Nervous system

Question 1

Why does the presynaptic knob contain many mitochondria?

Answer 1

energy from ATP is requirerd to generate neurotransmitters and to actively transport calcium ions out of the presynaptic knob.

Question 2

What are the products from each hydrolysis of ACH by acetylcoholinesterase?

Answer 2

ethanaic acid and choline

Question 3

What does undirectionalability in a synapse mean?

Answer 3

Synapses can only pass impulses in one direction that transmitter is only released by the presynaptic knob and receptors are found only on the post synaptic knob. In this way syanapses act like valves.

Question 4

What do dendrites do?

Answer 4

from connections (synapses) with neurons which make up the CNS. One motor neuron may connect with many different neurons in the brain or spinal cord.

Question 5

What does the nucleus do?

Answer 5

Contains the DNA of the neuron

Question 6

What is depolarisation?

Answer 6

A temporary reversal of the normal electrical chgarge between the inside and outside of the cells.

Question 7

What are nerve impulses?

Answer 7

Waves of depolarisation that moves along the axon.

Question 8

What happens at rest in the nerve cell?

Answer 8

Inside is negative compared to the outside

Question 9

What is the nodes of Ranvier?

Answer 9

gaps between Schwann cells. the combination of the myelin sheath and the nodes mean impulses can travel down a motor neurone much quicker than if they weren’t presnt.

Question 10

What is a reflex?

Answer 10

A rapid short-lived involuntary reponse to a specific stimulus.

Question 11

Why are simple reflexes important?

Answer 11

-involuntary actions, do not involve decision making areas of the brain.
-rapid, fast electrical impulses and short neurone pathways.
-control of continuous and repetiticve actions e.g. breathing

Question 12

Describe the reflex arc process

Answer 12

SRSRMER
-First a stimulus is detected such a a hot plate by a receptor and thsi generates an inpulse in a sneosry neurone.
-sensory neurone impulse diffuses to relay neurone, then diffuses to motor neurone (by synapses)
-Motor neurone carries impulse to effector (muscle glands) which produces a response

Question 13

What does the axon terminals do?

Answer 13

the end of the axon splits inot the axon terminals, connecvting with the effector. The ends of the terminals swell into the synaptic end bulbs.

Question 14

What does the myelin sheath do?

Answer 14

A lipid coat that covers most of the axon. Individual sections of the sheath are sperate cells known as schwan cells which wrap around the axon.

Question 15

Label the structure of a motor neuron

Answer 15

.

Question 16

What is a reflex arc?

Answer 16

The shortest pathway taken by impulses in a simple reflex

Question 17

Label the reflex arc

Answer 17

.

Question 18

What 2 sections is the nervous system divided into?

Answer 18

central NS: The brain and spinal cord
perpheral NS: the sensory and motor nerves.

Question 19

What do sensory neurones do?

Answer 19

carry nerve impulsews from receptors towards the CNS.

Question 20

What do motor neurons do?

Answer 20

carry nerve impulses away from the CNS to the effectors.

Question 21

What do sensory neurons do? (detail)

Answer 21

transmit inbfo from snes organs and receptors found around the body to the CNS. The CNS processes the info and coordinates the repsinse. the respinbse is sent down motor neurons to an effector like a muscle or gland to carry out the repsonse

Question 22

What does the cell body do?

Answer 22

Contains most of the cell organelles.

Question 23

what does the axon do?

Answer 23

the fibre of the neurone stretches from the CNS to the effector

Question 24

What is a neuromuscular junction?

Answer 24

A synapse between a motor neurone and a muscle. the post-synaptic membrane is the self membrane of the msucle cell.

Question 25

What happens when the nerve cell is negative?

Answer 25

When stimulated by a synapse or receptor, the charge changes from N to P. This chnage in the charge of bthe neurone is passed along the axon in a wave with one part of the neurone chnaging to + being the stimulus to change to the next part to positive. This wave travels along the axon until it reaches a synapse.

Question 26

Draw an example of nerve impulses with depolarisation

Answer 26

.

Question 27

What is the CNS composed of?

Answer 27

brain, spinal cord

Question 28

What does the CNS contain (neurons)?

Answer 28

relay neurons (interneurons)

Question 29

What is the peripheral nervous system composed of?

Answer 29

cranial nerves, spinal nerves, peripheral nerves.

Question 30

What does the PNS contain?

Answer 30

Sensory neurons, motor neurons.

Question 31

What is the proces of transmission across a synapse (6 steps)?

Answer 31

.

Question 32

What is one of the most common neurotransmitters in humans?

Answer 32

Acetylcholine (ACH)

Question 33

What is ACH made up of?

Answer 33

ethanoic acid and choline

Question 34

What are the synapses called that use ACH as transmitter?

Answer 34

cholinergic synapses

Question 35

Where are cholinergenic synapses found?

Answer 35

In the CNS at the neuromuscular junction.

Question 36

Why are neurons with a myelin sheath more efficent?

Answer 36

Only the sections between the schwann cells (nodes of ranvier) become depolarised, so the impulse ‘jumps’ along the axon.

Question 37

What are the group of chemical involed in communication between neurons at synapses called?

Answer 37

neurotransmitters

Question 38

What is the function of the synapse?

Answer 38

To allow sensory impulses to travel in one direction and to ensure that each impulse remails individual and doesn’t merge together with…

Question 39

What is a synaptic cleft?

Answer 39

neurons are seperated from each other from this.

Question 40

What is the presynaptic neurone?

Answer 40

The neurone which releases the transmitter

Question 41

What is a synaptic knob?

Answer 41

the end of the axon swells to form this. The knob contains mitochondria.

Question 42

What is the synaptic vesicles?

Answer 42

This is where the transmitter is stored

Question 43

What is the presynaptic membrane?

Answer 43

When the synaptic vesicles is stimulated this will fuse the membrane and relaease the neurotranmitter into the cleft.

Question 44

What is the postsynaptic neurone?

Answer 44

once the neurotransmitter is released into the cleft it will diffuse to this which has specific receptor molecules to bind to transmitter.

Question 45

Label the synapse

Answer 45

.

Question 46

How could some drugs stimulate the nervous system by creating impulses in postsynaptic neurons?

Answer 46

-mimic the neurotransmitter
-cause the release of excess neurotransmitters
-reducing the activity of the enzyme which breaks it down.

Question 47

How could a drug inhibit the nervous sytem?

Answer 47

By causing fewer impulses in the psotsynaptic membrane.

Question 48

How can you monitor the nervous system?

Answer 48

electroencephalograms

Question 49

how do electroenccephalograms work?

Answer 49

electrodes are placed on the scalp. These detect the tiny changes in charges of the neurone in the brain. This is then recorded as a wave on a ECG trace.