Download BIOLOGY AND BEHAVIOR

BIOLOGY AND BEHAVIOR:
THE NEURON AND ACTION
POTENTIAL
CHAPTER 2
The mighty NEURON aka:
the Naughty Neuron
• Nerve cell which transmits electrical and
chemical information (via
neurotransmitters) throughout the body.
Each nerve cell is separate from another
and is called a Neuron – a string of these
is a nerve cell.
• Learning takes place by new dendrites
actually sprouting to make connection with
other neuron.
NEURONS
• Cell body – has the nucleus in it.
• Dendrite: means tree branches. It is the
receiver of the messages from other
neurons. It sends the message down it’s
own axon.
• Axon: carries the messages from the cell
to other neurons. At the end of the axon
are terminals or bulbs .
Neurons continued
• Synapse: the space between the endings of the
axon and the waiting dendrites.
• Vesicles: containers in the axon bulb of the
neurotransmitters.
• Neurotransmitters: the chemicals that propel
the message across the synapse from the end of
the axon to the awaiting dendrite. Discovered 20
years ago. Die off in adulthood.
• Myelin: grease coating on the axon - speeds up
message. Not much in the digestive track.
NEUROTRANSMITTERS
• Acetylcholine – Ach. Most and best
understood NT. Memory, sleep.
Deteriorates with Alzheimers.
• Dopamine – bodily movements – lack of
causes Parkinson’s disease. Too much
may cause schizophrenic episodes.
• Endorphins: relieve pain and increase
our sense of well-being.
• Serotonin: our feel good NT
ACTION POTENTIAL
• Message breaks a threshold and goes to
the awaiting dendrite, to the cell body,
down the neuron’s axon surrounded by
myelin to make it faster, to the axon bulbs
vesicles where the appropriate NT is
squeezed out of the vesicle to go across
the synapse to the awaiting dendrite
receptor.
SPINAL CORD
• Functions as an automatic brain…relays
impulses to and from the higher brain.
• Central Nervous System:
the brain and the spinal cord
* The Peripheral Nervous system:
The Somatic and the Autonomic
Nervous systems: Autonomic =
Sympathetic – energizes. Parasympathetic –
slows you down – back to homeostasis.
THE BRAIN
•
•
•
•
•
•
Uses 20% of all our oxygen
Eats most of our sugar intake
Uses 20 watts of power
MOST demanding organ in the body
Has 2 hemispheres
Has 4 Lobes
LOBES
• Frontal: contains the motor strip and
frontal association area.
– Motor strip – body movements, ear to ear
strip.
– Elaborate associations, complex thinking.
– Personality here
– Damage here changes ones personality.
– 30% of the brain
LOBES continued
• Parietal Lobe: area of the brain that
contains the sensory strip.
• Occipital Lobe: interprets visual
information. In the back of the brain.
• Temporal Lobe: area of the brain
responsible for hearing. One each side of
the brain (temples)
HEMISPHERES
• Doesn’t tend to be genetic.
• Ambidextrous: messages get stuck in the
middle, possible brain trauma.
• Left brain: Logical and analytical, deals
with verbal and speech material.
• Right brain: Artistic, creative, and
emotional. Deals with space, art, music,
emotions.
CEREBRAL CORTEX AND THE
LOWER BRAIN
• Outermost layer of brain – the BARK
• Made up of hemispheres, lobes, frontal
association
• Covers the lower brain
• Controls higher level thinking
• 2/3’s of the brain
• Macaroni like material – if we rolled it out –
big as a bath towel.
LOWER BRAIN
• Basic animal unit
• Cortex fits over and around it – it’s the part
that keeps you going
– Thalamus: RELAY system. Takes in
messages and sends them out.
– Cerebellum – coordinates and organizes
bodily movements for balance and accuracy.
Looks like golf balls on the side of the spinal
cord.
Lower Brain continued
– Hypothalamus: regulates basic needs: 4
F’s: fleeing, fighting, feeding, fornication and
temperature. Size of a small pea under the
thalamus.
– Reticular activating system: RAS: Sits at
the base of the brain and regulates activity of
the body. Makes us alert or tired. Drugs in
surgery act on the RAS so it doesn’t notice
pain.
Motor Cortex
Sensory Areas of the brain