movement of an impulse across a synapse
action potential arrives at presynaptic neuron
synaptic vesicles fuse to membrane of the axon
neurotransmitters are released into synaptic cleft and defuse across synapse
dendrites of cell membrane of the effector react
neurotransmitters bind to receptor proteins with trigger channels to open depolarizing postsynaptic membrane
nervous system
sends electrochemical messages throughout the body to maintain homeostasis. fast acting.
Homeostasis
a state of relative equilibrium within the body
Central Nervous System (CNS)
brain, spinal cord, (interneurons)
Peripheral Nervous System (PNS)
the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body.
stomatic nervous system
voluntary actions, Effectors skeletal muscles
autonomic nervous system
involuntary movements, smooth and cardiac muscles
sympathetic nervous system
fight or flight: releases epinephrine
parasympathetic nervous system
rest and digest, returns body to state of rest
Ephinephrine
increases heart rate oxygen goes to skeletal muscles raises blood glucose levels dilates airways, (increased oxygen)
neurons
basic structural and functional unit of the nervous system
responds to stimuli, conducts and sends electrochemical signals
Shwann cells
glial cell that forms myelin around the axon of neurons.
protects, and speeds up rate of reaction
glial cell
nourish neurons, remove their waste and defend against infection
surround, nourish, support, protect
Nerves
bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs
sensory receptors
receive stimuli and form a nerve impulse
sensory neurons
transmit impulses to interneurons in spinal cord and brain
Interneurons
Central nervous system neurons transmit impulses between the sensory inputs and motor outputs
motor neurons
neurons that carry outgoing information from the brain and spinal cord to effectors
Effectors
muscles, glands and or organs that respond to impulse from motor neurons
reflex arc
sensory receptor, sensory neuron, interneuron (in spine) motor neuron, and effector is involved in a quick response to a stimulus
normal neuropathways
sensory receptor, sensory neuron, interneuron (in spine), interneuron (in brain) motor neuron, and effector slower then reflex arc
Dentrites
Branches that reach out from the cell body and receive signals from surrounding neurons
cell body
contains nucleus and processes input from dendrites (if the input reaches threshold relays it to the axon)
Axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
Axon bulb
The axon bulb is the area at the end of the axon, where signal transmission to the next neutron occurs.
Nodes of Ranvier
unmyelinated sections of a myelinated neuron that impulses "jump" between
all-or-none response
if threshold is not reached axon does not fire at all if threshold is reached the cell fires entire length of the axon
threshold potential
minimum amount if stimulus needed to make a neuron fire
membrane potential
voltage across a membrane
resting membrane potential
the electrical charge of a neuron when it is not active
Neuron at rest
has Na+ on the outside and K+ on inside. is negative
sodium-potassium pump
uses ATP to actively transport sodium ions out of a cell and potassium ions into the cell
membrane depolarization
sodium gates open and all sodium outside rushes in creating a reversal of charge (happens at nodes of ranvie)
hyper polarization
Refractory period cell is more negative then it is a resting potential.Sodium potassium pump kicks on transporting sodium out and potassium in. returning cell resting potentail
membrane repolarization
Refractory period Potassium channels open causing K+ to leave the cell and repolarize it. resulting in hyperpolarization
Synapse
the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron
neuromuscular junction
the synapse between a motor neuron and a skeletal muscle cell
action potential
a neural impulse; a brief electrical charge that travels down an axon
Neurotransmitters
chemical messengers that cross the synaptic gaps between neurons
summation
the combination of two or more excitatory neurotransmitters that reach the threshold of the other neuron
excitatory neurotransmitter
neurotransmitter that causes the receiving cell to fire, by depolarizing it (lowering threshold level)
inhibatory neurotransmitters
inhibit the next neuron from firing by triggering the opening of potassium gates resulting in hyperpolarization ( raising threshold level)
Actylcholine
One of the most common neurotransmitters in a neuromuscular junction
Norepinephrine
A neurotransmitter used by brian and some autonomic neurons . complements epinephrine lack of: exhaustion excess of: anxiety
Acetylcholinesterase
the enzyme that breaks down acetylcholine in the synaptic cleft
two was neurotransmitters are removed from the synapse
enzymes reabsorption into the axon bulb