Chapter 3 - The biology of behavior
Genes and Behavior
- Your genetic material is composed mainly of DNA (deoxyribonucleic acid) and is passed down in the form of chromosomes from both
your mother and your father
- A chromosome is a very long thread of DNA wrapped around proteins to hold it all
together
- You inherit 23 chromosomes from one parent and 23 chromosomes from the other
parent
- End up with 23 pairs of chromosomes (46 individual chromosomes) in every cell of
your body
- The total amount of your unique DNA is referred to as your genome
- Each person’s unique and incomparable genome is called his or her genotype
- What form a gene takes and how it gets expressed in observable characteristics is
known as the phenotype
- Genes are the segments of DNA that code for protein synthesis,ise the functional
segment of DNA
- Most traits, height, weight, intelligence, and personality, are the result of many dozens or hundreds of genes, known as polygenic
traits
- Traits that have a one-to-one connection to a gene are known as monogenic traits
- Some humans have a change or mutation in their genetic sequence
- Different forms of genes are known as alleles, one you inherit from your mother and the other from your father
- Dominant alleles show their effect even if there is only one copy of that allele in the pair
- Recessive alleles show their effects only when both alleles are the same
Principles of behavioral genetics
- Psychologists turn to science to study heredity effects on behavior
- There are three principles of behavioral genetics that are relevant to psychology
- Relationship between specific genes and behavior is complex, usually with many genes involved in each trait
- By studying twins and adoptees, and genetic markers, behavior geneticists can disentangle the contributions of heredity
(nature) and environment (nurture) that influence behavior
- The environment influences how and when genes affect behavior
Relative effects of genes and environment teased apart
- Characteristics are influenced by genetics (heritability)
- Teasing apart and identifying genetic and environmental influences on behavior can be done but requires special techniques
- Researchers use two different research methods to study the relative effects of nature and nurture (twin adoption studies and gene by
environment studies)
Environment can change gene expression: epigenetics
- Study of changes in the way genes are expressed
- Activated (turned on) or deactivated
- (turned off) without changing the sequence of DNA
, THe nervous system
- Controls all the actions and automatic processes of the body
- Everything we experience and do results from the activity of nerve cells
- Nerve cells are organized in a net of circuits far more complex than any electrical system
you could imagine
Organization of the nervous system
- Has two main parts and several components
- Divided into central nervous system which includes the brain and spinal cord
- Peripheral nervous system consists of all the other nerve cells in the body
- Peripheral nervous system includes the somatic nervous system and the autonomic
nervous system
- Somatic nervous system serves the skeletal muscles of the body, it sends messages out to the skeletal muscles from the CNS and
transmits sensory information back to the CNS from the skeletal muscles
- The autonomic nervous system (ANS) serves the involuntary systems of the body, such as internal organs and glands
- ANS has two main branches
- Sympathetic nervous system
- Parasympathetic nervous system
- Nerves of both of these systems control muscles in organs such as stomach, small intestine, bladder, and in glands (sweat glands)
- Sympathetic nervous system activities bodily systems in times of emergency by increasing heart rate, dilating the pupils of the eyes, or
inhibiting digestion
- Responsible for what the physiologist WALTER CANNON (1939) LABELED THE FIGHT OR FLIGHT RESPONSE
- FUNCTION OF THE Parasympathetic nervous system is largely one of relaxation, returning the body
to a less active and restful state
- All of the systems that are aroused by the sympathetic nervous system are relaxed by the
parasympathetic
- ANS PRODUCES MANY OF THE PHYSICAL SENSATIONS WE EXPERIENCE DURING EMOTIONAL AROUSAL, SUCH AS
A RACING HEART OF SWEATY PALMS
CELLS OF THE NERVOUS SYSTEM: GLIAL CELLS AND NEURONS
- Central nervous system is made up of glial cells and neurons
- GLIA is the greek word for glue, glial cells serve the primary function of holding the CNS
together
- Neurons are the cells that process and transmit information throughout the nervous system
- Information is transmitted between neurons by means of chemicals
neurotransmitters
The structure and types of neurons
- Late 1800s, Spanish anatomist Santiago Ramon y Cajal, deciphered the precise nature and structure of nerve cells (neurons)
- He identified the three major parts of the neuron: cell body, dendrites, and axon
- The cell body, or soma, of the nyerons contains a nucleus and other components needed for cell maintenance and function
- The genes that direct neural change and growth lie within the nucleus itself
- Extending from one side of the soma is a long projection called an axon
- Axons transmit electrical impulses toward the adjacent neuron
Genes and Behavior
- Your genetic material is composed mainly of DNA (deoxyribonucleic acid) and is passed down in the form of chromosomes from both
your mother and your father
- A chromosome is a very long thread of DNA wrapped around proteins to hold it all
together
- You inherit 23 chromosomes from one parent and 23 chromosomes from the other
parent
- End up with 23 pairs of chromosomes (46 individual chromosomes) in every cell of
your body
- The total amount of your unique DNA is referred to as your genome
- Each person’s unique and incomparable genome is called his or her genotype
- What form a gene takes and how it gets expressed in observable characteristics is
known as the phenotype
- Genes are the segments of DNA that code for protein synthesis,ise the functional
segment of DNA
- Most traits, height, weight, intelligence, and personality, are the result of many dozens or hundreds of genes, known as polygenic
traits
- Traits that have a one-to-one connection to a gene are known as monogenic traits
- Some humans have a change or mutation in their genetic sequence
- Different forms of genes are known as alleles, one you inherit from your mother and the other from your father
- Dominant alleles show their effect even if there is only one copy of that allele in the pair
- Recessive alleles show their effects only when both alleles are the same
Principles of behavioral genetics
- Psychologists turn to science to study heredity effects on behavior
- There are three principles of behavioral genetics that are relevant to psychology
- Relationship between specific genes and behavior is complex, usually with many genes involved in each trait
- By studying twins and adoptees, and genetic markers, behavior geneticists can disentangle the contributions of heredity
(nature) and environment (nurture) that influence behavior
- The environment influences how and when genes affect behavior
Relative effects of genes and environment teased apart
- Characteristics are influenced by genetics (heritability)
- Teasing apart and identifying genetic and environmental influences on behavior can be done but requires special techniques
- Researchers use two different research methods to study the relative effects of nature and nurture (twin adoption studies and gene by
environment studies)
Environment can change gene expression: epigenetics
- Study of changes in the way genes are expressed
- Activated (turned on) or deactivated
- (turned off) without changing the sequence of DNA
, THe nervous system
- Controls all the actions and automatic processes of the body
- Everything we experience and do results from the activity of nerve cells
- Nerve cells are organized in a net of circuits far more complex than any electrical system
you could imagine
Organization of the nervous system
- Has two main parts and several components
- Divided into central nervous system which includes the brain and spinal cord
- Peripheral nervous system consists of all the other nerve cells in the body
- Peripheral nervous system includes the somatic nervous system and the autonomic
nervous system
- Somatic nervous system serves the skeletal muscles of the body, it sends messages out to the skeletal muscles from the CNS and
transmits sensory information back to the CNS from the skeletal muscles
- The autonomic nervous system (ANS) serves the involuntary systems of the body, such as internal organs and glands
- ANS has two main branches
- Sympathetic nervous system
- Parasympathetic nervous system
- Nerves of both of these systems control muscles in organs such as stomach, small intestine, bladder, and in glands (sweat glands)
- Sympathetic nervous system activities bodily systems in times of emergency by increasing heart rate, dilating the pupils of the eyes, or
inhibiting digestion
- Responsible for what the physiologist WALTER CANNON (1939) LABELED THE FIGHT OR FLIGHT RESPONSE
- FUNCTION OF THE Parasympathetic nervous system is largely one of relaxation, returning the body
to a less active and restful state
- All of the systems that are aroused by the sympathetic nervous system are relaxed by the
parasympathetic
- ANS PRODUCES MANY OF THE PHYSICAL SENSATIONS WE EXPERIENCE DURING EMOTIONAL AROUSAL, SUCH AS
A RACING HEART OF SWEATY PALMS
CELLS OF THE NERVOUS SYSTEM: GLIAL CELLS AND NEURONS
- Central nervous system is made up of glial cells and neurons
- GLIA is the greek word for glue, glial cells serve the primary function of holding the CNS
together
- Neurons are the cells that process and transmit information throughout the nervous system
- Information is transmitted between neurons by means of chemicals
neurotransmitters
The structure and types of neurons
- Late 1800s, Spanish anatomist Santiago Ramon y Cajal, deciphered the precise nature and structure of nerve cells (neurons)
- He identified the three major parts of the neuron: cell body, dendrites, and axon
- The cell body, or soma, of the nyerons contains a nucleus and other components needed for cell maintenance and function
- The genes that direct neural change and growth lie within the nucleus itself
- Extending from one side of the soma is a long projection called an axon
- Axons transmit electrical impulses toward the adjacent neuron
