Textbook Notes (363,144)
Canada (158,220)
York University (12,357)
Psychology (3,541)
PSYC 1010 (1,075)
Chapter 3

Chapter 3 Notes

11 Pages
Unlock Document

York University
PSYC 1010
Rebecca Jubis

Chapter 3 The Biological Bases of Behaviour Communication in the Nervous System (NS) - Nervous system = complex communication network in which signals are constantly being transmitted, received and integrated o Handles information Nervous Tissue: The Basic Hardware - Two categories of cells in the nervous system: o Neurons individual cells that receive, integrate and transmit information Mostly communicate only with other neurons, small amount receive/carry out messages from outside the NS Common features: Soma/cell body contains the nucleus and most of the chemical machinery common to cells Dendrite (one branch of a dendrite tree) are specialized to receive info Axon long, thin fibre that transmits signals away from the soma to other neuron/muscles/glands o Myelin sheath insulating material encasing some axons, speeds up transmission of info, degeneration leads to decrease in transmission efficiency (ex: multiple sclerosis) Terminal buttons secrete chemicals called neurotransmitters which transmit info from one neuron to another Synapse junction where info is transmitted from one neuron to another o Glia (glue) provide various types of support for neurons Smaller but more ample than neurons by 10 to 1 (50% of brains volume) Supply nourishment to neurons, remove their waste products, provide insulation around axons (myelin sheaths derived from these) May also send and receive chemical signals (can to other glial cells) Deterioration = memory loss (Alzheimers), psych/mood disorders The Neural Impulse: Using Energy to Send Information The Neuron at Rest: A Tiny Battery - Hodgkin and Huxley: studied squids because they have giant axons o Neural impulse = complex electrochemical reaction o Charged ions = in/outside of neurons, Na+, K+ and Ca- move through semipermeable membrane but at different rates Leads to more (-) ions in the inside = resting potential of a neuron: stable (-) charge when cell is inactive The Active Potential - Voltage of neuron constant = no messages being sent o When stimulated channels in membrane open, Na+ rushes in, making it positive for an instant creates an action potential (brief shift in a neurons electrical charge that travels along an axon) Voltage spikes Channels close absolute refractory period: minimum length of time after an action potential during which another action potential cannot begin 1-2 millisecs Followed by a relative refractory period where more intense stimulation is required to get an action potential because the threshold has been elevated The All-or-None Law - Neuron either fires an action potential (all are the same size) or not - Neurons can control the rate they fire action potentials at o Ex: stronger stimulus/thicker axons = more rapid firing The Synapse: Where Neurons Meet Sending Signals: Chemicals as Couriers - Two neurons = separated by a synaptic cleft (gag between the terminal button of one neuron and the cell membrane of another o Neuron that sends message across the gap = the presynaptic neuron o Neuron that receives it = the postsynaptic neuron - Messages travel across the gap when action potentials release neural transmitters (stored in synaptic vesicles) and diffuse across the synaptic cleft to the membrane of the postsynaptic neuron and bind at the receptor sites there o Receptor sites respond the some neurotransmitters but not others Receiving Signals: Postsynaptic Potentials - Reaction between neurotransmitter and receptor site causes a postsynaptic potential (PSP) a voltage change at the receptor site - PSP do not follow the all-or-none principle o Vary in size, increase/decrease the probability of a neural impulse in the receiving cell depending on the voltage change - 1 of 2 types of messages can be sent from cell to cell depending on which receptor sites are activated: o Excitatory PSP positive voltage shift that increases the likelihood that the postsynaptic neuron will fire action potentials o Inhibitory PSP negative voltage shift that decreases the likelihood that the postsynaptic neuron will fire action potentials Effects produced last a fraction of a second until reuptake (neurotransmitters being sponged up from the synaptic cleft by the presynaptic neuron) occurs Integrating Signals: Neural Networks - State of a neuron is a weighted balance between excitatory and inhibitory influences (signals are integrated)o Lots of excitatory = buildup of electrical potential and possible action potential firing o Lots of inhibitory = cancel effects of excitatory PSP - Our thoughts/actions depend on patterns of neural activity in complex networks (cell assemblies) o New synaptic connections are made while old ones die off - Synaptic pruning: NS forms more synapses than you need when you are really young then gradually eliminates that less active ones o Therefore - elimination of synaptic connections = more important in the sculpting of neural networks than the creation of new ones - Hebbian Learning Rule: when one neuron stimulates another repeatedly, the synapse changes and learning has taken place Neurotransmitters and Behaviour - Neurotransmitters = fundamental to behaviour (muscle movements, mental health, mood) o 9 well-established, classical ones plus others o Cannot bind to any site, needs to fit the receptor for binding to occur Each only woks at specific synapses, makes communication more precise Acetylcholine (Ach) - Only transmitter between motor neurons and voluntary muscles - Contributes to attention, ar
More Less

Related notes for PSYC 1010

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.