Transcript D. Brain - Liberty Christian School

Chapter 10 –
Central Nervous System
The Brain and Spinal Cord
 An
amazing part of the
body that can take millions
of bits of information and
make sense of it
Amazing Brain Trick #1
Slide 3
I. Central Nervous System

A. Coverings of the Br. & Sp. C
1. Bones
 a. Skull encases the brain
 b. Vertebrae encases the spinal
cord
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2. Meninges
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a. Dura mater – literally means “hard
mother”, inside layer of the bone
b. Arachnoid membrane – delicate cob
webby membrane in the middle of the
brain
c. Pia mater – contains blood vessels, the
layer next to the spinal cord

3. Spaces between the meninges
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a. Epidural space – “on the dura”,
between the bones and outside the dura
mater
b. Subdural space – between the dura
mater and arachnoid
c. Subarachnoid space – between
arachnoid and pia mater, space that
contains the CSF
B. CSF
Cerebrospinal Fluid
 Cushion of fluid around and
within the brain and spinal
cord

1. Path of CSF

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Fluid filtered from the blood in the
capillaries
Circulates through brain ventricles
Into the canal of the spinal cord
Where it is absorbed back into the
blood
2. Total amount of CSF
 140
ml
 At all times
Amazing Brain Trick #2
Count the number of “F”s in this sentence!
ANSWER: There are 6 F’s in this
sentence
C. Spinal Cord

1. Structure

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a. Extends from foramen magnum to 1st
lumbar vertebrae, ~18 in long.
b. Nerve roots exit the spinal cord
 1. Dorsal nerve roots carry sensory
information to the spinal cord (right and
left)
 2. Ventral nerve roots carry
information out of the spinal cord (right
and left)

2. Function of the spinal cord
 a. Provides conduction routes to and
from the brain
 1. Ascending tracts – conduct
impulses up the cord to the brain
 2. Descending tracts – conduct
impulses down the cord from the
brain
D. Brain

1. Anatomy
 a. Weighs about 3 pounds
 b. Neurons do not undergo
mitosis except during prenatal and a few months postnatal
VIDEO
GAMES

c. There are six regions
1. Medulla oblongata
2. Pons
3. Midbrain
4. Cerebellum
5. Diencephalon
6. Cerebrum (cerebral
cortex)

2. Brainstem
 a. Medulla oblongata –
attaches to the spinal cord.
Most vital part of the brain
because it contains the vital
centers (respiratory, cardiac,
and blood pressure) and
vomiting, coughing, sneezing,
hiccuping

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b. Pons – helps to regulate
respiration and reflexes of 5th
(V), 6th (VI), 7th (VII), and 8th
(VIII) cranial nerves
c. Midbrain – contains
centers for certain cranial
nerve reflexes (pupil and eye
movement)

3. Cerebellum – controls skeletal
muscles
 a. Produces skilled movement
by coordinating groups of
muscles
 b. Maintains balance (lack
would be = staggering). That is
why the police have you walk a
“straight line” in a sobriety test.
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c. Control’s posture and
coordinated movements (lack
would be ataxia = overshooting
the mark)….that is why you
touch your alternating fingers
to your nose)
d. Alcohol directly inhibits the
cerebellum’s function in the
body

4. Diencephalon – contains thalamus
and hypothalamus
 a. Thalamus – relay station from
sensory impulses to brain
1. Sensations of pain,
temperature, touch
2. Emotions – pleasantness and
unpleasantness
3. Arousal or alerting mechanism
(maintaining awake states)

b. Hypothalamus – link
between psyche (mind) and
soma (body). For instance,
pleasure center for primary
drives eating (appetite),
drinking, sex. Also is crucial
part of mechanism for
maintaining normal body
temperature

5. Cerebrum
 a. Structure
1. Divided into right and left
hemispheres
2. Four lobes
 a. Frontal
 b. Parietal
 c. Temporal
 d. Occipital
Convolutions (gyrus) – means
“sausages”…folds in the brain
 4. Brain communication pathways
 a. Projection tracts – extension
connecting to the ascending and
descending tracts
 b. Association tracts – connect
from one convolution to another
 c. Commissural tracts –
communicate from one
hemisphere to the other
 3.

b. Function of cerebrum
1. Sensory function of cortex
 a. Somatic senses– touch,
pressure, temperature, body
position
 b. Cortex contains sensory map
of the body– notice face and
hands which has a lot of nerve
receptors
 c. Special senses– vision, hearing
Motor function of cortex – controls
muscle movements
 3. Integrative function of cortex
 a. Consciousness – who you are and
how others are. Varying levels of
consciousness include fully awake,
SWS(Slow wave sleep-dreamless),
REM (rapid eye movement-dreaming),
altered states of consciousness (coma)
 b. Language – ability to speak and
write words and understand spoken
and written words
 2.
Emotions – subjective
experience and objective
expressing of emotions
5. Memory – capable of
storing and retrieving short
term and long term
information
6. Specialization of
hemispheres
4.
a. Left – language and
dominant hand movements
in 90% of population. You
can determine a persons
dominant hand by watching
them talk in most cases.
b. Right – perception of nonspeech auditory stimuli –
coughing, crying, laughing
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E. Diagnostic Tools

1. Lumbar puncture (AKA: Spinal
Tap)– withdrawal of CSF with a needle
inserted around the 4th lumbar vertebrae
(to keep from hitting the spinal cord
directly). Patient lies on their side,
drawing knees up to chest which
separated the vertebrae for insertion.
Used to detect bacterial infections, etc.

2. EEG – electroencephalogram
– measures brain waves. 2 flat
EEG with in 24 hours apart with
no spontaneous breathing
(without respirator) = brain
dead
EEG
F. Disorders

1. CVA- cerebrovascular accident
(stroke) – oxygen is cut off from
part of the brain and cause the
neurons to cease to function.
Paralysis appears on opposite side
of the body than the damage to the
brain.
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2. Cerebral Palsy (CP) –
damage to motor areas. They
can often talk and are smart, but
can be mistaken for mentally
retarded due to the need for
helmets (since the cannot control
their body movements) and their
look.

3. Dementia – general term for “losing
your mind”….boxers who have received
too many blows to the head
 a. Alzheimers – increasing loss of
memory (forget to turn off stove after
cooking or water after washing their
hands). This progresses to infantile
behavior….they will often talk about
their “past”….what they can
remember.
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b. Huntington’s Disease –
genetic disorder characterized by
chorea (involuntary purposeless
movement)….this goes into
severe dementia and eventually
death. 1st symptoms do not
appear until 30-40 years old (by
that time you’ve usually
populated and spread the gene).
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4. Seizure Disorders – seizures are
sudden bursts of neural activity – may
be mild, zoning out (petit) to severe full
blown with convulsions (tonic clonic).
You can have isolated seizures due to
high temperatures, over-stimulation of
neurons from video games, TV shows
….but if it recurs and becomes chronic
then it is termed epilepsy.
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5. Meningitis – inflammation of
the meninges. Neck becomes
stiff, fever, headache. If only the
spinal meninges are affected,
then it is called spinal
meningitis. Death can occur
within 24 hours of onset of
symptoms.

6. Hydrocephalus – “water on the brain”
– CSF accumulates in the brain due to
blockage (tumor) and it can’t be
drained…yet the mechanism for making
more won’t shut off, so you have an
overabundance. Head can become the
size of a basketball. If occurs in infants
(unossified skull can accommodate
hydrocephalus better than adults) –
treatment would be placing a “stunt” in
the brain to pump out the extra CSF.
Results in coma or death in adults.

7. Parkinsons – is a decrease of output
of neurotransmitter, dopamine.
Dopamine’s function is to inhibit or turn
off the excitatory effects of another
neurotransmitter, acetylcholine (ACH).
Without dopamine, the excitatory affects
of ACH are not restrained and it results
in excess signals going to voluntary
muscles. Symptoms are tremors in head,
limbs, a shuffling gait, and forward tilt
of trunk.

8. West Nile VirusAbout 20 percent of people develop a mild infection called West Nile
fever (80% are unaffected). Common signs and symptoms of West
Nile fever include: Fever, Headache, Body aches, Fatigue, Skin rash
(occasionally), Swollen lymph glands (occasionally), Eye pain
(occasionally)
Serious infection signs and symptoms
In less than 1 percent of infected people, the virus causes a serious
neurological infection. Such infection may include inflammation of
the brain (encephalitis) or of the brain and surrounding membranes
(meningoencephalitis). Serious infection may also include infection
and inflammation of the membranes surrounding the brain and
spinal cord (meningitis), inflammation of the spinal cord (West Nile
poliomyelitis) and acute flaccid paralysis — a sudden weakness in
your arms, legs or breathing muscles. Signs and symptoms of these
diseases include: High fever, Severe headache, Stiff neck,
Disorientation or confusion, Stupor or coma, Tremors or muscle
jerking, Lack of coordination, Convulsions, Pain, Partial paralysis or
sudden weakness