n e r v o u s s y s t e m
TRANSCRIPT
NERVOUS SYSTEM
Abalos, Ailyn
Juatas, Kenneth
Llorin, Patricia
Mansibang, Rania
Sunio, Leslie
DMD 1-F
Functions Of Nervous System
Communication and coordination
- Adapt and respond to changes from
both inside and outside the body
sends messages to the rest of the body
controls all of the body functions
Site of reasoning
The Organization of Nervous
System
Your nervous system has three
components…
Brain
- control center
Nerves
-carry messages
Spinal cord
-a thick bundle of nerves
Brain
Characteristics of the Brain
Weight: 1.3-kg (3-lb) mass of pinkish-gray jellylike tissue
Varies in gender:
Male: 1380 grams
Female: 1250 grams
With 100 billion nerve cell:
Neurons
Neuroglia (supporting-tissue) cells
4 types of Memory:
Short-term memory – when we say things over and
over again so you remember them.
Long term memory – we remember important
events or things that we do over and over again.
Ancestral Memory – We remember things right
when we were born. Example is when humans
remember how to get milk from their mom or feeding
bottles.
Eidetic Memory – a.k.a photographic memory
The Cranial Cavity
1. Meninges
Dura Mater - outermost membrane. The
toughest and thickest.
Arachnoid Layer - middle membrane.
Pia Mater - innermost membrane. Consists
of small blood vessels.
2. Cerebrospinal Fluid – A clear liquid that bathes the entire brain and fills a series of four cavities called ventricles
3. Gray Matter – Composed of Nerve cell bodies
4. White Matter – Composed of myelinated nerve fibers
5. Nucleus – Mass of nerve cells in any part of the brain and spinal cord.
6. Ganglion – Mass of nerve cell outside of the brain and spinal cord.
7. Commisure – Band of fibers joining corresponding opposite parts of the brain and spinal cord.
8. Brain:
Left and Right Brain Functions
The right brain is associated with artistic
ability like singing, painting, writing poetry,
etc.
Left-brain dominated people may find their
thought processes vague and difficult to
follow, for they are quite opposite in the way
they think. Left-brain dominated people tend
to be more logical and analytical in their
thinking and usually excel at mathematics and
word skills.
A. Embryological developmental of the Brain:
1. Forebrain - Prosencephalon
Telencephalon (Cerebrum)
Diencephalon (Thalamus and Hypothalamus)
2. Midbrain – Mesencephalon
Corpora Quadrigemina
Cerebral Peduncles
Iter (Cerebral aqueduct or aqueduct of Sylvius)
3. Hindbrain – Rhombencephalon
Metencephalon (cerebellum, pons varolii)
Myelencephalon (medulla oblongata)
5 Main Parts of the Brain
1. Cerebrum (Telencephalon)
2. Pons and Cerebellum (Metencephalon)
3. Midbrain (Mesencephalon)
4. Thalamus and Hypothalamus
(Diencephalon)
5. Medulla Oblongata (Myelencephalon)
1. Forebrain
Cerebrum (Telencephalon)
Cerebrum(the Latin word for brain)
a.k.a “cerebral cortex”
two large dome-shaped, almost symmetrical hemispheres
intelligence, memory and reason
Composed of gray matter thrown into infoldings: shallow; gyrusor gyri, deep; fissures
Innermost part is made of white matter
Great longitudinal fissure (or longitudinal cerebral fissure, or longitudinal fissure, or interhemispheric fissure) is the deep groove which separates the two hemispheres of the vertebrate brain.
•The cerebral cortex is made of grey matter, and
covers the cerebrum and cerebellum.
•The different lobes of the cerebral cortex subdivide
processing responsibilities based on sensory input
or motor function.
Fissures the Cerebrum:
1. Longitudinal Fissure – They are mirror twins
for motor and sensory activities of the body.
*Connected in the midline by corpus
callosum – allows the two cerebral
hemispheres to share learning and memory.
2. Lateral Fissure (Sylvian Fissure) – located
between frontal and parietal lobes. For speech
and hearing.
Corpus Callosum
•is a thick band of nerve fibers that
divides the cerebrum into left and
right hemispheres.
•It connects the left and right sides of
the brain allowing for communication
between both hemispheres.
•transfers motor, sensory, and
cognitive information between the
brain hemispheres.
3. Central Fissure (Rolandic Fissure) – Between
the frontal and parietal lobes; for both motor
and sensory functions.
4. Transverse Fissure – found between the
cerebrum and cerebellum.
5. Palate Occipital Fissure – between occipital
and parietal lobes.
Lobes of the Cerebrum
FRONTAL LOBE - involved
with decision-making,
problem solving, and
planning
Lobes of the Cerebrum
PARIETAL LOBE - receives
and processes sensory
information.
TEMPORAL LOBE (LEFT & RIGHT HEMISPHERE) - involved with emotional responses,
memory, and speech.
OCCIPITAL LOBE involved with vision
and color recognition.
Functions of the Cerebral Cortex
Determining Intelligence
Determining Personality
Thinking
Perceiving
Producing and Understanding Language
Interpretation of Sensory Impulses
Motor Function
Planning and Organization
Touch Sensation
Wernicke’s - language
comprehension
Primary auditory
cortex
auditory (sound) pitch
and volume.
Broca's area - speech
production, language
processing,
controls facial neurons
Motor cortex -
movements and
coordination.
Somatosensory cortex
processes input from the
various systems in the body
which are sensitive to touch.
(Sensations)
•The cerebral cortex is made of grey matter, and
covers the cerebrum and cerebellum.
•The different lobes of the cerebral cortex subdivide
processing responsibilities based on sensory input
or motor function.
Visual
Amygdala
It is a limbic system:
•Emotions
•Motivations
•Survival.
•Fear
•Anger
•Pleasure.
•Hormonal Secretions
•MemoryHippocampus
•Memory forming, organizing,
and storing.
•Connecting emotions and senses,
such as smell and sound, to
memories.
2. Hindbrain
Metencephalon:
A. Cerebellum
B. Pons Varolli
2. A Cerebellum“little brain”
two smaller hemispheres located at the back of the cerebrum
Oval in shape
Occupies the posterior cranial fossa
Seperated from the cerebrum by the tentorium cerbelli
The outer layer of the cerebellum consists of fine folds called folia.
the outer layer of cortical gray matter surrounds a deeper layer of white matter and nuclei (groups of nerve cells).
Three fiber bundles called cerebellar peduncles connect the cerebellum to the three parts of the brain stem.
Anterior Lobe – posture
Posterior Lobe – coordination of movement
Flocculonodular Lobe – equilibrium
Cerebellum
•The area of
the hindbrain that
controls motor
movement
coordination, balance,
equilibrium
and muscle tone.
The Brainstem
3 parts: midbrain, pons, and medulla oblongata
The brain stem is evolutionarily the most primitive part of the
brain and is responsible for sustaining the basic functions of
life, such as breathing and blood pressure.
A canal runs longitudinally through these structures carrying
cerebrospinal fluid.
Distributed along its length is a network of cells, referred to as
the reticular formation that governs the state of alertness.
Mammillary
body
-recognition
memory.
Pituitary Gland
•"master gland,"
•makes hormones
Pons
Reticular Formation
Spinal cord
Fornix
Hypothalamus
Functions:
• path for messages traveling between the
upper brain and spinal cord
• the seat of basic and vital functions such as
breathing, blood pressure, and heart rate, as
well as reflexes like eye movement and
vomiting.
Reticular Formation
is a netlike formation of nuclei known as the
reticular formation.
The reticular formation controls respiration,
cardiovascular function, digestion, levels of
alertness, and patterns of sleep.
It also determines which parts of the constant flow
of sensory information into the body are received
by the cerebrum.
Reticular Formation
Functions:
Sleep
Walking
Sex
Eating
Elimination
Behavioral motivation
Breathing
Beating of the heart
Control of Consciousness – most important
2.B Pons Varolli
slunted in front of the cerebellum between the midbrain and the medulla oblongata.
A bridge-like structure composed entirely of white matter
It joins the two haves of the cerebellum
Trigeminal Nerve (Cranial Nerve 5) emerges from pons
FUNCTION:
The pons serves mainly as a relay station linking
the cerebral cortex and the medulla oblongata.
Pons
•connects the cerebral cortex with
the medulla oblongata
•serves as a communications and
coordination center between the
two hemispheres of the brain
•As a part of the brainstem, it
helps in the transferring of
messages between various parts of
the brain and the spinal cord.
3. Midbrain
Mesencephalon
also called mesencephalon,
region of the developing
vertebrate brain containing cranial nerves that
stimulate the muscles controlling eye movement,
between the forebrain and hindbrain
Concerned with motor coordination
Connects the cerebellum with the cerebrum
Functions:
At the bottom of the
midbrain are reflex and
relay centers
relating to pain,
temperature, and touch,
as well as several regions
associated with the, such
as the red nucleus and
the
substantia nigra - for
reward, addiction, and
movement
A pair of nuclei
called the superior
colliculus
– Controls reflex
actions of the
eye, such as
blinking,
opening and
closing the pupil,
and focusing the
lens.
A second pair of
nuclei, called the
inferior colliculus,
– controls auditory
reflexes, such as
adjusting the ear
to the volume of
sound.
Sylvian/Cerebral
aqueduct/Iter
– canal that connects
the 3rd and 4th
ventricles of the
brain.
Cerebral Peduncles
– pair of cylindrical bodies
made up of nerve fibers
tracts which connect the
forebrain with the
hindbrain
- Bundle of Axons
Corpora
Quadrigemina
– 4 rounded
nuclear masses
Corpora quadrigeminaCerebral aqueduct
Central gray
stratum
Interpeduncular space
Substantia nigraRed nucleus of
tegmentum
4. MEDULLA OBLONGATA
Myelencephalon
lowest portion of the brainstem
At the top, it is continuous with the pons and the midbrain;
at the bottom, it makes a gradual transition into the spinal cord at the foramen magnum.
extends from the pons above and is continuous with the spinal cord below.
Pyramidal in shape (broad above and narrow below)
The nerve cells of the medulla are grouped to form “nuclei” out of which emerge cranial nerves 6-12.
Medulla oblongata
is a portion of the
hindbrain that
controls autonomic
functions:
•breathing,
•digestion,
•heart and blood
vessel
•swallowing
•sneezing
Functions:
Organ of conduction for the passage of impulses between
brain and spinal cord
Contains center for control of bodily functions:
• Cardiac Inhibitory Center – holds heart rate to slower rate
through cranial nerve 10 or Vagus Nerve.
• Vasoconstrictor Center – narrowing of lumen of the arteries
• Respiratory Center – controls rate and depth of respiration
• Reflex Center – sneezing, coughing, vomiting, winking and
the movements and secretions of the alimentary canal.
5. Diencephalon Thalamus and Hypothalamus
Diencephalon
A. Thalamus
large mass of gray matter
located in the cerebral
hemisphere.
acts as a relay station
between the cerebrum and
the rest of the brain and
spinal cord.
B. Hypothalamus
lies below the thalamus
contains temperature-
regulating mechanisms and
relations with the pituitary
gland.
hunger, thirst, defense
reactions; fear, rage and
satiety.
Thalamus
•It is involved in sensory perception
and regulation of motor functions.
•is a limbic system structure
•it connects areas of the cerebral
cortex that are involved in sensory
perception and movement
• controls sleep and awake states of
consciousness.
Limbic System
The limbic system is a group of brain
structures that plays a role in emotion,
memory, and motivation.
Hypothalamus
•plays a central role in
controlling our autonomous
nervous system (ANS),
•responsible for regulating
homeostatic metabolic processes
in the body.
•Examples of homeostatic
processes include sleeping,
eating, thirst, blood pressure,
body temperature, and
electrolyte balance.
Hypothalamus
-regulates hunger, thirst, sleep, body
temperature, sexual drive, and other
functions.
Fornix connects
the Hippocampus to
the Hypothalamus
Spinal Cord
a long, thin, tubular bundle
of nervous tissue and
support cells that extends
from the brain.
The spinal cord begins at
the Occipital bone and
extends down to the space
between the first and
second lumbar vertebrae.
It is around 45 cm (18 in)
in men and around 43 cm
(17 in) long in women.
Functions of Spinal Cord
Serve as a conduit for motor information,
which travels down the spinal cord
Serve as a conduit for sensory information,
which travels up the spinal cord.
Serve as a center for coordinating certain
reflexes.
Cervical Spinal Cord
Divided into eight
levels. Each level
contributes into
different functions in
the neck and arms.
Sensations from the
body are similarly
transported from the
skin and other areas of
the body from the
neck, shoulders, and
arms up to the brain.
Thoracic Spinal cord
The nerves of the
spinal cord supply
muscles of the chest
that help in breathing
and coughing.
This region also
contains nerves in the
sympathetic nervous
system.
Lumbosacral Spinal Cord
The lumbosacral
spinal cord and nerve
supply legs, pelvis,
and bowel and
bladder. Sensations
from the feet, legs,
pelvis, and lower
abdomen are
transmitted through
the lumbosacral nerves
and spinal cord to
higher segments and
eventually the brain
Peripheral Nervous System
- main function of the PNS is to connect
the central nervous system (CNS) to the
limbs and organs.
- peripheral nervous system of humans has
thirty-one pairs of spinal nerves,
CRANIAL NERVES
I. Olfactory NerveY
Function:
-Sense of Smell
- Sensory
Function:
Transmits visual information to the brain; Located in
Optic canal.
Sense of sight
III. OCCUMOTOR NERVE
Function:
The oculomotor
nerve is the third of
twelve paired cranial
nerves. It controls most
of the eye's movement
and constriction of the
pupil, and maintains an
open eyelid
IV. TROCHLEAR NERVEFunction:
It is a motor nerve which
stimulates and supplies the
superior oblique muscle of the
eye. The trochlear nerve is also
a part of the cranial nerves
which stems from the brain and
connects to the eyes. Trochlear
nerve function is interconnected
to the superior oblique muscle.
Which is also responsible for
the movement of the eyes as it
is one of the six extra ocular
muscles that together help in
the movement and alignment of
the eyes. It acts as a pulley to
move the eyes down—toward
the tip of the nose
Receives sensation
from the face and
innervates the muscles
of mastication.
Sensory and Motor
VI. ABDUCENS
Innervates the lateral
rectus, which abducts
the eye.
Motor
VII. FACIALProvides motor innervation to
the muscles of facial
expression, posterior belly of
the digastric muscle,
and stapedius muscle, receives
the special sense of taste from
the anterior 2/3 of the tongue,
and provides
secretomotor innervation to
the salivary glands (except
parotid) and the lacrimal gland;
Located and runs
through internal acoustic
canal to facial canal and exits
at stylomastoid foramen
VIII. VESTIBULOCOCHLEARFunction :
The vestibulocochlear
nerve has separate
acoustic and vestibular
divisions. The acoustic
portion of the nerve allows
for proper hearing. The
vestibular division is
essential for normal
balance.
IX. GLOSSOPHARYNGEAL
The glossopharyngeal
nerve allows for taste
on the back portion of
the tongue, provides
the sensations of pain
and touch from the
tongue and tonsils,
and participates in the
control of muscles
used during
swallowing
X. VAGUS
Function :
The vagus nerve plays
an important role in the
human body. It controls
the sensory and motor
functions of the heart
and glands. It also
participates in the
process of digestion.
XI. ACCESORYFunction:
The spinal accessory
nerve allows the
trapezius muscle and
sternocleidomastoid
muscle to control the
movements of the
head.
XII. HYPOGLOSSAL
Provides motor
innervation to the
muscles of the tongue
Important for
swallowing (bolus
formation) and speech
articulation.
Located
in hypoglossal canal.
Spinal Nerves
carries motor, sensory, and autonomic
signals between the spinal cord and the
body.
Humans have 31 left-right pairs of spinal
nerves, each roughly corresponding to a
segment of the vertebral column:
– 8 cervical spinal nerve pairs (C1-C8)
– 12 thoracic pairs (T1-T12)
– 5 lumbar pairs (L1-L5)
– 5 sacral pairs (S1-S5)
– 1 coccygeal pair.
Cervical nerves (innervate the neck and
the arms): cords conducting nerve impulses
from the neck and arms to the cerebellum
via the spinal cord.
Intercostal nerve: cord conducting nerve
impulses between the ribs.
Lumbar and sacral nerves (innervate the
legs and pelvic organs): nerves originating
in the lower back and extending into the
pelvis and legs.
Sacral plexus: network of nerves of the
sacrum.
Lumbar plexus: network of nerves of the
lower back.
Spinal cord: substance belonging to the
nervous system, found in the holes of the
vertebrae.
Brachial plexus: network of nerves of the
arm.
Cerebrum: seat of the mental capacities.
Cervical nerve
Lumbar and sacral nerves
The formation of the spinal nerve
from the dorsal and ventral roots
dorsal roots carry afferent sensory axons,
while the ventral roots
carry efferent motor axons.
Neuron
also known as neurone or nerve cell
basic unit of nervous system
Is an electircally excitable cell that
processes and transmits information by
electrical and chemical signaling.
there are billions neurons in the body. In
fact, there are 12 - 14 billlions of neurons in
one partof the brain alone.
Basic nerve cell structure
PARTS:Cell Body/ soma / perikaryon
=> the factory of the neuron. It produces all the
proteins for the dendrites, axons and synaptic
terminals.
Neuronal membrane
=> serves as a barrier to enclose the cytoplasm inside
the neuron, and to exclude certain substances that float
in the fluid that bathes the neuron.
Nodes of Ranvier
=> gaps between myelinated segment
Myelin Sheath
=> protects the axon, and prevents interference
between axons as they pass along in bundles,
sometimes thousands at time.
Axon=> transmit impulses away from the cell
body.
=>The main conducting unit of the neuron.
=>Conduct nerve impulses thru another
cells.
=>Capable of conveying electrical signals
along distances that range from as short as
0.1 mm to as long as 2 m.
Dendritesthe main apparatus for receiving signals from
other nerve cells.
The “ antennae” of the neuron.
They transmit impulses towards the cell body.
covered by thousands of synapses
200 000 axon terminals make contact with
dendrites of Purkinje neurons in
cerebellum.
diameter decrease from proximal to distal
end.
Nerve Ending (Presynaptic Terminals)
=> Synapses are the junctions formed with
other nerve cells where the presynaptic
terminal of one cell comes into 'contact'
with the postsynaptic membrane of another.
It is at these junctions that neurons are
excited, inhibited, or modulated.
Types of SynapsesElectrical synapses
Occur where the presynaptic terminal is in electrical
continuity with the postsynaptic. Ions and small
molecules passing through, thus connecting channels
from one cell to the next, so that electrical changes in
one cell are transmitted almost instantaneously to the
next. Ions can generally flow both ways at these
junctions i.e. they tend to be bi-directional, although
there are electrical junctions where the ions can only
flow one way, these are know as rectifying junctions.
Rectifying junctions are used to synchronise the
firing of nerve cells.
Chemical synaptic junction is more
complicated. The gap between the post- and
presynaptic terminals is larger, and the mode
of transmission is not electrical, but carried by
neurotransmitters, neuroactive substances
released at the presynaptic side of the
junction.
a. Type I is an excitatory synapse,
generally found on dendrites
b. type II is an inhibitory synapse,
generally found on cell bodies
Transmission of signals…
SYNAPSE
Also known as the neuromuscular junction
A structure that permits a neuron to pass an
electrical or chemical signal to another cell.
a place in the body where the axons of motor
nerves meet the muscle, thus transmitting
messages from the brain which cause the muscle
to contract and relax.
neuromuscular junctions control the movements of
the body and cause the heart to beat.
SYNAPSE
Classification of neuron according to the
Direction:
Afferent neurons convey information from
tissues and organs into the central nervous
system and are sometimes also called
sensory neurons.
Efferent neurons transmit signals from the
central nervous system to the effector cells
and are sometimes called motor neurons.
Interneurons connect neurons within
specific regions of the central nervous
system.
Classification of neurons according to their
functions:
motor neurons : control muscle fibers or
effecteral organs eg: endocrine.
sensory neurons : receive sensory stimuli.
sensory
neuronerelay
neurone
motor
neurone
Sensory neurons
Carries impulses from receptors e.g pain receptors in skin to the CNS( brain or spinal cord)
Relay neuron
Carries impulses from sensory nerves to motor nerves
Motor neuron
Carries impulses from CNS to effector e.g. muscle to bring about movement or gland to bring about secretion of hormone e.g ADH
NEUROGLIA
smallest cells of nervous tissue
Function : metabolic, support, n protection.
2 types Neuroglial Cells
1. Macroglial
2. Microglial
1. Macroglial
A. Astrocyte
– largest
- long processes
- processes of the astrocytes are also
present at the periphery of the brain and
spinal cord forming a layer under pia mater
: separates conn. Tissue of pia mater from
the nerve cells.
Types of astrocyte
a1. protoplasmic : in grey matter of brain n
spinal cord
:processes are shorter and
thicker
a2. fibrous : in white matter
: long smooth processes
B. Oligodendrocytes
– smaller than astrocytes
- lesser processes n shorter
- can be found both in grey n white matter.
Function:
1. take part in metabolism of neurons
2. form protective barrier around neurons.
C. Ependimocytes
– looks like an epithelial layer.
- line the central canal of spinal cord n
ventricles of the brain which are filled with
cerebrospinal fluid.
- take part in elaboration of cerebrospinal
fluid.
- serve as a barrier btw fluid and neural
elements.
- at last they form supporting framework of
the system.
2. Microglia
– small cells, highly-densed elongated bodies
n short processes with numerous small
branches.
- condensed, elongated nucleus.
- in adults, microglia are derived from
monocytes of the bone marrow blood n they
are phagocytes.
Somatic Nervous System
> part of the PNS associated with the
voluntary control of body movements via skeletal
muscles.
> It is consists of efferent nerves responsible for
stimulating muscle contraction, including all the
non sensory neurons connected with
skeletal muscles and skin.
> Its Sensory axon carries signals inward from
receptors in the skin, skeletal muscles, and
tendons while its motor axons carries signals out
to the body’s skeletal muscles.
Autonomic Nervous Systemthe part of the PNS that acts as a control
system functioning largely below the level of
consciousness.
It controls visceral functions.
The ANS affects heart rate, digestion, respiration
rate, salivation, perspiration, diameter of the
pupils, micturition (urination), and sexual arousal.
Whereas most of its actions are involuntary, some,
such as breathing, work in tandem with the conscious
mind.
Its sensory and motor axon carry signals from and to
smooth muscles, cardiac (heart) muscle, and the
different regions inside the body.
Division of Autonomic Nervous System
Parasympathetic Nervous System
The parasympathetic system specifically is
responsible for stimulation of "rest-and-digest"
activities that occur when the body is at rest,
including sexual
arousal, salivation, lacrimation (tears), urination, d
igestion, and defecation
Sympathetic Nervous System
Its general action is to mobilize the body's
resources under stress; to induce the fight-or-flight
response. It is, however, constantly active at a
basal level to maintain homeostasis.