Chapter 12: Nervous Tissue Flashcards
Which NERVE potential travels the longer distance in a typical sensation?
Nerve action potential
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.
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.
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
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
Serotonin is an example of a(n).
a. biogenic amine
b. ATP and other Purines
c. catecholamine
d. neuropeptide
a. biogenic amine
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
During an action potential’s absolute refractory period, a second stimulus of sufficient strength will produce another action potential.
True
False
False
Gray matter has its distinctive color due to myelination of axons.
True
False
False (gray matter contains unmyelinated)
The spinal cord is connected to the brain through the
Foramen magnum
Components of the PNS include
Nerves and sensory receptors
Most neurons have 3 parts:
Cell body
Dendrites
Axon
Cell body contains nucleus surrounded by cytoplasm that includes:
Lysosomes, mitochondria, and Golgi complex. Contains free ribosomes and Nissl bodies
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
Dendrite
Receiving/input portion of neuron. Carried electrical signals (usually graded potentials) toward cell body.
Non myelinated, short, and have multiple branches
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
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
How many pairs of cranial nerves?
12
How many pairs of spinal nerves?
31
Sensory receptor
Monitors change in external or internal environment (smell receptor, photoreceptor, touch receptor)
The PNS is divided into
Sensory and motor divisions
The PNS is divided into
Motor and sensory divisions
Sensory (afferent) division of PNS conveys input into the CNS from sensory receptors in the body
True
The motor (efferent) division of the PNS conveys output FROM the CNS to effectors (muscle and glands)
True
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
- 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
MORE
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
