Unit 1 Flashcards
(40 cards)
An _________ _______ (nerve impulse) is an electrochemical process that results from the movement of ions across a neuron’s semi- permeable membrane (through voltage sensitive ion channels).
Action Potential
A stimulus that is strong enough to trigger the ______ _______ (minimal stimulus required to open the sodium channels) will cause an action potential
Threshold Level
Like the trigger of a gun, once a threshold level has been reached, an action potential will occur regardless of the degree the threshold level is exceeded. This is known as the _____ _____.
All or none response
Neuron is polarized (positive outside and negative inside)
Resting Potential
assuming threshold level was achieved
Depolarization
Na+ channels close and the K+ channels open allowing potassium to diffuse out of the neuron
Repolarization
Too much for polarization
Hyperpolarization
even though the membrane is now polarized again, the ion concentrations are reversed. It is the responsibility of the sodium potassium pump to restore the original concentrations.
Reestablishment of membrane potential
potassium channels are slow to close, there is a brief overshoot of potential called
Hyperpolarization
the recovery time required before a neuron can respond to another impulse.
Refractory Period
The end plates found on the _____ _____ contain _____ _____ that possess chemicals called ________ ______.
Presynaptic Neuron
Synaptic Vesicles
Neurotransmitters
A _______ is a gap that acts as a junction between the axon of one neuron and the dendrite of another neuron.
Synapse
Once an action potential reaches the end plate of a neuron the “message” must be converted to another form to bridge gap between the two cells called the
Synapse
The synaptic knob (button) contains ______ ______ that possess the chemical neurotransmitter substances. These chemicals may have an _____ or _______ effect on the neuron.
Synaptic vesicles
Excitatory
Inhibitory
The synaptic knob (button) contains ______ ______ that possess the chemical neurotransmitter substances. These chemicals may have an _____ or _______ effect on the neuron.
Synaptic vesicles
Excitatory
Inhibitory
Once the membrane is depolarized, the vesicles fuse to the membrane and release their neurotransmitters via
Exocytosis
The neurotransmitters diffuse across the synapse toward the _____ _____ where they bind to ______ causing the depolarization of the next neuron.
Postsynaptic neuron and receptors
Stimulates the neuron to increase the size of its pores so that more Na+ enters the membrane. This is produced at the presynaptic knob.
Acetylcholine
Is an enzyme produced by the presynaptic neuron, which functions in the breakdown of the neurotransmitter acetylcholine.
Cholinesterase
The __________ __________ ________ is made up of myelinated neurons that transmit actions potentials between body tissues and the CNS
Peripheral Nervous System (PNS)
Focuses on the external environment and controls voluntary (conscious) and involuntary (reflexes) skeletal muscle movement.
Sensory-Somatic Nervous System
Focuses on the internal environment and controls “automatic” functions of the body’s internal organs.
Autonomic Nervous System
Predominates in times of high activity or stress (flight-or-fight).
Sympathetic division
Predominates during rest (rest-and-digest response).
Parasympathetic division
