Chapter 12 Nervous Tissue
The point at which two excitable cells contact to exchange information is called a
synapse
Where do synapses occur in the CNS, in white matter or in gray matter?
synapses in CNS always occur in GRAY MATTER
The slightly expanded tips of telodendria are called
synaptic knobs
Collectively, glial cells do all of the following except A) physically protect and help nourish neurons B) guide young migrating neurons during development C) provide a supporting framework for all nervous tissue D) synthesize neurotransmitters and conduct nerve impulses
synthesize neurotransmitters and conduct nerve impulses
place the ct covering surrounding a nerve in order from superficial to deep (1-3) -perineurium -epineurium -endoneurium
1. epineurium 2. perineurium 3. endoneurium
what are the two kinds of supporting cells in the PNS?
1.satellite cells 2.Schwann cells produce myelin and myelin sheaths
6. List the 2 divisions of the nervous system.
CENTRAL, PERIPHERAL
4. How many general types of synapses are there, what are their names, and which is common?
THE MOST COMMON IS THE CHEMICAL SYNAPSE. THERE ARE VERY FEW ELECTRICAL SYNAPSES.
What subdivision of the nervous system regulates contraction of the muscle tissue in the heart?
The visceral motor (autonomic) division of the peripheral nervous system regulates contraction of cardiac muscle
Describe how the electrical impulse from one neuron is passed to another neuron.
When an electrical impulse in the presynaptic neuron reaches the icon terminal, it stimulates the release of chemical neurotransmitters from this neuron -The neurotransmitters DIFFUSE across the synaptic cleft, bind to receptor sites on post synaptic neuron (usually on dendrite or cell body) and stimulate an electrical response in the postsynaptic neuron -In this way, electrical signal is passed via a chemical messenger, from one neuron to another
Why is white matter white?
White matter in CNS is white, because majority of the nerve fibers in these regions are MYELINATED
an example of an effector is a. the eye b. a gland c. a sensory neuron d. motor neuron
a gland
What type of sensation is a) pain from a pulled muscle b) nausea c) taste
a) Somatic sensory b) visceral sensory c) special visceral sensory sensation
a ganglion is a collection of ..
a. neuron cell bodies
Axon regeneration in the CNS is restricted by which of the following factors? A) oligodendrocytes do not release a nerve growth factor B) crowded axons in the brain and spinal cord complicate regrowth C) astrocytes and connective tissue coverings may form obstructive scar tissue D) all of the above
all the above
The ____________ is the only functional class of neuron entirely restricted to the ____________ nervous system. A) association neuron; central B) sensory neuron; central C) motor neuron; peripheral D) interneuron; periphera
association neuron; central
The largest and most abundant of the CNS glial cells, ____________ help form the blood-brain barrier.
astrocytes
Which term describes the collection of lipids and proteins that may form a protective coating around an axon?
neurofibril
Which of the following is not a part of the CNS? A) microglia B) spinal cord C) neurolemmocyte D) brain
neurolemmocyte
Which glial cells participate in the repair of damaged nerves? A) satellite and ependymal cells B) neurolemmocytes C) oligodendrocytes D) astrocytes and microglia
neurolemmocytes
Which types of glial cells are found in the peripheral nervous system?
neurolemmocytes and satellite cells
Afferent neurons of the PNS synapse in the CNS with
neuron cell bodies in the gray matter
Which structural classes of neurons are always sensory in function?
unipolar and bipolar
Structural categories of neurons include which of the following?
unipolar, bipolar, and multipolar
Motor (efferent) division is part of which nervous systems? What are there structure/function?
**Somatic nervous system s- somatic motor (voluntary) f-conducts impulses from CNS to skeletal muscles **Automatic nervous system (ans) s-visceral motor (involuntary) f-impulses from cns to cardiac muscles, smooth muscles, glands
The ____________ is the only functional class of neuron entirely restricted to the ____________ nervous system. A) association neuron; central B) sensory neuron; central C) motor neuron; peripheral D) interneuron; peripheral
A) association neuron; central
Which nervous system divisions or components contain no afferent neurons? A) somatic and visceral sensory B) CNS and PNS C) PNS and ANS D) ANS and SNS
ANS and SNS
a) In which direction are afferent signals carried? b)What type of information do these signals contain?
Afferent signals carry: a) sensory information toward the b) CNS
Both peripheral nerves and the white matter of the spinal cord are composed of axonal processes. Why is it possible to regain function after an injury to a peripheral nerve, but not after an injury to the spinal cord?
After a peripheral injury, axons in the PNS can regrow within regeneration tubes formed by surging Schwann cells -In the CNS, neuroglia do not guide regrowing axons and, in fact, secrete inhibitory chemicals that block neuronal regrowth
Which neuroglia are common in regions where synapses occur?
Astrocytes are common in regions where synapse occurs because they regulate ionic and neurotransmitter levels in neural tissue
What type of neural circuit contains multiple neurons synapsing on a single neuron, altering its potential to produce a nerve impulse?
Converging circuit contains multiple presynaptic neurons synapsing on a single postsynaptic neuron.
11. List the three types of membranes found surrounding nerve and neurons.
EPINEURIUM, PERINEURIUM, ENDONEURIUM
What are the functional divisions of the nervous system?
Functional classification is based on the direction the nerve impulse travels; - Sensory input (afferent neurons) *neurons conduct impulses toward the CNS - Integration (association neurons) *lie in the CNS between motor and sensory neurons. - Motor output (efferent neurons) * neurons carry impulses away from the CNS
If there is no interneuron in a reflex arc, as in the stretch reflect, what functions as the integration center?
Integration center occurs in the gray matter in the CNS at synapse between the sensory neuron and motor neuron
What is the structural classification of most sensory neurons?
Most sensory neurons are UNIPOLAR (pseudo unipolar) neurons
1. Name the 2 types cells of the nervous system.
NEURONS, NEUROGLIA
3. What are the two divisions of the autonomic nervous system, and what is their relationship to each other?
PARASYMPATHETIC AND SYMPATHETIC NERVOUS SYSTEMS, ANTAGONISTIC
Name the connective tissue wrapping that encloses a bundle of nerve fibers into a fascicle.
Perineurium wraps a bundle of nerve fibers (axons) into fascicle
9. List the 5 essential components of a polysynaptic reflex arc in correct sequence.
RECEPTOR, SENSORY NEURON, ASSOCIATION NEURON/INTERN NEURON, MOTOR NEURON, EFFECTOR
5. Name the two types of neuroglia that secrete myelin and where are they found?
SCHWANN CELLS (NEUROLEMMOCYTE) IN THE PNS, AND OLIGODENDROCYTES IN THE CNS
2. What are the three functional classifications of neurons?
SENSORY (AFFERENT), MOTOR (EFFERENT), INTERNEURON (ASSOCIATION)
8. What is another name for sensory and motor?
SENSORY/AFFERENT, MOTOR/EFFERENT
10. Name the cell junction that mediates the transfer of information from one neuron to the next.
SYNAPSE
If you touch a hot stove, you reflexively withdraw your hand. The sensation of the pain comes after your hand has moved. Why does it take longer to feel pain than it does to move your hand?
Sensory impulse must be carried to the brain for processing the conscious sensation of pain. - This processing takes more time than is required for processing the simple withdrawal reflex.
regulates ionic composition of the fluid around neurons in the cns.. a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
astrocytes
remove neurotransmitter in the CNS... a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
astrocytes
With regard to control of effectors, ____________ is to involuntary as ____________ is to voluntary.
autonomic; somatic
With regard to control of effectors, ____________ is to involuntary as ____________ is to voluntary. A) somatic; visceral B) somatic; peripheral C) autonomic; somatic D) central; peripheral
autonomic; somatic
a synapse between an axon terminal and a neuron cell body is classified as
axoSOMATIC
most nerves are composed of
axons of afferent and efferent neurons
Which of the following structures is not part of the central nervous system? a) brain b) a nerve c) the spinal cord d) a tract
b) a nerve
which of the following parts of a neuron occupies the gray matter in the spinal cord? a. tracts of long axons b. motor neuron cell bodies c. sensory neuron cell bodies d. nerves
b. motor neuron cell bodies
Neurons that have only two processes attached to the cell body are called
bipolar.
A nerve impulse involves ____________ across a neuron's plasma membrane. A) changes in voltage B) movement of ions C) both a and b D) neither a nor b
both a and b
What accounts for the gray color of gray matter? A) presence of Nissl bodies B) absence of myelin C) both of the above D) neither of the above
both of the above
The glial cells that help produce CSF in the CNS are
ependymal cells.
Which one of the following is not a step in the conduction of a nerve impulse across a chemical synapse? neurotransmitter molecules diffuse across the synaptic cleft to the postsynaptic cell the nerve impulse causes an influx of Ca2+ ions into the synaptic knob calcium ions entering the synaptic cleft cause the endocytosis of synaptic vesicles a voltage change in the postsynaptic cell triggers a nerve impulse to begin there
calcium ions entering the synaptic cleft cause the endocytosis of synaptic vesicles
Which one of the following is not a step in the conduction of a nerve impulse across a chemical synapse? A) the nerve impulse causes an influx of Ca2+ ions into the synaptic knob B) calcium ions entering the synaptic cleft cause the endocytosis of synaptic vesicles C) neurotransmitter molecules diffuse across the synaptic cleft to the postsynaptic cell D) a voltage change in the postsynaptic cell triggers a nerve impulse to begin there
calcium ions entering the synaptic cleft cause the endocytosis of synaptic vesicles
Which effectors are innervated by visceral motor neurons?
cardiac muscle, smooth muscle, and glands
Structurally, the nervous system consists of which two subdivisions?
central and peripheral
In terms of nerve impulse conduction, unmyelinated is to ____________ as myelinated is to ____________. A) oligodendrocytes; neurolemmocytes B) neurolemmocytes; oligodendrocytes C) continuous; saltatory D) saltatory; continuous
continuous; saltatory
myelin is most like which of the following cell parts introduced in chapter 2? a. the cell nucleus b. smooth endoplasmic reticulum c. ribosomes d. the plasma membrane
d. the plasma membrane
Nerves are bundles of parallel axons in the PNS that have three successive connective tissue wrappings, called the
endoneurium, perineurium, and epineurium
line the central cavity of the brains? a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
ependymal cells
Which pair names only neuroglia of the central nervous system? A) astrocytes and interneurons B) ependymal cells and astrocytes C) microglia and neurolemmocytes D) oligodendrocytes and satellite cells
ependymal cells and astrocytes
Efferent neurons transmit nerve impulses
from the CNS to muscles or glands
Clusters of neuron cell bodies located outside the CNS are called
ganglia
All of the following are types of neuronal circuits except A) converging B) diverging C) proliferating D) reverberating
proliferating
what are neurons in the nervous system?
receive stimuli and transmit action potentials
At a chemical synapse, ____________ are found only in the plasma membrane of the ____________ cell. A) neurotransmitters; postsynaptic B) receptor proteins; postsynaptic C) neurotransmitters; presynaptic D) receptor proteins; presynaptic
receptor proteins; postsynaptic
Which type of neuronal pool utilizes nerve impulse feedback to repeatedly stimulate the circuit?
reverberating circuit
diverging
sensory pathway sharing info
what are neuroglia in the nervous system? what are the 4 kinds?
supporting cells act to support, protect, nourish, and insulate neurons 1astrocytes 2microglia 3ependymal 4oligodendrocyte
what are the DIVISIONS of the Autonomic nervous system (ANS) ? Functions of them?
*Sympathetic division f- Mobilizes body system during activity *Parasympathetic division f-Conserves energy f-promotes house keeping during rest
What are the structural divisions of the nervous system? Examples of them?
- Central nervous system (CNS) Ex. brain, spinal cord - Peripheral nervous system (PNS) *external to cns Ex. nerves, ganglia
What are the Structural classification groups neurons:
-multipolar (motor & interneurons) -bipolar (special senses, ex, vision) -unipolar (sensory neuron)
Myelination affects nerve impulse conduction in which of the following ways? A) allows saltatory conduction from one neurofibril node to the next B) permits nerve impulses to travel continuously along the entire axon C) slows the nerve impulse by exposing only limited parts of the axon D) all of the above
A) allows saltatory conduction from one neurofibril node to the next
Do Schwann cells cover unmyelinated axons in the PNS?
YES Schwann cells DO cover unmyelinated axons in PNS; HOWEVER axons are NOT WRAPPED by concentric layers of Schwann cells. -Numerous unmyelinated axons embedded in a single Schwann cells
The epineurium is
a thick, dense irregular connective tissue layer enclosing the nerve.
A multipolar neuron that synapses on a gland cell is functionally classified as A) a visceral motor neuron B) a somatic motor neuron C) a sensory neuron D) an interneuron
a visceral motor neuron
a) What structural type is most abundant? b) What neurons in the PNS are of this type?
a) Multipolar neurons are the most abundant type of neuron b) Motor neurons of the PNS are multipolar neurons
a) Which neuroglia make myelin in the CNS? b) In the PNS?
a) OLIGODENDROCYTES produce myelin in the CNS b) SCHWANN cells produce myelin in the PNS
Although classified as glial cells, ____________ are also ____________ that line the cavities in the brain and spinal cord and help form the choroid plexus. A) astrocytes; phagocytes B) microglia; phagocytes C) ependymal cells; epithelial cells D) oligodendrocytes; epithelial cells
ependymal cells; epithelial cells
At an electrical synapse, presynaptic and postsynaptic membranes interface through
gap junctions.
Touch, vibration, and proprioception are examples of
general somatic senses
An example of an effector is a
gland.
The word root glia, as in "glial cells," most nearly means
glue
Which description doesnot accurately characterize neuronal pools? A) consist of complex patterns of interconnected neurons B) have limited number of input sources and output destinations C) may be localized or distributed in several different regions of the CNS D) have numerous types of circuits defined by structural features
have numerous types of circuits defined by structural features
Which neurons are located only within the CNS?
interneurons
Which description refers to oligodendrocytes? A) small cells with slender branches from the cell body B) large, star-shaped cells with numerous cell processes C) large, bulbous cells with slender cytoplasmic extensions D) flattened cells wrapped around axons to form myelin
large, bulbous cells with slender cytoplasmic extensions
Which glial cells behave much like certain leukocytes? A) microglia B) ependymal cells C) oligodendrocytes D) satellite cells
microglia
cns phagocytes? a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
microglia
Which glial cells behave much like certain leukocytes (white blood cells)?
microglia : macrophages of CNS
Which functional division of the nervous system includes the SNS and ANS?
motor
converging
motor integrating information
Choose all that apply!!! A nerve impulse involves ____________ across a neuron's plasma membrane movement of ions changes in voltage none of the above
movement of ions changes in voltage
Neurons with numerous dendrites and a single axon are structurally classified as
multipolar neurons
The synaptic knob of a neuron may contact another neuron anywhere except on its
myelin sheath
The two distinct cell types that compose all nervous tissue are
neurons and glial cells
Which type of neuron process receives stimuli?
neuronal process cell process that receive stimuli = DENDRITES
Which of these cells transfer and process information? A) neurolemmocytes B) astrocytes C) neurons D) oligodendrocytes
neurons
Although they outnumber ____________ by as much as ten to one, ____________ account for only about half of the total volume of the nervous system. A) neuroglia; neurons B) neurons; glial cells C) interneurons; sensory neurons D) astrocytes; oligodendrocytes
neurons; glial cells
At a chemical synapse, the presynaptic membrane releases a signaling molecule called a
neurotransmitter
which one forms myeline in the CNS a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
oligodendrocytes
Their methods are different, but ____________ in the CNS and ____________ in the PNS perform similar functions. A) astrocytes; neurolemmocytes B) oligodendrocytes; neurolemmocytes C) microglia; satellite cells D) ependymal cells; satellite cells
oligodendrocytes; neurolemmocytes
serial processing
pass info from one point to another
Synapses are categorized on the basis of
point of contact and mode of impulse transmission
Sensory (afferent) division structure/function? **afferent means carry out
s(Structure)- somatic and visceral sensory nerve fibers f(function) -conducts impulses from receptors to CNS
Motor (efferent) division structure/function?
s-motor nerve fibers f-conducts impulses from the cns to effectors (muscle and glands)
forms myelin in the pns a. astrocytes b. ependymal cells c. microglia d. oligodendrocytes e. satellite cells f. Schwann cells
schwann cells
reverberating circuits
self propagating or repeating information
In the PNS, components of the afferent division include
sensory neurons
a monosynaptic reflex is an example of
serial processing
parallel processing
sharing info as in the sense of smell
What is the Synapse?
the structural and functional unit of communication between neurons and other cells.
