Introduction to peripheral nervous system

Question 1

What are the two types of principle cells in the nervous system?

Answer 1

neurones
neuroglia

Question 2

What are the two basic functions of neuroglia?

Answer 2

1. Support, nurture and protect neurones ​
2. Maintain the homeostasis (balance) of the fluid that bathes neurones

Question 3

what are the 3 basic functions of neurones?

Answer 3

1. Receive signals (or information).
2. Integrate incoming signals (to determine whether or not the information should be passed along).
3. Communicate signals to target cells (other neurons or muscles or glands).

Question 4

Are neuroglia excitable? what does this mean?

Answer 4

they are non-excitable as they do not transmit impulses

Question 5

why do neurones vary in size, shape and characteristics?

Answer 5

because they have different features depending on their role

Question 6

What does the cell body of a neurone look like?

Answer 6

star shaped with nucleus in the centre

Question 7

The cell body is the neurones _____

Answer 7

core

Question 8

what are the three functions of the neurone’s cell body?

Answer 8

1. to hold genetic information
2. maintain structure
3. provide energy to drive activity

Question 9

What does the cell body contain? (3)

Answer 9

1. the nucleus
2. the cytoplasm
3. organelles within the cytoplasm

Question 10

where are the dendrites located on a neutron?

Answer 10

they are the root like shapes on the ends of the points of the cell body

Question 11

What is the functions of dendrites?

Answer 11

1. to receive incoming information

Question 12

What are the two types of signals that dendrites can receive?

Answer 12

excitatory or inhibitory

Question 13

what do excitatory impulses do to the neuron?

Answer 13

they make the neurone fire and generate an electrical impulse

Question 14

what do inhibitory impulses do to the neuron?

Answer 14

they keep the neuron from firing

Question 15

Most neurones receive ______ input signals through the ________, receiving thousands of input signals.

Answer 15

many
dendrites

Question 16

whether or not a neurone is exited into firing an impulse depends on what?

Answer 16

the amount of excitatory and inhibitory signals it receives

Question 17

If a neurone does end up firing, Where does the nerve impulse (or action potential) go?

Answer 17

the nerve impulse, or action potential, is conducted down the axon.​

Question 18

What shape and size is the axon?

Answer 18

it is the same diameter for most of its length and doesn’t have any spines

its size is dependent on its function

Question 19

does a larger diameter axon has the ability to send signals faster or slower than a smaller axon?

Answer 19

much faster

Question 20

what is the name of the special fatty insulating substance that covers many axons? what does this form?

Answer 20

myelin which forms the myelin sheath

Question 21

What secrets myelin in the fibres of the peripheral nervous system?

Answer 21

Schwann cells

Question 22

what secrets myelin in the fibres of the central nervous system?

Answer 22

oligodendrocytes

Question 23

what is the function of the myelin sheath?

Answer 23

it helps to contain the nerve impulse, allowing it to move rapidly along the axon

Question 24

What are the gaps along the myelin sheath? are they myelinated?

Answer 24

nodes of ranvier, they are non-myelinated

Question 25

What is the function of the nodes of ranvier?

Answer 25

they expose the axon at various points to allow for regeneration of the impulse which supports the speed at which the nerve impulse passes along the axon

Question 26

Where do axons arise from the cell body?

Answer 26

at a cone-shaped elevation called the axon hillock

Question 27

what is the first portion of the axon called and what arises here? what name does this also give it?

Answer 27

the initial segment the nerve impulse the trigger zone

Question 28

along the length of the axon there may be side branches called ____ ________ which are typically at ______ angles to the axon.

Answer 28

axon collaterals right

Question 29

What is at the end of the axon?

Answer 29

fine processes called the axon terminals

Question 30

What does the tip of the axon terminal bulge out to form?

Answer 30

the synaptic bulb

Question 31

what does the synaptic bulb contain?

Answer 31

neuro-transmitting chemicals

Question 32

What is the small gap between one neurone and the next or the target cell called?

Answer 32

the synapse/synaptic cleft

Question 33

what moves across the synapse? what do they do?

Answer 33

neuro-transmitting chemicals pass across the synapse to send the impulse either into the next neurone or effector cell

Question 34

what are the 5 differences of a non-myelinated neurone to a mylienated neurone?

Answer 34

non-myelinated neurones have: 1. no myelin sheath 2. no nodes of ranvier 3. lower speeds of transmission 4. shorter axons 5. can lose nerve impulse during conduction

Question 35

In what kind of environment are unmyelinated neurones found? give an example in the body.

Answer 35

found in areas where a short axon is appropriate – for example within the brain where the signal has to travel very short distances.

Question 36

How does MS affect neurones?

Answer 36

Oligodendrocytes are damaged, and myelin is damaged and stripped away from the axon

Question 37

What symptoms in MS demonstrate the disruption of messages along the axon? (3)

Answer 37

muscle weakness poor coordination of movement changes in senstation

Question 38

what are the three types of neurones?

Answer 38

motor neurones interneurones sensory neurones

Question 39

what are three characteristics of motor neurones?

Answer 39

- typically multipolar - efferent - take signals away from the CNS

Question 40

What does multipolar mean?

Answer 40

that they have two or more dendrites and one axon

Question 41

What does efferent mean?

Answer 41

they carry signals away from the CNS and towards the effector eg muscle cell

Question 42

where are interneurones found? (2)

Answer 42

between motor and sensory pathways within the CNS

Question 43

how do interneurones communicate?

Answer 43

to communicate between the motor and sensory pathways and can also communicate with each other to form small circuits

Question 44

What are three characteristics of sensory neurones?

Answer 44

1. unipolar 2. afferent 3. carry signals toward the CNS

Question 45

What does unipolar mean?

Answer 45

they only have one nerve process extending from the cell body

Question 46

What does afferent mean?

Answer 46

they carry the signal towards the CNS.

Question 47

what is at the end of the axon in a sensory neuron?

Answer 47

receptor endings

Question 48

What is a bundle of axons in the peripheral nervous system called?

Answer 48

a nerve

Question 49

What is a bundle of axons found In the central nervous system called?

Answer 49

a tract

Question 50

What is the longest nerve in the body?

Answer 50

the sciatic nerve

Question 51

What are the 4 types of neuroglia cells (glial cells) in the CNS?

Answer 51

oligodendrocytes, astrocytes, microglia, and ependymal cells in the CNS

Question 52

What are the two types of neuroglial cells in the PNS?

Answer 52

schwann cells, satellite cells

Question 53

What do neuroglia have the ability to do that neurones do not?

Answer 53

they have the ability to divide and multiply

Question 54

Neuroglia act like the _____ that holds the __________ tissue together.

Answer 54

glue nervous

Question 55

In the case of traumatic injury, what are neuroglia able to do?

Answer 55

fill the space that neurones once held

Question 56

Which of the glial cells act as the regulator for the CNS?

Answer 56

Astrocytes

Question 57

Which of the glial cells act as the regulator for the PNS?

Answer 57

satellite cells

Question 58

Astrocyes form the main ____________ _______ of the nervous system.

Answer 58

supporting tissue

Question 59

What do astrocytes attach together? what do they form?

Answer 59

the attach neurones to blood vessels the blood brain barrier

Question 60

What do satellite cells support?

Answer 60

neurones in the PNS

Question 61

What do satellite cells regulate?

Answer 61

the external chemical environment

Question 62

What are satellite cells sensitive to? what can this do?

Answer 62

injury - exacerbate the pain response

Question 63

What produces the myelin in the central nervous system?

Answer 63

Oligodendrocytes

Question 64

What creates the myelin in the PNS?

Answer 64

Schwann cells

Question 65

Schwann cells participate in ____ _____ regeneration.

Answer 65

PNS axon

Question 66

satellite cells ​regulate ___________ of __________ between _________ and ___________ fluid.

Answer 66

exchange materials neurons interstitial

Question 67

What is interstitial fluid?

Answer 67

fluid in spaces between tissues

Question 68

What is white matter formed by?

Answer 68

clusters of myelinated processes from the neurones found deep in the brain or periphery of the spinal cord

Question 69

How do neurones pass messages?

Answer 69

electrical signals pass along the axon, this comes to the synaptic bulb which triggers the release of neurotransmitters to neurotransmitter receptors on the post synaptic neurone

Question 70

When a neurone passes a message, electrical signals pass along the _____ to the ________. This then goes to the _________ _____ where the signal is transferred from __________ to ________ so it can cross the __________ ______. At the other side there is a ____________ _____, which has __________________ ________ that receive the ________________ molecules.

Answer 70

axon synapse synaptic bulb electrical chemical synaptic cleft postsynaptic neuron neurotransmitter receptors neurotransmitter

Question 71

_____ triggers synaptic vesicle __________, thereby releasing the _________________ contained in the vesicles and initiating __________ _____________

Answer 71

Ca2+ triggers synaptic vesicle exocytosis, thereby releasing the neurotransmitters contained in the vesicles and initiating synaptic transmission

Question 72

The natural state of a neurone is a ___________ concentration, meaning that there are more ___________ charged ions ________ than ______ the cell. This neurone is in a state of rest and described as the _________ __________ ___________.

Answer 72

negative positively outside inside resting membrane potential.

Question 73

During the resting membrane potential, there are more __________ ions outside the __________ and more ____________ ions inside. The concentration of ions isn’t _____ though – ions are flowing in and out of the neurone constantly as the ions try to __________ their concentrations.

Answer 73

sodium neurone potassium static equalise

Question 74

How is the neurone able to maintain a negative concentration gradient because of the cell membrane?

Answer 74

1. the cell membrane is super permeable to potassium ions so lots of potassium leaks out of the neurone through the potassium leakage channels (holes in the cell wall) 2. The cell membrane is semi-permeable to sodium ions so they slowly leak into the neurone through sodium leakage channels

Question 75

The cell is also able to maintain a negative resting membrane potential because it ______ to. It has a pump that pumps __________ back into the ____ and pumps _______ out at the same time.

Answer 75

wants potassium cell sodium

Question 76

What happens during depolarisation of the neuron?

Answer 76

the opening of voltage gated sodium channels

Question 77

What happens during depolarisation of the neuron?

Answer 77

closure of the voltage gated sodium channels and opening of the potassium voltage gated channels to restore the resting membrane potential

Question 78

What are the three stages of action potentials?

Answer 78

depolarisation repolarisation hyperpolarisation

Question 79

what happens during hyper polarisation?

Answer 79

potassium channels remain open which temporarily further action potentials (refractory period)

Question 80

What is temporal summation?

Answer 80

stimuli in different places in the synapse at the same time

Question 81

What is spatial summation?

Answer 81

stimuli in the same place in the synapse at different times