Download NS Student Notes 2

Name:
BIOLOGY 12:
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THE CENTRAL NERVOUS SYSTEM
The CNS consists of the ________ and _________________.
The CNS lies in the _________ of the body and is the place where ________________________
________ and _________________________.
Protected by _________ (skull, vertebrae). They are also wrapped up in three protective
membranes called _______________ (DURA MATER, ARACHNOID, PIA MATER) meningitis
is inflammation of these membranes
Spaces between meninges filled with _______________________ for ____________ and
_____________. This fluid also found within _________________ of the spinal cord and
_____________ of brain. (Spinal Tap- withdraw fluid to test for meningitis).
SPINAL CORD: THE NERVOUS SYSTEM’S “SUPERHIGHWAY”
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Responsible for reflexes and means of communication between brain and PNS
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GRAY MATTER: contains _______________ and associated dendrites of
neurons and ________________________________.
 Where synapses occur
 Interneurons are located here
 WHITE MATTER: ______________________________________ that
run together in bundles called _________ that connect the cord to the
brain.
within white matter, ascending tracts take information to the brain, descending tracts in
the ventral part carry information down from the brain.
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THE BRAIN
 weighs about 3 pounds; average volume of 1400cm 3
 When you were born, you had the maximum number of neurons (~200 billion). Thousands are lost
daily, never to be replaced and apparently not missed, until the cumulative loss builds up in very
old age
 The brain itself contains parts which function in the coordination of movement, sensing, &
consciousness (and all that entails), as well as areas that are below the level of conscious
control.
 The brain is vastly complex, and is certainly not thoroughly understood. There are many ways of
looking at the brain functionally and structurally. The simplest first way of looking at it is dividing it
up into parts that run “automatically” (the unconscious brain) and the parts in which our
consciousness resides (the conscious brain).
V
U
Pons
THE UNCONSCIOUS BRAIN
THALAMUS (V)
 ___________________________ (except for smell) from all parts of the body and _________
them to the cerebrum (appropriate regions of cortex for interpretation).
 Serves as a CENTRAL RELAY STATION for sensory impulses coming up spinal cord and
other parts of brain to the cerebrum.
 The thalamus has connections to various parts of the brain, and is part of the ARAS (the
ascending reticular activating system), which sorts out incoming stimuli, passing on to
the cerebrum only those that require ________________________. i.e. it lets you ignore input
(like your teacher talking) so you can do other things (yak to your friends about Grad). The
ARAS extends from the medulla oblongata to the thalamus.
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CEREBELLUM (Z)
 2nd largest part of brain
 receives sensory information from eyes, ears, joints, and _____________ (which senses
balance) about the present position of body parts
 receives motor output from cerebral cortex about where these parts should be
 controls __________ and _________________________.
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Functions in ________________________ and makes sure skeletal muscles work together
smoothly. Responsible for ____________________________, __________, and _________.
Assists in learning of new motor skills such as playing piano or hitting a baseball
BRAIN STEM consists of midbrain, pons and medulla oblongata
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MEDULLA OBLONGATA (X)
 Lies closest to spinal cord
 Contains reflex centres that control _____________________________________________
like coughing, sneezing, vomiting, hiccoughing, swallowing.
 An "ancient" part of brain.
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MIDBRAIN- Central relay station between rest of brain and medulla oblongata
 Has reflex centers for visual, auditory, and tactile responses
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PONS –(means “bridge”) located in brainstem (above/superior to medulla)
 contains bundles of axons traveling between the ____________ and ______
 functions with medulla to _______________________________ and has ___________
centers involving head movements in response to visual and auditory stimuli
HYPOTHALAMUS (W)
 regulates ___________________ by maintaining _______________________
 contains centers for hunger, sleep, thirst, _________________________________________
 Controls ______________________ (U) (serves as a link between the nervous system and
the endocrine systems)
 plays a role in sexual response and mating behaviors, and the “fight-or-flight” response, and
pleasure. Yes, there are pleasure centers in the hypothalamus (these have been stimulated
experimentally with electrodes in studies using rats).
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CORPUS CALLOSUM (Y)
 horizontal connecting piece between the two hemispheres of the brain
 contains tracts that ______________________ (information) between the two cerebral
hemispheres.
 It has been noted that severing the corpus callosum can control severe epilepsy (which is
thought to be caused by a disturbance of the normal communication between the RAS and the
cortex), but also means the two halves of brain don't communicate with each other normally
and will function ____________. Each half has its own __________ and “________” of
thinking. Sometimes you’ll hear this
discussed as “right brain” versus “left brain” thinking. See below.
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THE CONSCIOUS BRAIN: THE CEREBRUM
Primary Sensory Area
Primary Motor Area
leg
arm
Motor
Elaboration
hand
lips
Frontal
Conscious
Thought
tongue
leg
arm
hand
Hearing
swallowing
Speech Production
(“Broca’s Area”)
Parietal
Speech Production
vocab/grammar storage.
“Wernicke’s area”
lips
tongue
mouth
Olfaction
(smell)
Vision
Occcipital
Temporal
perceptual judgment
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largest, most prominent, most highly developed portion of the brain
very convoluted (folded) with approximately 0.5m2 of surface area. WHY?
Gray matter consists of the CEREBRAL CORTEX (responsible for sensation, voluntary
movement, and thought processes associated with consciousness) and basal nuclei (ensure
proper muscle groups are activated or inhibited)
White matter(consisting of long myelinated axons organized into tracts) contains tracts that send
signals from upper part to lower part of brain, and vice versa
________________________ resides only in this part of the brain.
Intellect, learning, memory, sensations are formed here
Divided into right and left CEREBRAL HEMISPHERES, each consisting of FOUR LOBES:
1. FRONTAL – primary motor area
 voluntary ___________________________________ (e.g. problem solving, concentration,
planning, judging the consequences of behavior, moving your tongue and mouth to speak
(left side only= Broca’s area).
2. PARIETAL – primary somatosensory area
 _________ e.g. touch, temperature, pressure, pain, taste. Understanding speech, using
words
3. TEMPORAL - _________________, interpretation of experiences, _____________ of visual
scenes, music, and complex sensory patterns.
4. OCCIPITAL - _____________, combining visual experiences with other sensory experiences.
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All the lobes have _____________________________ that receive information from other lobes
and integrate it into higher, more complex levels of consciousness. Association areas are
concerned with intellect, artistic, and creative abilities, learning, and memory.
 Prefrontal area = association area in frontal lobes that receives info from other association
areas and uses this information to reason and plan our actions
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The ______________________ of the brain controls the ______________ of the body (except
for smell), and vice versa. Thus, an image viewed with the right eye is actually “seen” with the
left occipital lobe. The left hand is controlled by the right frontal lobe, and so on.
A person with a severed corpus callosum may appear normal in most situations, but careful
experiments reveal much about lateralization of the brain. For example, a patient holding a
key in the left hand, with both eyes open, will readily name it as a “key.” If blindfolded, though,
the subject will recognize the key by touch and use it to open a lock, but will be completely
unable to name it. The center for speech is in the left hemisphere, but sensory information
from the left hand crosses (normally) the corpus callosum and enters the right side of the brain.
In this patient, sensory input and spoken response are dissociated.
Right Brain/Left Brain: Different Qualities and an Uneasy Alliance?
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The Left Hemisphere
The Right Hemisphere
The “logical side”
The “intuitive side”
speaks
processes data
evaluates
analyzes differences
is factual
is structured
has time and measures
“speaks but cannot know”
You use the LEFT side of the brain when
you know what you’re looking for
 creates images
 processes senses
 symbolizes
 seeks similarities
 is spiritual
 is spontaneous
 has no time and measures
 “knows but cannot speak”
You use the RIGHT side of the brain when
you “know it when you see it”
talking
setting goals
planning
measuring
seeing differences
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feeling
speculating
visualizing
empathizing
sensing similarities
many individuals posses both right brain and left brain traits. Some people just have a more
dominant side. It is very helpful to know some of your traits since this point out your strengths
as well as your weaknesses.
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