Biology and Psychology

Biology and Psychology – Brandon Skenandore

What are some of the basic concepts of the theory of evolution?

Struggle for existence, natural selection determines the species that prosper and those that fade away

Mutations: random genetic variations that lead to differences among individuals in physical traits, individuals whose traits are better adapted to environment are more likely to survive (or, be “naturally selected”)

Concepts of adaptation and natural selection have been applied to psychological traits, and are key concepts in evolutionary psychology

What is evolutionary psychology?

Studies the ways in which adaptation and natural selection are connected w/ mental processes and behavior

Not only physical traits but also patterns of behavior evolve and are transmitted genetically from generation to generation

Behavior patterns are termed instinctive or species-specific because they evolve within certain species.

What is meant by an “instinct”?

A stereotyped pattern of behavior that is triggered in a specific situation. Nearly identical among the members of the species in which it appears

Tends to resist modification, even when it serves no purpose or results in punishment

What is meant by “heredity”?

Defines one’s nature – which is based on one’s biological structures and processes

What is meant by “genetics”?

Subfield of biology that studies heredity

Behavioral genetics bridges the sciences of psychology and biology.

Concerned with the genetic transmission of traits that give rise to patterns of behavior.

Molecular genetics attempts to identify specific genes that are connected w/ behavior and mental processes.

What are the roles of genes and chromosomes in heredity?

Genes are most basic building blocks of heredity

They regulate development of specific traits

Chromosomes are made up of strings of genes

Each cell in the body contains 46 chromosomes arranged in 23 pairs

Chromosomes are large complex molecules of DNA (deoxyribonucleic acid)

3 billion DNA sequences throughout chromosomes, these sequences (A,T, C, G) make you grow the way you do

Polygenic traits are influenced by combinations of genes

Genotype provided by genetic code, full genetic potential as determined by the sequencing of chemicals in DNA (acquire language)

Phenotype is the manner in which genetic code manifests itself because of your experiences and environmental circumstances (what language you speak)

Nature (heredity) and Nurture (environmental influences)

Sex Chromosomes determine whether we are female or male, 23rd pair of chromosomes

Down Syndrome occurs when people do not have the normal number of 46 chromosomes (23 pairs), most have an extra chromosome on the 21st pair

What are kinship studies?

Ways in which psychologists compare presence of traits and behavior patterns in people biologically related or unrelated

Monozygotic (MZ) twins identical, when fertilized cell (zygote) divides and separates, develops two people w/ same genetic makeup

Dizygotic (DZ) twins share 50% of genes

What is selective breeding?

Selection by humans instead of nature

Breed plants and animals to enhance desired physical and behavioral traits, breed cattle and chickens to be bigger and fatter for more meat

What are neurons?

Cells that can be visualized as having branches, trunks, and roots, we are born with over 100 billion neurons

Different functions, center stage of nervous system

Glial cells remove dead neurons and waste products from the nervous system, nourish and insulate neurons, and direct their growth

Dendrites extend like roots from cell body, receive incoming messages

Each neuron has an axon that extends like a trunk from the cell body, very thin, but those that carry messages from toes to spinal cord extend several feet axons are wrapped tightly with white, fatty myelin, makes them look like strings of sausages under microscope

Afferent neurons: neurons that transmit messages from sensory receptors to the spinal cord and brain

Efferent neurons: neurons that transmit messages from the brain or spinal cord to muscles and glands

What are neural impulses?

The electrochemical discharge of a nerve cell, or neuron

Difference in electrical charge polarizes the neuron with a negative resting potential (electrical potential across the neural membrane when it is not responding to other neurons)

When area on the surface of resting neuron is stimulated by other neurons, cell membrane in the area changes permeability to allow positively charge sodium ions to enter, area of entry becomes positively charged, or depolarized.

Action potential: electrical impulse that provides the basis for the conduction of a neural impulse along an axon of a neuron

What happens when a neuron fires?

Releases neurotransmitters

All-or-none principle: either a neuron fires or it doesn’t

Refractory period: time of recovery when sodium is prevented from passing through the neuronal membrane.

What is a synapse?

A junction between the axon terminals of one neuron and the dendrites or cell body of another neuron

Which neurotransmitters are of interest to psychologists? What do they do?

The chemical keys to communication into the synaptic cleft, influence the receiving neuron

Fits into specifically tailored harbor, or receptor site

Acetylcholine (ACh) controls muscle contractions

Prevalent in part of brain called the hippocampus, (structure involved in formation of memories)

Dopamine is involved at the level of the brain and affects voluntary movements, learning and memory, and emotional arousal

Deficiencies are linked to Parkinson’s disease

Norepinephrine accelerates the heart rate, affects eating, and is linked with activity levels, learning, and remembering

Serotonin is involved in behavior patterns and psychological problems, including obesity, depression, insomnia, alcoholism, and aggression

Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that may lessen anxiety

Endorphins inhibit pain by locking pain-causing chemicals out of their receptor sites

What are the parts of the nervous system?

Consists of the brain, spinal cord, and nerves (bundle of axons from many neurons) linking them to the sensory organs, muscles, and glands

Central Nervous System consists of brain and spinal cord

Peripheral Nervous System is made up of the afferent and efferent neurons

What are the divisions and functions of the peripheral nervous system?

Consists of sensory and motor neurons that transmit messages to and from the central nervous system.

Somatic Nervous System: division of peripheral nervous system, connects the central nervous system with sensory receptors, skeletal muscles, and the surface of the body

Autonomic nervous system (ANS): Division of the peripheral nervous system that regulates glands and activities such as heartbeat, respeiration, digestion, and dilation of the pupils

Sympathetic branch: most active during emotional responses, fear, anxiety, spend the body’s reserves of energy

Parasympathetic branch: most active during digestion and others that restores the body’s reserves of energy

What are the divisions and functions of the central nervous system?

Spinal cord: “information superhighway”, capable of “local government”, controls some responses to external stimulation through spinal reflexes (unlearned response to a stimulus that may involve only two neurons), sometimes there is a third neuron, or interneuron, transmits the neural impulse from the sensory neuron through spinal cord to motor neuron.

Spinal cord consists of gray matter (nonmyelinated neurons, spinal reflexes), and white matter (longer, nyelinated axons, carry messages to and from the brain)

How do researchers learn about the functions of the brain?

Test rats with lesions (injury that results in impaired behavior or loss of function)

What are the structures and functions of the brain?

Medulla: oblong area of hindbrain, regulates heartbeat nd respiration

Pons: structure of the hindbrain involved in respiration, attention, and sleep and dreaming

Cerebellum: part of hindbrain, involved in muscle coordination and balance

Reticular activating system (RAS): involved in attention, sleep, and arousal

Thalamus: area near center of brain, involved in relay of sensory information to the cortex, functions of sleep and attention

Limbic system: group of structures, involved in memory, motivation, emotion that forms a fringe along the inner edge of the cerebrum

Amygdale: part of the limbic system, apparently facilitates stereotypical aggressive responses

Cerebrum: large mass of forebrain, consists of two hemispheres

Cerebral cortex: wrinkled surface area (gray matter) of the cerebrum

Corpus callosum: a thick fiber bundle that connects the hemispheres of the cortex

What are the parts of the cerebral cortex?

Frontal lobe: lies to front of the central fissure

Parietal lobe: lies just behind the central fissure

Tempral lobe: lies below the lateral fissure, near the temples of the head

Occipital lobe: lies behind and below the parietal lobe and behind the temporal lobe

Somatosensory cortex: section of cortex, sensory stimulation is projected, lies just behind the central fissure in parietal lobe

Motor cortes: section of cortex, lies in frontal lobe, across the central fissure from sensory cortex. Neural impulses in motor cortex are linked to muscular responses throughout the body

What parts of the cerebral cortex are involved in thinking and language?

Prefrontal region of the brain

Broca’s area, Wernicke’s area, damage to either likely to cause an aphasia (disruption of ability to understand or produce language)

Wernicke’s aphasia: characterized by difficulty comprehending the meaning of spoken language

Broca’s aphasia: language disorder characterized by slow, laborious speech

What would it mean to be “left-brained” or “right-brained”?

Hardly any evidence, functions overlap

Does it matter whether one is left-handed? Why are people right-handed or left-handed?

Left-handedness linked to language problems and health problems, but more artistic and mathematic.

What happens when the brain is split in two?

Epilepsy (temporary disturbances of brain functions, involve sudden neural discharges) sometime fixed with split-brain operations, corpus callosum severed, different sides of brain act independently.

What is the endocrine system?

The body’s system of ductless glands, secrete hormones ( substance secreted by endocrine, regulates various body functions) and release them directly into the bloodstream

Some hormones influence only the pituitary gland (secretes growth hormone, prolactin, antidiuretic hormone, and other hormones)

Growth hormone: pituitary hormone, regulates growth

Prolactin: pituitary hormone, regulates production of milk and maternal behavior (in animals)

Antidiuretic hormone (ADH) conserves body fluids by increasing reabsorption of urine, connected w/ paternal behavior on mammals

Oxytocin: stimulates labor, lactation

Malatonin: pineal hormone, regulates sleep-wake cycle, onset of puberty

Thyroxin: thyroid hormone, increases metabolic rate

Corticosteroids: steroids produced by adrenal cortex, regulates carbohydrate metabolism, increase resistance to stress by fighting inflammation and allergic reactions

Epinephrine: stimulates sympathetic ANS activity

Testosterone: male sex hormone, promotes growth of male sexual characteristics

Estrogen: several female sex hormones

Progesterone: female sex hormones, growth of organs and maintains pregnancy