Nervous System Flashcards
tissue that is formed by a network of many billion nerve cells, all assisted by many more supporting cells
nervous tissue
3 basic functions of the nervous system
- Sensory - to detect
- Integrative - to process/analyze
- Motor - to elicit an appropriate motor response
division of the nervous system that includes the brain and spinal cord
Central Nervous System
division of the nervous system that consists of all the nervous tissue outside CNS
Peripheral Nervous System
what do you call the environmental changes that neurons respond to by altering the ionic gradient that exists across their plasma membranes
stimuli
this ionic gradient is also called an electrical potential but cells that can rapidly change this potential are said to be excitable or irritable
what do you call the environmental changes that neurons respond to by altering the ionic gradient that exists across their plasma membranes
stimuli
this ionic gradient is also called an electrical potential but cells that can rapidly change this potential are said to be excitable or irritable
Neurons react promptly to stimuli with a reversal of the ionic gradient also called ____.
membrane depolarization
the neuron’s rxn to stimulus is propagated across its entire plasma membrane from the place that received the stimulus. the propagation is called?
action potential
may also be called depolarization wave or nerve impulse
the nervous system develops from what embryonic layer?
ectoderm
ectoderm = outermost of the 3 embryonic layers
With signals from the underlying axial structure, the notochord, ectoderm on the mid-dorsal side of the embryo thickens to form the epithelial ____?
neural plate
the sides of the neural plate fold upward and grow toward each other medially to form the what?
neural tube
Cells of this tube give rise to the entire CNS, including neurons and most glial cells
As the neural tube detaches from the now overlying ectoderm, many cells separate from it and produce a mass of mesenchymal cells called the ____?
neural crest
Cells from the neural crest give rise to the entire PNS
what do you call the functional unit in both the CNS and PNS?
neurons
are neurons capable of mitosis?
no
cells that are smaller than neurons but far more outnumbers them; they are also known as support cells
glial cells
they are 10 times more abundant than neurons in the mammalian brain
division of the PNS that transmits action potentials from the periphery to the CNS
Sensory (Afferent) division
Sensory division may be further classified into Somatic (consciously) or Visceral (unconsciously)
division of the PNS that transmits action potentials from the CNS towards the periphery
Motor (Efferent) division
Motor division may be further classified into Somatic (consciously) or Autonomic (unconsciously)
a division of the ANS that maintains normal body homeostasis
parasympathetic division
has its ganglia within or near effector organs
a division of the ANS that maintains the body’s responses during emergencies and excitement
fight-or-flight
sympathetic division
sympathetic division has its ganglia close to the CNS
a division of the ANS that is located in the wall of the digestive tract
can function without input from the CNS or other parts of the PNS
Enteric Nervous System (ENS)
what are the 3 main parts of a neuron?
- cell body
- dendrites
- axon
this part of the neuron contains the nucleus and the cell’s organelles; serves as the synthetic or trophic center for the entire neuron
cell body (perikaryon or soma)
part of the neuron that is classified as the numerous elongated processes extending from the perikaryon and specialized to receive stimuli from other neurons
dendrites
also known as little trees; receiving end of a neuron
dendrites receive information from other neurons or receptors and transmit it toward the cell body
a single long process ending at synapses specialized to generate and conduct nerve impulses to other cells (eg, nerve, muscle, and gland cells)
axon
type of neuron with one axon and two or more dendrites; most common
multipolar neurons
type of neuron with one dendrite and one axon; comprise the sensory neurons of the retina, olfactory epithelium, and the inner ear
bipolar neurons
type of neurons that have two extensions; one towards the periphery and one towards the CNS
most sensory neurons are part of this type
pseudounipolar
type of neurons that have many dendrites but no true axon; do not produce action potentials but regulate electrical changes of adjacent CNS neurons
Anaxonic neurons
type of neurons based on function wherein action potential is conveyed to the CNS; most are unipolar in structure
Sensory Neurons
sensory neurons are ____, they receive stimuli from receptors throughout the body.
afferent
type of neurons based on function that convey action potentials away from the CNS to the effector organs in the PNS thru cranial and spinal nerves; most are multipolar in structure
Motor Neurons
Motor neurons are ____, sending impulses to effector organs such
as muscle fibers and glands.
efferent
type of neurons based on function wherein it is mainly located within the CNS between the sensory and motor neurons
Interneurons
keyword: between
this is seen sa reflex arc
____ motor nerves are under
voluntary control and typically innervate skeletal muscle
Somatic
____ motor nerves control the involuntary or unconscious activities of glands, cardiac muscle, and most smooth muscle.
autonomic
part of the neuron that contains the nucleus and surrounding cytoplasm, exclusive of the cell processes
cell body (perikaryon)
.
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A typical neuron has an unusually large, ____ nucleus with a prominent nucleolus, indicating intense synthetic activity
euchromatic or heterochromatic
euchromatic
what do you call the regions of the perikarya that have concentrated RER and other polysomes that are basophilic?
Nissl bodies (chromatophilic substance)
Usually covered with many synapses, ____ are the principal signal reception and processing sites on neurons
dendrites
In the CNS most synapses on dendrites occur on ____, which are dynamic membrane protrusions along the small dendritic branches, visualized with silver staining
dendritic spines
Most neurons have only ____ axon, typically longer than its dendrites
how many axons?
one
The plasma membrane of the axon is often called the ____ and its contents are known as _____.
Axolemma; Axoplasm
Axons originate from a pyramid-shaped region of the perikaryon called the ____?
axon hillock
Axons of interneurons and some motor neurons also have major
branches called ____ that end at smaller branches with synapses influencing the activity of many other neurons.
collaterals
Each small axonal branch ends with a dilation called a terminal
____ that contacts another neuron or non-nerve cell at a synapse to initiate an impulse in that cell.
bouton
It is an electrochemical process initiated at the axon hillock when
other impulses received at the cell body or dendrites meet a
certain threshold.
action potential
____ are sites where nerve impulses are transmitted from one neuron to another, or from neurons and other effector cells
Synapses
Most synapses act by releasing ____, which are usually small molecules that bind specific receptor proteins to either open or close ion channels or initiate second-messenger cascades.
neurotransmitters
The ____ (terminal bouton)
contains mitochondria and numerous ____ from which neurotransmitter is released by exocytosis
presynaptic axon terminal; synaptic vesicles
The ____ contains receptors for the neurotransmitter, and ion channels or other mechanisms to initiate a new impulse
postsynaptic cell membrane
the space between the presynaptic and postsynaptic membranes
synaptic cleft
Organelles and macromolecules
synthesized in the cell body move by____ along axonal microtubules via ____ from the perikaryon to the synaptic terminals
anterogade transport; kinesin
____ in the opposite direction along microtubules via ____ carries certain other macromolecules, such as material taken up by endocytosis (including viruses and toxins), from the periphery to the cell body
Retrogade transport; dynein
The action potential is propagated along the axon as a wave of membrane depolarization produced by
voltage-gated ____ & ____ channels
Na+ & K+
Synapse that is usually associated with and transmit a
nerve impulse to another neuron’s cell body (or soma)? to a dendritic spine?
Axosomatic synapse; Axodendritic synapse
a synapse characterized by the connection of one axon terminal to another axon terminal
axoaxonic synapse
network of fine cellular processes emerging from neurons and glial cells are called?
neuropil
____ extend many processes, each of which becomes sheetlike and wraps repeatedly around a portion of a nearby CNS axon
Oligodendrocytes
The resulting ____ from oligodendz electrically insulates the axon and facilitates rapid transmission of nerve impulses.
myelin sheath
Identify the neuroglia
Myelin production, electrical insulation in the CNS
oval or round cell body; w/ fewer processes; smaller than astrocytes
Oligodendrocytes
Identify the Neuroglia
Structural and metabolic support of neurons, especially at synapses; repair processes in the CNS
star-shaped w/ many processes
Astrocytes
Identify the Neuroglia
Aid production and movement of CSF; lines ventricles of the brain and spinal cord
Epithelial cells arranged in 1 layer
Ependymal Cell
Identify the Neuroglia
Defense and immune-related activities; protects CNS from disease & engulfs invading microbes
smaller cells; few processes
Microglia
Identify the Neuroglia
Myelin production, electrical insulation in the PNS
Flattened cells that encircle PNS axons
Schwann Cells
Identify the Neuroglia
Structural and metabolic support for neuronal cell bodies in the PNS
Flattened cells around cell bodies of neurons in ganglia
Satellite cells
Proximal regions of the astrocytic processes are reinforced with bundles of intermediate filaments made of ____, which serves as a unique marker for this glial cell.
glial fibrillary acid protein (GFAP)
type of astrocytes that have long delicate processes that are abundant in white matter
fibrous astrocytes
type of astrocytes that have shorter processes and predominate in gray matter
protoplasmic astrocytes
type of astrocytes that have shorter processes and predominate in gray matter
protoplasmic astrocytes
astrocytes forms what you call an ____ to fill tissue defects after CNS injury; done thru proliferation
astrocytic scar
____ are columnar or cuboidal cells that line the fluid-filled ventricles of the brain and the central canal of the spinal cord
Ependymal cells
where do microglia originate?
from monocytes
microglia are not from neurulation; they belong to the same fam as macrophages and other antigen-presenting cells
Schwann cells are sometimes called ____ and are only found in the PNS and are the counterparts of the oligodendz in the CNS
neurolemmocytes
disease wherein the myelin sheaths surrounding axons are damaged by an autoimmune mechanism that interferes with the activity of the affected neurons and produces various neurologic problems
multiple sclerosis
unlike an oligodendrocyte, a schwann cell forms myelin around a portion of how many axons?
one axon
cells of the PNS that exert a trophic or supportive effect on the neurons
Satellite cells
cluster of neuronal cell bodies located in the PNS; Closely associated with cranial and spinal nerves
neuronal cell bodies = gray matter
Ganglion
In the PNS, gray matter consists of clusters of neuron cell bodies, each of which is called a ganglion (gang′glē-on; pl. ganglia; a swelling or knot). (Seeley’s, 11th ed.)
cluster of neuronal cell bodies in the brain are called?
Nuclei
Bundle of axons that is located in the PNS is called?
bundle of axons = white matter
Nerve
White matter of the CNS forms nerve tracts, or conduction pathways, which propagate action potentials from one area of the CNS to another. In the PNS, bundles of axons and their connective tissue sheaths are called nerves (Seeley’s, 11th ed.)
bundle of axons that is located in the CNS that interconnects neurons in the spinal cord and brain?
Tract
White matter of the CNS forms nerve tracts, or conduction pathways, which propagate action potentials from one area of the CNS to another. In the PNS, bundles of axons and their connective tissue sheaths are called nerves (Seeley’s, 11th ed.)
what do you call the connective tissue layers that protect the brain?
Meninges
what are the major structures comprising the CNS?
Cerebrum, Cerebellum, Spinal Cord
this is accdg to Junqueira
what matter makes up the thick cortex of the cerebrum and the cerebellum?
gray matter
neurons from what part of the brain function in the integration of sensosry information and the initiation of voluntary motor responses?
neurons of the cerebral cortex
In the brain, where can you find the six layers of neurons with diff sizes and shapes? This is where u can find the efferent pyramidal neurons which is the most conspicuous (evident) of these cells.
cerebral cortex
neurons from what part of the brain coordinates muscular activity throughout the body and has 3 layers?
cerebellar cortex
what are the 3 layers of the cerebellar cortex?
- molecular layer
- purkinje cells
- granular layer
A thick outer ____ layer of the cerebellar cortex that has much neuropil and scattered neuronal cell bodies.
molecular layer
A thin middle layer of the cerebellar cortex that consists only of very large neurons called ____.
purkinje cells
These are conspicuous even in H&E-stained sections, and their dendrites extend throughout the molecular layer as a branching basket of nerve fibers
A thick inner ____ layer of the cerebellar cortex contains various very small, densely packed neurons
granular layer
In cross sections of the spinal cord, the ____ matter is peripheral and the ____ matter forms a deeper, H-shaped mass
white matter; gray matter
The two anterior projections of this gray matter, ____, contain cell bodies of very large motor neurons whose axons make up the ventral roots of spinal nerves.
anterior horns
The two ____ contain interneurons which receive sensory fibers from neurons in the spinal (dorsal root) ganglia
posterior horns
Near the middle of the cord the gray matter surrounds a small ____, which develops from the lumen of the neural tube, is continuous with the ventricles of the brain, is lined by ependymal cells, and contains CSF.
central canal
what are the three layers of meninges?
- Dura mater
- Arachnoid mater
- Pia mater
this layer consists of dense irregular connective tissue organized as an outer periosteal layer continuous with the periosteum of the skull and an inner meningeal layer.
Dura mater
what do you call the drainage channels that form where the two layers of the dura mater are separated from each other?
Dural venous sinuses
Around the spinal cord the dura mater is separated from the periosteum of the vertebrae by the ____, which contains a plexus of thin-walled veins and loose connective tissue
epidural space
this meningeal layer has a sheet of CT in contact w/ dura mater and a system of loosely arranged trabeculae composed of collagen and fibroblasts (continuous w/ pia mater)
arachnoid mater
what do you call the large, sponge-like cavity that surrounds the trabeculae of the arachnoid mater and is filled with CSF?
subarachnoid space
what do you call the endothelial cells lining the sinuses that function as sites for absorption of CSF into the blood of the venous sinuses?
arachnoid villi
ito ‘yung responsible sa pag-transport ng CSF from subarachnoid space to dural venous sinus then pabalik sa lateral ventricles then CSF production ulet
meningeal layer that consists of flattened, mesenchymally derived cells closely applied to the entire surface of the CNS tissue
Pia mater
the functional barrier that controls the passage of substances from blood into the CNS tissue
blood-brain barrier
The main structural component of the BBB is the ____, in which the cells are tightly sealed together with well-developed occluding junctions
capillary endothelium
The ____ that envelops the basement membrane of capillaries in most CNS regions contributes to the BBB and further regulates passage of molecules and ions from blood to brain.
limiting layer of perivascular astrocytic feet
this consists of highly vascular tissue and is found in the roofs of the third and fourth ventricles and in parts of the two lateral ventricular walls
choroid plexus
choroid plexus function is to remove water from blood and release it as the CSF; CSF is clear, contains Na+, K+, and Cl- ions but very little protein + very sparse lymphocytes
a condition characterized as the decrease in the absorption of CSF or a blockage of outflow from the ventricles during fetal or postnatal development is called?
hydrocephalus
hydrocephalus promotes a progressive enlargement of the head followed by mental impairment
what are the 4 functions of the CSF?
- Mechanical protection
- Provides nutrients to the CNS
- Homeostatic function
- Circulation
what are the 4 substances that can pass thru the blood-brain barrier?
- Alcohol
- Drugs
- Anesthesia
- Metabolite B1
what are the main components of the PNS?
nerves, ganglia, and nerve endings
what is the counterpart of a tract in the PNS?
Nerve
a mature schwann cell myelin sheath has up to how many lamellae?
100 lamellae
meaning: naka-100 na ikot siya smth & its cytoplasm is the outermost layer
Between adjacent Schwann cells on an axon the myelin sheath shows small ____ where the axon is only partially covered by interdigitating Schwann cell processes.
nodes of Ranvier
At the nodes of Ranvier the axolemma is exposed to ions in the interstitial fluid and has a much higher concentration of voltage-gated Na+ channels, which renew the action potential and produce what type of conductions?
saltatory conductions
remember that nodes of Ranvier = myelinated axons; myelinated = saltatory conduction whereas unmyelinated is continuous conduction
3 layers of a nerve
- Epineurium
- Perineurium
- Endoneurium
layer of a nerve that consists of reticular fibers, scattered fibroblasts, and capillaries
endoneurium
groups of axons with schwann cells and endoneurium are bundled together as ____? they are bundled together by a sleeve of ____?
fascicles; perineurium
Perineurium contains flat fibrocytes with their edges sealed together by tight junctions. 2-6 layers of this CT make up the blood-nerve barrier
layer of a nerve that has a dense, irregular fibrous coat which extends deeply to fill the space between fascicles?
epineurium
____ fibers carry information from the internal body regions & the environment to the CNS
Afferent
____ fibers carry impulses from the CNS to effector organs commanded by these centers
Efferent
Nerves containing only sensory fibers are called? what about those composed of fibers that carry impulses to the effectors? what about a mix of these 2?
sensory nerves; motor nerves; mixed nerves
what do you call the ovoid structures containing neuronal cell bodies and their surrounding satellite cells?
Ganglia
Are unmyelinated axons in the PNS enveloped by Schwann cells?
Yes or No
Yes; axons r enveloped by schwann cels but there are no myelin sheath wraps arnd each axon
type of ganglia that receive afferent impulses that go to the CNS and is associated w/ both cranial nerves and the dorsal roots of spinal nerves
Sensory ganglia
type of ganglia that affects the activity of smooth muscle, secretions of glands, heart rate, and many involuntary acts +++ homeostasis
Autonomic ganglia
The neurons of these ganglia are
pseudounipolar and relay information from the ganglion’s
nerve endings to the gray matter of the spinal cord via synapses with local neurons. what is the type of ganglia being described?
Sensory ganglia
____ are small bulbous dilations in autonomic nerves, usually with multipolar neurons.
Autonomic Ganglia
____ are small bulbous dilations in autonomic nerves, usually with multipolar neurons.
Autonomic Ganglia
The ganglia in the walls of the digestive tract is known as?
intramural ganglia
Which of the following is characteristic of the chromatophilic material called Nissl substance in neural tissue?
a. Found throughout neurons
b. Site of mRNA translation for proteins of the axolemma
c. Most abundant in unipolar neurons
d. Becomes more abundant as an individual gets older
e. An example of intermediate filament proteins
b. Site of mRNA translation for proteins of the axolemma
Which of the following events occurs immediately after an action potential reaches a synapse at an axon terminal?
a. Vesicle fusion with the presynaptic terminal membrane
b. Calcium ion influx at the presynaptic terminal
c. Neurotransmitter binding to receptors on the postsynaptic
membrane
d. Neurotransmitter release into the synaptic cleft
e. Binding of the neurotransmitter at the presynaptic terminal
b. Calcium ion influx at the presynaptic terminal
A report from a hospital pathology laboratory indicates that a microscope slide with a small specimen of neural tissue contains “numerous GFAP-positive” cells. What is the most likely source of this specimen?
a. A region of white matter
b. A sensory ganglion
c. An autonomic ganglion
d. A region of gray matter
e. Pia mater
d. A region of gray matter
In the choroid plexus water from capillaries is transported directly into the cerebrospinal fluid by what structure(s)?
a. Ependyma
b. Astrocytes
c. Cells of the arachnoid mater
d. Lining of the central canal
e. Microglial cells
a. Ependyma
What term applies to collections of neuronal cell bodies (somata) in the central nervous system?
a. Ganglia
b. Neuroglia
c. Nodes
d. White matter
e. Nuclei
e. Nuclei
Which structure contains trabeculae around which cerebrospinal fluid (CSF) flows?
a. Arachnoid mater
b. Ependyma
c. Dura mater
d. Pia mater
e. Gray matter
a. Arachnoid mater
Which of the following is a characteristic of the connective tissue layer that surrounds individual fascicles in large peripheral nerves?
a. A delicate region of connective tissue in contact with Schwann cells
b. Called the dura mater
c. Important as part of the blood-nerve barrier in the nerve
d. Rich in myelin
e. The thickest sheath of connective tissue in the nerve
c. Important as part of the blood-nerve barrier in the nerve
A 35-year-old woman presents with weakness and spasticity in the lower left extremity, visual impairment and throbbing in the left eye, and difficulties with balance, fatigue, and malaise. There is an increase in CSF protein, elevated gamma globulin, and moderate pleocytosis. MRI confirms areas of demyelination in the anterior corpus callosum. Imaging identifies plaques that are hyperintense on T2-weighted and fluid attenuated inversion recovery (FLAIR) images, and hypointense on T1-weighted scans. Which of the following cells are specifically targeted in her condition?
a. Microglia
b. Oligodendrocytes
c. Astrocytes
d. Schwann cells
e. Multipolar neurons
b. Oligodendrocytes
ang ginawa kong hint here would be the corpus callosum demyelination (part siya ng brain, meaning, CNS)
A 22-year-old man receives a severe, traumatic compression injury to his radial nerve during a motorcycle crash. He shows an advancing Tinel sign. Which one of the following qcharacterizes regeneration of axons after this nerve injury?
a. It occurs in the absence of motor nerve action potentials.
b. It occurs at a rate of about 100 mm/d.
c. It occurs in the segment distal to the site of axon damage.
d. It occurs by a process that involves Schwann cell proliferation.
e. It occurs in conjunction with degeneration and phagocytosis of
the endoneurium
d. It occurs by a process that involves Schwann cell proliferation.
A 2-year-old boy presents with hearing impairment, poliosis (a white shock of hair), complete heterochromia and sectoral heterochromia, hypertelorism, a low hairline with eyebrows that touch in the middle, white pigmentation of the skin, and suspected neurologic deficits. He is diagnosed with Waardenburg syndrome with a mutation in the PAX-3 gene that affects neural crest differentiation. Which of the following structures would most likely also be affected in this patient?
a. Purkinje cells
b. Pyramidal neurons
c. Ventral horns of the spinal cord
d. Astrocytes
e. Neurons and satellite cells of the spinal ganglion
e. Neurons and satellite cells of the spinal ganglion
the hint for me here was the neural crest differentiation. I’m aware that neural crest = PNS whereas neural tube = CNS (this is from neurulation). After neural crest differentiation prob i looked for smth n part ng PNS (satellite cells)
