Chapter 12: Nervous Tissue Flashcards by Hanan Taha

Which NERVE potential travels the longer distance in a typical sensation?

Nerve action potential

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Na/K-ATPase is considered to be an electrogenic pump because

a. it contributes to the negativity of the resting membrane potential.
b. the sodium ions are negatively charged.
c. it exhibits low permeability.
d. it hydrolyzes ADP into ATP.
e. destroys the resting membrane potential.

a. it contributes to the negativity of the resting membrane potential.

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A depolarizing graded potential

a. makes the membrane more polarized.
b. makes the membrane less polarized.
c. occurs when chioride enters the cytosol.
d. occurs when acetylcholine enters the cytosol.

b. makes the membrane less polarized.

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These statements describe what part of an action potential?
• Sodium activation gates are closed.
• Sodium inactivation gates are open.
• Potassium gates are open.
• Repolarization is occurring.

a. Latent period
b. Absolute refractory period
c. Relative refractory period
d. depolarizing phase
e. repolarizing phase

c. Relative refractory period

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Which statement best describes the direction of signal transmission?

a. signals go only from the postsynaptic neuron to presynaptic neuron
b. signals go only from the presynaptic neuron to postsynaptic neuron
c. signals way travel in both directions across a synapse
d. none of these choices

b. signals go only from the presynaptic neuron to postsynaptic neuron

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Serotonin is an example of a(n).

a. biogenic amine
b. ATP and other Purines
c. catecholamine
d. neuropeptide

a. biogenic amine

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This type of neural circuit consists of a single presynaptic neuron synapsing with several postsynaptic neurons.

a. Diverging circuit
b. Converging circuit
c. Reverberating circuit
d. Parallel after-discharge circuit
e. Simple series circuit

a. Diverging circuit

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During an action potential’s absolute refractory period, a second stimulus of sufficient strength will produce another action potential.

True
False

False

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Gray matter has its distinctive color due to myelination of axons.

True
False

False (gray matter contains unmyelinated)

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The spinal cord is connected to the brain through the

Foramen magnum

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Components of the PNS include

Nerves and sensory receptors

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Most neurons have 3 parts:

Cell body
Dendrites
Axon

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Cell body contains nucleus surrounded by cytoplasm that includes:

Lysosomes, mitochondria, and Golgi complex. Contains free ribosomes and Nissl bodies

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Nissl bodies are clusters of rough ER that produce proteins used to replace cellular components, material growth of neuron, and regeneration of damaged axons in the PNS

True

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Dendrite

Receiving/input portion of neuron. Carried electrical signals (usually graded potentials) toward cell body.

Non myelinated, short, and have multiple branches

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A nerve is a bundle of of hundreds to thousands of___ plus associated connective tissue and blood vessels that lies outside the brain and spinal cord

Axons

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What’s an axon?

Single, long process of a nerve cell that travels a nerve impulse TOWARD axon terminal AWAY from the cell body to effector (muscle or gland). It contains axoplasm (cytoplasm of axon) and is surrounded by plasma membrane (axolemma)

Joins to cell body at axon hillock

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How many pairs of cranial nerves?

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How many pairs of spinal nerves?

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Sensory receptor

Monitors change in external or internal environment (smell receptor, photoreceptor, touch receptor)

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The PNS is divided into

Sensory and motor divisions

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The PNS is divided into

Motor and sensory divisions

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Sensory (afferent) division of PNS conveys input into the CNS from sensory receptors in the body

True

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The motor (efferent) division of the PNS conveys output FROM the CNS to effectors (muscle and glands)

True

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The motor division of the PNS is divided into the:

somatic and autonomic nervous system

The somatic nervous system conveys output from the CNS to ___ . Motor responses are consciously controlled which means its ___

Skeletal muscles Voluntary

The autonomic nervous system conveys output from the CNS to ___, ___, and ____. Motor responses are not consciously controlled meaning it’s ____.

Smooth muscle, cardiac muscle, glands Involuntary

The autonomic nervous system (ANS) is composed of two main branches called:

Sympathetic and parasympathetic nervous system

Parasympathetic nervous system

Rest and digest

Sympathetic nervous system

Fight or flight

A third branch of the autonomic nervous system is the___ which regulates activities of the ___.

Enteric nervous system GI tract (smooth muscle and glands)

What are the 3 basic functions of the nervous system?

Sensory, integrative, and motor function

Sensory function___, integrative function ___, and motor function___.

Detect, process, respond

Two cell types in nervous tissue are:

Neurons and neuroglia

Axons are short in the CNS and long in the PNS

True

Function of neuroglia

Support, nourish, and protect neurons. They also maintain interstitial fluid that baths them They can divide through an individuals lifetime

A stimulus is any change in the environment that is strong enough to initiate an action potential

True

Neurons possess ____, the ability to respond to stimulus and convert it into an action potential

Electrical excitability

An action potential (nerve impulse) is an electrical signal that travels along the surface of the membrane of a neuron

True

An action potential begins and travels due to the movement of ions (such as sodium and potassium) between interstitial fluid and the inside of a neuron through specific ___ in its plasma membrane.

Ion channels

Cytoskeleton of a neuron contains neurofibrils, composed of bundles of ___ that provide support and cell shape. It also contains microtubules which assist in moving materials between the ___ and ___

Intermediate filaments Cell body, axon

A collection of neuron cell bodies OUTSIDE of the CNS is called:

Ganglion

The axon hillock is a cone shaped elevation that joins

The axon to the cell body

The part of the axon closest to the axon hillock is called:

Initial segment

Nerve impulses are generated at the junction of the axon hillock and initial segment in this area

Trigger zone

Side branches typically at a 90 degree angle on right side of the axon is called:

Axon collateral

Axon terminal

Many fine branches of an axon where synaptic vesicles undergo exocytosis to release neurotransmitter molecules

The site of communication between two neurons or between neuron and effector is called:

Synapse

Neurotransmitters is released from synaptic vesicle and ___ or ___ another neuron, muscle fibre, or gland

Excites or inhibits

Nerve cell fibers are a. axons b. dendrites c. both axons and dendrites d. Nissl bodies

c. both axons and dendrites

Which of the following ions pass through the resting neuronal cell membrane most easily? a. sodium b. calcium c. potassium d. phosphate

c. potassium

The cells within the nervous system that fill spaces and support neurons are collectively called a. endothelia b. Schwann cells c. neuroglia d. ependyma

c. neuroglia

During the absolute refractory period a. protein anions are leaving the neuron b. a high intensity stimulus can generate a new action potential c. neurotransmitters are being secreted d. Na channels are inactivated

d. Na channels are inactivated

The Nissl bodies function in a. protein production b. Cat+ storage c. insulation d. Schwann cell production

a. protein production

Retinal neurons are classified as a. multipolar b. unipolar c. bipolar d. pseudounipolar

c. bipolar

When threshold of a neuron is reached, ___ is produced a. a summation b. an action potential c. a resting potential d. a graded potential

b. an action potential

In myelinated nerves, the a. action potential occurs at a neurolemmocyte b. action potential occurs at each neurofibril node (node of Ranvier) c. action potential moves like a continuous wave across the cell membrane d. threshold is lower than in unmvelinated nerves

b. action potential occurs at each neurofibril node (node of Ranvier)

The autonomic nervous system is part of the a. PNS b. SNS c. CNS d. All of these

a. PNS

Which type of neuroglial cells is found supporting neuronal cell bodies within ganglia? a. astrocytes b. satellite cells c. ependymal cells d. microglia

b. satellite cells

Masses of myelinated nerve fibers appear a. white b. gray c. brown d. transparent

a. white

13. Synaptic vesicles are found within the) a. Schwann cells b. axon hillock c. Nissl bodies d. synaptic end-bulbs

d. synaptic end-bulbs

A resting nerve fiber is polarized because the concentration of a. Na and K+ ions is higher on the inside of the cell membrane b. Na and K+ ions is higher outside the cell membrane c. Na is higher on the inside and K+ is higher on the outside d. Na is higher on the outside and K+ is higher on the inside

d. Na is higher on the outside and K+ is higher on the inside

Saltatory conduction a. occurs only on unmyelinated fibers b. occurs only if nodes of Ranvier are lacking c. occurs only if the myelin sheath is continuous d. occurs only on myelinated fibers

d. occurs only on myelinated fibers

Sensory impulses are carried to the central nervous system by a. afferent neurons b. efferent neurons c. motor neurons d. interneurons

a. afferent neurons

During depolarization of a neuron a. Na and K+ both move out of the cell b. Na and K+ both move into the cell c. Na moves into the cell d. K+ moves out of the cell

c. Na moves into the cell

Autonomic nerve fibers that originate within the central nervous system and innervate the visceral organs are classified as a. somatic sensory nerves b. somatic motor nerves c. visceral sensory nerves d. visceral motor nerves

d. visceral motor nerves

Which of the following cells are ciliated and function to move CSF? a. astrocytes b. satellite cells c. ependymal cells d. microglia

c. ependymal cells

The dendrites of a neuron a. conduct impulses toward the cell body b. secrete neurotransmitters c. conduct impulses away from the cell body d. do not carry impulses, only axons do

a. conduct impulses toward the cell body

Which of the following is not a function of glial cells? a. produce myelin sheath b. participate in metabolism of neurotransmitters c. generate action potentials d. give support to neurons

c. generate action potentials

Which of the following is true of unipolar neurons? a. All are efferent b. All are afferent c. They have several dendrites and one axon d. They have several axons and only one dendrite

b. All are afferent

The generation of an action potential is an electrochemical event. The electrical portion occurs a. within the neuron b. only in nerves with neurolemma c. within the myelin sheath d. in microglia

a. within the neuron

Which of the following is associated with ganglia? a. oligodendrocyte b. ependymal cell c. satellite cell d. Schwann cell

c. satellite cell

Which of the following is made up in part of neuron cell bodies? a. node of Ranvier b. Schwann cell c. myelin d. gray matter

d. gray matter

Which of the following occurs as the resting potential is reestablished? a. Nat enters the cell b. repolarization c. K+ enters the cell d. depolarization

b. repolarization

Which of the following is characteristic of unmyelinated fibers? a. A fibers b. continuous conduction c. Schwann cells d. saltatory conduction

b. continuous conduction

The phagocytic cells of the central nervous system are called a. astrocytes b. microglia c. collaterals d. Nissl cells

b. microglia

Which ions are rapidly moving into the cell during the depolarization period of an action potential? a. sodium b. potassium c. calcium d. chloride

a. sodium

Axons of the general visceral efferent neurons that extend to autonomic ganglia are a. A fibers b. B fibers c. C fibers d. D fibers

b. B fibers

At a synapse, the neuron sending the signal is called the a. presynaptic b. postsynaptic c. axodendritic d. axoaxonic

a. presynaptic

An inhibitory postsynaptic potential causes a. depolarization b. repolarization c. EPSPs d. hyperpolarization

d. hyperpolarization

If the sum of all excitatory effects is greater than all inhibitory effects on a postsynaptic neuron but threshold is not reached, then the response is a. an IPSP b. an action potential c. an EPSP d. no change in the membrane potential

c. an EPSP

In the brain, this surrounds the white matter a. dendrites b. gray matter c. ganglia d. neuron

b. gray matter

In the spinal cord, this surrounds the gray matter a. white matter b. Nissl bodies c. axon terminal d. neurons

a. white matter

Which type of CNS neuroglia are the most similar in appearance?

Astrocytes and oligodendrocytes

Pyramidal cells are found in the cerebral cortex of the brain while purkinje cells are found in the

cerebellum

The cerebellum and cerebrum are covered by

Thin layer of gray matter

What makes up gray matter?

Unmyelinated axons and dendrites

What gives gray matter its gray colour?

Nissl bodies

What gives white matter its white colour?

Myelin

Which part of the neuron would Nissl bodies be found?

Soma (cell body)

What happens if an injury to the oligodendrocyte happens?

Slower rate of action potential transmission in a neuron (These cells form and maintain myelin sheath around CNS axons)

Integration of information from sensory neurons can happen in

The brain

Blood vessels are present in both white and gray matter

True

Structural classifications of neuron are based on the number of___ extending from cell body

Processes

Structural classification of neuron

Multipolar Bipolar Unipolar

Multipolar neuron

- SEVEREAL dendrites, one axon - all motor neurons are this type - mostly found in the brain and spinal cord

Bipolar neuron

- ONE main dendrite, one axon - found in retina, inner ear, and olfactory area of brain

Unipolar neuron

-have dendrites and one axon that are fused together to form a continuous process that emerges from cell body -begin in embryo as bipolar neurons -most function as sensory receptors -located mostly in ganglia of spine/cranial nerves

Functional classifications of neurons

Sensory, motor, and interneurons

Sensory (afferent) neurons

-Contain sensory receptors at distal ends (dendrites) or are located just after sensory receptors that are separate cells -Once stimulus activates sensory receptor the sensory neuron forms and action potential in its axons and the action potential is conveyed into the CNS through cranial or spinal nerves. Most are unipolar.

Sensory neurons

Most are unipolar, contain sensory receptors at dendrites (distal ends). Action potential is generated in axon and is converted INTO the CNS through cranial or spinal nerves

Motor neurons (efferent)

Multipolar, convey action potentials AWAY from the CNS to effectors (muscle/glands) in the PNS through cranial or spinal nerves

Interneurons (association)

Multipolar, located in CNS (mostly) between sensory and motor neurons Process incoming sensory information and elicit motor response by activating appropriate motor neurons.

Neuroglia can be classified by

Size, cytoplasmic process, and intracellular organization

6 types of neuroglia

4 in the CNS = Astrocytes, oligodendrocytes, microglial, ependymal 2 in the PNS = Schwann and satellite cells

Slow and fast axonal transport systems for conveying materials to and from the cell body and axon terminals

True

What are the 2 types of neuroglia that produce myelin sheaths for axons?

Oligodendrocytes = CNS Schwann cells = PNS

Hyperpolorizing graded potential makes membrane potential ___ negative

Depolarizing graded potential makes membrane potential ___ negative.

LESS

Function of Astrocytes

Secrete chemicals that maintain selective permeability characteristics of endothelial cells of capillaries (blood brain barrier).

Function of oligodendrocytes

Form and maintain myelin sheath around CNS axons

Function of microglial cells

They remove cellular debris and phagocytize microbes and damaged nervous tissue. They appear like slender processes with spine like projections.

Function of Ependymal cells

Produce, moniter, and assist with circulation of CSF Line ventricles of brain and central canal of spinal cord spaces to protect and nourish brain and spinal cord.

Function of Schwann cell

Form myelin sheath around a SINGLE axon in PNS Participate in axon regeneration

Function of satellite cells

Regulate exchange of material between neuronal cell bodies and interstitial fluid Flat, surround cell bodies of neurons of PNS ganglia

Chapter 12: Nervous Tissue Flashcards

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