Transcript Genotype - White Plains Public Schools

Chapter 3:
Biological Bases
of Behavior
Heredity and Behavior
Evolution and Natural Selection
• Charles Darwin- The Origin of Species
• Natural Selection- theory that
favorable adaptations to features of
the environment allow some
members of a species to reproduce
more successfully than others
• What does this mean?
Evolution and Natural Selection
 Over time organisms producing
more favorable traits for survival
will become more numerous than
others
AKA: Survival of
the fittest
Evolution and Natural Selection
• Short-term effects:
Evolution and Natural Selection
• Long-term effects:
Genotype vs. Phenotype
Genotype
Phenotype
• Inherited genetic • Determines
structure from
observable
parents
appearance
• Determines
• Resulting from
development and
interaction between
behavior
genotype and
environment
Process of Natural Selection
Environmental Pressure
Competition
Selection of Fittest
Reproductive Success
Frequency of Genotype
Language
• Most important milestone for
human species
Language
• Vital for:
• Instruction
• Sharing experiences
• Social Bonds
• Transmitting wisdom
Language
• Basis for cultural evolution
• Allows for rapid
adjustments to
environmental changes
• Culture is possible
because of the potential
of human genotype
changes
Variation in Human Genotype
• Heredity- the inheritance of physical
and psychological traits from
ancestors; transmission of traits from
parents to offspring
• Genetics- the study of heredity
Basic Genetics
• DNA is found in the nucleus of
each human cell
• DNA- the physical basis for
genetic information
• DNA is organized into genes
• Genes- biological units of herdity
Genes
• Contain the instruction
for phenotypic traits:
(some examples)
- body build
- physical strength
- intelligence
• Found on
chromosomes
Sex Chromosomes
• Contain coding for male or female
characteristics
• Mother contributes “X” chromosome
• Father contributes “X” or “Y”
chromosome
• XX= female
• XY= male
Genes
• 50% of genes in
common with siblings
• Set of genes is unique
• Difference in genes
and environment
determine traits
Goal
• Important goal of psychology is to
understand the balance between
your genetics and your
environment
Genes and Behavior
• Human behavior genetics- unites
genetics and psychology to
explore the relationship between
inheritance and behavior
Happiness
• Researchers propose that happiness
has a strong genetic component,
less than an environmental
component
• Is happiness set
at birth?
Genes
• Conclusion:
Genes you receive from your
parents have broader effects than
determining hair and eye color
Sociobiologists use evolutionary
explanations to analyze social
behavior and social systems
Sad Brain  Happy Brain 
• Read “Sad Brain, Happy Brain”
and answer all questions on
handout
Biology and Behavior
People to Know
• Rene Descartes- French Philosopher
- human action is mechanical
reflex to environmental stimulation
People to Know
• Sir Charles Sherrington- discovered reflexes are direct
connections between sensory and
motor nerve fibers
- nervous system involves increasing
and decreasing neural activity
People to Know
• Santiago Ramon y Cajal- detected gaps between adjacent
neurons and theorized how info
flowed from one to another
People to Know
• Donald Hebb- believed the brain
was integrated series of
structures (cell
assemblies) performing
specific functions
Neuroscience
• Neuroscience- study of the brain
and the links between brain
activity and behavior
Phineas Gage
• Pre-accident: levelheaded, calm
• Post-accident:
hostile, impulsive,
extremely
emotional,
obscene language
Phineas Gage
• Loss of tissue revealed the
relationship between frontal
lobes and control of emotional
behavior
Paul Broca
• Studied brain’s role in language
• Discovered area of brain connected
to language- now known as “Broca’s
area”- translates thoughts into
speech or signs
Lesions
• Researchers began method of
destroying or injuring brain tissue
on purpose to study results
• Damages are “lesions”
• Experimental work on nonhumans only
Lobes of the Brain
Broca’s Area
People to Know
• Walter Hess- pioneered use of
electrical currents in the brain
- determined what part of the
brain performs specific functions
Recording Brain Activity
• EEG- traces electrical activity of the
brain
• PET Scan- image produced by recording
radioactivity emitted by cells during
different activities
• MRI- scan of brain using radio waves
and magnetic fields
• fMRI- combines PET and MRI
The Nervous System
Organization of Nervous System
Brain Structures and
Functions
Brain
• Brain- most important component of
your CNS
• Brain Stem- regulates the body’s
basic life processes
• Medulla- center for breathing, blood
pressure and heart rate
• Pons- connects spinal cord with brain
Brain
• Reticular Formation- arouses cerebral
cortex to incoming sensory signals
- responsible for consciousness and
awakening from sleep
- massive damage  coma
• Thalamus- channels incoming sensory
into to appropriate area of cerebral
cortex
Brain
• Cerebellum- attached at base of
skull
- responsible for body
movement, posture, and
equilibrium
Brain
Limbic System
• Hippocampus- involved in the
ability to acquire memories
- injury can effect recall of
memory
• Amygdala- role in emotional
control and formation of
emotional memories
Limbic System
• Hypothalamus- regulates/maintains
homeostasis, involved in motivated
behavior
• Equilibrium- consistency of the
body’s internal conditions
Cerebrum
• Cerebrum- regulates brain’s
higher cognitive and emotional
functions; 2/3s of brain
• Cerebral Cortex- outer surface
• Corpus Callosum- nerve fibers
connecting 2 hemispheres of
cerebrum
Cerebrum
• Frontal Lobe- responsible for motor
control and cognitive activitiesplanning, decision making, goal
setting
• Parietal Lobe- responsible for
sensations, touch, pain, and temp;
contains somatosensory complex
Cerebrum
• Occipital Lobe- contains primary
visual cortex
• Temporal Lobe- contains primary
hearing
Cerebrum
• Motor Cortex- controls the actions of
the body’s voluntary muscles
• Somatosensory Cortex- processes
information about temp, touch, body
position, and pain; devoted to parts
of body that provide sensory input
(lips, tongue, thumb, index finger)
Cerebrum
• Auditory Cortex- receives
information from both ears 
processes auditory info
• Visual Cortex- devoted to visual
input and transmits detailed visual
info
Cerebrum
• Association Cortex- portion of the
brain where high level brain
process occur, such as planning
and decision making occur
Cerebrum
Hemispheric Lateralization
• Info from the right visual field goes
to the left hemisphere
- Vice versa
• In most people this info is shared
quickly between the two
hemispheres via the corpus callosum
Hemispheric Lateralization
• Speech is controlled by the left
hemisphere in most individuals
• Speech is the most highly lateralized
function of the brain
• This doesn’t mean the left hemisphere
is better!
• Right hemi controls more manual tasks
Hemispheric Lateralization
• Conclusion:
- The right hemisphere controls
the left side of your body
- The left hemisphere controls the
right side of your body
Who’s Better at What?
• Look over the handout “Who’s Better
at What?”
• Respond to the following questions:
- Do you agree/disagree with the
info on the handout?
- Are you a “left brain” or “right
brain” person?
Hemispheric Lateralization
1. Women have greater density of
neurons in a portion of the
temporal cortex involved in
language
2. Different brain areas develop more
strongly for men and women
3. Hemi’s of women’s brain shares
more functions than men’s
Neurons
• Neuron- cell that receives, processes
and transmits into to other cells
Neurons
PARTS:
1. Dendrites- receive incoming signals
2. Soma- cell body; contains nucleus;
passes info to the axon
3. Axon- conducts info away from
soma to the terminal buttons
Neurons
4. Myelin Sheath- covers axon to
increase speed of info
- MS cells attack and deteriorate
myelin sheath
5. Terminal Buttons- bulb-like
structures through which neurons
stimulate nearby glands, muscles, or
other neurons; release neurotrans.
Types of Neurons
1. Sensory (Afferent) Neurons- carry messages
from sense receptor cells towards the CNS
(sensitive to light and sound)
2. Motor (Efferent) Neurons- carry messages
away from CNS towards muscles and glands
3. Interneurons (in brain)- relay messages
from sensory neurons to other
interneurons, or to motor neurons
Glial Cells
• Hold neurons in place
• Housekeeping- clean-up damaged or
dead neurons
• Absorb excess neurotransmitters
• Insulation- form the myelin sheath
• Prevent toxic substances in blood
from reaching brain cells
Action Potentials
• Neurons receive excitatory (“fire”) or
inhibitory (“don’t fire”) inputs
• Neural communication is produced by the
flow of elec. charged particles – ions
• Inactive/Resting State- more potassium ions
inside, more sodium ions outside the
neuron
• Membrane of the cell has a pump to keep
this in balance
Action Potentials
• Fluid inside the membrane has a
slight negative charge (polarized)
• This polarization = resting potential
• When nerve cells get excitatory or
inhibitory inputs the balance of ions
will change
Action Potential
• Inhibitory inputs cause ion channels
to work harder to keep the inside of
cell negatively charged  won’t fire
• Excitatory inputs allow ion pump to
allow sodium in which allows the cell
to fire (sodium ions have a positive
charge)
Action Potentials
• Action Potential begins when the
inside of the cell is depolarized and
sodium rushes into the cell  makes
the ion positively charged
• A domino effect propels the action
potential down the axon 
successive depolarization
Action Potentials
• Neuron returns to a resting state:
when neuron becomes positive,
channels that allowed sodium in
close, channels that stopped
potassium  open
Cell returns to negative charge and
ready for next stimulation
All or None!
• “All or None”- action potential is
not affected by increases in
intensity of stimulation once
threshold level is reached and is
firing
• If threshold is not reached  no
firing
Refractory Period
• Action potential has passed:
1. Absolute refractory period- no stimulation
can generate another action potential
2. Relative refractory period- neurons will
only fire in response to a stronger stimulus
• This ensures that action potential will only
travel in one direction  can’t move
backward b/c “earlier” parts of axon are in
refractory state
Synaptic Transmission
1. Action potential reaches terminal
buttons
2. Synaptic vesicles rupture and
neurotransmitters are released
3. Neurotransmitters disperse across
synaptic cleft
4. Neurotransmitters attach to receptor
molecules
Synaptic Transmission
• Neurotransmitters attach to the
postsynaptic membrane only if 2 conditions
are met:
- the only neurotransmitter attached to
that receptor molecule
- shape of neurotransmitter must match
the shape of the receptor molecule
5. Once job is complete  detaches and
decomposes or is reabsorbed