Anatomy: Action Potentail and Reflexes

What does not describe a reflex?

Multidirectional

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.

What statement best describes the resting state of a neuron?

Neurons are polarized with more sodium ions outside the cell and more potassium ions inside the cell.

After repolarization, what ions are pumped out of the cell?

Sodium

A polarized neuron is characterized by the presence of more ________ ions along the plasma membrane outside the cell and less ________ ions along the plasma membrane inside the cell.

Sodium, potassium

Which of the following terms indicates a nerve impulse has been initiated and is being transmitted?

action potential

What type of neuron connects sensory and motor neurons in neural pathways?

interneurons (association neurons)

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron,

ion channels in the plasma membrane of the receiving neuron open.

Ms. Young feels deep pressure during a tooth extraction. Which type of sensory receptor detects this sensation?

lamellar corpuscle

How are neurons with several processes branching off the cell body, such as motor neurons and interneurons (association neurons), structurally classified?

multipolar

A molecule that carries information across a synaptic cleft is a

neurotransmitter

The gap between two communicating neurons is termed ________.

synaptic cleft

The small space between the sending neuron and the receiving neuron is the

synaptic cleft

If a signal from a sending neuron makes the receiving neuron more negative inside,

the receiving neuron is less likely to generate an action potential.

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

K+, Na+

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

-70 mV

What part of the neuron releases vesicles containing neurotransmitters?

Axon terminals

A sensory neuron carries stimuli from the central nervous system to the effector.

False

The withdrawal, or flexor, reflex is one of the only voluntary reflexes.

False

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

Na+ and Cl-

An action potential is caused by an influx of ________ ions into the cell.

Sodium

What ion depolarizes the membrane when it diffuses into the axon of a neuron?

Sodium

What is the first event of an action potential?

Sodium gates open and the membrane depolarizes.

Neuron processes that convey incoming messages toward the cell body are dendrites, whereas those that generate nerve impulses and typically conduct them away from the cell body are axons.

True

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

both the electrical and chemical gradients

What is the primary role of the interneuron (association neuron)?

connect motor and sensory neurons in their pathways

Which of the following is the correct sequence in a typical reflex arc?

receptor, afferent neuron, integration center, efferent neuron, effector

Which of these lists the components of a reflex arc in the correct sequence?

receptor; afferent neuron; control center; efferent neuron; effector

When calcium ions enter the synaptic terminal

they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.

Rick quickly pulled his hand away from the hot stove. What type of reflex is this?

withdrawal reflex