Lecture 1: Nerve Impulse and Synaptic Transmission

Question 1

What are the 2 divisions of the Peripheral Nervous system?

Answer 1

1. Sensory (Afferent) division
2. Motor (Efferent) division

Question 2

The Sensory (afferent) division of the PNS transmits impulses ____ the CNS

Answer 2

The sensory divisions transmit impulses to the CNS.
When the stimuli are detected, the message is sent to the brain to let it know that it is there.

Question 3

The motor (efferent) division of the PNS transports impulses ____ the CNS

Answer 3

from
The efferent division is the brain telling the body how to respond to a stimulus.

Question 4

Name the two fibres of the Sensory (afferent) division of the PNS:

Answer 4

1. Somatic Sensory Fibre
2. Visceral Sensory Fibre

Question 5

What is the function of the Somatic Sensory Fibres?

Answer 5

Transmit impulses from the skin, skeletal muscles and joints TO the CNS

Question 6

What is the function of the Visceral Sensory Fibre?

Answer 6

Transmit impulses from visceral organs TO the CNS

Question 7

Name the two systems of the motor (efferent) division of the PNS:

Answer 7

1. Somatic Nervous System
2. Autonomic Nervous System

Question 8

There are two principal types of cells. What are they?

Answer 8

1. Neuroglial Cells
2. Neurons

Question 9

Explain the role of the two principal cells of the nervous system.

Answer 9

Neuroglial cells surround and wrap delicate neurons

Neurons are the functional unit of the nervous system. Neurons communicate by transmitting electrical signals.

Question 10

In neurons only an axon can generate an action potential.

True or False

Answer 10

True

Question 11

Astrocytes are the most abundant neuroglia cells in the CNS. Their functions include: (5 functions)

Answer 11

1. Support and Brace Neurons
2. Guide migration of young neurons
3. Control Chemical environment
4. Responds to nerve impulses and NT
5. Participates in information processing in
   the brain

Question 12

The function of the microglial neuroglia cell of the CNS is: (2)

Answer 12

Migrate toward injured neurons
Transform to phagocytize microorganisms and neuronal debris.

Question 13

The Functions of the Ependymal neuroglial cells of the CNS are to: (2)

Answer 13

Line central cavities of the brain and spinal column
Form a permeable barrier between cerebral spinal fluid in cavities and tissue fluid bathing CNS cells

Question 14

The function of Oligodendrocytes of the CNS.

Answer 14

form insulating myelin sheaths around the CNS nerve fibres

Question 15

What are the two neuroglial cells of the PNS:

Answer 15

1. Satellite Cells
2. Schwann Cells

Question 16

The purpose of satellite cells of the PNS is to: (3)

Answer 16

1. Surround neuron cell bodies
2. Support Neurons
3. Control Chemical Environment

Question 17

Satellite cells of the PNS function similar to _______ cells of the CNS

Answer 17

Astrocytes

Question 18

The function of the Schwann cell is to:

Answer 18

1. Surround all peripheral nerve fibres and form myelin sheaths
2. Vital to the regeneration of damaged peripheral nerves

Question 19

The electrical charge difference across the cell membrane when the cell is not actively transmitting signals is known as the:
________ _________ _______

Answer 19

Resting Membrane Potential

Question 20

During resting membrane potential the ____ is higher outside of the cell.

Answer 20

Na+

Question 21

During resting membrane potential ___ is higher inside the cell.

Answer 21

K+

Question 22

What is the most important ion to contribute to a resting membrane potential?

Answer 22

K+

Question 23

The Resting Membrane Potential is maintained by the movement of ions through: (2)

Answer 23

1. Leaking ion-gated channels
2. Na+/K+ pump

Question 24

The K+ ion gated leak channels allows K+ to diffuse _____ of the cell

Answer 24

outside

Question 25

The Na+ ion-gated leak channel allows Na+ to _______ the cell

Answer 25

enter

Question 26

The Na+ gated ion leak channel allows an unlimited number of Na to enter the cell. True or False

Answer 26

False Na+ gated channels only allows a small amount of Na+ to enter the cell

Question 27

What is the function of the Na+/K+ Pump and what does it require to work.

Answer 27

A transport pump that moves Na+ ions out of the cell and K+ ions into the cell. This is an active transport that requires ATP

Question 28

What is the role of the resting membrane potential

Answer 28

The excitability of the neurons allows cell to respond to stimuli (like an action potential) and Signal transmission

Question 29

What triggers an action potential?

Answer 29

A change in the resting membrane (depolarization).

Question 30

An action potential occurs when:

Answer 30

membrane potential goes from negative to positive and then to negative again.

Question 31

Action potentials decay in amplitude with the distance travelled. True or False

Answer 31

False Action potentials do not decay in amplitude with the distance travelled.

Question 32

In neurons, only ______ can generate actions potentials.

Answer 32

axons

Question 33

When the membrane potential reaches a threshold it is an ____ __ _____ resposne

Answer 33

All-or-nothing

Question 34

Depolarization occurs when the membrane potential becomes more or less negative

Answer 34

less depolarization occurs as a result of the membrane potential becoming less negative goes from -70mV to -50mV

Question 35

When depolarization occurs the Na+ voltage-gated channels are _____ allowing Na+ to _____ the cell.

Answer 35

Na+ voltage-gated channels are open, allowing Na+ to enter the cell

Question 36

What causes the membrane potential to become more positive

Answer 36

the influx of Na+

Question 37

During Repolarization, the Na+ channels will begin to ________. This will ______ the influx of Na+

Answer 37

During Repolarization, the Na+ channels will begin to deactivate (close). This will stop the influx of Na+

Question 38

During Repolarization, the K+ channels are ____, allowing K+ to move ____ of the cell

Answer 38

K+ channels are open, allowing K+ to move out of the cell.

Question 39

The Influx of K+ causes the membrane potential to return toward the _____ resting membrane potential.

Answer 39

The influx of K+ causes the membrane potential to return toward the negative resting membrane potential.

Question 40

During Hyperpolarization, the K+ channels close slowly, causing an excessive efflux of K+. This will make the inside of the cell more/less negative than the resting membrane potential

Answer 40

more negative

Question 41

During hyperpolarization, the K+ channels and the ________ restore the normal ion gradient. bringing it back to resting membrane potential.

Answer 41

Na+/K+ pump

Question 42

After an action potential, the neuron enters a ________ period.

Answer 42

Refractory

Question 43

During the refractory period, a neuron cannot fire another action potential or requires a stronger stimulus. True or False

Answer 43

True

Question 44

What is the difference between the absolute refractory period and the relative refractory period.?

Answer 44

During the absolute refractory period, no new action potential can be initiated regardless of the strength of the stimulus, while during the relative refractory period, an action potential can be initiated with a stronger-than-usual stimulus

Question 45

The chemical synapse is the most common type and composed of 2 parts:

Answer 45

1. The Axon Terminal Presynaptic Neuron 2. The Receptor Region on the Postsynaptic Neuron's membrane

Question 46

There are 6 steps involved in the information transfer across a chemical synapse:

Answer 46

1. Action Potential arrives at the axon terminal on the presynaptic neuron 2. Voltage-gated Ca+ channels open, and Ca enters the axon terminal 3. Ca+ entry causes neurotransmitter release 4. Neurotransmitters diffuse across the synaptic cleft and bind to the postsynaptic receptor 5. The binding of neurotransmitters opens ion channels, creating graded potentials 6. Neurotransmitter effects are terminated

Question 47

The neurotransmitter effect is terminated in one of three ways:

Answer 47

1. Reuptake by astrocytes or axon terminal 2. Degradation by enzymes 3. Diffusion away from synaptic cleft

Question 48

Name the two types of post-synaptic potentials.

Answer 48

1. EPSP: Excitatory Post Synaptic Potential 2. IPSP: Inhibitory Post Synaptic Potential

Question 49

EPSP triggers an action potential is EPSP is at threshold strength. True or False

Answer 49

True