Chapter 12

Select all that are true regarding the resting membrane potential.

It has a negative value, it is measure in millivolts, it can range from -40 to -90 millivolts

Select all of the following that would increase the magnitude of a postsynaptic potential.

More neurotransmitter released from the presynaptic neuron, more chemically gated channels open in the postsynaptic neuron

Check all that apply to myelinated axons.

Myelinated axons have faster action potential conduction than unmyelinated axons, in myelinated axons, the action potentials "jump" from node to node, and do not have to travel the entire length of the axon membrane, myelinated axons use less energy than unmyelinated axons.

Indicate the glial cells that form a myelin sheath around axons. Check all that apply.

Oligodendrocyte & Neurolemmocyte

What is the correct order for the events of neurotransmitter release from the synaptic terminal? 1. Extracellular Ca2+ enters terminal and binds to sensor protein in the cytoplasm 2. Exocytosis of neurotransmitter into synaptic cleft 3. Action potential reaches axon terminal 4. Ca2+-protein complex stimulates fusion of the docked synaptic vesicle with the plasma membrane 5. Voltage-gated Ca2+ channels open

3, 5, 1, 4, 2

Which part of a neuron contains calcium pumps and channels?

Synaptic bulbs

Select all the characteristics of graded potentials.

The current generated is localized, The current generated decreases with distance.

Select all that occur when an action potential reaches the transmissive segment of an axon.

Voltage-gated calcium channels open,Vesicles containing neurotransmitter fuse with the plasma membrane,Neurotransmitter is released into the synapse by exocytosis.

The _______ is a period when a membrane cannot respond to another stimulus (no matter how strong).

absolute refractory period

When a neurotransmitter binds a protein channel, it opens and lets sodium diffuse down its concentration gradient. This is an example of a

chemically gated sodium channel

If neurotransmitter from Neuron A causes Neuron B to hyperpolarize, this is an example of an

inhibitory postsynaptic potential

Nerve growth factors that stimulate outgrowth of severed axons are secreted by

neurolemmocytes

A typical synapse in the CNS consists of a presynaptic neuron and a postsynaptic neuron, separated by a narrow space called the

synaptic cleft

The fundamental physiological properties that enable nerve cells to communicate with other cells are

the ability to respond to environmental changes,the ability to produce electrical signals that are quickly conducted to other cells at distant locations,the ability to secrete a chemical that will stimulate the next cell when an electrical signal reaches the end of an axon.

When threshold is reached, depolarization occurs with the same amplitude of potential change. This is known as

the all-or-none principle.

If all the sodium leakage channels were removed from the cell membrane of a neuron,

the membrane potential would be about -90 millivolts.

An excitatory postsynaptic potential (EPSP) causes

the postsynaptic neuron's membrane potential to become more positive.

The negative value of the resting membrane potential means that

there are more negatively charged particles on the inside of the membrane than on the outside

An inhibitory postsynaptic potential (IPSP)

will make it more difficult for the postsynpatic neuron to reach threshold.

Which glial cell is starlike in shape and helps form the blood-brain barrier?

Astrocytes