Synapse

Question 1

Neuron Synapses

Answer 1

 The transfer of an electric or chemical signal from the
presynaptic neuron to the postsynaptic neuron is
called synaptic transmission

 It is fundamental in understanding the functions of voluntary movement, cognition, sensation and emotion

Question 2

Synapse

Answer 2

 The gap between the sending and receiving cells
 Neurotransmitter release into synaptic cleft
 Post-synaptic receptor = back to electrical

Question 3

Action Potential Through a Neuron

Answer 3

In response to a signal the soma end of the axon becomes depolarized

The depolarization spreads down the axon. Meanwhile the first part of the membrane repolarizes.

Because Na+ channels are inactivated and additional K+ channels have opened, the membrane cannot depolarize again.

The action potential continues to travel down the axon

Question 4

Action Potential

Answer 4

Definition = the change in electrical potential associated with the passage of an impulse along the membrane of a
muscle cell or nerve cell.

 Balance of chemicals

 “All or nothing” principle

Question 5

All or Nothing Principle

Answer 5

Axon Hillock location of the decision whether to fire or not

 Either a nerve will ‘fire’ or it will not

 There is no in-between

Must reach threshold in order to ‘fire’ or send the action
potential

Question 6

EMG-Electromyography

Answer 6

measures the electrical activity of a muscle

Question 7

voltage gated ion channels
(4)

Answer 7

Sodium channel-Generates the upstroke in Action Potential

Calcium channel- Maintains the plateau of action potential: allows entry of Ca2+ in nerve terminals and muscle cells

Potassium channel-Generates the downstroke in action potential: controls the frequency o action potential
Transports K+ across membrane

Question 8

Ligand gated ion channels

Answer 8

• Neurotransmitter binds to receptor, triggering channel
• Acetylcholine (ACh) is neurotransmitter for neuromuscular junctions
• LGICs can create excitatory response (depolarisation) or
  inhibitory response (hyperpolarisation)

Question 9

Neuromuscular Junction

Answer 9

After use, ACh is broken down into acetic acid and
choline

This prevents sustained depolarisation and
continuous contraction

Question 10

Golgi Tendon Organ (GTO) and Muscle
Spindle

Answer 10

They are Mechanoreceptors

 Feedback mechanism controlling muscle length

 Sense muscle stretch and muscle contractions

 Affect stretch reflex – sensitive to change in muscle length and GTO = tension

Question 11

Golgi Tendon Organ

Answer 11

 After several secs GTO override muscle spindle

 Cause relaxation of antagonist

 Protects against excessive muscle
extensibility

 GTO found at MTJ