5 Nervous System Flashcards
Nervous System
- the primary control system of the body
- provides higher mental function and emotional expression
- maintains _
- regulates activities of _
homeostasis
muscles and glands
Communication of nervous system involves a combination of _
electrical and chemical signals
3 Overlapping Functions of NS
- Monitors stimuli and the gathered information called _
- It processes and interprets the sensory input and decides response—a process called _
- It then causes a response, or effect, by activating muscles or glands (effectors) via _
- sensory input
- integration.
- motor output.
Central nervous
system (CNS) consists of
the _,
brain and spinal cord
Act as the integrating and
command centers of the
nervous system
Central nervous
system (CNS)
They interpret incoming sensory information and issue instructions based on past experience and current conditions
Central nervous
system (CNS)
two divisions peripheral nervous system
- afferent division
- efferent division
afferent division could be stimulated through 2 stimulus:
- sensory stimuli
- visceral stimuli
efferent division is divided into:
- somatic ns
- autonomic ns
the autonomic ns subdivided into 3
- sympathetic ns
- parasympathetic ns
- enteric ns
includes all parts of the nervous
system
peripheral nervous system (PNS)
PNS consists mainly of the _ that extend from the spinal cord and brain
nerves
_ carry impulses to and from the spinal cord
Spinal nerves
_ carry impulses to and from the brain. These nerves serve as communication lines.
Cranial nerves
They link all parts of the body by carrying impulses from the sensory receptors to the CNS and from the CNS to the appropriate glands or muscles
PNS
sensory division aka
afferent division,
motor division aka
efferent division
consists of nerves that convey impulses toward the CNS
sensory division, or afferent division
division that
carries impulses from the
CNS to effector organs
motor division, or efferent division
delivering impulses from the skin,
skeletal muscles, and joints
Somatic Sensory Fibers
transmitting impulses from the visceral
organs
Visceral Sensory Fibers
allows us to voluntarily movement
Somatic nervous system
regulates events that are
involuntary movement
Autonomic nervous system
Support Cells
Neuroglia/
neuroglial cells
abundant star-shaped cells that account for nearly half of neural tissue
Astrocytes
Astrocytes brace and anchor neurons to their _
nutrient supply lines
It forms a living barrier between capillaries and neurons, helps determine capillary permeability, and plays a role in making exchanges between the two
Astrocytes
also helps to control the chemical environment in the brain
Astrocytes
spiderlike phagocytes
Microglia
monitor the health of nearby
neurons and dispose of debris
Microglia
microglial cells are phagocytes that defend CNS cells
line the central cavities of the brain
and the spinal cord
Ependymal Cells
participate in the production of cerebrospinal fluid (CSF) and helps to circulate the cerebrospinal fluid that fills those cavities and forms a protective watery cushion around the CNS.
Ependymal Cells
ependymal cells line cerebrospinal fluid-filled cavities
what is the Neuroglia that wrap their flat extensions (processes) tightly around CNS nerve fibers, producing fatty insulating coverings called _
2 answers
- oligodendrocytes
- myelin sheaths
2 Supporting cells in the PNS
- Schwann cells
- Satellite cells
form the myelin sheaths around nerve
fibers in the PNS.
Schwann cells
act as protective, cushioning cells for
peripheral neuron cell bodies
Satellite cells
nerve cells/ tissue
neurons
Cells specialized to transmit messages
neurons
Major regions of neurons
- Cell body
- processes
nucleus and metabolic center
of the cell
Cell body
– fibers that extend from the
cell body (dendrites and axons)
processes
Cell body of neurons consist of
- Nucleus
- Large nucleolus
Extensions
outside the cell
body
- dendrites
- axons
extensions of cell body that conduct
impulses toward
the cell body
Dendrites
extensions of cell body that conduct impulses away from the cell body (only 1!)
axons
Axons end in _
axonal terminals
Axonal terminals contain vesicles with
_
neurotransmitters
Axonal terminals are separated from the
next neuron by these gaps
2
- synaptic cleft
- synapse
gap between adjacent
neurons
Synaptic cleft
junction between nerves
Synapse
Myelin Sheaths features these cells and structure
- schwann cells
- nodes of ranvier
Protects and insulates the fibers and increases the speed of nerve impulse transmission
Myelin Sheaths
produce
myelin sheaths in jelly-roll
like fashion
Schwann cells
gaps
in myelin sheath along
the axon
Nodes of Ranvier
cell bodies and unmylenated
fibers
Gray matter
cell bodies and mylenated
fibers
white matter
these are clusters of cell bodies within the white matter of the central nervous system
Nuclei
collections of cell bodies
outside the central nervous system
Ganglia
3 Functional Classification of Neurons
- Sensory (afferent) neurons
- Motor (efferent) neurons
- Interneurons (association neurons)
- Carry impulses from the sensory receptors
- Cutaneous sense organs
- what receptors detect stretch or tension
Sensory (afferent) neurons
Proprioceptors
- Found in neural pathways in the central nervous system
- Connect sensory and motor neurons
Interneurons (association neurons)
Structural Classification of Neurons
- Multipolar neurons
- Bipolar neurons
- Unipolar neurons
Structural Classification of Neurons
many extensions
from the cell body
Multipolar neurons
Structural Classification of Neurons
one axon and one
dendrite
Bipolar neurons
Structural Classification of Neurons
have a short single
process leaving the
cell body
Unipolar neurons
How Neurons Function
3
- Irritability
- Conductivity
- plasma membrane at rest is polarized (Fewer positive ions are inside the cell than outside the cell)
ability to respond to stimuli
Irritability
ability to transmit an
impulse
Conductivity
process which a
stimulus depolarizes the
neuron’s membrane
Depolarization
depolarized
membrane allows
sodium (Na+) to flow
_ the membrane
inside
The exchange of ions
initiates an _ in the neuron
action
potential
If the action potential (nerve impulse) starts, it is propagated over the _
entire axon
Potassium ions rush out of the neuron after sodium ions rush in, which _ the membrane
repolarizes
- The _ restores the original configuration
- This action requires ATP
sodium-potassium pump
The impulse from axons and dendrites
continue to move
toward the _
cell body
Impulses travel
faster when fibers
have a _
myelin
sheath
Impulses are able to cross the synapse to another nerve through a substance called
neurotransmitter released from axon’s terminal and received by receptor of the dendrite of the next neuron
An action potential is started in the _
dendrite
not always
rapid, predictable, and
involuntary responses to stimuli
Reflex
direct route from a sensory
neuron, to an interneuron, to an effector
Reflex arc
Types of Reflexes
- autonomic reflexes
- somatic reflexes
4 Autonomic reflexes
- Smooth muscle regulation
- Heart and blood pressure regulation
- Regulation of glands
- Digestive system regulation
Somatic reflexes work via
Activation of skeletal muscles
is a three-neuro reflex arc in which the limb is withdrawn from painful stimulus
flexor, or withdrawal, reflex
three-neuron reflex arc (flexor) also consists of five elements
- receptor,
- sensory neuron,
- interneuron,
- motor neuron,
- an effector
Because there is always a delay at synapses (it takestime for neurotransmitter to diffuse through the synapticcleft), the more synapses there are in a reflex pathway,the _ takes to happen
longer the reflex
reflex that involve only spinal cord neurons and occur without brain involvement.
Spinal Reflexes
- As long as the spinal cord is functional, spinal reflexes, such as the flexor reflex, will work.
- By contrast, some reflexes require that the brain become involved because _ have to be evaluated to arrive at the “right” response.
many different types of information
kapag mayadong maraming nangyayari
CNS develops from the _
embryonic
neural tube
The neural tube becomes the _
brain and
spinal cord
The opening of the neural tube becomes
_
the ventricles
ventricles become
- Four chambers within the brain
- Filled with cerebrospinal fluid
Regions of the Brain
- cerebral hemispheres
- diencephalon
- brain stem
- cerebellum
- Paired (left and right) superior parts of the brain
- Include more than half of the brain mass
Cerebral Hemispheres
(Cerebrum)
Cerebral Hemispheres (Cerebrum) surface is made of ridges () and grooves ()
gyri
sulci
Fissures (deep grooves) divide the
cerebrum into _
Lobes of the Cerebrum
4 Surface lobes of the cerebrum
- frontal lobe
- parietal lobe
- occipital lobe
- temporal lobe
region of the brain that functions for speech, memory, logical and emotional responses, consciousness, the interpretation of sensation, and voluntary movement
The Cerebral Cortex
- is located in the parietal lobe posterior to the central sulcus
- Impulses traveling from the body’s sensory receptors (except for the special senses) are localized and interpreted in this area of the brain.
- Sensory Humunculus
Primary somatic sensory area
- somatosensory cortex
- speech, taste
- somatosensory association area
- reading
- allows us to consciously move our skeletal muscles
- Located in the anterior to the central sulcus in the frontal lobe
- The axons of these motor neurons form the major voluntary motor tract—the _ , which descends to the spinal cord
primary motor area
pyramidal tract, or corticospinal tract
- Also called the motor speech area
- Helps us speak by sending the motor signals that allow us to form words with our mouths
- found at the base of the precentral gyrus (the gyrus anterior to the central sulcus)
Broca’s area
- involved in higher intellectual reasoning and socially acceptable behavior
- anterior Part of the Frontal lobes
Anterior association area
also house areas involved with language comprehension
Frontal lobes
Complex memories appear to be stored in the _ and _ lobes
temporal
frontal
- area plays a role in recognizing patterns and faces, and blending several different inputs into an understanding of the whole situation
- Within this area is the speech area, located at the junction of the temporal, parietal, and occipital lobes
Posterior Cortex
Cerebral areas involved in what special senses
- gustatory area - taste
- visual area
- auditory area - hear
- olfactory area - smell
what part of brain
language, touch
parietal lobe
what part of brain
thinking, memory, behavior, movement
frontal lobe
what part of brain
hearing, learning, feelings
temporal lobe
what part of brain
sight
occipital lobe
what part of brain
breathing, heart rate and temperature
brain stem
what part of brain
balance and coordination
cerebellum
5 layers of cerebrum
- cortex ( gray matter )
- fissure (deep sulcus)
- gyrus (umbok)
- sulcus (guhit, deep)
- white matter
- Outer layer
- Composed mostly of neuron cell bodies
- composed of fiber tracts carrying impulses to, from, or within the cortex
Gray matter/ cortex
example of fiber tracts carrying impulses
commissures
arches above the structures of the brain stem and allows the cerebral hemispheres to communicate with one another
corpus callosum
connect areas within a hemisphere, and projection fiber tracts connect the cerebrum with lower CNS centers (the brain stem)
Association fiber tracts
– internal
islands of gray matter
Basal nuclei
Regulates voluntary motor activities by modifying info sent to the motor cortex
Basal nuclei
problem associated to Basal nuclei
unable
to control muscles,
spastic, jerky
genetic diseases caused in basal nuclei
Huntington’s Disease
Parkinson’s Disease
- Sits on top of the brain stem
- Enclosed by the cerebral hemispheres
Diencephalon
3 parts Diencephalon
- thalamus
- hypothalamus
- epithalamus
- Surrounds the third ventricle
- relay station for sensory impulses
- Transfers impulses to the correct part of the cortex for localization and interpretation
Thalamus
- Under the thalamus
- impt ANS center
- Helps regulate body temperature
- Controls water balance
- Regulates metabolism
Hypothalamus
important part of the limbic system (emotions)
Hypothalamus
thirst, appetite, sex, pain, and pleasure centers
is attached to the
hypothalamus
pituitary gland
reflex centers involved in olfaction (smell), bulge from the floor of the hypothalamus posterior to the pituitary gland
mammillary bodies
bulge - mukhang mammary gland
- Forms the roof of the third ventricle
- Houses the pineal body
- Includes the _ – knots of capillaries within each of the four ventricles and along with the ependymal cells lining the ventricles, form the cerebrospinal fluid.
epithalamus
choroid plexus
- about the size of a thumb in diameter and approximately 3 inches
- Provides a pathway for ascending and descending tracts,
- has many small gray matter areas
Brain Stem
structure of Brain Stem
- midbrain
- pons
- medulla oblongata
- extends from the mammillary bodies (floor of hypothalamus) to the pons inferiorly
- Composed of primarily of two bulging fiber tracts, the cerebral peduncles
Midbrain
a tiny canal that travels through the midbrain, connects the 3rd ventricle of the diencephalon (thalamus) to the 4th ventricle
Cerebral aqueduct
four rounded protrusions located dorsally that serves as the reflex centers involved with vision and hearing
Corpora quadrigemina
- The bulging center part of the brain stem
- Mostly composed of fiber tracts
- Includes nuclei involved in the control of breathing
Pons
- most inferior part of the brain stem
- merges into the spinal cord
- Includes important fiber tract area
- Includes area where the important pyramidal tracts (motor fibers) cross over to the opposite side
- centers that control heart rate, blood pressure, breathing, swallowing, and vomiting
- fourth ventricle lies posterior to the pons and medulla, and anterior to the cerebellum
Medulla Oblongata
diffuse mass of gray matter that extends to the entire length of the brain stem that involves in motor control of the visceral organ
Reticular Formation
- plays a role in consciousness and the awake/sleep cycle
Reticular activating system (RAS)
- also acts as a filter for the flood of sensory inputs that streams up the spinal cord and brain stem daily
Reticular activating system (RAS)
two hemispheres with convoluted surface that provides the precise timing for skeletal muscle activity and controls our balance
Cerebellum
continuously comparing the brain’s “intentions” with actual body performance by monitoring body position and the amount of tension in various body parts
Cerebellum
When needed, the cerebellum sends messages to initiate the appropriate corrective measures
5 Protection of the Central Nervous System
- scalp and skin
- skull and vertebral column
- meninges
- cerebrospinal fluid
- blood brain barrier
_ are three layers of membranes that cover and protect the brain and spinal cord
Meninges
- Double-layered external covering of meninges
- Folds inward in several areas
Dura mater
Meninges 3 layers
- dura mater
- arachnoid matter
- pia matter
layer of dura mater attached to surface of the
skull
periosteum
dura mater layer of outer covering of the brain
Meningeal layer
layer of meninges
* Middle layer
* Web-like
Arachnoid layer
layer of meninges
* internal layer
* Clings to the surface of the brain
Pia mater
A watery “broth” with components similar to blood plasma, from which it forms. However, it contains less protein and more vitamin C, and its ion composition is different
Cerebrospinal Fluid
Cerebrospinal Fluid is formed by
choroid plexus
- Forms a watery cushion to protect the brain
- Circulated in arachnoid space, ventricles, and central
canal of the spinal cord
Cerebrospinal Fluid
- Includes the least permeable capillaries of the body
- Excludes many potentially harmful substances
Blood Brain Barrier
Blood Brain Barrier is useless against some substances
5
Fats and fat soluble molecules
Respiratory gases
Alcohol
Nicotine
Anesthesia
Traumatic Brain Injuries
- concussion
- contusion
- cerebral edema
Slight brain injury
No permanent brain damage
concussion
Nervous tissue destruction occurs
Nervous tissue does not regenerate
contusion
Swelling from the inflammatory response
May compress and kill brain tissue
cerebral edema
- Commonly called a stroke
- result of a ruptured blood vessel supplying a region of the brain
- Brain tissue supplied with oxygen from that blood source dies
- Loss of some functions or death may result
Cerebrovascular Accident (CVA)
a one-sided paralysis
Hemiplegia
damage to the left cerebral hemisphere, where the language areas are located
Aphasias
loss of the ability
to speak
Motor Aphasias
loses the ability
to understand written or spoken language
sensory aphasia
can also cause marked changes
in a person’s disposition
Brain lesions
- glistening white continuation of the brain stem
- Provides a two-way conduction pathway to and from the brain, and it is a major reflex center
- Enclosed within the vertebral column, the _ extends from the foramen magnum of the skull to the first/second lumbar vertebra
- cushioned and protected by meninges
spinal cord
In humans, _ pairs of spinal nerves arise from the cord and exit from the vertebral column to serve the body area close by
31
The spinal cord is about the size of a thumb for most of its length, but it is enlarged in the _
regions where the nerves serving the upper and lower limbs arise and leave the cord
cervical and lumbar
collection of the spinal nerve
Cauda equine
spinal cord
conduction tracts
Exterior white mater –
spinal cord
mostly cell bodies
Internal gray matter
horns of Internal gray matter of the spinal cord
Dorsal (posterior) horns
Anterior (ventral) horns
Central canal is filled with _
cerebrospinal fluid
_ cover the spinal cord
Meninges
Nerves leave at the level of each _
vertebrae
White matter of the spinal cord is composed of
_
myelinated fiber tracts
3 regions of white matter in spinal cord
- dorsal column
- lateral column
- ventral column
- All tracts in the dorsal columns are _ that carry sensory input to the brain.
- The lateral and ventral columns contain _
ascending tracts
both ascending and
descending (motor) tracts
is a bundle of neuron fibers
Nerve
in neuron
Each fiber is surrounded by a delicate connective tissue sheats called an _
endoneurium
Neurons
Groups of fibers are bound by a coarser connective tissue wrapping, the _ to form fiber bundles, or fascicles
perineurium
all the fascicles are bound together by a tough fibrous sheath, the _, to form the cordlike nerve
epineurium
Classification of Nerves
- mixed nerves
- afferent nerves/ sensory
- efferent nerves/ motor
nerves
both
sensory and motor
fibers
Mixed nerves
The _ of cranial nerves primarily serve
the head and neck
12 pairs
Only one pair (of cranial nerves, which is)_ extends to the thoracic and abdominal cavities
the vagus nerves
12 cranial nerves
OL
OP
OC
TRO
TRI
AB
F
VE
G
VA
AC
H
- olfactory
- optic
- oculomotor
- trochlear
- trigeminal
- abducens
- facial
- vestibulocochlear
- glossopharyngeal
- vagus
- accessory
- hypoglossal
The 31 pairs of human spinal nerves are formed by the joining of the ventral and dorsal
roots of the spinal cord.
Divided into:
dorsal ramus and ventral
ramus
The smaller (spinal nerve) _ serve the skin and muscles of the posterior body trunk
Dorsal rami
The ventral rami of spinal nerves T1 through T12 form the _ , which supply the muscles between the ribs and the skin and muscles of the anterior and lateral trunk
intercostal nerves
The ventral rami of all other spinal nerves form complex networks of nerves called _ , which serve the motor and sensory needs of the limbs
plexuses
- is the motor subdivision of the PNS that controls body activities automatically
- Stabilized internal environment
Autonomic Nervous System
chain of two motor neurons of ANS
- preganglionic neuron
- postganglionic axon
- “fight-or-flight”
- Response to unusual stimulus
- Takes over to increase activities
Sympathetic
Sympathetic actions
- exercise,
- excitement,
- emergency,
- embarrassment
- housekeeping activites
- Conserves energy
- Maintains daily necessary body functions
Parasympathetic
Parasympathetic actions
- digestion,
- defecation
- diuresis
- The preganglionic neurons of the parasympathetic division are located in brain nuclei of several cranial nerves—III, VII, IX, and X (the vagus being the most important of these) and in the S2 through S4 levels of the spinal cord
- Parasympathetic NS aka
craniosacral division
- preganglionic neurons are in the gray matter of the spinal cord from T1 through L2
- Sympathetic NS also called the _
thoracolumbar division
- _ neurons are formed after birth, but growth and maturation continues for several years
- The brain reaches maximum weight as a young adult
- we can always grow dendrites
No more
a progressive degenerative disease of the brain that ultimately results in dementia (mental deterioration), memory loss (particularly for recent events), a short attention span and disorientation, and eventual language loss
Alzheimer’s disease (AD)
is associated with a shortage of acetylcholine (ACh) and structural changes in the brain
Alzheimer’s disease (AD)
Alzheimer’s disease (AD)
Microscopic examinations of brain tissue reveal _ (aggregations of beta-amyloid peptide) littering the brain like shrapnel between the neurons
senile plaques
Alzheimer’s disease (AD)
Another line of research has implicated a protein called _ , which appears to bind microtubule “tracks” together, much like railroad ties
tau
basal nuclei problem
It results from degeneration of specific neurons in the substantia nigra of the midbrain, which normally supply dopamine to the basal nuclei.
Afflicted individuals have a persistent tremor at rest
Parkinson’s Disease
Genetic disease that strikes during middle age leads to massive degeneration of the
basal nuclei and cerebral cortex.
Its initial symptoms are wild, jerky, and almost continuous flapping movements called _
(Greek for “dance”)
Huntington’s Disease
chorea
