Download cell body

Characteristics
•  Made up of two parts:
–  Central Nervous System
(CNS)
–  Peripheral Nervous
System (PNS)
•  Made up of:
–  Brain
–  Spinal Cord
–  Neurons
–  5 Senses
Job of the Nervous System
•  Allows you to react to a stimulus
–  Stimulus: change in the environment
–  Example: hot stove, tripping on a rock…
•  Your reaction is Automatic!
–  Example: if a bug flies in your eye, you blink.
You don’t have to think about it.
Neurons
Neuron
•  Dendrites - receive impulses from other
neurons and carry them to the cell body
•  Axon - an elongated extension of the
cell body that carries impulses away
from the cell body
•  cell body - containing the nucleus
Central Nervous System
•  Made up of 2 organs:
–  Brain
–  Spinal Cord
•  Controls everything you do
The human brain
•  Controls everything in the body
•  Made up of more than 10 billion nerves!
•  Three Parts
–  Cerebrum
–  Cerebellum
–  Brain Stem or Medulla
•  Protected by the skull
The Brain
Cerebrum
•  Contains 75% of your neurons
•  Composed of two equal
hemispheres
•  Frontal lobe reasoning, speech,
movement, and emotions
•  Parietal lobe touch, pressure,
temperature, and pain
•  Temporal lobe hearing and
memory
•  Occipital lobe vision
The Brain
Cerebellum
•  Located at the lower back of the
head.
•  Controls muscle coordination
and balance.
Brain stem or Medulla
•  Connects the cerebrum with the spinal
cord
•  The 3 main sections of the Brain Stem
•  Midbrain - controls reflexes and changes
pupil size
•  Medulla oblongata - controls heart rate,
breathing rate, and flow of blood through
the blood vessels.
•  Pons - relays signals between the
cerebrum and the cerebellum.
Spinal Cord
•  Protected by the vertebrae
•  Sends messages to the brain
•  Connects the brain to the rest of the nervous
system (PNS)
Peripheral Nervous System
(PNS)
•  Made up of:
–  Nerves that connect the Central Nervous
System (CNS) to the rest of the body
–  Sense organs
PNS Con’t
•  Ganglion - a mass of nerve cells
outside the central nervous system
•  Receptors - nerve cells that receive
information from internal and external
stimuli.
PNS Con’t
•  Conductors - nerve cells that transmit
information from receptors to the central
nervous system.
•  Effectors - receive information from the
central nervous system and transmit to
the body. These cells activate muscles.
Job of the PNS
•  Controls the body’s activities that you don’t
think about
–  Breathing
–  Heartbeat
–  Small intestine
controls
The Five Senses
•  Touch
•  Taste
•  Hearing
•  Smelling
•  Seeing
Seeing
•  Main organ is the eye
•  Made up of:
–  Iris (colored part)
–  Pupil (black hole)
•  The eye gathers pictures and sends
them to the brain through the optic
nerve
Eyes
Hearing
• Main organ is the ear
• Made up of:
– 9 parts
– 3 smallest bones in the body
• The ear takes in sound waves and transmits
them to the brain through the auditory nerve
deep within the ear
Touching
•  Main organ is the skin
•  The skin allows us to feel
things (temperature,
pressure, pain, etc.) and
transmit that information
back to the brain through
the nerves in the skin.
Smelling
•  Main organ is the nose
•  Made up of:
–  Nose
–  Olfactory cells
•  Transmits smells to the brain
through the olfactory bulb
Tasting
•  Main organ is your tongue
•  Made up of:
–  Taste buds (sweet, sour, bitter, salty)
–  Hypoglossal nerve
•  Taste information from the buds on your tongue is
transmitted to your brain through the hypoglossal
nerve in your tongue.
** There are NOT specific areas on your tongue that
have specific tastes!!!