CH 5: Nervous System Flashcards
primary control system of the body
nervous system
provides for higher mental functions and emotional expression, maintains homeostasis, and regulates the activities of
muscles and glands.
nervous system
Communication by the nervous system
involves a combination of
electrical and chemical signals
All body systems are influenced by the
nervous system
Three overlapping functions of the nervous system
- Sensory input
- Processes and interprets- integration
- Response or effect- via motor input
processes and interprets the sensory input
and decides response—a process called
integration
The Central nervous system (CNS) consists of the (2)
brain and spinal cord
Act as the integrating and command centers of the nervous system
central nervous system
Central nervous system _____ incoming sensory information and __ ___ based on past experience and current conditions.
interpret
issue instructions
includes all parts of the nervous system.
peripheral nervous system (PNS)
Peripheral nervous system (PNS) consists mainly of the ____ that extend from
the ____ and____.
nerves
spinal cord
brain
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
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
peripheral nervous system
consists of nerves that convey impulses toward the CNS
sensory division or afferent division
Functional Classification (2)
-sensory division, or afferent division
-motor division, or efferent division
Two division of sensory division, or afferent division
Somatic Sensory Fibers
Visceral Sensory Fibers
Difference between
Somatic Sensory Fibers
Visceral Sensory Fibers
Somatic Sensory Fibers-delivering
impulses
Visceral Sensory Fibers-transmitting
impulses
Two division of motor division, or efferent division
Somatic Nervous System
Autonomic Nervous System
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
Autonomic nervous system has two parts
Parasympathetic
* Sympathetic
support cells
neuroglia
abundant star-shaped cells that account for nearly half of neural tissue
astrocytes
brace and anchor neurons to their nutrient
supply lines
astrocytes
It forms a living barrier between capillaries and neurons, helps determine capillary permeability, and plays a role in making exchanges between the two.
astrocytes
helps to control the chemical environment
in the brain
astrocytes
spiderlike phagocytes
microglia
monitor the health of nearby neurons and
dispose of debris
microglia
line the central cavities of the brain and the
spinal cord
ependymal cells
participate in the production of cerebrospinal fluid (CSF)
ependymal cells
Ependymal Cells participate in the production of
cerebrospinal fluid (CSF)
protective watery cushion around the CNS.
ependymal cells
Neuroglia that wrap their flat extensions
(processes) tightly around CNS nerve fibers, producing fatty insulating coverings called myelin sheaths
oligodendrocytes
Neuroglia that wrap their flat extensions
(processes) tightly around CNS nerve fibers, producing fatty insulating coverings called
myelin sheaths
Supporting cells in the PNS come in two major varieties
-Schwann cells
-Satellite cells
Difference between
-Schwann cells
-Satellite cells
Schwann cells- form the myelin sheaths
around nerve fibers in the PNS.
Satellite cells- act as protective,
cushioning cells for peripheral neuron cell
bodies
form the myelin sheaths
around nerve fibers in the PNS.
-Schwann cells
act as protective,
cushioning cells for peripheral neuron cell
bodies
-Satellite cells
nervous tissue
neurons
Cells specialized to transmit messages
neurons
Major regions of neurons (2)
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 (2)
*Nucleus
*Large nucleolus
Extensions outside the cell body (2)
dendrites
axons
conduct impulses toward the cell body
dendrites
conduct impulses away from the cell body (only 1!)
axons
Axons end in
axonal terminals
contain vesicles with
neurotransmitters
Axonal terminals
Axonal terminals are separated from the next neuron by a gap (2)
*Synaptic cleft
*Synapse
gap between adjacent
*Synaptic cleft
junction between nerves
*Synapse
myelin sheaths (2)
*Schwann cells
*Nodes of Ranvier
gaps in myelin sheath along the axon
*Nodes of Ranvier
produce myelin sheaths in jelly roll like fashion
Schwann cells –
Protects and insulates the fibers and increases the speed of nerve impulse transmission.
myelin sheaths
neuron cell body are mostly found in the
central nervous system
– cell bodies and
unmylenated fibers
Gray matter
– clusters of cell bodies within
the white matter of the central nervous system
Nuclei
– collections of cell bodies outside the
central nervous system
Ganglia
Function Classification of Neurons
- Sensory (afferent) neurons
- Motor (efferent) neurons
- Interneurons (association neurons)
Carry impulses from the sensory receptors
- Sensory (afferent) neurons
Carry impulses from the sensory receptors (2)
- Cutaneous sense organs
- Proprioceptors
– detect stretch or
tension
Proprioceptors
Carry impulses from the central nervous
system
Motor (efferent) neurons
Found in neural pathways in the central
nervous system
Interneurons (association neurons)
Connect sensory and motor neurons
Interneurons (association neurons)
Structural classification of neurons
- Multipolar neurons
- Bipolar neurons
- Unipolar neurons
many extensions from the cell body
Multipolar neurons
neurons one axon and one dendrite
Bipolar
have a short single process leaving the cell body
Unipolar neurons
How neurons function (physiology)
Irritability
Conductivity
ability to respond to stimuli
Irritability
ability to transmit an impulse
Conductivity
The plasma membrane at rest is
polarized
______ ____ ___are inside the cell than
outside the cell
Fewer
positive ions
a stimulus depolarizes the
neuron’s membrane
Depolarization
allows sodium (Na+) to flow inside the membrane
depolarized membrane
Depolarization allows ____ to flow inside the membrane
sodium (Na+)
initiates an action potential in the neuron
exchange of ions
nerve impulse
action potential
rush out of the neuron after
sodium ions rush in, which repolarizes membrane
potassium ions
restores the original configuration
sodium-potassium pump
Action potential requires
ATP
Impulses travel faster when fibers have a
myelin sheath
released from a nerve’s axon terminal
Neurotransmitter
The ____ of the next neuron has receptors
that are stimulated by the ____
dendrite
neurotransmitter
Where action potential starts
dendrite
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 (2)
Autonomic Reflexes
Somatic Reflexes
- Autonomic reflexes REGULATIONS (4)
*Smooth muscle regulation
*Heart and blood pressure regulation
*Regulation of glands
*Digestive system regulation
Somatic reflexes REGULATIONS (1)
*Activation of skeletal muscles
a three-neuro reflex arc in which the limb is withdrawn from painful stimulus
Flexor, or Withdrawal Reflex
A three-neuron reflex arc also consists of five elements-
receptor
sensory
interneuron
motor neuron, effector
neuron
involve only spinal cord neurons and occur
without brain involvement.
Spinal reflexes
develops from the embryonic neural tube
central nervous system
*The neural tube becomes the (2)
brain
spinal cord
*The opening of the neural tube becomes the
ventricle
regions of the brain (4)
- Cerebral hemispheres
- Diencephalon
- Brain stem
- Cerebellum
Paired (left and right) superior parts of the brain
Cerebral Hemisphere (Cerebrum)
Include more than half of the brain mass
Cerebral Hemisphere (Cerebrum)
The surface of Cerebral Hemisphere (Cerebrum) is made of (2)
ridges (gyri)
grooves (sulci)
deep groove
Fissure
Surface lobes of the cerebrum (4)
*Frontal lobe
*Parietal lobe
*Occipital lobe
*Temporal lobe
Speech, memory, logical and emotional
responses, consciousness, the interpretation of sensation, and voluntary movement are all functions
cerebral cortex
located in the parietal lobe posterior to the central sulcus
primary somatic sensory area
primary somatic sensory area located in the _____ posterior to the ____
parietal lobe
central sulcus
mpulses traveling from the body’s
sensory receptors (except for the special
senses) are localized and interpreted in
this area of the brain.
primary somatic sensory area
is a map of brain areas dedicated to sensory processing for different anatomical divisions of the body1.
sensory homunculus
allows us to consciously move our skeletal
muscles,
primary motor area
Primary sensory area is located in the anterior to the ____ in the ____.
central sulcus
frontal lobe
Three divisions of cerebral cortex
-Primary somatic sensory area
-Primary motor area
-Broca’s area
The axons of primar motor neurons form
the major voluntary motor tract—the
_____ or ____,
which descends to the spinal cord
pyramidal tract, or corticospinal tract
Also called the motor speech area
Broca’s area
Helps us speak by sending the motor
signals that allow us to form words with
our mouths.
Broca’s area
Broca’s area is found at the base of the ______ (the gyrus _____ to the _____).
precentral gyrus
anterior
central sulcus
involved in higher intellectual
reasoning and socially acceptable behavior
Anterior association area
(anterior Part of the Frontal lobes)
Anterior association area
house areas involved with language comprehension
frontal lobes
Complex memories appear to be stored in the (2)
temporal and frontal lobes
area plays a role in recognizing patterns and faces, and blending several different inputs into an understanding of the whole situation.
posterior cortex
speech area, located at the junction of the (3)
temporal
parietal
occipital lobes
Area found in posterior contex
speech area
allows you to sound out
words.
speech area
usually in only one cerebral hemisphere.
speech area
Cerebral areas involved in special senses (4)
*Gustatory area (taste)
*Visual area
*Auditory area
*Olfactory area
outer layer and composed mostly of neuron cell bodies
gray matter
composed of fiber tracts carrying impulses to, from, or within the cortex.
gray matter
corpus callosum connects hemispheres. Such fiber tracts are called
commissures
above the structures of the brain stem
corpus callosum arches
allows the cerebral hemispheres to communicate with one another
corpus callosum arches
connect areas within a hemisphere,
association fiber tracts
connect the cerebrum with lower CNS centers, such as the brainstem.
projection fiber tracts
internal islands of gray matter
basal nuclei
Regulates voluntary motor activities by
modifying info sent to the motor cortex
basal nuclei
Problems of basal nuclei (3)
unable to control muscles, spastic,
jerky
- Involved in Huntington’s and Parkinson’s Disease
Basal Nuclei
Basal nuclei is involved in (2)
Huntington’s Disease
Parkinson’s Disease
Sits on top of the brain stem
diencephalon
diencephalon enclosed by
cerebral hemispheres
Enclosed by the cerebral heispheres
diencephalon
diencephalon is made up of three parts
*Thalamus
*Hypothalamus
*Epithalamus
Surrounds the third ventricle
thalamus
The relay station for sensory impulses
thalamus
Transfers impulses to the correct part of the cortex for localization and interpretation
thalamus
under the thalamus
hypothalamus
important autonomic nervous system center
hypothalamus
Important autonomic nervous system center (3)
*Helps regulate body temperature
*Controls water balance
*Regulates metabolism
An important part of the limbic system
(emotions)
hypothalamus
Hypothalamus is an important part of the
limbic system (emotions)
The _______ is attached to the
hypothalamus
pituitary gland
reflex centers involved in olfaction (the sense of smell), bulge from the floor of the hypothalamus posterior to the pituitary gland.
mammillary bodies
Forms the roof of the third ventricle
epithalamus
Epithalamus houses the
pineal body
knots of capillaries within each of the four ventricles and along with the ependymal cells lining the ventricles, form the cerebrospinal fluid.
choroid plexus
Brainstem is about the size of a
-thumb in diameter
- 3 inch
Provides a pathway for ascending and
descending tracts, the brain stem has many small gray matter areas.
brain stem
Structure of brain stem (3)
midbrain
pons
medulla oblongata
extends from the mammillary bodies to the pons inferiorly
midbrain
Midbrain is composed of primarily of two bulging fiber tracts
cerebral peduncles
a tiny canal that travels through the midbrain, connects the 3rd ventricle
of the diencephalon to the 4th ventricle
cerebral aqueduct
four rounded protrusions located dorsally that serves as the reflex centers involved with vision and hearing
Corpora quadrigemina
bulging center part of the brain stem
pons
Mostly composed of fiber tracts
pons
pons is mostly composed of
fiber tracts
Includes nuclei involved in the control of
breathing
pons
most inferior part of the brain stem
medulla oblongata
medulla oblongata merges into the
spinal cord
merges into the spinal cord
medulla oblongata
Includes important fiber tract area.
medulla onlongata
Includes area where the important pyramidal tracts (motor fibers) cross over to the opposite side.
medulla oblongata
(motor fibers)
pyramidal tracts
control heart rate, blood pressure,
breathing, swallowing, and vomiting, among
others.
medulla oblongata
Medulla oblongata control (5)
-heart rate
-blood pressure
-breathing
-swallowing
-vomiting
The _______ lies posterior to the ___ and ___ and anterior to the cerebellum
fourth ventricle
pons and medulla
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)
Reticular activating system (RAS) plays a role in (2)
-consciousness
-awake/sleep cycle.
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_____ sends messages
to initiate the appropriate corrective measures.
cerebellum
Protection of the Central Nervous System (5)
- Scalp and skin
- Skull and vertebral column
- Meninges
- Cerebrospinal fluid
- Blood brain barrier
Layers of Meninges (3)
- Dura mater
- Arachnoid layer
- Pia mater
Has a double-layered external covering
Dura mater
Dura mater have a double -layered external covering
Periosteum
Meningeal Layer
attached to surface of the skull
Periosteum
outer covering of the brain
Meningeal layer
middle layer of meninges
Arachnoid layer
weblike layer of meninges
arachnoid layer
internal layer of meninges
Pia mater
Layer of meninges that clings to the surface of the brain
Pia mater
A watery “broth” with components similar to blood plasma, from which it forms.
Cerebrospinal fluid
Cerebrospinal fluid is formed by the
choroid plexus
Forms a watery cushion to protect the brain
cerebrospinal fluid
Circulated in arachnoid space, ventricles, and central canal of the spinal cord
cerebrospinal fluid
Includes the least permeable capillaries of the body
blood brain barrier
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 (3)
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
cerebrovascular accident CVA
The result of a ruptured blood vessel supplying a region of the brain
cerebrovascular accident CVA
Brain tissue supplied with oxygen from that
blood source dies
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
-(loses the ability to understand written or spoken language
Motor Aphasia
Sensory Aphasia
can also cause marked changes in a
person’s disposition
Brain lesions
glistening white continuation of the brain stem
spinal cord
- Provides a two-way conduction pathway to and from the brain, and it is a major reflex center
spinal cord
Spinal cord is enclosed within the
vertebral column
The spinal cord extends from the ______ of the skull to the _______
foramen magnum
first or second lumbar vertebra
In humans, __ pairs of spinal nerves arise from the cord and exit from the vertebral column to serve the body area close by.
31
(collection of the spinal nerve)
Cauda equine
conduction tracts
Exterior white mater
Internal gray matter
mostly cell bodies
- Internal gray matter is divided into two
- Dorsal (posterior) horns
- Anterior (ventral) horns
- ____ filled with cerebrospinal fluid
- _____ cover the spinal cord
- Nerves leave at the level of each vertebrae
Central canal
Meninges
White matter of the spinal cord is composed of
myelinated fiber tracts
Three regions of white matter
dorsal column
lateral column
ventral column
- All tracts in the dorsal columns are ____ that carry sensory input to the brain.
ascending tracts
The lateral and ventral columns contain both
_____
ascending and descending (motor) tracts
is a bundle of neuron fibers
nerve
Each fiber is surrounded by a delicate connective tissue sheats called an
endoneurium
Groups of fibers are bound by a coarser
connective tissue wrapping, the ____ to form fiber bundles, or___.
perineurium
fascicles
all the fascicles are bound together by a
tough fibrous sheath, the_____, to form the cordlike nerve
epineurium
Classification of Nerves (3)
-Mixed nerves
-Afferent nerves
-Efferent nerves
–both sensory and motor fibers
–carry impulses toward the CNS
–carry impulses away from the CNS
*Mixed nerves –both sensory and motor fibers
*Afferent (sensory) nerves–carry impulses toward the CNS
*Efferent (motor) nerves –carry impulses away from the CNS
- The __pairs of cranial nerves primarily serve the head and neck. Only one pair (____) extends to the thoracic and abdominal cavities.
12
the vagus nerves
- The ___ pairs of human spinal nerves are formed by the joining of the ventral and dorsal roots of the spinal cord.
31
Spinal nerves are divided into (2)
dorsal ramus and ventral ramus
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
the cell bodies of the motor neurons are inside the CNS, and their axons
(in spinal nerves and their rami) extend all the way to the skeletal muscles they serve.
somatic division
has a chain of two motor neurons preganglionic neuron and postganglionic axon
autonomic nervous system
autonomic nervous system has a chain of two motor neurons
preganglionic neuron
postganglionic axon
Two types of autonomic functioning
-Sympathetic
-Parasympathetic
*Response to unusual stimulus
*Takes over to increase activities
Sympathetic
Fight or flight
sympathetic
Sympatheic remember as the “___” division = (4)
E
exercise, excitement, emergency, and embarrassment
housekeeping activites
parasympathetic
*Conserves energy
*Maintains daily necessary body functions
Parasympathetic
Parasympathetic remember as the “__” division - (3)
D
digestion,
defecation, and diuresis
The preganglionic neurons of the parasympathetic division are located in brain nuclei of several cranial nerves
III, VII, IX, and X
S2 through S4 levels of the spinal cord
Anatomy parasympathetic is also known as
craniosacral division
preganglionic neurons are in the ___ of
the spinal cord from ____
gray matter
T1 through L2
Preganglionic neurons are also called
thoracolumbar division
____are formed after birth, but growth and maturation continues for several years
(new evidence!)
No more neurons
The brain reaches maximum weight as a
young adult
No more neurons are formed after birth but we can always grow
dendrites
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
Alzheimer’s Disease is associated with a shortage of
acetylcholine (ACh)
Microscopic examinations of brain tissue reveal ____ (aggregations of beta amyloid peptide) littering the brain like shrapnel between the neurons.
senile plaques
Another line of research has implicated a protein called ___, which appears to bind microtubule “tracks” together, much like railroad ties.
tau
basal nuclei problem
Parkinson’s disease
It results from degeneration of specific neurons in the substantia nigra of the midbrain, which normally supply dopamine to the basal nuclei.
Parkinson’s disease
Genetic disease that strikes during middle age leads to massive degeneration of the basal nuclei and cerebral cortex.
Huntington’s Disease
Huntington’s Disease initial symptoms are wild, jerky, and almost continuous flapping movements called
chorea (Greek for “dance”)
