Biological Aspects of Psychology PDF

WEEK 2 – BIOLOGICAL ASPECTS OF PSYCHOLOGY Biological psychology – the psychological speciality focused on the physical and chemical changes that cause, and occur in response to, behaviour and mental processes All behaviour and mental processes are based on biological processes. All b...

WEEK 2 – BIOLOGICAL ASPECTS OF PSYCHOLOGY Biological psychology – the psychological speciality focused on the physical and chemical changes that cause, and occur in response to, behaviour and mental processes All behaviour and mental processes are based on biological processes. All biological processes are influenced by enviornment. Nervous system – an enormous and complex combination of cells that allows an organism to gain information about what is going on inside and outside the body and respond appropriately Main functions of nervous system: recieve information (input_, integrate that information with past experiences (processing) and guide actions (output) Neurons – fundamental units of the nervous system; nerve cells Glial cells – cells in the nervous system that hold neurons together and help them communicated with one another. Without glial cells, neurons could not function. Common features of neurons Neurons have an outer membrane, nervous system cells have a cell body that contains the nucleus, nervous system cells contain mitochondria. Structure of neurons Axons – fibres that carry signals from the body of a neuron out to where communication occurs with other neurons Dendrites – neuron fibres that receive signals from the axons of the other neurons and carry those signals to the cell body Synapses – the tiny gaps between neurons across which they communicated Action potential – an abrupt wave of electrochemical changes travelling down an axon when a neuron becomes depolarised. A neuron has ‘fired’. Speed relies on myelin The neurons cell membrane lets some chemical ions pass through but blocks others. These ions are atoms that carry a positive or negative elctrical charge. Ions with a positive charge are attracted to those with a negative charge. When a neuron is polarised, the inside of the cell is more negatively charged than the outside When a neuron is depolarised, the negative charge inside the cell becomes less negative or even positive Myelin – a fatty substance that wraps around some acons and increases the speed of action potential Nodes of ranvier – gaps in the myselin sheath that allow the action potential to be propagated and regenerated. Refractory period – A short rest period between action potentials Synapses and communication between neurons Neurotransmitters – chemicals that assist in the transfer of signals from one neuron to another Neural receptors – specialised cells that detect certain forms of energy and transduce them into nerve cell activity. A neurotransmitter binds to its own receptors. When a neurotransmitter binds to a receptor, it stimulates channels in the membrane of the postsynaptic cell to open, allowing chemical ions to flow in or out. The flow of these ions into and out of the postsynaptic cell produces change in its membrane potential. The chemical signal that crosses the synamse creates an electrochemical signal in the postsynaptic cell. Excitatory and inhibitory signals Postsynaptic potential – The change in the membrane potential of a neuron that has receive stimulation from another neuron Excitatory postsynaptic potential – a postsynaptical potential that depolarises the neuronal membrane, making the cell more likely to fire an action potential Inhibitory postsynaptic potential – a postsynaptical potential that hyperpolarises (slightly more polarised) the neuronal membrane, making a cell less likely to fire an action potential Part Function Type of signal carried Axon Carries signals away from theThe action potential, an all or cell body nothing electrochemical signal that shoots down the axon, releasing neurotransmitters Dendrite Detects and carries signals toThe postsynaptic potential, he cell body an electrochemical signal moving towards the cell body Neurotransmitter A chemical released by one A chemical message telling cell that binds to the he next cell to fire or not fire receptors on another cell ts own action potential Receptor Protein on the cell membraneRecognises certain receives chemical signals neurotransmitters, allowing it o begin a postsynaptic potential in the dendrite Synapse Provides an area for the Chemicals that cross the ransfer of signals between synapse and reach receptors neurons, usually between theon another cell axon of one cell and the dendrite of another Organisation and functions of the nervous system Neural networks – neurons that operate together to perfrom complex functions Peripheral nervous system Subsystem Characteristics Somantic nervous system Transmits information from the senses to the CNS and carries signals from the CNS to the muscles Sensory neurons – cells in the nervous system that provide nformation to the brain about the enviornment Motor neurons – cells in the nervous system that the brain uses to influence muscles and other organs to respond to he environment Autonomic nervous systemCarries messages between the CNS and the heart, lungs and other organs Sympathetic nervous system – readies the body for vigorous activity. ‘fight or flight’ Parasympathetic nervous system – influences activity related to protection. ‘rest and digest’ Central nervous system Spinal cord – relays signals from the peripheral senses to the brain and conveys messages from the brain to the rest of the body In the spinal cord, sensory neurons are called afferent neurons Motor neurons are called efferent neurons Reflexes – involuntary unlearnt behaviours directed by the spinal cord without instructions from the brain Brain Hindbrain – an extension of the spinal cord contained inside the sckull where nuclei control blood pressure, heart rate, breathing and other vital functions, particularly occurs in the medulla oblongata Reticular formation – a collection of cells and fibres in the hindbrain and midbrain that are involved in arousal and attention Locus coeruleus – small nucleus in the reticular formation that is involved in attention Cerebellum – the part of the hindbrain whose main functions include controlling finely coordinated movements and storing memories about movement. Midbrain – relays information from the eyes, ears and skins and controls certain types of automatic behaviours Forebrain – highly developed part of the brain that is responsible for the most complex aspect of behaviour and mental life Thalamus – a forebrain structure that relays signals from most sense organs to higher levels in the brain and plays an important role in processing and making sense out of this information Hypothalamus – a structure in the forbrain that regulates hunger, thirst and sex drive Amygdala – a structure in the forebrain that among other things is critically involved in dear and reward learning Hippocampus – a structure in the forebrain associated with the formation of new memories Limbic system - a set of brain structures that play important roles in regulating emotion and memory Cerebral hemisphere – the left and right halves of the outermost part of the brain Cerebral cortex – the outer surface of the brain Sensory cortex – the parts of the cerebral cortex that receive stimulus information from the senses Visual information is received by the visual cortex, made up of cells in the occipital lobe Auditory information is received by the auditory cortex, made up of cells in the temporal lobe Skin, touch, pain and temperature is received in the somatosensory cortex, made up of cells in the parietal lobe Motor cortex - in the frontal lobe, the part of the cerebral cortex where neurons control voluntary movements in specific parts of the body Association cortex – the parts of the cerebral cortex that receive information from more than one sense or that combine sensory and motor information to perform complex cognitive tasks Corpus callosum – fibres that connect the right and left cerebral hemispheres and allows them to communicate with each other Lateral dominance (lateralisation) - the tendency for one cerebral hemisphere to excel at a particular function compared to the other hemisphere. Neural plasticity –the ability to create new synapses and to change the strength of synapses Brain divisions mportant structures Hindbrain Cerebellum – controls fine movements and coordinates cognitive porcesses Medulla oblongata – Regulates breating, heart rate and blood pressure Reticular formation – regulates arousal and attention Midbrain Substantia nigra – initiates smooth movements Various nuclei – Relay sensory signals to forebrain; create automatic responses to certain stimuli Forebrain Amygdala – Connects sensations and emotions Cerebral cortex – Analyses sensory information; controls voluntary movements, abstract thinking and other complex cognitive activity Corpus callosum – Transfers information between the two cerebral hemispheres Hippocampus – Forms new memories Hypothalamus – regulates hunger, thirst and sex drive Thalamus – Interprets and relays sensory information Neurotransmitters Neurotransmitter Normal function Disorder Acetylcholine Memory, movement Alzheimers disease Norepinephrine Mood, sleep, learning Depression Seretonin Mood, appetite, impulsivity Depression Dopamine - Movement, reward Parkinsons, schizophrenia GABA - inhibitory Sleep, movement Anxiety, epilepsy Glutamate - excitatory Memory Damage after stroke. Endorphins – a class of neurotransmitters that bind to opiate receptors and moderate pain Endocrine system Aspect Role Hormones Provide feedback to the brain and to the pituitary gland; this is a negative feedback system. Endocrine organs release hormones into blood stream System as a whole Regulates functions ranging from stress to physical growth Made up of glands that communicate with each other via hormones The brain Has ultimate control over the secretion of hormones Governs stress reactions like fight or flight Neurons and neurotransmitters are commincation chemicals used within the human system and affect behaviour and mental processes QUESTIONS For one neuron to communicate with another, a neurotransmitter has to cross the synapse between them The nervous system's main functions are to receive, process, and transmit information The two types of cells in the nervous system are neurons and glial cells The peripheral nervous system sends sensory information from the eyes, ears, and other sense organs to the central nervous system The somatic nervous system transmits information from the senses to the central nervous system and then carries signals from the central nervous system to the muscles that move the skeleton The autonomic nervous system carries messages back and forth between the central nervous system and the heart, lungs, and other organs and glands. The oldest part of the brain is the brainstem Memory problems seen in Alzheimer's disease are related to the shrinkage of the hippocampus The main neurotransmitter for slowing or inhibiting brain activity is GABA (gamma-aminobutyric acid A group of neurons that use the same neurotransmitter is called a neural pathway or neurotransmitter system The neurotransmitter glutamate can cause brain damage during a stroke Neurons and neurotransmitters are communication chemicals used within the human system and affect behavior and mental processes The pituitary gland releases adrenocorticotropic hormone (ACTH), which causes the adrenal glands to release the hormone cortisol into the bloodstream.