[Part 2]- B10- the nervous system 🧠🩻

Question 1

What’s a key role of the nervous system ?

Hint: react to…

Answer 1

• a key role of the nervous system, is that it enables humans to react to their surroundings and co-ordinate their behaviour.

Question 2

What’s a reflex action ?

Hint: reponse to stimulus

Answer 2

• a reflex action, is a automatic and rapid response to a stimulus.

Question 3

What’s a reflex arc ?

Hint: pathway of information- from what neurone?

Answer 3

• a reflex arc, is the pathway of information from a sensory neuron, through an interneuron, to a motor neuron. [nerve cell]

Question 4

Describe the reflex arc when you touch a hot object [6] 🕯️

Hint: receptor, pass from the receptor, along… to the CNS.

Hint #2: end of the sensory neurone, chemical diffuses, relay neurone triggers, impulse pases along relay neurone, released again and motor neurone to effector

Answer 4

1) the stimulus [heat] is first detected by a receptor [in the skin].

2) and electrical impulses, now pass from the receptor along a sensory neurone, to the central nervous system.

3) ; at the end of the sensory neurone, there’s a junction known as a synapse

4) at the synapse, a chemical is released and this chemical now diffuses across, to a relay neurone in the central nervous system, where it triggers an electrical impulse.

5) this electrical impulse now passes along the relay neurone, and reaches another synapse.

6) a chemical is then released again and, this chemical triggers an electrical impulse, in a motor neurone.

7) the electrical impulse now passes down the motor neurone, to an effector [the muscle- the muscle now contracts, pulling the hand away from the heat ]

Question 5

• Fill in the gaps: sensory neurones, are connected to _________
• and _________, allow us to sense our environment

Answer 5

• sensory neurones, are connected to receptors
• and receptors, allow us to sense our environment

Question 6

What are relay neurones ?

Hint: transmits electrical impulses

Answer 6

• relay neurones, are the nerve cell that transmits electrical impulses from sensory neurones to motor neurones.

Question 7

What are motor neurones ?

Hint: carries electrical impulses from…

Answer 7

• motor neurones, are a type of nerve cell that carries electrical impulses from the CNS, to effectors [such as muscles or glands.]

Question 8

What’s the difference between reflexes 🆚 the central nervous system, acting as the coordinator ?

Answer 8

• reflexes are automatic and rapid because, there is no decision making, by the conscious part of the brain
• ; with the central nervous system, acting as the coordinator, the brain actually makes decisions about what action to take

Question 9

How do reflexes protect us from danger ?

Hint: reflex pathway is kept short

Answer 9

• reflexes help to protect us from danger because, they are automatic and rapid.
• This is because, there is no decision making, by the conscious part of the brain
• as the reflex pathway is kept short, and it involves the smallest number of neurones and synapses possible.

Question 10

What’s the difference between sensory neurones 🆚 motor neurones 🆚 relay neurones ?

Hint: connected to receptors, CNS to…, transmits electrical impulses from sensory neurone to…

Answer 10

• sensory neurones, are connected to receptors- [receptors allow us to sense our environment]
• ; motor neurones, are a type of nerve cell that carries electrical impulses from the CNS to effectors such as muscles or glands.
• and relay neurones, are the nerve cell that transmits electrical impulses from sensory neurones to motor neurones.

Question 11

Describe the reflex arc [7]

Hint: receptor, sensory neurone synapsed with…, messages sent across a…, sets up another eletrical…, motor neurone, another eletrical…, appropriate reponse

Answer 11

1) a receptor detects the stimulus, and a electrical impulse is sent by the receptor, via the sensory neurone, to the CNS (spinal cord).

2) a sensory neurone is then synapsed with a relay neurone.

3) and, chemical messengers are sent across a synapse

4) it then sets up another electrical signal in the relay neurone (in the CNS).

5) a relay neurone, is then synapsed with motor neurone.

6) chemical messengers are then sent across a synapse, and it then sets up another electrical signal in the motor neurone.

7) finally, an electrical signal is sent along motor neurone to the effector (muscle or gland) where appropriate response happens.

Question 12

Name some examples of reflexes

Answer 12

• some examples of reflexes are:
• Knee jerk- if you tap the patellar tendon in the knee (just under the knee-cap), the knee will jerk.
• Touching a hot object- if you touch a hot object, your hand will quickly move away to protect you from a burn.

Question 13

Give one other example of a reflex arc [1]

Answer 13

• Eye blink

Question 14

What are synapses ?

Answer 14

• synapses, are a gap between neurones where the transmission of information is chemical, rather than electrical.

Question 15

Why else are [whole] reflexes very fast ?

Answer 15

• [whole] reflexes are very fast because, it’s shorter than a normal nerve pathway

Question 16

What’s a nerve ?

Hint: carries

Answer 16

• a nerve is a long, thin fibre that carries signals between the brain and other parts of the body.
• and they are made up of nerve cells called neurones.

Question 17

What’s a neurone [nerve cell] ?

Hint: responsible

Answer 17

• a neuron, [nerve cells] is a specialized cells responsible for transmitting electrical, and chemical signals in the nervous system

Question 18

Describe how information is passed along neurones

Answer 18

• for an impulse to be conducted from one neurone to another, it must travel across the synapse
• an impulse arrives at the first axon, and neurotransmitters, are then released from the first axon.
• neurotransmitters bind to the second axon
• and an impulse is created, in the second axon

Question 19

What’s the function of a synapse ?

Hint: allow

Answer 19

• the function of a synapse, is to allow for the transmission of signals between nerve cells, and effector cells [e.g- muscles and glands.]

Question 20

Explain in detail, how impulses travel along a synapse [7] 🧠

Answer 20

1) the impulse reaches the end of the first axon, and arrives at the synapse

2) ; the end of the first axon has vesicles containing chemicals called neurotransmitters.

3) The arrival of the electrical impulse, triggers the release of the neurotransmitters from these vesicles into the synaptic cleft (the gap between the first and second axons).

4) The neurotransmitter diffuses across the synaptic cleft and binds with receptors on the second axon.

5) and because the receptors are complementary to the neurotransmitter, only specific chemicals can bind to it.

6) Finally, the Binding of neurotransmitters to the receptors leads to the stimulation of the second neurone.

7) and a new electrical impulse is started in the second axon.

[The receptors are only on one side of the synaptic cleft which ensures the impulse can only travel in one direction.]

Question 21

Using your own knowledge of synapses, explain the effects of stimulants [drugs]

Hint: to diffuse

Answer 21

• stimulants cause more neurotransmitter molecules to diffuse across the synapse

Question 22

Using your own knowledge of synapses, explain the effects of depressants [drugs]

Answer 22

• Stimulants and depressants both affect the synapses between neurones, in the nervous system:
• as depressants stop the next neurone sending nerve impulses – they bind to the receptor molecules, that it needs to respond to the neurotransmitter molecules.

Question 23

What’s the difference between a neurone [nerve cell] 🆚 a nerve ?

Hint: the nervous system

Answer 23

• neurones [nerve cells], are specialized cells that are responsible for transmitting electrical, and chemical signals in the nervous system
• ; nerves are long, thin fibers that carry signals between the brain and other parts of the body.
• [nerves] they are made up of nerve cells called neuron