Biological Bases of Behavior - Semester 1

Nature-nurture issue

The longstanding controversy over the relative contributions of our heredity and our environment to the development of psychological traits and behaviors.

Natural selection

The principle that, among the range of inherited trait variations, those contributing to reproduction and survival will most likely be passed on to succeeding generations.

Evolutionary psychology

The study of behavior and mental processes using the principles of natural selection.

Behavior genetics

The study of the relative power and limits of hereditary and environmental influences on behavior and mental processes.

Mutation

A random error in gene replication that leads to a change.

Environment

Every external influence, from prenatal nutrition to our experiences with the people and things around us.

Heredity

The genetic transfer of characteristics from parents to offspring.

Genes

The biochemical units of heredity.

Genome

The complete instructions for making an organism.

Identical twins

Monozygotic twins; twins who develop from a single fertilized egg that splits in two and are therefore genetically identical.

Monozygotic twins

Identical twins; twins who develop from a single fertilized egg that splits in two and are therefore genetically identical.

Fraternal twins

Dizygotic twins; twins who develop from separate fertilized eggs and are therefore genetically no closer than other siblings.

Dizygotic twins

Fraternal twins; twins who develop from separate fertilized eggs and are therefore genetically no closer than other siblings.

Interaction

The interplay that occurs when the effect of one factor (such as environment) depends on another factor (such as heredity).

Epigenetics

The study of the molecular mechanisms by which environments can influence genetic expression without actually changing DNA.

Heritability

The proportion of variation among individuals that we can attribute to genes.

Genetic predisposition

An inherited tendency or susceptibility toward a particular condition or behavior.

Nervous system

The body's "fast" communication system, uses electrical signals and chemicals called neurotransmitters to transmit messages.

Central nervous system

The brain and spinal cord.

Brain

The mass of nerve tissue that is the main control center of the nervous system.

Spinal cord

A major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain.

Peripheral nervous system

The sensory and motor neurons that connect the central nervous system to the rest of the body.

Nerves

Bundled axons that form neural "cables" connecting the central nervous system with muscles, glands, and sense organs.

Sensory neurons

Neurons that carry incoming information from the sensory receptors to the brain and spinal cord; sometimes called afferent neurons.

Motor neurons

Efferent neurons; neurons that carry outgoing information from the brain and spinal cord to the muscles and glands; sometimes called efferent neurons.

Interneurons

Neurons within the brain and spinal cord that communicate internally and intervene between the sensory inputs and motor outputs.

Somatic nervous system

The division of the peripheral nervous system that controls the body's skeletal muscles.

Autonomic nervous system

The part of the peripheral nervous system that controls the glands and the muscles of the internal organs.

Sympathetic nervous system

The division of the autonomic nervous system that arouses the body, mobilizing its energy (fight or flight).

Parasympathetic nervous system

The division of the autonomic nervous system that calms the body, conserving its energy (rest and digest).

Reflex

A simple, automatic response to a sensory stimulus, such as the knee-jerk response.

Reflex arc

A simple nerve pathway that includes a sensory neuron detecting a stimulus, an interneuron in the spinal cord, and the motor neuron that produces an automatic response.

Neuron

A nerve cell the basic building block of the nervous system.

Cell body

The part of a neuron that contains the nucleus; the cell's life-support center.

Dendrites

The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.

Axon

The extension of a neuron that passes messages through its branches to other neurons or to muscles or glands.

Axon terminal

The end of a neuron where neurotransmitters are stored.

Myelin sheath

A layer of fatty tissue segmentally encasing the fibers of neurons; enables faster transmission speed of neural impulses as the impulse hops from one node to the next.

Multiple sclerosis

An autoimmune disease marked by tremors, weakness, loss of coordination, paresthesia, and more; caused by deterioration of the myelin sheath.

Glial cells

Cells in the nervous system that support, nourish, and protect neurons; may play a role in learning, thinking, and memory.

Action potential

A neural impulse; a brief electrical charge that travels down an axon.

Resting potential

The normal, unfired state of a neuron, when the inside of the neuron is more negatively charged than the positively-charged outside of the neuron.

Depolarization

The first step of action potential when sodium ions rush into the cell causing the interior to lose it's negative charge.

Repolarization

The second step of action potential when potassium ions rush out the cell causing the interior to become negatively charged again.

Refractory period

The period after an action potential when a neuron cannot fire again.

Threshold

The level of stimulation required to trigger a neural impulse.

All-or-none response

A neuron's reaction of either firing with a full-strength response or not firing at all.

Synapse

The junction between the axon terminal of the sending neuron and the dendrite or cell body of the receiving neuron.

Neurotransmitters

Chemical messengers stored in the axon terminals of neurons that cross the synaptic gaps between neurons, binding with receptor sites on the receiving neuron and influencing whether that neuron will generate a neural impulse.

Reuptake

The process in which a neurotransmitter is reabsorbed into the sending neuron.

Excitatory neurotransmitters

Chemicals released from the axon terminal of a neuron that excite the next neuron into firing.

Inhibitory neurotransmitters

Chemicals released from the axon terminal of a neuron that inhibit the next cell from firing.

Acetylcholine (ACh)

A neurotransmitter that enables muscle action, learning, and memory; undersupply linked to Alzheimer's disease.

Dopamine

A neurotransmitter that influences movement, learning, attention, and emotion; oversupply linked to schizophrenia, undersupply linked to Parkinson's disease.

Serotonin

A neurotransmitter that affects mood, hunger, sleep, and arousal; undersupply linked to depression.

Norepinephrine

A neurotransmitter that helps control alert and arousal; undersupply linked to depression.

GABA

An inhibitory neurotransmitter; undersupply linked to seizures, tremors, and insomnia.

Glutamate

An excitatory neurotransmitter involved in memory; oversupply linked to migraines or seizures.

Endorphins

A category of neurotransmitters involved in pain control and pleasure; overuse of opioids might suppress the body's natural supply.

Substance P

A neurotransmitter involved in pain perception and immune response; oversupply linked to chronic pain.

Myasthenia gravis

An autoimmune disease marked by severe weakness, loss of muscle control, and paralysis; caused by the blocking of ACh transmission.

Agonist

A molecule that, by binding to a receptor site, stimulates a response.

Antagonist

A molecule that, by binding to a receptor site, inhibits or blocks a response.

Reuptake inhibitor

A substance that slows or blocks the reabsorption of a neurotransmitter into the sending neurons, keeping it in the synaptic gap.

Endocrine system

The body's "slow" communication system; uses chemicals called hormones to transmit messages.

Hormones

Chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

Adrenaline

Hormone secreted by the adrenal glands when under stress, particularly responsible for immediate fight-or-flight response.

Leptin

A hormone produced by the body's fat cells that suppresses hunger and increases metabolism.

Ghrelin

A hormone produced by the stomach that stimulates hunger.

Melatonin

A hormone produced by the pineal gland that induces sleep.

Oxytocin

A hormone released by the pituitary gland that is enables important functions such as orgasm during sex, labor contractions during childbirth, and milk flow while nursing; seems to promote social bonding.

Pituitary gland

The endocrine system's "master gland" which, under the influence of the hypothalamus, regulates growth and controls other endocrine glands.

Psychoactive drug

A chemical substance that alters perceptions and moods.

Substance use disorder

Continued substance craving and use despite significant life disruption and/or physical risk.

Tolerance

The diminishing effect with regular use of the same dose of a drug, requiring the user to take larger and larger doses before experiencing the drug's effect.

Addiction

Compulsive craving of drugs or certain behaviors despite known adverse consequences.

Withdrawal

The discomfort and distress that follow discontinuing the use of an addictive drug.

Depressants

Drugs - such as alcohol - that reduce neural activity and slow body functions.

Opioids

Drugs - such as heroin - that typically act as pain relievers.

Stimulants

Drugs - such as caffeine, nicotine, and cocaine - that excite neural activity and speed up body functions.

Hallucinogens

Drugs - such as marijuana - that distort perceptions and evoke sensory images in the absence of sensory input.

Near-death experience

An altered state of consciousness reported after a close brush with death, often similar to drug-induced hallucinations.