1. The Nervous System
Medical Term “Neuro”

2. Overview
The entire nervous system relies on the transmission of electrical impulses
These impulses are done by neurons, the operating cells of the brain and spinal cord
Nervous impulses travel from neuron to neuron as they send information from one area of the body to another.
The speed is almost instantaneous! (268 miles/hour)

3. Different parts of the Nervous System
Central Nervous System (CNS)
Network of nerve tissue (neurons) found in the brain and spinal cord
Peripheral Nervous System (PNS)
All nerve tissue (neurons) outside the brain and spinal cord. They include:
12 Cranial (head) nerves that enervate the head/senses
31 pairs of spinal nerves that enervate the arms, trunk, and legs

4. Motor vs Sensory Fundamental understanding of nervous system
Sensory Nerves (“you sense”)
These nerves receive sensory info from the body
Also known as Afferent Nerves
e.g. smell, taste, touch, sight
Breeze against your face
That impulse is sent from the nerves in your body to your brain via the spinal cord
Motor Nerves (“you move”)
The brain sends out impulses to muscles
Also known as Efferent Nerves
You move your arm
You blink
e.g. Burning your hand on the stove.
Most nerves are both sensory and motor

5. Neurons Neurons Cells responsible for electrical transmission
The brain, spinal cord, and nerves are all comprised of neurons
100 billion neurons just in brain

6. 3 Major Parts of the Neuron
1. Cell Body
Contains nucleus and organelles.
2. Dendrites
Short, stubby branches that carry impulses to the cell body from another neuron
They are the “receiving” part of neuron
3. Axons
Long extension that carries impulses from the cell body
They transmit impulses to dendrites of the next neuron.
They are the “giver” part of a neuron.
Axons are surrounding by fat which helps accelerate the electrical impulse.

7. Neurons (cont) Synapse
Open area where the axon of one neuron communicates with the dendrite of the next one.
Neurotransmitter
The Chemical released there to send the “message” across
Famous neurotransmitters
Epinephrine (Adrenaline)
Dopamine
Serotonin
Acetylcholine

8. Glial Cells Glial cells are the “bodyguards” of neurons
They are not responsible for electrical impulse
Their job is to:
Surround the neurons to anchor them in place
Produce the fat (myelin) of the axon to speed transmission
Destroys pathogens
Supplies nutrients to neurons.

9. Activity Get into your groups
Write down 10 examples of sensory impulses
Write down 10 examples of motor impulses

10. The Brain

11. The Brain
Responsible for every physical and mental activity of the body
Memory, emotion, thought, judgment, reasoning, consciousness, etc.
It is made of white and grey matter
Comprised of mostly fat
Protected by the cranium
Weighs 3 pounds
The four major structures of the brain
1. Cerebrum
2. Cerebellum
3. Diencephalon
4. Brain Stem

12. 1. Cerebrum Largest and uppermost part of brain
It has 2 hemispheres (left and right)
Corpus Callosum- joins hemispheres together and quickens communication b/t the two sides.
Left side of cerebrum focus on logic and reason
Right side focus on creativity
Gyri (sing. gyrus) are the folds or mountains on the cerebrum
Sulci (sing. sulcus) are the dips or cracks on the cerebrum.

13. Arrangement of Neurons
Most neurons in the brain are arranged in either two layouts.
1) Long layers of neurons
Cerebral Cortex is the outermost layer of the cerebrum made of Grey Matter
Consists of layers of neurons about 4 mm thick
Responsible for thought, awareness, consciousness and learning
2) Cluster of neurons (aka brain nuclei)
Seen mostly in deeper parts of the brain (hypothalamus, thalamus)

14. Grey vs White Matter
The brain is comprised of Grey Matter and White Matte
Grey Matter is made largely from layers of the bodies of neurons.
White matter is mostly comprised of glia and the long axons of neurons connecting one part of the brain to another.

15. 1. The Cerebrum
Each hemisphere of the cerebrum is divided into 5 lobes
Frontal
Parietal
Temporal
Occipital
These 4 named after the bone that is directly above them
Insula (Limbic)
The inner side of hemisphere that faces the other hemisphere.
Includes Hippocampus

16. Temporal Lobe of Cerebrum
Responsible for hearing
Features the hippocampus
Main area for memory

17. Frontal Lobe of Cerebrum
Responsible for emotions

18. Occipital Lobe of Cerebrum
Responsible for vision processing

19. Parietal Lobe of Cerebrum

20. Limbic Lobe of Cerebrum
Includes the Hippocampus
Responsible for memory and spatial navigation
Alzheimer’s and other forms of dementia affect the Limbic.

21. 2. Diencephalon (Interbrain)
2 main parts
Thalamus “The Relayer”
Receives all sensory info from the body and sends it to the appropriate part of the brain for processing
Also, it receives impulses from the cerebrum and relays them to various parts of body via efferent motor nerves
The Hypothalamus
Regulates the Autonomic Nervous System (ANS)
Heartbeat, body temperature, smooth muscle control, fluid balance.
Things you can’t control

22. 3. Cerebellum “Baby Brain”
2nd largest part of the brain
Sits in the posterior portion of the skull, next to occipital bone.
Maintains balance and equilibrium
Coordinates muscular movement

23. 4. Brain Stem Comprised of: 1. Midbrain 2. Pons 3. Medulla
Brain stem is a pathway for impulse conduction between the brain and spinal cord

25. Are you left or right brained?
Based on this picture, extrapolate 5 characteristics of people who are predominately:
Right-brain
Left-brain

27. Meninges (sing. Meninx)
3 layers of matter that surround the brain
1. Dura mater
Hard, fibrous material
2. Arachnoid Space
Web-like middle space bathed in cerebro-spinal fluid (CSF)
3. Pia mater
Thin layer actually on the brain
Meningitis-infection of the brain layers.

28. Cerebro-spinal Fluid (CSF)
Syrupy fluid that bathes and protects the brain and spinal cord.
Ventricles
Chambers full of CSF fluid that are inside the brain
Lateral
3rd Ventricle
4th Ventricle

29. Spinal Cord Transmits sensory impulses from the body to the brain, and
Transmits motor impulses from the brain to the body
Located in the spinal cavity of the vertebrae with spinal nerves exiting between each vertebrae to enervate the arms, trunks, and legs.
Spinal cord runs from the brain and to Lumber 3.
Cauda Equina- strands of nerves that run down the rest of the spinal cavity.

30. Plexus Big branches of nerves that come off of spinal cord Brachial
Comes of the spine near lower c-spine
Enervates the upper extremity
Lumbar
Comes off L-spine
Enervates hips, groin, abdominal area
Sacral
Comes off sacrum
Enervates the lower extremity

31. Cranial Nerves Most important nerves in the body. There are 12
All originate off the brain stem
Listed in Roman numerals
I-(Olfactory)-Smell
II-(Optic)-Eyesight
III (Oculomotor), IV (Trochlear), and VI (Abducents)-Eye Movement
V (Trigeminal)-Facial Sensation
VII (Facial)-Facial motor
VIII (Vestibulocochlear)-Ear
IX (Glossopharyngeal) and XII (Hypoglossal)- Tongue and Swallowing
X (Vagus) -Controls diaphragm, all organs in body
XI- (Spinal)

32. Pathology Meningitis-Inflammation of the meninges
Concussion-Bruising of brain tissue
Hydrocephalus- Swelling of the brain due to increase amount of CSF fluid
Encephalitis-Infection of the brain, typically due to bacteria or virus

33. Hydrocephalus “Water in the brain”
Excess CSF fluid in the brain
The choroid plexus of the ventricles, the cells responsible for producing CSF, either produce too much, or the venous system doesn’t absorb it fast enough
It compresses (squeezes) the brain tissue which increases intracranial pressure.
Etiology
Mal-development in utero
May develop during adulthood by a tumor, infection, etc
Signs
Disease occurs in infants
Head swells as brain pushes unsutured cranial bones apart
Scalp veins dilate
Decreased mental abilities

34. Hydrocephalus Diagnosis Lumbar tap CT/MRI Treatment Shunt
A shunt is a tube inserted in the ventricles to move the excess fluid to the right atrium or abdomen.

35. Seizures Uncontrolled, excessive discharge of neurons
Multiple causes and types
May be caused by external stimuli, drugs, secondary disease.
Generalized seizure- loss of consciousness due to multiple parts of the brain seizing
Partial- no loss of consciousness, normally only one part of brain seizes.
Petit mal seizure (Generalized)
Occurs in children
Lasts a few seconds, twitches and lip smacking ensue
Child returns to normal c no memory of it
Grand mal seizure (Generalized)
Begins with twitching, nausea, depression
Aura-visual or auditory hallucination
Loss of consciousness follows
The tonic-clonic stage ensues of strong muscle contraction/relaxation as the body contorts itself into strange position. Foaming of the mouth, screaming, and incontinence may ensue.
Contractions dissipate, patients wakes up achy and then falls into a deep sleep.

36. Seizures
Treatment
Anti-convulsive and sedative drugs are given to lessen chance of seizure or to minimize outbursts.

37. Huntington’s Disease Genetic disorder, 13 from House has it.
Progressive atrophy (or deterioration) of neurons
Ventricles swell
Symptoms: Wild mood swings, wild jerky movements of extremities, gradual loss of cognitive and motor skills
Prognosis: Death!

38. Schizophrenia
Chronic mental condition which features the following symptoms:
Visual and auditory hallucinations
Delusions of personal grandeur
The belief that people are plotting against you.
Detachment, increased drug use, and suicidal ideation.

39. Dissociative Identity Disorder
Formerly Multiple Personality Disorder.
Person has at least 2 distinct personalities (alter egos)
One personality controls the other
Main personality has time of amnesia.
Cause: Trauma (physical/sexual)
Controversy:
CIA
Implanted personalities.

40. Herniated Disc The intervertebral disc is comprised of two components:
Nucleus pulposus- inner gelatinous filling
Annulus fibrosis- tough outer layer
Poor body mechanics, trauma, or degenerative condition cause the nucleus to leak out.
It impinges or touches either the spinal cord or the nerve roots that go down the arm or leg
Causes loss of motor or sensory sensation and intermittent pain in leg or arm (depending on which plexus it is impinging).
Minor day surgery may fix it easily

41. Assignment Identify the following terms: Neuron Dendrite Axon
Synaptic Gap
Cerebellum
Corpus Callosum