Week 2 - Biological Psychology Flashcards
The nervous system is composed of a vast network of nerve pathways and structures that mediate all aspects of being a human being which include:
Motor activity Cognitive activity Sensory and perceptual activity Emotional and behavioural activity Physiological activity
Describe the nervous system
Provides the biological basis, or substrate, for psychological experience
Define the central nervous system and it’s parts
Directs psychological and basic life processes, responds to stimuli.
Parts of the CNS:
Spinal cord: received sensory input, sends information to the brain, responds with motor output.
Brain: directs psychological activity processes information, maintains life support.
Define the peripheral nervous system and describe its parts
Carries information to and from the central nervous system
Part of the PNS:
Somatic nervous system: conveys sensory information to the central nervous system and sends motor messages to muscles. Transmits commands to voluntary skeletal muscles and receives information from muscles and skin.
Autonomic nervous system: serves basic life functions, such as beating of the heart and response to stress. Sends and receives info from the glands and organs of the body.
Parts of the autonomic nervous system:
Sympathetic nervous system: readies the body in response to threat, activated the organism.
Parasympathetic nervous system: calms the body down, maintains energy.
Define neurons
Cells of the nervous system specialised for receiving and transmitting electrochemical signals.
Send and receive messages from the body to the brain and vice versa by dispersing chemicals called neurotransmitters.
Approx 85 billion in brain alone, each connecting with 10,000s other neurons on average.
Various shapes, lengths and types.
Different types of neurons have specific functions or send/receive specific messages.
Parts of a neuron (top down)
Dendrites Cell body Nucleus (has genetic information, DNA, chromosomes) Axon hillock Axon body Myelin sheath Node of ranvier Collateral branches Terminal buttons
Nerve impulse direction is downward
Describe glial cells
Variety of shapes, sizes and roles
Okay a supportive role to neurons:
-repair following injury
- clear up debris
- prevent some substances from entering brain (blood-brain barrier) stops harmful bacteria
- insulate neuron axons (on the myelin sheath)
Describe the resting potential of a neuron
In its resting state the fluid environment outside the axon is more positively charged than the inside. It’s somewhat like a small battery with an electrical potential of approximately-60mV.
What are graded potential in neural transmission?
Graded potentials (post synaptic potentials) are electrical charges caused by neural signals arriving from the axons of other cells. These can be either
Excitatory - membranes potential becomes more positive and closer to the threshold (depolarisations) - more likely to fire.
Inhibitory - membrane potential becomes more negative and further away from the threshold - less likely to fire.
These are summed at the axon hillock, and if the threshold of excitation is reached (~-55mV), an action potential is triggered (the nerve cell fires!!)
Describe some features of action potentials
They’re all or none
Uniform in size (not graded)
Travel the length of the axon in one direction
Entire process (AP) takes 1-2ms
Neurons can fire up to 100-1000 per second
What the absolute refractory period?
Brief period of time when another action potential cannot occur.
Describe synaptic transmission (when nerve impulses travel down the axon to the axon terminal):
Synaptic vesicles (with neurotransmitter molecules inside) head toward the synapse. Then the neurotransmitter molecules get released into the receptor site.
Describe the processes involved in synaptic transmission:
- Neurotransmitters are encased in vesicles in the axon terminals.
- When an AP is triggered in pre synaptic neuron, NTs are released into the synaptic cleft.
- The NTs attach to receptors (on the dendrites or cell body of the other cell) and produce a graded potential in the post synaptic neuron.
- The neurotransmitter is inactivated (released) from receptor and taken back into the pre synaptic cell (reuptake), or broken down by enzymes in synaptic cleft, or drift away.
What does it mean when said that the chemical process of synaptic transmission is very precise?
Only one type of neurotransmitter can stimulate a specific post-synaptic receptor site.
Only one type of receptor site can accept a specific neurotransmitter.
(Seratonin to a serotonin receptor site)
What’s an excitatory neurotransmitter?
Cause depolarisation (or an excitatory graded potential), increasing probability of and action potential.
What’s an inhibitory neurotransmitter?
Cause hyperpolarisation (or an inhibitory graded potential), reducing probability of an action potential.
Often neurotransmitters can either be inhibitory or excitatory depending on location/pathway.
What is glutamate?
The main excitatory transmitter in CNS. Involved in learning, memory and transfer of sensory input.
-alcohol and memory enhancers interact with some glutamate receptors (NMDA receptors)
What is GABA?
The main inhibitory transmitter in CNS. Dampens neural activity. Involved in learning, memory and sleep
-alcohol and anti-anxiety drugs increase GABA activity
What is acetylcholine (ACh)?
Involved in muscle contraction (PNS), cortical arousal (CNS) including aspects of selective attention, sleep and memory.
-nicotine increases ACh, Botox blocks ACh.
What is noradrenaline (aka norepinephrine)
Involved in cortical arousal and autonomic nervous system activity
-(meth)amphetamine increases noradrenaline
What’s dopamine?
Motor function and reward (eg food, sex, psychoactive drugs, gambling)
- increases levels associated with schizophrenia
- reduces levels associated with Parkinson’s disease
- drugs of dependence/ rewards increase dopamine
What is seratonin?
Involved in cortical arousal, mood, sleeping, eating
- SSRIs used to treat depressions increase serotonin
- ecstasy (MDMA) increases serotonin
What’re endorphins?
Involved in pain control and mood elevations (euphoria) Eg runners high
- sometimes referred to as ‘endogenous opioids’
What is anandamide?
Associated with pain control, eating behaviour, motivation, memory and sleep
-endogenous cannabinoid
What’s a psychoactive drug?
Any drug (prescribed or illicit) that interacts with the neurotransmitter system and affects mood, arousal and behaviour.
What are agonists?
Enhance the effect of a neurotransmitter, either by increasing the amount and release, or by mimicking it and binding to receptors
- morphine: binds to endorphin receptors to reduce pain
- Prozac (SSRIs): reduces serotonin reuptake, increasing its availability
What’re antagonists?
Inhibit the effect of a given neurotransmitter, either by reducing the amount and release or by blocking the receptors
- Botox: blocks release of acetylcholine, thereby stopping its effect on muscles. Reduces tremors (and wrinkles)
- antipsychotics: block dopamine receptors, reducing action of dopamine
Detection of threat (real or perceived) to individual organism, results in:
- Activation of the sympathetic system: stimulates peripheral organ and musculature response.
- increased breathing and heart rate
- digestion / salivation inhibited
- pupil dilation
- bladder/ vowel relaxation
- hair stands erect - Response: theatre is appropriately responded to (flight or fight) or our perception changes
- Activation of the parasympathetic branch:
Decrease the activation state of the peripheral organs and musculature, resorting normal levels of function
Useful in some situations, but not always (panic attacks)
What’s the endocrine system?
System of glands that control vital functions (eg growth, metabolism, cardiovascular function, reproduction)
What’re hormones?
Chemicals released into bloodstream by endocrine glands.
- hormones travel through the bloodstream and bind to cell receptor sites in organs of body (allow a global response)
- similar actions and roles (and in some cases molecular structure) as neurotransmitters in the CNS.
Name parts of the endocrine system?
Hypothalamus: regulates both the ANS and endocrine system (but activating the pituitary gland).
Pituitary gland (master gland) -releases hormones which have a direct effect, or which activate glands further down the chain.
Oxytocin (‘love molecule’): involved in birth contractions, milk production, maternal/ romantic love, interpersonal trust.
Describe the HPA axis (endocrine system - hypothalamus, pituitary gland and adrenal cortex)
Worlds in conjunction with sympathetic system to respond to stress.
Adrenal glands: release adrenaline and cortisol, triggering (or maintaining) flight or fight response.
Designed for immediate action. When chronically activated (via HPA axis), can lead to long term health problems.
Describe some other glands involved with the endocrine system:
Thyroid gland: releases growth and metabolism hormones.
Hyperthyroidism can be associated with fatigue and depression m.
Pancreas: controls blood sugar level (produces insulin).
Gonads (testes/ovaries): release sex hormones (estrogen/testosterone).
During an action potential, what flows in and out?
Positive ions flow in (sodium) and negative ions flow out (potassium)
