Neurons and synaptic transmission

Question 1

Name the components of a neuron

Answer 1

Dendrites
Soma (cell body)
Nucleus
Myelin sheath
Node of ranvier
Axon
Terminal button

Question 2

What are the cells making up the nervous system called? What are they specialised to do?

Answer 2

Neurons - specialised to conduct electrical impulses

Question 3

What is the role of a sensory neuron?

Answer 3

To take messages into the nervous system from the environment

Question 4

What are the components of a sensory neuron?

Answer 4

Receptor cell
Axon
Myelin sheath
Cell body

Question 5

What is the role of a relay/inter neuron?

Answer 5

Within the CNS - allows sensory and motor neurons to communicate

Question 6

What are the components of a relay/inter neuron?

Answer 6

Dendrite
Soma
Axon
Pre synaptic terminal

Question 7

What is the role of a motor neuron?

Answer 7

Takes messages out of the CNS to an effector

Question 8

What are the components of a motor neuron?

Answer 8

Dendrite
Soma
Axon
Myelin sheath
Node of ranvier

Question 9

What are neurons covered in? What does the biochemical structure of this allow it to do?

Answer 9

Complex cell membranes made up of several layers
Allows it to conduct or transmit pulses of electrical activity

Question 10

What are pulses of electrical activity called?

Answer 10

Action potentials

Question 11

Where do action potentials begin and where do they travel?

Answer 11

Begin on the dendrites and travel across the cell body and along the axon

Question 12

What is similar and different about action potentials?

Answer 12

Similar: all have the same electrical properties and look identical

Differences: frequency and pattern

Question 13

What is the maximum rate at which action potential can be conducted along the neuron? What causes this?

Answer 13

Around 250-400 impulses per second, because of the molecular make up of the neuronal cell membrane

Question 14

Who is the myelin sheath found and not found in?

Answer 14

Found in advanced animals such as humans and other mammals

Not found in more primitive animals

Question 15

What is the myelin sheath?

Answer 15

A fatty cover along the axon

Question 16

What are the nodes of ranvier?

Answer 16

Gaps in myelin sheath

Question 17

What can action potentials do? (Nodes of ranvier)

Answer 17

They can jump from gap to gap, known as saltatory conduction

Question 18

Is saltatory conduction faster or slower than the standard continuous conduction along the neuronal axon?

Answer 18

Faster

Question 19

What is the synapse?

Answer 19

A gap between the presynaptic neuron and the post synaptic neuron

Question 20

What is the first step of synaptic transmission?

Answer 20

Action potential pushes vesicles containing NTs to the presynaptic membranes

Question 21

What is the second step of synaptic transmission?

Answer 21

NTs enter synaptic cleft (exocytosis)

Question 22

What is the third step of synaptic transmission?

Answer 22

NTs diffuse across the synapse

Question 23

What is the fourth step of synaptic transmission?

Answer 23

NTs bind to specific receptors

Question 24

What is the fifth step of synaptic transmission?

Answer 24

Action potential created

Question 25

What is the sixth step of synaptic transmission?

Answer 25

Receptors release NTs back into synaptic gap

Question 26

What is the seventh step of synaptic transmission?

Answer 26

Released and unused NTs are then either reuptaken by the presynaptic membrane or digested by enzymes in the synapse

Question 27

What is reuptake?

Answer 27

When the NT is taken up again by the presynaptic neuron where it is stored and made available again at a later time

Question 28

What are the two ways neurotransmitters can be described in their actions?

Answer 28

Inhibitory or excitatory

Question 29

What do excitatory NTs do?

Answer 29

Increase the likelihood that an excitatory signal is sent to the post synaptic cell which is then more likely to fire

Question 30

What do inhibitory NTs do?

Answer 30

Decrease the likelihood of the neuron firing

Question 31

An excitatory NT binding with a postsynaptic receptor causes an electrical charge in the membrane of the cell, resulting in an..

Answer 31

Excitatory postsynaptic potential (EPSP), meaning the cell is more likely to fire

Question 32

An inhibitory NT binding with a postsynaptic receptor causes an electrical charge in the membrane of the cell, resulting in an…

Answer 32

Inhibitory postsynaptic potential (IPSP), meaning the postsynaptic cell is less likely to fire

Question 33

Can a nerve cell receive both IPSPs and EPSPs at the same time?

Answer 33

Yes

Question 34

How do you determine the likelihood of the cell firing?

Answer 34

Adding up the excitatory and inhibitory synaptic input

Question 35

What does the net summation determine?

Answer 35

Whether the cell fires or not

Question 36

What are the two ways the strength of EPSPs can be increased?

Answer 36

Spatial summation Temporal summation

Question 37

What is spatial summation?

Answer 37

A large number of EPSPs are generated at many different synapses on the same postsynaptic neuron at the same time

Question 38

What is temporal summation?

Answer 38

A large number of EPSPs are generated at the same synapse by a series of high frequency action potentials on the presynaptic neuron