Neurons and synaptic transmission

Question 1

Resting potential

Answer 1

Voltage difference inside vs. outside the neuron (inside is more negative)

Question 2

Polarisation

Answer 2

Another term for electrical gradient

Question 3

Electrical gradient

Answer 3

Difference in electrical charge across the membrane

Question 4

Concentration gradient

Answer 4

Difference in ion concentration across the membrane

Question 5

Selectively permeable

Answer 5

Membrane allows some substances to pass more easily

Question 6

Sodium-potassium pump

Answer 6

Actively transports 3 Na⁺ out, 2 K⁺ in

Question 7

Action potential

Answer 7

Electrical signal sent along the axon

Question 8

Threshold

Answer 8

Minimum depolarisation needed to trigger an action potential

Question 9

Depolarisation

Answer 9

Charge moves toward zero; inside becomes less negative

Question 10

Hyperpolarisation

Answer 10

Increase in negativity inside the cell

Question 11

Voltage-gated channels

Answer 11

Open/close based on membrane voltage

Question 12

All-or-none law

Answer 12

Action potential has same size and speed regardless of stimulus strength (as long as threshold is reached)

Question 13

Local anaesthetics

Answer 13

Block sodium channels to stop APs

Question 14

Resting state

Answer 14

More K⁺ inside, more Na⁺ outside

Question 15

At threshold

Answer 15

Na⁺ channels open, Na⁺ flows in

Question 16

Peak depolarisation

Answer 16

K⁺ channels open, K⁺ flows out

Question 17

Return to resting

Answer 17

Na⁺/K⁺ pump restores original ion balance

Question 18

Propagation

Answer 18

AP travels along the axon, maintaining strength

Question 19

Refractory period

Answer 19

Time after AP where another AP is harder or impossible

Question 20

Absolute refractory

Answer 20

No new AP possible (Na⁺ channels inactive)

Question 21

Relative refractory

Answer 21

AP only with stronger stimulus (K⁺ still flowing out)

Question 22

Myelin

Answer 22

Insulating layer around axons

Question 23

Myelinated axons

Answer 23

Axons with myelin; faster conduction

Question 24

Saltatory conduction

Answer 24

AP jumps from node to node (Nodes of Ranvier)

Question 25

Local neurons

Answer 25

Tiny neurons without axons; use graded potentials

Question 26

Graded potential

Answer 26

Varies in size; spreads passively without regenerating

Question 27

Synapse

Answer 27

Junction between two neurons

Question 28

Reflex

Answer 28

Automatic response to stimulus

Question 29

Reflex arc

Answer 29

Circuit from sensory input to motor output

Question 30

Presynaptic neuron

Answer 30

Sends the signal

Question 31

Postsynaptic neuron

Answer 31

Receives the signal

Question 32

Temporal summation

Answer 32

Repeated stimuli over time add together

Question 33

Spatial summation

Answer 33

Simultaneous stimuli from different locations add together

Question 34

EPSP

Answer 34

Excitatory graded potential (Na⁺ enters, depolarising cell)

Question 35

IPSP

Answer 35

Inhibitory graded potential (Cl⁻ enters or K⁺ leaves, hyperpolarising cell)

Question 36

Spontaneous firing rate

Answer 36

Neurons can fire APs without input

Question 37

Role of inhibition

Answer 37

Not just lack of excitation – actively reduces firing

Question 38

Interaction

Answer 38

Neuron "adds up" EPSPs and IPSPs to decide whether to fire an AP

Question 39

Outcome

Answer 39

If total depolarisation crosses threshold → AP is fired