A&P Ch 8 HW & quizzes

Binding of a neurotransmitter to its receptors opens ________ channels on the __________ membrane.

chemically gated; postsynaptic

What do ependymal cells do?

Ependymal cells line the central canal and ventricles of the brain and produce cerebrospinal fluid (CSF).

In a synapse, neurotransmitters are stored in vesicles located in the

presynaptic neuron

dendrites:

receive messages

Detect information from external environment or our physical position in the environment

Somatic sensory receptors

Receptors monitoring the internal environment

Visceral receptors

The velocity of the action potential is fastest in which of the following axons?

a small myelinated axon

axons:

send messages

Afferent nervous system

sensory information moving toward CNS

An action potential releases neurotransmitter from a neuron by opening which of the following channels?

voltage-gated Ca^2+ channels

What is the value for the resting membrane potential for most neurons?

-70 mV

Process of a stimulus reaction:

1. A stimulus arrives. 2. Voltage-gated sodium channels open. 3. Sodium enters the cell. 4. Cell is depolarized. 5. Voltage-gated sodium channels close as voltage-gated potassium channels open. 6. Potassium leaves the cell. 7. Cell is repolarized.

Conduction along a neuron that does not have myelin.

Continuous propagation

What occurs when multiple neurons feed into a single neuron?

Convergence

The membranes of neurons at rest are very permeable to ______ but only slightly permeable to ______.

K+; Na+

Neuron with two or more dendrites and a single axon.

Multipolar

Polarized state of a neuron; measuring at -70 mV

Resting membrane potential

Oligodendrocytes are to CNS as ______ are to PNS.

Schwann cells

Produce myelin in PNS

Schwann cells

Hyperpolarization results from _______.

slow closing of voltage-gated K+ channels

When a stimulus reaches and excites a neuron causing a sodium ions to move inside and changing the measurement from -70 mV towards +30 mV (depolarization).

Action potential

How is an action potential propagated along an axon?

An influx of sodium ions from the current action potential depolarizes the adjacent area.

Maintain blood-brain barrier; structural framework for CNS; repairs damaged neural tissues

Astrocytes

Neuron with continuous dendrites and axon with the cell body.

Unipolar

Peripheral nervous system

all nerve tissue outside the CNS

A given stimulus either triggers a typical action potential or it does not produce one at all.

all-or-none principle

Sympathetic nervous system

associated with fight or flight situations

Parasympathetic nervous system

associated with resting and digesting phase

Where in the neuron is an action potential initially generated?

axon hillock

Neuron with two processes-one dendrite and one axon with the cell body in between.

bipolar

Situation when the membrane potential becomes more negative than -70 mV.

hyperpolarization

The ventral root (CNS) carries _______ information ________ the spinal cord.

motor; from

cell body:

nucleus

Period of time when the neuron cannot respond normally to further stimulation.

refractory period

When the sodium gates close and the potassium gates open causing the measurement inside the cell to move from +30 mV towards -70 mV.

repolarization

What is the difference between saltatory and continuous propagation of nerve impulses?

Saltatory carries impulses at a faster rate than continuous propagation.

Conduction that occurs along a neuron with myelin.

Saltatory propagation

Found in the PNS and support neuron cell bodies

Satellite cells

Also called afferent; transmit impulses from sensory receptors to CNS

Sensory neurons

Middle meningeal layer surrounding the brain and spinal cord

arachnoid

During depolarization, which gradient(s) move(s) Na+ into the cell?

both the electrical and chemical gradients

Unlike neurons, neuroglia are

capable of cell division

Opening of voltage-gated sodium channels in the membrane of a neuron results in

depolarization

Outermost layer; outer portion fused with skull periosteum

dura mater

Binding of the neurotransmitter to its receptor causes the membrane to _______.

either depolarize or hyperpolarize

Location of gray matter (neuron cell bodies) in the PNS

ganglia

Local potential or changes in the membrane potential that cannot spread far from the site of stimulation.

graded potential

Central nervous system

includes the brain and spinal cord

Also called association neurons; located in the CNS only; interconnect sensory and motor neurons

interneurons

Autonomic nervous system

involuntary control of smooth muscles, cardiac muscle, and glands

The repolarization phase of an action potential results from ________.

the opening of voltage-gated K+ channels

Change necessary for an action potential to occur (-55 mV).

threshold

Bundles of axons (white matter) in CNS

tracts

The innermost meningeal layer firmly bound to the neural tissue (brain and spinal cord)

pia mater

Which term best matches the following description: polarized-positive on the outside and negative on the inside; measures at -70 mV.

resting membrane potential

Which of the following provides control over skeletal muscles?

somatic nervous system

The depolarization phase of an action potential results from the opening of which channels?

voltage-gated Na+ channels

Somatic Nervous system

voluntary control of skeletal muscles

What is the magnitude (amplitude) of an action potential?

100 mV

The entire spinal cord is divided into ______ segments.

31

Have cilia on one surface to help move CSF around the CNS

Ependymal

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped?

Na+ is pumped out of the cell and K+ is pumped into the cell.

Phagocytic cells that engulf cellular waste and pathogens

Microglia

Also called efferent; carry instructions from CNS to muscles and glands

Motor neurons

The concentrations of which two ions are highest outside the cell.

Na+ and Cl-

Produce myelin in CNS

Oligodendrocytes

Why does the action potential only move away from the cell body?

The areas that have had the action potential are refractory to a new action potential.

The mechanism by which the neurotransmitter is returned to a pre-synaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned?

acetylcholine

The brain and spinal cord comprise the

central nervous system

Efferent nervous system

motor commands moving from CNS to muscles/glands

Bundles of axons (white matter) in PNS

nerves

Portion of the brain where gray matter is located and is the sight for complex integration

neural cortex