biology and psychology

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Biology andPsychology

Introduction to Psychology



Questions to keep in mind

How does the brain connect to

explaining human behaviour?

How do biological psychologists breakdown the explanation?

How do neurons and brain activity

affect personality? How does heredity affect behaviour?



Neurons

Neurons: nerve cells

Work like branches, trunks, and roots

Receive messages We are born with more than 100

billion neurons, mostly found in thebrain

Glial cells: cells that nourish andinsulate neurons, direct growth, andremove waste products from thenervous system



Neurons



Neurons

Nucleus at the centre

Dendrites: rootlike structures,

attached to the cell body of theneuron, that receive impulses fromother neurons

Axon: a long, thin part of a neuron that

transmits impulses to toher neuronsfrom branching structures (terminalbuttons)



Neurons

Carry messages in one direction only

From dendrites or cell body through

the axon to the axon terminals Transmitted from terminal buttons to

other neurons, muscles or glands

As the mind ages, messages becomemore complex and axons grow toaccomodate



Neurons

Myelin: fatty substance that encases

and insulates axons, facilitating

transmission of neural impulses Myelin sheath minimises leakage of

the electrical current being carried

along the axon

Myelination is part of the maturationprocess



Neurons

Afferent neurons: transmit messages

from sensory receptors to the spinal

cord and brain (sensory neurons) Efferent neurons: transmit messages

from brain or spinal cord to musclesand glands (motor neurons



Neural impulse

Messages that travel within neurons

Process is electrochemical

Ions-positively and negatively chargedatoms

Difference in charges polarises aneuron

Creating an internal negative chargein relation to the body fluid outside of the cell membrane



Neural impulses

Resting potential

When the neural membrane is not

responding to other neurons

Action potential

Impulse the provides the basis for the

conduction of a neural impulse alongan axon of a neuron



Transmitting messages

Neurons release neurotransmitters

Messages must combine to reach a

threshold in order to fire

Can transmit several hundred

messages each second

All-or-none principle-firing an impulseof the same strength whenever itsaction potential is triggered



Neural impulse

Refractory period: phase following

firing during which a neuron is less

sensitive to messages from other neurons and will not fire

Synapse: junction between the axon

terminals of one neuron and the

dendrites or cell body of other neurons



Neurotransmitters

Chemical substances involved in the

transmission of neural impulses from

one neuron to another Released when a neural impulse

reaches the axon terminal

Receptor site: location on a dendriteof a receiving neuron tailored toreceive a neurotransmitter



Neurotransmitters

Some act to excite other

neurons/cause neurons to fire

Some act to inhibit receivingneurons/prevent neurons from firing

Excess and deficiencies link to

psychological disorders ACh, dopamine, norepinephrine,

serotonin, GABA and endorphins



Types of neurotransmitters

Acetylcholine (Ach): controls musclecontractions

Prevalent in the hippocampus,involved in the formation of memories

Dopamine: affects ability to perceivepleasure, voluntary movement and

learning and memory Involved in Parkinson¶s disease and

schizophrenia



Types of neurotransmitters

Norepinephrine: speeds up theheartbeat and other body processes

and is involved in general arousal,learning and memory and eating

Links to mood disorders

Serotonin: involved in emotional

arousal and sleep Linked to eating disorders, alcoholism,

depression, aggression and insomnia



Types of Neurotransmitters

Gamma-aminobutyric acid (GABA):inhibitory neurotransmitter that helps

calm anxiety Endorphins: composed of amino acids

and are functionally similar tomorphine

Increase sense of competence,enhance functioning of immunesystem



Part of the Nervous system

Brain, spinal cord, and the nerves

linking them to the sensory organs,

muscles and glands Central nervous system (CPU): brain

and spinal cord

Peripheral nervous system: sensoryneurons and motor neurons



Nervous system

Somatic nervous system: sensory and

motor neurons that transmit messages

about sights, sounds, smells, temperature,body positions to the CPU

Autonomic nervous system (ANS):

regulates the glands and muscles of internal

organs

Controls activities such as heartbeat,respiration, digestion, and dilation of pupils



Nervous Systems

ANS

Sympathetic: most active during

emotional responses i.e. fear andanxiety

Parasympathetic: most active during

processes that restore the body¶s

reserves of energy



Central Nervous System

Spinal cord: column of nerves within the

spine that transmits messages from sensory

receptors to the brain and from the brain tomuscles and glands

Spinal reflex: a simple unlearned response

to a stimulus that may involve only two

neurons

Gray matter: in the spinal cord, neural

segments that are involved in spinalreflexes



CNS

White matter: axon bundles that carry

messages from and to the brain

We have many reflexes

Controlled and uncontrolled

Determine scientific human bodily

responses and behaviours



The Brain

Electroencephalograph (EEG): method of

detecting brain waves by means of

measuring the current between electrodesplaced on the scalp

Brain imaging techniques

CAT scan

PET scan MRI

fMRI



Parts of the human brain



The Limbic system



Cerebral Cortex



Left Brain-Right Brain

Right-brained: intuitive, creative, andemotional

Left-brained: intellectual undertakingsthat require logical analysis andproblem solving, language, andmathematical computation

Epilepsy: temporary disturbances of brain functions that involve suddenneural discharges



Endocrine system

Body¶s system of ductless glands that

secrete hormones and release them

directly into the blood-stream Duct: a passageway that carries

substances to specific locations

Hormones: substance secreted by anendocrine gland that regulates variousbody functions



Master and commander

Pituitary gland: secretes growth

hormone, prolactin, antidieretic

hormone, and other hormones Hypothalamus: secretes hormones

that stimulate secretion of hormones

by the pituitary gland; involved in

basic drives i.e. hunger, sex, andaggression



Evolution and heredity

Darwin¶s struggle for existence, survival of

the fittest

Natural selection: holds the adaptivegenetic variations among members of a

species enable individuals with those

variations to survive and reproduce

Instinct: stereotyped pattern of behaviour that is triggered by a particular stimulus



Heredity

Transmission of traits from parent to

offspring by means of genes

Genetics: the area of biology thatfocuses on heredity

Looks at both species-specific

behaviour patterns and individual

differences among the members of aspecies



Cells, chromosomes and

DN A



Genetics

Kinship studies

Determine influence of genetic and

environmental factors

Twin studies

Monozygotic twins MZ

Dizygotic twins DZ

Adoption studies Selective breeding: to achieve desired

traits

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