The Nervous System
Nervous System
• Complex, highly organized system which
coordinates all the activities of the body.
Neuron
• Neuron= nerve cell
• Basic structural unit of
the nervous system
• Myelin sheath –lipid (fat) covering of axon –
increases rates of impulse transmission and
insulates and maintains the axon
• Khan Academy: Neuron
Application: Nerve Cell Diagram
Synapses
• The axon of one neuron lies close to the
dendrites of many other neurons
• Space in between them is called a synapses
• Impulses coming from one axon jump the
synapse to get to the dendrite of another
neuron
Neurotransmitters
• Chemicals located in axon
• Allow nerve impulses to pass from one neuron
to another
2 Main Divisions of Nervous System
• Central Nervous System – brain and spinal
cord
• Peripheral Nervous System – nerves:
• 12 pairs of cranial nerves extending out from brain
• 31 pairs of spinal nerves extending out from spinal cord
Central Nervous System
Application
• Using text, draw and label a diagram of the
brain. Use colored pencils to identify each
structure of the brain.
CNS – Central Nervous System
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Brain and spinal cord
Brain weights about 3lbs
Contains about 100 billion neurons
Main sections include:
Cerebrum- largest section of brain – thought,
reasoning, memory, speech, sensation, sight,
smell, hearing, voluntary body movement.
Cerebrum
• 2 hemispheres: left and right
• Cells in Lt hemisphere control movements on right side
of body and cells in Rt hemisphere control movements
that occur on left side of body
• 4 lobes: frontal, parietal, temporal, occipital
• Fissures – deep grooves
• Longitudinal fissure – b/w left and right hemispheres
• Sulci- shallow groves
• Gyri – elevated ridges
Broca’s – speech
Wernicke’s – speech comprehension
Application:
• Patient has a stroke on the left side of the
body. Which side of the body would
weakness or paralysis occur?
Application
• Using Body Structures and Functions text:
– Identify the 5 major fissures and their location in
the brain
Fissures: Longitudinal, Transverse,
Central, Lateral, Parieto-occipital
Cerebrum: Frontal Lobe
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Speech
Emotions
Personality
Morality
Intellect
Cerebrum: Parietal Lobe
• Pain
• Touch
• Heat
• Cold
• Balance
(sensory and motor)
Cerebrum: Occipital Lobe
• vision
Cerebrum: Temporal Lobe
• Hearing
• Smell
• Left hemisphere –
Wernicke’s area (speech
understanding and
comprehension)
Cerebellum
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Muscle coordination
Balance
Posture
Walking
dancing
CNS – brain (cont’d)
• Diencephalon – area between cerebrum and
midbrain- contains thalamus and hypothalamus
– Thalamus – acts as a relay center and directs sensory
impulses to cerebrum. Damage may cause increased
sensitivity to pain or loss of consciousness.
– Hypothalamus – regulates autonomic nervous system,
temp, appetite, water balance, sleep , blood vessel
constriction and dilation, emotions (anger, fear,
pleasure, pain, affection)
CNS –brain (cont’d)
• Midbrain- section below the cerebrum at top
of brain stem. Responsible for conducting
impulses between brain parts and certain eye
and auditory reflexes.
CNS – brain (cont’d)
• Pons – located in brain stem
• Conducting messages to other parts of the
brain
• Reflexes such chewing, tasting, saliva
production, assisting with respiration
• Medulla Oblongata – lowest part of brain stem
which connects to spinal cord
– Regulates heartbeat, respiration, swallowing,
coughing, blood pressure
Meninges
• 3 membranes which cover and protect the
brain and spinal cord
– Dura mater – thick, tough, outer layer
– Arachnoid membrane – delicate and weblike
middle layer
– Pia mater - closely attached to brain and spinal
cord. Contains blood vessels that nourish the
nerve tissue
Ventricles
• Brain has 4 ventricles which are hollow spaces
filled with cerebrospinal fluid.
– CSF serves as a shock absorber to protect brain
and spinal cord.
– Transports nutrients to CNS
– Removes metabolic wastes
• Spinal cord continues down from medulla
oblongata and ends at 1st or 2nd lumbar
vertebrae.
• Surrounded and protected by vertebrae
• Responsible for reflex actions
– Afferent (sensory) nerves carry messages from all
parts of the body to the brain and spinal cord
– Efferent (motor) nerves carry messages from brain
and spinal cord to muscles and glands
Peripheral Nervous System
• Consists of somatic and autonomic nervous
system
• Somatic: 12 pairs of cranial nerves and 31
pairs of spinal nerves
• Autonomic : controls involuntary actions of
body
Peripheral Nervous System: Somatic
• Responsible for sight, hearing, taste, smell
• Touch, pressure, pain, temp
• Send out impulses for voluntary and
involuntary muscle control
Peripheral Nervous System: autonomic
• Controls involuntary functions of nervous
system
• 2 divisions: sympathetic and parasympathetic
• Sympathetic nervous system: fight or flightprepares the body for action in time of
emergency by increasing heart rate, blood
pressure, respirations
• Parasympathetic nervous system: counteracts
actions of sympathetic nervous system
Diseases of the Nervous System
Description, diagnostic tests, S&S, Tx,
prevention if available
•DHO: Cerebral palsy, CVA, encephalitis,
epilepsy, hydrocephalus, meningitis, MS,
neuralgia, paralysis, Parkinson’s Disease,
Shingles
•BS&F: Dementia, Alzheimer’s Disease,
hematoma
Application: Diseases of the
Nervous System
• Using Body Structures and Functions
textbook, compare and contrast the following:
• 1. meningitis and encephalitis
• 2. cerebral palsy and multiple sclerosis
• 3. Parkinson’s Disease and essential tremors
• 4. Dementia and Alzheimer’s Disease
Lou Gehrig’s Disease
• Amyotrophic Lateral Sclerosis (ALS)
• Chronic, degenerative neuromuscular disease
• S&S: initially, weakness and atrophy of
voluntary muscles followed by paralysis
• Later stages: pt loses ability to communicate,
breathe, eat, move. However, mental acuity is
unaffected
• no cure
prognosis: 2-5 years
• Etiology of ALS
Carpal Tunnel Syndrome
• Painful hand and arm condition due to
pinching of the median nerve in the wrist
• Caused by repetitive hand movements
• S&S: pain, muscle weakness, impaired
movement, tingling of thumb, ring, and
middle fingers
• Tx: anti-inflammatory meds, splinting, surgery
to enlarge tunnel and relieve pressure on
nerve
Cranial Nerves
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olfactory
optic
oculomotor
trochlear
trigeminal
abducens
• VII facial
• VIII vestibulocochlear
(auditory)
• IX glossopharyngeal
• X vagus
• XI spinal accessory
• XII hypoglossal
Fxns of Cranial Nerves
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olfactory smell
optic
vision
oculomotor
eyelid/eyeball movement
trochlear turns eye downward and lateral
trigeminal face/mouth touch/chewing
abducens turns eye laterally
Fxns of Cranial Nerves (cont’d)
• VII facial
facial expressions, tears, saliva,
taste
• VIII vestibulocochlear (auditory) hearing
• IX glossopharyngeal taste
• X
vagus stimulates dig. organs, taste
• XI spinal accessory trapezius and
sternocleidomastoid
• XII hypoglossal tongue
Application:
• Your group is to come up with a mnemonic to
memorize cranial nerves AND a way to
visually memorize functions of the cranial
nerves.
Cranial Nerve Exam
• cranial nerve exam