath, where the electrical signal is regenerated
- synaptic terminals: the axon branches out and at the end is the synaptic terminal, it transports the signal to the next neuron
Neuron at resting potential
- 70mv(milivolts)
- high concentration of NA+(sodium), low K+(potassium) outside of cell,
-low concentration of NA+ (sodium) inside of cell, high concentration of K+ (potassium) inside of cell
-outside of cell has a net positive charge - inside of cell has a net negative charge
- all voltage-gated Na+ and K+ ion channels are closed
- NA+ and K+ pumps- maintaining concentration
- ungated K+ and NA+ pumps open-facilitated diffusion( negative proteins keep most K+ in inside of cell from attraction) and there are way less NA+ channels open
- membrane potential: a resting neuron has potential energy bc of the electircal charge difference across the plasma membrane and the different concetraion of ions
steps of transmitting an electric signal in one node of ranvier
- the neuron is at resting potential( -70mv) All voltage-gated ion channels are closed- ungated ion channels are open, more K+ are open than NA+ and K+ ions will never reach equllibrium bc they attracted to negative protiens inside cell, there is a high concetration of K+ inside cell, low NA+ in cell, low K+ outside cell, high NA+ outside cell, net negative inside, net postive outside
- a stimulus causes some NA+ channels to open, if the voltage reaches thresolhold, which is -50mv, more NA+ channels open, an action potential is triggered, the cell starts to depolarize
- Once action potential is reached(35 mv), the NA+ ion channels close and lock, the K+ channels open and K+ rushes out, the interior of the cell starts to become more negative(repolarize)
- once resting potential is reached (-70mv) the K+ ions are slow to close causing hyperpolarization- the interior of the cell becomes more polar than resting potential
- Sodium Potassium pumps regulate the ions and return the K+ aack into the int of the cell, and the NA+ outside of the cell and bring the neuron back to resting potential.
membrane potential
a resting neuron has potential energy-electrical charge difference can be changed by the flow of ions across a membrane traslates into the transmission of an electric signal
how does the action potential generated by a stimulus in one node of ranvier trigger an action potential in the other nodes of ranvier along the axon
Once action potential is reached NA+ ions flow through myelin sheaths to the next node, where they act as a stimulus and allow the neuron to reach the thresold, triggering action potential at this node,
why is it important that the NA+ gated are closed and locked
The NA+ ions in the interior of the cell do not only foward to trigger the next node, but alos backward. The locjked NA+ channels prevents a previous node from triggering an action potential, so the electrical signal does not go backwards. =
synapse
a junction where neurons communicate with eachother
synaptic cleft
a physical space between two neurons-only in chemical synapses, which are more common
chemical synapse
more common, a physical space between 2 neurons(synaptic cleft), uses a chemicla signal to communictae netween 2 neurons
1. action potential reaches synaptic terminal
2. a synaptic vesicle (nuerotransmitters surronded by a plasma membrances) fuses with the plasma membrane and lets the nuerotransmitters into the synaptic cl;eft
3. the nuertotransmitters binds to a receptor on the NA+ channels
4. NA+ ions flow into the neron,
4. may triggers action potential
excitatory neurotransmitter
causes an action potential to be reached
1. NR bonds with receptor on NA+ channel- opens channel
2. NA+ ions flow in- threshold is reache d
3. Action potential is triggered
4. action p-otential is reached 890
inhibatory neurotansmitterq
prevents an action potential from being reached
- prevent na+ channel from opening
- open K+ channels
- hyperpolafize, make it more negaive
antangonistic pairs
two pairs of muscles, electric signals cannot tell muscles to relax they can only tell muscles to contract, one relaxes, one contracts
a muscle
a bundle of muscle fibers
muscle fibers
muscle cells, long cylinder
multinuclienated
muscle fibers(muscle cells) have multiple nuclei bc they r so long, nuclie for different section so cytoplasm
myofiber
a long strands of protien, in the cytoplams of the muscle fiber
