Transcript BIOLOGICAL BASES OF BEHAVIOR

BIOLOGICAL BASES OF BEHAVIOR (8-10%)
• 8-10%
The Neuron
• Is the basic building block of the
nervous system. It uses both
chemical & electrical signals to
communicate messages to other
neurons.
• Glial cells guide the growth, provide
support to the developing neurons.
Structures of a neuron
The Neuron
•
•
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•
•
Soma
Dendrites
Axon
Myelin Sheath
Axon Terminal
Button
• Vesicle
Vesicles contain neurotransmitters
SYNAPSE
• the gap between
nerve cells.
NEUROTRANSMITTERS
Types of
Neurons
Sensory
Motor
Interneuron
HOW A NEURON FIRES
All your behavior begins with actions of your
neurons. A neuron gets incoming information
from its receptor sites spread around the
dendrites. That information is sent to the cell
body. Neural impulses are electrical in nature
along the neuron. The neuron at rest is more
negative inside the cell membrane relative to
the outside of the cell membrane.
• The neuron’s resting potential is -70mV
(inside the axon). When sufficiently
stimulated outside the cell of about +10mV
a net flow of sodium ions into the cell
causes a change known as the action
potential.
• If stimulation is not strong enough, the
neuron does not fire.
• The strength of the action potential is
constant. It either fires or doesn't –known
as the “all or none principle.”
Neural communication refers to how the
neurons relay messages to each other. It is
referred to an electrochemical reaction.
Neurons are surrounded by fluid. The fluid
inside a neuron contains negative charged
atoms, called ions, ( - ) from the fluid located
outside the neuron, which has positive
charged ions (+).
• Positive ions will flow into the neuron if not
stopped or pumped out by the membrane.
This is called the electrical potential, which is
measured in millivolts.
• The resting potential is the neuron’s usual
charge, which is –70 millivolts.
• When the resting potential has changed
enough, about +10mv, the membrane changes
and a message is sent, which is referred to as
the action potential
• The speed at which an action potential travels
the axon ranges from 2 to 250 mph.
• Neurotransmitter are released into the synapse,
where they attach to specific receptor sites on
dendrites, like a key fitting into a lock.
• Some of the synapses are excitatory, where an
action potential is generated and the message gets
sent., and some are inhibitory, preventing neural
impulses.
• The constant flow of these neuro-chemical
impulses regulates your metabolism, temperature,
respiration, as well as your behavior & thoughts,
decisions and memory.
 Refractory Period- a resting pause, when the
neuron pumps the positively charged ions back
outside…then it can fire again.
 Excitatory-signal to send the message
 Inhibitory-signal to stop the message
 Threshold -the level of stimulation required to
trigger a neural impulse
 Agonist-excite by mimicking particular
neurotransmitters or block their reuptake.
 Antagonists-inhibit a neurotransmitter’s release
or block its effect.
The Nervous System
Nervous
system
Central
(brain and
spinal cord)
Peripheral
Autonomic (controls
self-regulated action of
internal organs and glands)
Somatic or Skeletal (controls
voluntary movements of
skeletal muscles)
Sympathetic
(arousing)
Parasympathetic
(calming)
THE CENTRAL NERVOUS SYSTEM
CNS
Consists of our brain & spinal cord.
PERIPHAL NERVOUS SYSTEM
PNS
Divided into two major sub-divisions:
• Somatic Nervous system –
Controls our voluntary muscle
movements
• Autonomic nervous system
AUTONOMIC NERVOUS SYSTEM
• This controls the automatic functions of
our body-our heart, lungs, internal
organs, and glands. These nerves control
our flight or flight response to perceived
threat.
• The autonomic nervous system is divided
into 2 categories: the sympathetic & the
parasympathetic nervous system
Sympathetic nervous system
• Mobilizes our body to respond to stress.
This part carries messages to the control
systems of the organs, glands, & muscles.
It is the alert system of the body.
It activates our heart rate, blood
pressure,& respiration rate.
PARASYMPATHETIC NERVOUS SYSTEM
• Is responsible for slowing our body
down after a stress response.
WAYS OF STUDYING THE BRAIN
1.
2.
3.
4.
5.
Accidents (the case of Phineas Gage)
Lesions (use electric current to burn area)
EEG (Electroencephalogram (brain waves)
CAT or CT(shows structure, stroke, tumor)
PET Scan (shows activity)
positron emission tomography
6. MRI (maps structure)
7. fMRI (shows activity)
functional magnetic resonance imaging
BRAIN STRUCTURE & FUNCTION
CEREBRAL CORTEX
 Frontal Lobes
 involved in speaking and muscle
movements and in making plans and
judgments
 Parietal Lobes
 includes the sensory cortex, registers body
sensations
 Occipital Lobes
 include the visual areas
Temporal Lobes
 includes the auditory areas, processes
hearing & speech
 Aphasia
 impairment of language, usually caused by
left hemisphere damage either to Broca’s
area (impairing speaking) or to Wernicke’s
area (impairing understanding)
 Broca’s Area
 an area of the left frontal lobe that directs
the muscle movements involved in speech
 Wernicke’s Area
 an area of the left temporal lobe involved in
language comprehension and expression
LIMBIC SYSTEM
Cerebellum
 the “little brain”
attached to the
rear of the
brainstem
 it helps coordinate
voluntary
movement and
balance
SPLIT BRAIN
CORPUS CALLOSUM
BRAIN PLASTICITY
• Means the brain is somewhat flexible
or plastic. Other parts of the brain
can adapt themselves to perform
other functions if needed.
• Younger brains are more plastic and
more likely to compensate for
damage.
ENDOCRINE
SYSTEM
the body’s
“slow” chemical
communication
system
a set of glands
that secrete
hormones into
the
bloodstream