Basic definitions (all topics)

Question 1

define axonal transport

Answer 1

transport of proteins from where they are made in the nucleus/cell body, to the terminal boutons of the axon where they are needed - for example neurotransmitters. this is done by the molecule kinesin ‘walking’ down the cytoskeleton of the neuron.

Question 2

define resting membrane potential

Answer 2

the relative charge across the membrane of a neuron (sits at -70mv)

Question 3

define graded potential

Answer 3

a localised change in the membrane potential of a neuron. these can be hyperpolarisations or depolarisations and depend on the strength of the incoming stimuli (hence they are graded)

Question 4

define action potential

Answer 4

a wave of negative electrical excitation (depolarisation) that travels down the axon of a neuron. they are unidirectional and are all or nothing events, unlike graded potentials which can vary in strength.

Question 5

define depolarisation

Answer 5

a change in membrane potential that gets less negative (closer to 0)

Question 6

define hyperpolarisation

Answer 6

a change in membrane potential that gets more negative (further away from 0)

Question 7

define saltatory conduction

Answer 7

this is the way that an action potential travels down a myelinated axon, whereby depolarisation only occurs in non-myelinated gaps called nodes of Ranvier. this speeds up the conduction of an action potential as less voltage gated channels have to open along the length of the axon.

Question 8

define synaptic delay

Answer 8

communication at a chemical synapse is slower than the propegation of action potentials as chemicals must diffuse across the synaptic cleft which takes time. this slows nervous communication down as synaptic transmission takes 0.3-5ms to happen.

Question 9

define neuroglia

Answer 9

neuroglia or glial cells are the support cells of the nervous system. they perform many different roles, including providing neurons with nutrients and maintaining the chemical environment. they also create myelin sheaths etc.

Question 10

define neuropraxia

Answer 10

a category of nerve damage whereby nerves are compressed or stretched but remain in tact. this type of injury may result in temporary loss of sensation or function but will return once the source of the compression or stretch is removed.

Question 11

define axonotmesis

Answer 11

a category of nerve damage where individual axons within a nerve are broken but the nerve itself (connective tissues etc) remains in tact. this will cause temporary loss of function or sensation but will usually heal and this will be restored after time

Question 12

define neurotmesis

Answer 12

a category of nerve damage where an entire nerve is severed. this is a severe injury, leads to distal loss of sensation and function that is likely to be permanent. some healing may occur but this can be complex and also lead to pain.

Question 13

define ischemic damage

Answer 13

damage caused to a nerve due to lack of oxygen supply. this leads to cellular respiration stopping. no cellular respiration leads to the cell depolarising and an influx of calcium ions. these ions cause excitotoxicity.

Question 14

define excitotoxicity

Answer 14

prolonged exposure to excitatory neurotransmitters such as glutamate can lead to a cascade of neurotoxicity which leads to loss of function or cell death

Question 15

define myofibril

Answer 15

an organelle within a muscle cell that is made up of end to end sarcomeres which are the contractile elements of muscle cells.

Question 16

define sarcomere

Answer 16

a contractile unit of a muscle cell, it is the space between two adjacent z discs. it consists primarily of thin filaments (actin) and thick filaments (myosin)

Question 17

define sarcoplasmic reticulum

Answer 17

an elaborate smooth endoplasmic reticulum found only in muscle cells. it stores and releases calcium ions

Question 18

define terminal cisterns

Answer 18

large sarcoplasmic reticulum channels at the junction of the I and A bands of a myofibril

Question 19

define T tubules

Answer 19

at each I-A band junction the sarcolemma of the cell protrudes deep into the cell interior, forming an elongated tube called the T tubule. it is flanked by two terminal cisterns

Question 20

define T tubule Triad

Answer 20

a t tubule flanked by two terminal cisterns

Question 21

define end plate potential

Answer 21

the binding of ACh to a receptor on the sarcolemma at a neuromuscular junction causes a local depolarisation (like a graded potential) which in a muscle is called an end plate potential

Question 22

define excitation-contraction coupling

Answer 22

the process just before muscle contraction can start. it involves ca2+ being released at the terminal cisterns. Ca2+ then binds to troponin, which shifts tropomyosin out of the way of the myosin binding site on actin. once this shift has occurred a myosin head can bind to actin.

Question 23

define cross bridge cycling

Answer 23

the process of muscle contraction itself. myosin head binds to actin, it releases ADP and P as it shift back, bringing the actin filament closer to the M line of the sarcomere. ATP is then added, myosin head detaches. as it returns to its ‘ready’ position it hydrolyses ATP to ADP and P and is energised so it can re bind to the next section of actin.

Question 24

define motor unit

Answer 24

all the muscle fibres innervated by one motor neuron. they can be small (and therefore engaged when small contraction is needed), medium or large (engaged when maximum effort is required)

Question 25

define frequency coding

Answer 25

as the frequency of action potentials increases, the muscle doesn't have time to relax in between stimuli and therefore it remains contracted

Question 26

define decussation

Answer 26

crossing the midline of the body (in relation to spinal tracts)

Question 27

define memory

Answer 27

the acquisition, encoding, storage and retrieval of information in the nervous system

Question 28

define declarative memory

Answer 28

consciously accessible information such as facts and figures

Question 29

define non-declarative memory

Answer 29

unconscious information including procedural memory (motor learning)

Question 30

define anterograde amnesia

Answer 30

memory disorder characterised by a lack of ability to form new long term memories, but older memories are easily accessible

Question 31

define retrograde amnesia

Answer 31

memory disorder characterised by a lack of ability to recall older long term memories but the ability to form new short term memory is in tact.

Question 32

define long term potentiation

Answer 32

the process by which one time maximal stimulation of a neuron (in the hippocampus if to do with memory but also occurs at spinal level in spinal hyperexcitability) causes the neuron to become more sensitive to a normal level of stimulus. this is done through the activation of/unblocking of NMDA receptors, which allow calcium ions into the cell which start a complex intracellular cascade.

Question 33

define learning

Answer 33

a relatively permanent change in behaviour or knowledge occurring as a result of experience

Question 34

define classical conditioning

Answer 34

learning through association

Question 35

define operant conditioning

Answer 35

learning through consequences (positive or negative reinforcements and punishment)

Question 36

define observational learning

Answer 36

learning through others

Question 37

define avoidance learning

Answer 37

learning a behaviour in order to avoid a negative stimulus (involves principles of classical and operant conditioning)

Question 38

define pain

Answer 38

originally = a response to a painful stimuli now = a subjective experience that is unique to the individual, exists where the person says it does, and is also an interaction between biological, psychological and social factors.

Question 39

define pain catastrophising

Answer 39

negative cognitive-affective response to actual or anticipated pain. irrationally negative forecast of events and negative cognitive schema of pain

Question 40

define nociception

Answer 40

the process of encoding noxious stimuli

Question 41

define peripheral sensitisation

Answer 41

when long term damage is experienced, free nerve endings release substance P. substance P causes vasodilation and neurogenic inflammation. however it also causes mast cells to release more histamine, which in turn activates the free nerve endings - it becomes a cycle of increased sensitisation to histamines and other early activators of free nerve endings.

Question 42

define spinal hyperexcitability

Answer 42

also known as central sensitisation and follows the process of long term potentiation whereby a large stimulus causes not just AMPA receptors but also NMDA receptors to open, which leads to Ca2+ entering the cell and an intracellular cascade which leads to heightening the sensitivity of AMPA receptors and the development of more AMPA receptors. making the neuron more responsive to lower level stimuli.

Question 43

define referred pain

Answer 43

pain experienced in an area of the body where the source of pain is not - this arises from pre-natal development/embryonic growth where the nervous system begins to form before the anatomical layout of the body is finalised/as it is when we are born. for example the diaphragm begins to form in the neck, so pain can be felt in the neck when the diaphragm is the biological source of nociceptive signals.

Question 44

define the pain gate

Answer 44

an inhibitory interneuron sits in the spine thats role is to inhibit the second order neuron. when nociceptive signals are sent through one adjacent fibre, this inhibits the inhibitory neuron. however when simultaneous mechanoreceptive signals are sent through an adjacent mechanoreceptor, the inhibitory neuron is switched back on so that nociceptive signals are blocked at the second order neuron. this explains 'rub it better'

Question 45

define neuropathic pain

Answer 45

damage to the somatosensory system resulting in pain perception without current physical cause.

Question 46

define hyperalgesia

Answer 46

increased sensitivity following tissue injury. primary = local to site of damage. secondary = extending to the surrounding 'undamaged' areas.

Question 47

define allodynia

Answer 47

increased sensitivity to non-noxious stimuli following severe tissue injury. central mechanism whereby microglia switch inhibitory input to excitatory

Question 48

define proprioception

Answer 48

knowledge of the position of the body without visual information.

Question 49

define proprioceptive deafferentation

Answer 49

no afferent proprioceptive information reaches the brain. this leads to symptoms such as poor balance, uncoordinated movement and poor postural control

Question 50

define pharmacokinetics

Answer 50

what the body does to a drug i.e. metabolism, absorption processes

Question 51

define pharmacodynamics

Answer 51

what the drug does to the body i.e. drug-receptor interactions

Question 52

define a drug

Answer 52

a chemical substance of known structure which when administered to a living organism, has a biological effect

Question 53

define a medicine

Answer 53

usually, one or more drugs combined and administered to achieve therapeutic effect. not all drugs are medicines. they aim to prevent disease or restore/modify physiological function. they can also be used to make a medical diagnosis

Question 54

define therapeutics

Answer 54

the use of drugs to diagnose, prevent and treat illness (or pregnancy)

Question 55

define formulations

Answer 55

how an active drug is combined with other substances to produce a medicine

Question 56

define excipients

Answer 56

substances formulated alongside a drug i.e. bulking agents, preservatives, coatings etc.

Question 57

define ligand

Answer 57

a molecule that binds to a receptor (can be endogenous or exogenous, synthetic or natural) common examples include drugs and neurotransmitters

Question 58

define receptor

Answer 58

a molecular target for a drug

Question 59

define agonist

Answer 59

a molecule that activates a receptor

Question 60

define antagonist

Answer 60

a molecule that blocks or reverses/dampens the action of an agonist

Question 61

define target

Answer 61

a molecule, usually a protein, that is accessed by a drug to produce a therapeutic effect

Question 62

define affinity

Answer 62

how well a ligand binds to a receptor. very strong affinity may lead to irreversible binding.

Question 63

define steric properties

Answer 63

physical, 3D shape properties of a receptor and a ligand that determine how well they bind

Question 64

define pharmacogenetics

Answer 64

the effect of genetics on how the body responds to drugs. (genetics determines production of proteins, proteins determine drug action)

Question 65

define allosteric agonists

Answer 65

agonists that bind to somewhere on a receptor other than the original ligands binding site. this often changes the shape or charge of the binding site itself and leads to an inability for the intended ligand to bind to the receptor

Question 66

define orthosteric agonists

Answer 66

agonists that bind to the original binding site in place of the intended ligand on the receptor, blocking the intended ligand

Question 67

define a G protein linked trans-membrane receptor

Answer 67

these are receptors that sit within/across the length of the cell membrane. when the receptor is triggered (through ligand binding) the shape of the receptor is altered. this triggers the activation of G proteins which then start a complex intracellular cascade which have man intracellular effects including altering cellular excitability

Question 68

define pro-drug

Answer 68

a drug that is not active until it has been metabolised by enzymes (usually in the digestive system during first pass metabolism).

Question 69

define absorption

Answer 69

the process by which a drug reaches systemic circulation

Question 70

define enteral administration

Answer 70

administration of a drug via the gut i.e. ingesting a tablet

Question 71

define parenteral administration

Answer 71

administration of a drug not via the gut i.e. injection or topical administration

Question 72

define first pass metabolism

Answer 72

metabolism of a drug that occurs in the intestine or liver before it reaches systemic circulation. this leads to reduced bioavailability of the drug

Question 73

define bioavailability

Answer 73

the proportion of an active drug that is free to bind to its target. it is affected by the route of administration and formulation of the drug

Question 74

define protein binding (in relation to drug distribution)

Answer 74

drugs in the blood stream are either free/unbound or bound to plasma proteins (this is a dynamic and reversible process). only free/unbound drugs can enter cells or bind to receptors.

Question 75

define metabolism (of a drug)

Answer 75

the process of breaking down a drug so it is fit for excretion. phase I = often produces toxic metabolites (usually done by cytochrome P450 enzymes in the liver, involves changing the chemical structure of a drug through processes such as oxidation) Phase II = the addition of an endogenous substance (conjugation via covalent bonding) to produce a non-toxic conjugate that can be excreted.

Question 76

define biliary excretion

Answer 76

excretion via the gut... in the form of faeces

Question 77

define drug half life

Answer 77

the amount of time it takes for the bioavailability of a drug to half. there are usually about 4/5 half lives before there is a non-therapeutic dose of the drug left in the body

Question 78

define NSAIDs

Answer 78

non-steroidal anti-inflammatory drugs that are widely used to reduce pain, fever and swelling

Question 79

define analgesic

Answer 79

a drug that relieves or reduces the experience of pain.

Question 80

define the arachidonic acid cascade

Answer 80

the method of action for NSAIDs whereby arachidonic acid (produced by phospholipase A2) is converted by COX enzymes into prostanoids such as prostoglandin. NSAIDs block the action of COX enzymes.

Question 81

define paracetamol

Answer 81

an analgesic drug that is similar to, but not technically an NSAID. its action within the body is poorly understood but it may inhibit COX 2 centrally. its metabolite after phase I metabolism (NAPQI) is toxic, so a limited dose of 4g per day can be taken.

Question 82

define opioid

Answer 82

a compound resembling opium in its physiological effects.