Nervous System L6 Flashcards
Nuerons
Cells transmit impulses via action potential
Glial Cells
Cells support function of neurons
Neuron traits
Excitability
Conductivity
Secretion
Amitotic
Excitiability
Respond to stimuli
Conductivity
Send electrical signal along neuron
Secretion
Release neurotransmitter that influence other cells
Amitotic
No mitosis, do not divide
Neuron components
Dendrites
Cell body
Axon
Myelination
Dentritic
Receives signals and sends to cell body
Cell body (Soma)
Initiate/receive signals from dendritic, contains nucleus, surrounded by plasma membrane
Axon
One per neuron, Carry action potential away from cell, release neurotransmitters from axon terminal to nerve, muscle, or glands
Myelination
Axon wrapped in lipoprotein sheath, giving white appearance (gray matter)
Saltatory conduction
Increase speed of transmission
Gaps between myelinated gaps called
Nodes of Ranvier
Sensory neurons
Carry action potential signal toward brain and spinal cord (ex: touch from skin to brain)
Motor neurons
Carry action potential away from brain to spinal cord ( voluntary movements)
Interneurons
99% neurons, process information,
connect directly to sensory and motor neurons
Nerve
Bundle of axon
Epineurium
Covers entire nerve
Perineurium
Group of axon fasicle
Endoneurium
Surrounds individual axon
6 types of support functions of neurons
Atrocytes
Ependymal cells
Microglia
Satellite cells
Schwan’s cells
Oligodendrocytes
Oligodendrocytes
Form the myelin sheath in Central Nervous System (CNS)
Schwann Cells
Form myelin sheath in Peripheral Nervous System (PNS)
Satellite Cells
Regulate exchange of nutrients and waste
Microglia
Phagocytic immune cell in brain, clear debris from damaged tissue of CSF
Ependymal Cells
Choroid plexus helps produce Cerebral Spinal Fluid (CSF)
Action potentional
Electrical signal down the axon, leads to release of neurotransmitters to neuron or muscle it connects to
Voltage inside cell
-70mV
Passive Transport
ion channels allowing facilitated diffusion of Na+ and K+ during action potential, moving down concentration gradient
Chemically gated channels
Open when chemical combined with the gate
Voltage gated channels
Open when particular voltage is reached
Resting membrane potential
Outside has Na+ and Cl-ions, inside is -70mV, more K+ and PO4-ions
At rest, if channels opened how do the ions distribute
Sodium passively move into cell, potassium passively move out of cell
Polarization
When change happens
Depolarization
Chemically gated Na+ opens, allow Na+ to flow into cell, the positive ions makes cell less negative, decrease in change
Hyperpolarization
K+ channels closes slowly, allowing K+ to leave cell, charge inside cell moves beyond -70mV
Threshold Potential
-55mV is reached, all the sodium channels open
Graded potential
Can depolarize/hyperpolarize cell, happens when chemical binds with a receptor ex: ACH + Na+= Na+ rush into cell to depolarize membrane but not strong enough for action potential
Excititory postsynaptic potential
Bring neuron closer to threshold by making cell less negative
Inhibitory postsynaptic potential
Pushes neuron away from threshold by letting in Cl-ions, making cell more negative
Repolarization
Once inside of cell reach +30mV, Na+ channel closes, all K+ channels open down axon, returns cell to -70mV
All action potential in axon have same
Strength
Larger diameter fiber have ____ impulse
Faster
Effect of myelination
Myelinated fibers conduct faster due to saltatory conduction (skip gates)
Refractory period
Period after beginning of action potential where it’s impossible or difficult to fire another action potential
Absolute refractory period
No stimulus can initiate another action potential
Relative refractory period
The period of time when another action potential is possible with sufficient strength (must overcome hyperpolarization)
Strength of stimuli is not based on strength but ___
Frequency
Synapse
Where one neuron meets another structure and communicates with it
Neurotransmitter
Cross synapse and trigger a response insecond structure
Sensory Nervous System(afferent)
Somatic Sensory-conscious to stimuli
Visceral Sensory-unconscious to stimuli
Motor Nervous System(Efferent)
Somatic Motor-control voluntary skeletal muscle
Autonomic- control involuntary smooth/cardiac muscles and glands
Sympathetic nervous system
Fight or flight, Initiate response that helps us escape danger
Parasympathetic
Rest and digest, helps conserve energy and restore nutrients
Ganglion
bunch of cell body where neurons synapse
Preganglionic nerve
nerve bringing signal into ganglion
Postganglionic nerve
nerve carrying signal away from ganglion
short/long preganglionic nerves and short postganglionic nerve release?
Acetylcholine
Long postganglionic nerve release
epinephrine/norepinephrine
Atrocytes
form blood brain barrier, regulate what gets into brain, build new connections