Chapter 7: The Nervous System

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The average resting membrane potential of an axon is

-70mV

An axon will depolarize only if the membrane potential reaches between -70mV and -55mV. This follows the

All-or-none law

Which cells are needed for the formation of synapses in the CNS?

Astrocytes

Which type of cell lines the ventricles of the brain and help produce cerebrospinal fluid?

Ependymal cells

A nerve is a bundle of axons in the CNS

False

All axons in the PNS have a myelin sheath

False

Anterograde transport uses dynein molecular motor proteins

False

Axonal transport from the cell body to the dendrites and axon is retrograde transport

False

Both neurons and neuroglia will easily divide by mitosis

False

Destruction of astrocytes would decrease the rate at which action potential are transmitted

False

Excitable cells are incapable of maintain a constant resting membrane potential

False

Glial cells normally lose their mitotic ability prior to birth

False

Most brain tumors in adults are found within neruons

False

Nerve cells depolarize due to the influx of K+

False

Sensory nerves cause muscle contraction

False

Somatic motoro neruons innervate involuntary effecctors

False

The average resting membrane potential of a neuron is -85mV.

False

The blood-brain barrier prevents hydrophobic molecules from diffusing into the brain

False

The nerve is the basic structural and functional unit of the nervous system

False

Degeneration of spinal motor neurons in adults may be due to a lack of _____ factory

Glial-derived neutrophil (GDNF)

What type of neuron is found entirely in the CNS?

Intraneuron and association neuron are correct

Which type of cell of the CNS is phagocytotic?

Microglia

The following is NOT a structural classification of neurons?

Motor neruon

The following is Not a functional classification of neurons?

Multipolar

Blocking________ channels would prevent neuron depolarization

Na+

During an action potential

Na+ influx causes depolarization

The myelin sheaths of PNS meurons are producced by

Schwann Cells

Action potential transmission in the PNS is decreased if which cells are damaged?

Schwann cells

The minimum depolarization needed to open Na+ gates is called the

Threshold

Action potential frequency encode stimulus intensity

True

All axons in the PNS are surrounded by schwann cells

True

All cells ave a membrane potential

True

Astrocytes can be excited by changes in intracellular Ca2+ concentrations

True

Cells become more negative during hyperpollarization

True

Ganglia are clusters of nerve cell bodies located in the peripheral nervous system

True

Most motor meurons are multipolar

True

Myelinated axons transmit action potentials more rapidly than unmyelinated axons

True

Retrograde axonal transport maybe responsible for movement of herpes virus, rabies virus, and tetanus toxin from nerve terminals to the cell body

True

Schwann cells and oligiodendrocytes have similar functions

True

The blood-brain barrier may prevent medications from reaching brain tissues

True

Sensory meurons

are pseudounipolar and carry impulses towards the CNS

The blood-brain barrier results mostly from the action of ________, a type of glial cells

astrocytes

The most numerous of all cells of CNS nerbous tissue are the

astrocytes

Which division of the nervous system innervates involuntary effectors?

autonomic nervous system

Local anesthetics block conduction of action potential in sensory neurons by

binding to sodium channels

Gliotransmmitters

can stimulate neurons

The brain and spinal cord compromise the

central nervous system

The following is NOT true about axonal transport?

is a passive process

Retrograde transport

moves toward the cell body, moves membranes, vesciles and viruses, use molecular mmotor proteins of dynein.

The disease_______ is chracterized by destruction of CNS myelin sheaths and the formation of hardened scars

multiple sclerosis

Rgeneration of CNS axons may be prevented in part by inhibitory proteins in the membranes of the

myelin sheath

Axonal regeneration is inhinited by

myelin-associated inhibitory protein

What matter is

myelinated axons in the Cns

What sctructure is found around PNS axons that is not found around CNS axons?

neurilemma

Fetal neuron growth requires the actions of a group od chemicals know as

neutrophils

The gap node of exposedaxon in the myelin sheath is the

node of Ranvier

The myelin sheaths of CNS neurons are produced by

oligodendrocytes

Which of the following is true of axon

originates at the axon hillock on the cell body

The following is NOT a function of astrocytes?

phagocytose foreign materials in the CNS

The membrane of restin nerve ccells is more permeable to ______ ions than _______

poatassium, sodium

The mechanisms that allow many Na+ ions to move into the axon is

positive feedback

The following is NOT a function of neutrophins?

regeneration of injured motor neurons

Cells supporting neuron cell bodies in ganglia are termed

satellite cells

A bundle of axons in the CNS is called a/an

tract

The following is NOT true about dendrites

transmits action potential toward the cell body

Ion channels that open in response to depolarization are called

voltage-gated channels


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