Nervous Co Ordination And Muscles

Question 1

Acetylcholine

Answer 1

A type of neurotransmitter that is used for communication between neurones

Question 2

Actin

Answer 2

A type of protein filament found in myofibrils . It forms thin filaments consisting of 2 long twisted chains

Question 3

Action potential

Answer 3

The temporary change in electrical potential across the membrane of an axon in response to the transmission of a nerve impulse

Question 4

All or nothing

Answer 4

A principle that states that all stimuli above a certain threshold value will generate the same size of action potential regardless of the strength of the stimulus

Question 5

A bands

Answer 5

Darker bands in a myofibril which consist of overlapping Actin and myosin filaments

Question 6

Antagonistic muscles

Answer 6

Pairs of muscles that work in opposite directions

Question 7

Cell body

Answer 7

Region of the neurone that contains the organelles notable the nucleus and other effector organs. It used the neurotransmitter acetylcholine

Question 8

Cholinergic synapse

Answer 8

An excitatory or inhibitory synapse formed between neurones or neurones and other effector organs. It uses the neurotransmitter, acetylcholine

Question 9

Depolarisation

Answer 9

A sudden temporary change in the membrane potential of a neurone in response to the transmission of a nerve impulse . The inside of the axon is less negative than the outside

Question 10

Fast twitch muscle fibres

Answer 10

A type of muscle fibre that contracts more rapidly with more power over a shorter period. They are adapted for anaerobic respiration and intense activity

Question 11

Generator potential

Answer 11

Depolarisation of the membrane of a sensory receptor cell that occurs in response to a stimulus

Question 12

Hyper polarisation

Answer 12

A decrease is the membrane potential of an axon, so that it is even more negative than the resting potential

Question 13

H zone

Answer 13

Lighter region in the centre of each A band

Question 14

Inhibitory synapse

Answer 14

A synapse that decreases the likelihood of an action potential in the postsynapstic neurone by causing potassium ions to leave the postsynaptic neurone and chlorine ions to enter. This results in hyperpolarisation of the post synaptic neurone

Question 15

I bands

Answer 15

Lighter bands in a myofibril , which consist of non overlapping actin and myosin filaments

Question 16

Myelin sheath

Answer 16

An electrically insulating layer consisting of the membranes of Schwann cells. It increases the speed of nerve impulses

Question 17

Myofibrils

Answer 17

Tiny contractile muscle fibres which group together. Numerous myofibril bundles constitute muscles. Myofibrils consist of 2 proteins actin and myosin

Question 18

Myosin

Answer 18

A type of protein filament found in myofibrils . It forms thick filaments consisting of long tails with bulbous heads positioned to the side

Question 19

Myosin binding site

Answer 19

A site on actin that is normally blocked by tropomyosin. During muscle contraction, it becomes exposed allowing a myosin head to attach

Question 20

Nodes of ranvier

Answer 20

Gaps between adjacent shwann cells in the myelin sheath at which action potential can occur

Question 21

Phosphocreatine

Answer 21

A compound stored in muscles that serves as a phosphate reserve enabling ATP regeneration

Question 22

Polarisation

Answer 22

Describes the condition in which an axon has a membrane potential of -65 mV (resting potential)

Question 23

Refractory period

Answer 23

The time period after an action potential during which further action potentials are prevented . This ensures that action potentials can only be propagated in one direction. It limits the frequency of action potentials and ensures nervous impulses are discrete

Question 24

Repolarisation

Answer 24

The re establishment of the testing potential -65 mV

Question 25

Resting potential

Answer 25

An electrical potential diff of -65 mV across the membrane of an axon. The inside of the the axon is more negative than the outside. The membrane is described as polarised

Question 26

Saltatory conduction

Answer 26

The process by which a nerve impulse is propagated along a myelinated neurone. Depolarisation occurs at the nodes of ranvier and action potentials jump from node to node, speeding up transmission

Question 27

Sarcomere

Answer 27

Each repeating unit of striations between adjacent z lines

Question 28

Shwann cells

Answer 28

Cells that wrap around the axon . They have a range of roles including electrical insulation, axon protection, nerve regeneration and phagocytosis

Question 29

Sodium potassium pump

Answer 29

A carrier protein found in the plasma membrane of an axon. It actively transports three sodium ions out of the axon for every 2 potassium ions that it pumps into the axon

Question 30

Sodium potassium pump

Answer 30

A carrier protein found in the plasma membrane of an axon. It actively transports 3 sodium ions out of the axon for every 2 potassium ions that it pumps into the axon

Question 31

Spatial summation

Answer 31

A type of summation involving the release of neurotransmitters from multiple pre sympathetic neurones. The concentration of neurotransmitter exceeds the threshold value and triggers and action potential in the postsynoptic neurone

Question 32

Sliding filament theory

Answer 32

The mechanism by which a muscle contracts. During contraction Myosin filaments pull actin filaments to the centre of the sarcomere. The actin filaments slide along the myosin filaments. The sarcomere is shortened and the muscle length is reduced

Question 33

Slow twitch muscle fibres

Answer 33

A type of muscle fibre that contracts more slowly with less power over a greater period. They are adapted for aerobic respiration and an able endurance

Question 34

Synaptic cleft

Answer 34

A small gap between neurones across which a nerve impulse is transmitted via neurotransmitters

Question 35

Synaptic vesicles

Answer 35

Secretory vesicles located in the presynaptic neurone that store neurotransmitters. Upon fusion with the presynaptic membrane, their contents are released into the synaptic cleft

Question 36

Temporal summation

Answer 36

A type of summation involving the release of neurotransmitters from a single presynaptic neurone at a high frequency. The concentration of neurotransmitter exceeds the threshold value and triggers an action potential in the postsynaptic neurone

Question 37

Threshold value

Answer 37

A certain size of stimulus that is required to generate an action potential

Question 38

Tropomyosin

Answer 38

A protein found in muscles that forms a fibrous strand wrapped around an actin filament

Question 39

Z line

Answer 39

The line in the centre of each I band