Chapter 11 Assignment

the membrane potential becoming more positive in value is called _____ whereas ____ refers to the membrane potential becoming more negative than the resting membrane potential

depolarization; hyperpolarization

groups of related nerve cell bodies located outside the central nervous system are called

ganglia

structures called _______ are involved in electrical synapses

gap junctions

a student observes a stained slide of brain tissue under the microscope. she notices a large number of neuron cell bodies and dendrites. what type of brain tissue is she looking at?

gray matter

identify the statement that best differentiates gray matter and white matter

gray matter consists of cell bodies and dendrites, whereas white matter consists mostly of myelinated axons

what effect does acetylcholine have on the presynaptic neuron?

ligand-gated Na+ channels open and Na+ diffuses into the cell

depolarization occurs because

more sodium ions diffuse into the cell than potassium ions diffuse out of it

the _______ of a neuron release neurotransmitters

presynaptic terminals

for a typical neuron, what limits the maximal frequency attainable of action potentials moving down an axon?

refractory period

the neurons that conduct information towards the central nervous system are

sensory (afferent) neurons

as a result of Ca2+ diffusing into the presynaptic cell

synaptic vessels migrate to the plasma membrane and release acetylcholine

when threshold is reached, depolarization of the same magnitude occurs for all action potentials. if threshold is not reached, an action potential does not begin at all. this describes

the all-or-none law

hyperpolarization, or afterpotential, occurs because

the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level

an action potential arriving at the presynaptic terminal causes

voltage gated Ca2+ channels to open, and Ca2+ to diffuse into the cell

the _________ is a period of time when a membrane cannot respond to another stimulus no matter how strong

absolute refractory period

the division of the peripheral nervous system that transmits electrical impulses from sensory receptors to the central nervous system is the _____ division, while the ____ division of the peripheral nervous system transmits electrical impulses from the central nervous system toward muscles and glands

afferent; efferent

along myelinated axons of the peripheral nervous system, ion currents must cross the plasma membrane of the neuron

at nodes of Ranvier

the division of the nervous system that transmits electrical impulses to cardiac muscle, smooth muscle, and glands is the ______ nervous system, while the division that transmits electrical impulses to skeletal muscle is the _______ nervous system

autonomic; somatic

the central nervous system includes the

brain and spinal cord

the equilibrium centers of the brain receive information from inner ear structures as well as the retina of the eyes. this arrangement is an example of a

converging circuit

The _________ nervous system communicates with the skeletal muscles and the _____ nervous system communicates with the smooth and cardiac muscle as well as glands

somatic; autonomic