Transcript The Central Nervous System

The Central
Nervous System
The Central Nervous
System
• The CNS coordinates the activities that go on
within the body. It also processes and analyzes the
information brought in by the PNS and the sensory
organs.
• The CNS is composed of:
o The brain
o The spinal cord.
The Brain
• The brain is composed of nerve cells, (neurons).
• There are 3 main parts of the brain:
o The cerebrum
o The cerebellum
o The brain stem.
• The brain is protected by the cranium, (skull),
and the meninges, (membranes that envelope
the brain.
• The brain communicates with the rest of the
body through a series of nerves, called cranial
nerves.
The Cerebrum
• The cerebrum is the largest part of the brain.
• It controls voluntary movements, interprets the
senses, is responsible for intelligence, and is the
centre for emotions.
• It is divided into two hemispheres:
o The left hemisphere controls the right side of the body.
o The right hemisphere controls the left side of the body.
• The outer most part of the brain is called the
cerebral cortex. It processes higher brain
functions like reasoning and planning.
4 Lobes
• The cerebrum is also divided into four lobes. Each
lobe processes different things.
• The frontal lobe:
o Behaviour and emotion control, thinking, planning and reasoning,
movement.
• The temporal lobe:
o Hearing, memory, language.
• The parietal lobe:
o Perception, arithmetic, spelling
• The occipital lobe:
o Vision
Brain Function
Description
Controls voluntary
movements
When we want to do a specific
movement, like raising our hands or
dancing, the part of the cerebrum
associated with motor control sends a
nerve impulse to our muscles, allowing
this to happen.
Interprets messages picked
up by the sensory organs.
When one of our sensory organs picks
up a stimulus, nerve impulses travel to a
specific part of the cerebrum. The
specific region will analyze the
information, identify it, and sometimes
send a nerve impulse via the motor
nerves to cause a reaction.
Controls intelligence
Problem-solving, reading, writing and
speaking are intellectual activities.
Different regions of the cerebrum are
simultaneously responsible for each of
these intelligence-activities.
Function
Description
Controls Emotion
Managing emotions is a complex, and
not well understood function of the
brain. Like with intelligence, different
regions simultaneously work to control
emotion.
Regulates physiological
functions
The hypothalamus, which lies below
the cerebrum, is responsible for major
functions of the body, including
hunger, thirst, alertness and
temperature regulation. It also
controls the activity of the pituitary
gland.
The Cerebellum
• The cerebellum is
associated with balance
and movement. It
coordinates movement
based on various amount
of information and
stimulus from all around
the body.
• The cerebellum enables
us to walk, run, speak,
play sports, play
instruments, etc.
The Brain Stem
• The brain stem is attached to the spinal cord, the
cerebrum and the cerebellum.
• It processes all internal stimuli, (hunger, thirst,
heartburn), and controls involuntary movements.
o When you eat, the brain stem ensures proper digestive
processes occur.
o Signals glands to secrete like normal.
o Etc.
Summary of the Brain
Part
Description
Largest part of the brain.
Cerebrum
Divided into left and right
hemispheres.
Outer layer called the
cerebral cortex.
Role
Complex analysis of
stimuli from the PNS.
Controls intelligence,
emotions and
physiological functions.
Controls voluntary
Divided into various lobes. movements.
Cerebellum
Located underneath the
cerebrum.
Brain Stem
Located between the
Processes internal stimuli.
cerebrum and the
cerebellum. Connected to Controls involuntary
both.
movements of the body.
Connects the brain to the
spinal cord.
Controls balance and
coordination.
The Spinal Cord
• The spinal cord is the communication cable that
runs through the body. It carries most of the nerve
impulses between the body and the brain.
• It also processes and conveys information related
to reflexes.
• Throughout the length of the spinal cord, one can
find 31 pairs of nerves, called the spinal nerves.
• The spinal cord is made of soft tissues, protected
by meninges and the spinal column, or vertebrae.
…
• The spinal cord is also the centre of the body that
processes reflexes.
• A reflex is a rapid and involuntary reaction to a
stimulus.
• For example: when a reflex occurs, the spinal cord
intercepts the stimuli before it reaches the brain.
The spinal cord causes and reaction. The brain will
analyze the situation only after the reflex.
• This is called a reflex arc – the path taken by a
nerve impulse in a reflex.
…
• Why do we have reflexes?
• It is our body’s response system to an emergency,
like if we touch something hot, or if a light is too
bright.
Image Credits
• http://img.webmd.com/dtmcms/live/webmd/consumer_assets/sit
e_images/media/medical/hw/h9991474_001.jpg
• http://www.cancerresearchuk.org/prod_consump/groups/cr_co
mmon/@cah/@gen/documents/image/cr_116645.jpg
• http://tonks.disted.camosun.bc.ca/courses/psyc110/biopsyc/f0411.jpg
• http://www.amfar.org/uploadedImages/Articles/Articles/In_The_
Lab/BRAIN.jpg
• https://staff.rockwood.k12.mo.us/baremorekeith/HAP/Document
s/Central%20Nervous%20System/spinal%20cord%20cross%20sectio
n%20with%20answers.jpg
• http://2.bp.blogspot.com/pKNLCVesC98/TyVV77lyVDI/AAAAAAAAAQE/7eMQSPcZ6HI/s1600
/Screen+Shot+2012-01-29+at+7.36.42+PM.png