Neuron structure and function

Question 1

What 3 features do mammalian neurones have

Answer 1

• Cell body
• Dendrons
• Axons

Question 2

What does the cell body contain

Answer 2

• Nucleus
• cytoplasm
• endoplasmic reticulum
• mitochondria

Question 3

What does the cell body produce

Answer 3

Neurotransmitters

Question 4

What’re neurotransmitters used for

Answer 4

Pass signals from one neurone to the next

Question 5

What’re dendrons

Answer 5

Short extensions from the cell body

Question 6

What’re dendrites

Answer 6

extensions off the dendron

Question 7

What’re dendrons responsible for

Answer 7

transmitting electrical impulses towards the cell body

Question 8

What’re axons

Answer 8

Singular elongated nerve fibres

Question 9

What do axons do

Answer 9

Transmit impulses away from the cell body

Question 10

What shape is the fibre of the Axon

Answer 10

cylindrical in shape consisting of a very narrow region of cytoplasm

Question 11

What’re the 3 types of neurones

Answer 11

• sensory
• motor
• relay

Question 12

How do sensory neurones transmit impulses

Answer 12

from sensory receptor cell to a relay neurone, motor neurone or the brain

Question 13

How many dendrons and axons do sensory neurones have

Answer 13

• one dendron

- one axon

Question 14

Where does the dendron carry the impulse on a sensory neurone

Answer 14

carries impulse towards the cell body

Question 15

Where does the axon carry the impulse on a sensory neurone

Answer 15

carries impulse away from the cell body

Question 16

Where do relay neurones transmit impulses

Answer 16

in-between neurones

Question 17

Do relay neurones have dendrites

Answer 17

No only short axons and dendrons

Question 18

What do motor neurones do

Answer 18

Transmit impulses from a relay neurone or sensory neurone to an effector

Question 19

What’re examples of effectors

Answer 19

Muscles

Glands

Question 20

What’re the axons and dendrites like on a motor neurone

Answer 20

one long axon

many short dendrites

Question 21

what’s the electrical impulse pathway

Answer 21

• Receptor
• Sensory neurone
• relay neurone
• motor neurone
• effector cell

Question 22

What’re axons covered with

Answer 22

Myelin sheath

Question 23

What’s the myelin sheath made of

Answer 23

Many layers of plasma membrane

Question 24

What produces the membrane on the myelin sheath

Answer 24

schwann cells by growing around the axon many times

Question 25

What's made each time a schwann cell grow

Answer 25

a double later of phospholipid bilayer is laid down

Question 26

What does the myelin sheath act as

Answer 26

an insulating layer and allows these myelinated neurones to conduct the electrical impulse faster

Question 27

What's the difference between the speed of myelinated and unmyelinated neurones

Answer 27

- myelinated: 100m/s | - unmyelinated: 1m/s

Question 28

What's the gap difference between each adjacent schwann cell

Answer 28

2-3 micrometers um

Question 29

What's the gap known as in-between schwann cells

Answer 29

the node of Ranvier

Question 30

What happens to the electrical impulse in myelinated neurones

Answer 30

jumps from one node to the next along the neurone (faster)

Question 31

What happens to the electrical impulse in unmyelinated neurones

Answer 31

the electrical impulse doesn't jump (slower)

Question 32

if there's a difference in charge what is the membrane known to be

Answer 32

polarised

Question 33

What's the resting potential unit

Answer 33

-70 mV

Question 34

What's the resting potential

Answer 34

Voltage across the membrane when its at rest

Question 35

What's the outside membrane like when a neurons at resting state

Answer 35

the membrane is positively charged compared to the inside

Question 36

What is the resting potential created and maintained by in a neurones membrane

Answer 36

- sodium potassium pumps | - potassium ion channels

Question 37

What does the sodium potassium pump do

Answer 37

Moves sodium ions out of the neurone

Question 38

Why can't sodium ions move back into the neurone

Answer 38

The membrane isn't permeable to sodium ions

Question 39

The neurone membrane being impermeable to sodium what does it create

Answer 39

sodium ion electrochemical gradient

Question 40

Why is there a sodium ion electrochemical gradient

Answer 40

there're more positive sodium ions outside the cell than inside

Question 41

What does the sodium potassium pump move into the neurone

Answer 41

Potassium

Question 42

Is the neurone membrane permeable or not to potassium

Answer 42

It's permeable

Question 43

What happens to potassium ions as the membrane is permeable to them

Answer 43

they diffuse back out through potassium ion channels

Question 44

What're the 5 stages of action potentials

Answer 44

- Stimulus - depolarisation - repolarisation - hyperpolarisation - resting potential

Question 45

What does a stimulus trigger in the ion channels

Answer 45

sodium ion channel in the cell membrane to open

Question 46

What happens if a stimulus is big enough

Answer 46

it'll trigger a rapid charge in potential difference

Question 47

What happens to the inside of the neurone in the stimulus stage

Answer 47

the inside becomes less negative

Question 48

What's the potential difference in depolarisation

Answer 48

around -55 mV opening voltage gated channels

Question 49

What're voltage gated ion channels

Answer 49

channels that open at a certain voltage

Question 50

What feedback type is depolarisation stage

Answer 50

positive

Question 51

What's the Pd in repolarisation stage

Answer 51

around +30 mV

Question 52

What happens to the channels in the repolarisation stage

Answer 52

sodium ion channels close | voltage gated potassium ion channels open

Question 53

What's the neurone membrane more permeable to

Answer 53

potassium

Question 54

As the neurone membrane more permeable to potassium what affect does it have on the resting potential

Answer 54

Brings it back to normal

Question 55

What feedback type is repolarisation stage

Answer 55

negative feedback

Question 56

What's hyperpolarisation

Answer 56

Potassium ion channels are slow to close so there's a slight over shoot

Question 57

What's the slight overshoot due to

Answer 57

too many potassium ions diffuse out of the neurone

Question 58

How does hyperpolarisation affect the resting potential

Answer 58

becomes more negative than resting potential (less than -70 mV)

Question 59

What occurs at the resting potential stage

Answer 59

all ion channels are reset

Question 60

What happens to some sodium ions when an action potential occurs

Answer 60

sodium ions that enter the neurone diffuse sideways which causes sodium channels in the next region to open

Question 61

What causes a wave of depolarisation

Answer 61

sodium ion channels opening in regions allowing sodium ions to diffuse into that region

Question 62

Where does the wave of depolarisation move

Answer 62

away from the parts of the membrane in the refractory period

Question 63

Why does the wave of depolarisation move away from parts of the membrane

Answer 63

these parts can't fire an action potential

Question 64

What happens once the threshold is reached

Answer 64

Action potential will always fire with the same change in voltage

Question 65

Will a bigger stimulus affect the change in voltage

Answer 65

No, it'll always be the same voltage no matter how big the stimulus

Question 66

What happens if the threshold isn't reached

Answer 66

action potential won't fire (all or nothing)

Question 67

What will a bigger stimulus cause

Answer 67

cause the stimulus to fire more quickly

Question 68

How does the brain interpret high frequency signals

Answer 68

a big stimulus and responds accordingly

Question 69

What is a myelin sheath

Answer 69

An electrical insulator

Question 70

What is the myelin sheath made of in the peripheral nervous system

Answer 70

Schwann cell

Question 71

Where does depolarisation occur in myelinated neurones

Answer 71

Nodes of Ranvier

Question 72

What does the neurones cytoplasm conduct enough of to do

Answer 72

electrical charge to depolarise the next node