Transcript The Brain & Cerebral Hemispheres

The Brain
Cerebrum
Hypothalamus
Pituitary gland
Cerebellum
Medulla
Areas of the brain
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The brain is composed of Cerebral
Hemispheres, Cerebellum and Medulla
Medulla
Cerebral
Hemispheres
Cerebellum
medulla
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Controls autonomic activities including heart rate, and
ventilation rate
Impulse transmitted from medulla via sympathetic or
parasympathetic branch of automatic nervous system
Medulla
Cerebral
Hemispheres
Cerebellum
cerebellum
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Co-ordination of body movement,
balance and posture
Cerebral
Hemispheres
Cerebellum
cerebrum/cerebral hemispheres
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Highly Folded and so has a large SA.
Patients with injuries to specific parts of the
brain can be studied to see how their
functions are altered.
Cerebral
Hemispheres
Cerebellum
Medulla
cerebrum/cerebral hemispheres
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Different parts of the brain can be stimulated
electrically to see which muscles in the body
respond
Conversely different parts of the body can be
stimulated to see which parts of the brain
show electrical activity.
More recently MRI (magnetic resonance
imaging) has been used in brain study
Areas of the cerebrum
C
om
plexm
ov
em
ent
m
otorarea
H
igherfunc
tions
as
s
oc
iationarea
S
peec
h
M
ain M
ain
m
otor s
ens
ory
area area
P
roprioc
ep
The Areas can be split into 3
groups
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Sensory Areas
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Motor Areas
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Association Areas
Association
Motor
Sensory
Sensory area
for impulses
from eyes
cerebrum/cerebral hemispheres
•Sensory areas of the cerebral hemispheres receive impulses
from sense organs and transmit them to the association areas
•The association areas of the cerebral hemispheres receive
impulses - interpret them in the light of similar past experiences
and transmit impulses to motor areas
•The motor areas transmit impulses to the effectors
•The size of the sensory and motor areas is related to the
number of receptors in that area
•The left and right cerebral hemispheres control the opposite
sides of the body
h
ip
legs
foot
toes
genitalia
thu m
b
leg
s
h and
finge
rs
e
y
e ose
n
e
c
a
f
s
lip
ankle
toes
should er
hip
k
t run
t ru nk
shoulder
elb ow
fo re ar
wrist m
Mapping of the sensory &
motor areas to the body
Sensory & Motor Maps
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The maps show that regions of the body with many
sensory (or motor) neurones have corresponding
large areas of the cerebrum linked to them.
So for example the lips occupy a larger region of
the sensory cortex than the shoulder, because
there are more sensory neurones in the lips.
Association Areas
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Are used to compare sensory input with previous
experiences, and make decisions
These areas are involved in speech, understanding
and memory retrieval
The frontal lobes are large in humans and it is
thought that they responsible for higher functions
like abstract thought, personality & emotion.
Speech
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The left side of the brain
Patients with speech problems gave 1st clues about
how the brain controls language
1981 Dr Paul Broca described a patient who could
only say the word “tan”.
When the patient died Broca examined the brain
and found damage to the left cerebral hemisphere
This part of the brain is now know as Broca’s area
Broca’s Area
Broca’s area
Wernicke’s Area
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In 1967 Karl Wernicke noticed damage to another
region of the cortex.
Werniche’s area is connected to Broca’s area by a
bundle of nerve fibres.
If this was damaged the patient can understand
language but cannot repeat words.
So Werniche’s area is concerned with
understanding language. Broca’s area is concerned
with controlling the muscles that produce speech
Wernicke’s Area
Wernicke’s area
Visual Processing
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The visual sensory area is at the back of the brain
& receives sensory input from the optic nerves
The 2 hemispheres see slightly different images
from the opposite of the visual field, and
differences can be used to judge distance
Optic Chiasma
Summary
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Sensory areas – receive input from receptors
Motor areas – Origin of impulses which bring
about voluntary movements
These receive/transmit impulses from the
opposite side of the body
Association areas – interpret sensory
information in the light of experience
A close shave