Synaptic transmission

Question 1

What is a synapse?

Answer 1

Transmission of electric nerve impulses between two nerve cells or neuron and effector

Question 2

Name 2 chemical messengers

Answer 2

Hormones and Neurotransmitters

Question 3

What are the 2 types of synapses, which one is more rare?

Answer 3

Electrical and chemical, electrical is rarer.

Question 4

Where are gap junctions most common?

Answer 4

Heart and smooth muscle

Question 5

Where can chemical synapses exist?

Answer 5

From neuron to neuron and neuron to effector

Question 6

Three types of Synapses?

Answer 6

Axosomatic, axodendritic, axoaxonal synapses.

Question 7

What are the 6 steps of the generation of a synaptic response?

Answer 7

1. AP conduction to the terminal
2. Calcium enters the picture
3. Vesicles are released
4. Chemical messenger binds
5. The chemical messenger moves on

Question 8

Name 3 ways neurotransmitter effect is terminated

Answer 8

Reuptake via astrocytes or axon terminal.
Degradation via enzymes.
Diffusion away from synaptic cleft.

Question 9

Name 2 ways molecules enter and exit a cell, what is required for it to happen?

Answer 9

Endocytosis and Exocytosis. ATP is required.

Question 10

What determines how much neurotransmitter is released?

Answer 10

Higher frequencies of impulses.

Question 11

How would the amount of neurotransmitter released affect the size of the graded potential?

Answer 11

Larger the amount of neurotransmitter, larger the graded potential.

Question 12

Which neurotransmitter is being released and which post synaptic receptor is activated is also important. Why?

Answer 12

The RMP can go up and down in a post synaptic cell.

Question 13

Synaptic transmission can be?

Answer 13

Excitatory or inhibitory

Question 14

Specialised types of synapses?

Answer 14

Excitatory Postsynaptic potential.
Inhibitory postsynaptic potential

Question 15

What types of summation is there?

Answer 15

No summation
Temporal summation
Spatial summation.

Question 16

What happens when both an EPSP and an IPSP are received?

Answer 16

They will almost completely cancel each other out.

Question 17

What is a neural circuit?

Answer 17

A functional group of neurons which process a special kind of information

Question 18

What are the 3 types of neuronal circuits?

Answer 18

1. Diverging circuit
2. Converging circuit
3. Reverberating circuit

Question 19

What is the neuromuscular junction?

Answer 19

When a motor neuron meets a skeletal muscle

Question 20

Which neurotransmitter binds to the receptor on the sarcolemma?

Answer 20

Acetylcholine (ACh)

Question 21

Describe phase 1 of the events at the neuromuscular junction.

Answer 21

1. Action potential arrives at axon terminal at neuromuscular junction.
2. Ach released, binds to receptors on sarcolemma.
3. Ion permeability of Sarcolemma changes
4. Local change in membrane voltage occurs.
5. Local depolarization (End-plate potential) ignites action potential in sarcolemma.

Question 22

Describe phase 2 of the events at the neuromuscular junction

Answer 22

1. AP travels across the entire sarcolemma.
2. AP travels along t-tubules.
3. SR releases Ca2+ which binds to troponin, myosin binding sites on actin become exposed.
4. Myosin head binds to actin, contraction begins.

Question 23

What breaks down Ach after performing its function?

Answer 23

Acetylcholine esterase.

Question 24

What would happen in the absence of ACh-esterase?

Answer 24

The muscle would stay contracted

Question 25

How do inhibitory synapses assist our physiology?

Answer 25

The patellar reflex

Question 26

What is reciprocal inhibition?

Answer 26

When efferent impulses of alpha motor neurons to antagonist muscles are reduced

Question 27

What is Myasthenia Gravis?

Answer 27

Autoimmune disease in which Ach receptors in the neuromuscular junction are destroyed, sufferers have Ach receptor anti-bodies.

Question 28

What are some symptoms of Myasthenia Gravis?

Answer 28

Muscle fatigue, Ptosis, Diplopia, difficulty chewing and swallowing, respiratory problems, myasthenia crisis causing respiratory arrest.

Question 29

What are some treatment options for Myasthenia Gravis?

Answer 29

ACh-esterase inhibitors

Question 30

What is Curare Poisoning?

Answer 30

Prevents ACh binding post synaptically, causes flaccid paralysis of skeletal muscle.

Question 31

How is Curare used in medicine?

Answer 31

Previously used in conjunction with general anasthesia.

Question 32

What do organophosphates do? How do you treat it?

Answer 32

inhibit ACh esterase. Cause contraction of pupils and convulsions, twitching and jerking through effects at neuromuscular junction. Atropine (ACh receptor blocker).

Question 33

What does botulism do? How can you treat it?

Answer 33

Prevents release of ACh, causes flaccid paralysis of muscles. Can be fatal, cause muscle weakness. Antitoxin, ventilator, stomach pump, surgery. Infants don't have immunity to prevent infection if ingested, therefore any child under 1 shouldn't be given honey.