Human Physiology Lab Terminology Quiz 1

Neuron

conducts electrical activity away from the cell body; nerve cell; responds to stimuli

Glial Cell

supporting cell aiding the functions of neurons

Afferent

conducts impulse towards the CNS

Efferent

conducts impulse away from the CNS

Somatic

motor neuron innervating skeletal muscles

Autonomic

nervous system that involves control of smooth muscles, cardiac, and glands

Schwann Cell

supporting cell of PNS; forms sheath around PNS nerve fibers

Snare Complex

proteins that function to anchor synaptic vesicles in axon terminals to the presynaptic plasma membrane

Myelin Sheath

sheath surrounding axons formed by Schwann cells or oligodendrocytes

Resting Membrane Potential

potential difference across a plasma membrane when the cell is unstimulated; negatively charged inside compared to outside

Depolarization

inside of the cell membrane becomes less negative compared to outside of the membrane; reversal of membrane polarity

Repolarization

Re-establishment of the resting membrane potential after depolarization has occurred

Hyperpolarization

increase in negativity from the resting membrane potential inside of the cell membrane

Dendrite

short, highly branched neural process that carries electrical activity to the cell body

Voltage-regulated Channel

protein channel in the membrane opening in response to stimulus of a depolarization to a threshold level

Action Potential

All or none electrical event in an axon which the polarity of a membrane potential is rapidly reversed and reestablished; used by the nervous system to communicate large distances

Absolute Refractory Period

The period of time during which a region of axon or muscle cell membrane cannot be stimulated to produce an action potential

Relative Refractory Period

The period of time during which a region of axon or muscle cell membrane can only be stimulated by a very strong stimulus

Neurotransmitters

chemical in synaptic vessels of nerve endings that is released into synaptic cleft where it causes either excitatory or inhibitory postsynaptic potentials

Synapse

junction across which a nerve impulse is transmitted from an axon terminal to a neuron, muscle, or gland

Ligand Regulated Gate

channels opening in response to binding of a chemical ligand to its receptor in postsynaptic membrane

Graded Potential

A change in the membrane potential (depolarization or hyperpolarization) with amplitudes that are varied, by variation in the stimulus intensity

Excitatory Post Synaptic Potential

graded depolarization of postsynaptic membrane in response to stimulation; can be summed over short distances

Inhibitory Post Synaptic Potential

hyperpolarization of post synaptic membrane; makes it more difficult to attain threshold level

Agonist

molecule that specifically binds to and activates a receptor protein

Antagonist

molecule that binds and reduces the activity of receptor proteings

G-protein

association of three membrane associated protein subunits, regulated by guanosine

Interneuron

neuron located in the CNS; also called association neuron