B5 Synapses and Reflexes (page 60)

Question 1

Neurones transmit information very quickly to and from the brain, what happens next?

Answer 1

your brain quickly decides how to respond to a stimulus. But relflexes are enen quicker.

Question 2

What is Snapses?

Answer 2

The connection between two neurones.

Question 3

How do Synapse work?

Answer 3

The nerve signal is transferred by chemicals which diffuse (move) accross the gap.

These chemicals then set off a new electrical signal in the next neurone

see diagram on page 60.

Question 4

Reflexes help prevent what?

Answer 4

Injury

Question 5

What are Reflexes?

Answer 5

they are rapid, automatic responses to certain stimuli that don’t involve the conscious part of the brain - they can reduce the chances of being injured.

Question 6

If someone shines a bright light in your eyes, what happens, what reflext will your body do?

Answer 6

your pupils automatically get smaller, so the less light gets into the eye - this stops it getting damaged.

This is an example of Reflexes.

Question 7

If someone gets a shock, what reflex will your body do?

Answer 7

your body releases the horone adrenaline automatcially - it doesnt wait for you to decide that your’re shocked.

This is an example of Reflexes

Question 8

The passage of information in a reflex (from a receptor to effector) is called what?

Answer 8

a reflex arc.

Question 9

The Reflex Arc goes through what boby system?

Answer 9

The central Nervous System.

Question 10

The neurones in reflex arcs go through what in the body?

Answer 10

go through the spinal cord or through an unconscious part of the brain.

Question 11

When a Stimulus (e.g. a painful bee sting) is detected by receptors what happens?

Answer 11

impulses are sent along a sensory neurone to a relay neurone in the CNS.

Question 12

When impulses reach a synapse between the sensory neurone and the relay neurone, what happens?

Answer 12

they trigger chemicals to be released. (see diagram on pg 60).

These chemicals cause impulses to be sent along the relay neurone.

(relay neurones connect sensory neurones to motor neurones).

Question 13

When the impulses reach a synapse between the relay neurone and a motor neurone, the same thing happens, which is what?

Answer 13

Chemicals are released and cause impulses to be sent along the motor neurone.

Then impulses travel along the motor neurone to the effector (which is usually a muscle, like in diagrame on page 60).

The muscle then contracts and moves your hand away from the bee.

(you don’t have to think about the response (which takes time), it’s quicker than normal responses).

Question 14

Tell me the process of the reflex ark when a bee stings a finger?

Answer 14

1) bee stings finger
2) Stimulation of the pain receptor
3) Impulses travel along the sensory neurone
4) Impulses are passed alog a relay neurone, via a synapse.
5) Impulses travel along a motor neurone, via a synapse.
6) When impulses reach muscle, it contracts.

Question 15

Do reflexes bypass your conscious brain completely when a quick response is essential?

Answer 15

yes.

(your body just gets on with things. If you had to stop and think first, you’d end up a lot more sore (or worse).

Question 16

What is a reflex action? (1 mark)

Answer 16

A rapid automatic response to a stimulus that doesn’t involve the conscious part of the brain (1 mark)

Question 17

A chef touches a hot pan. A reflex reaction causes him to immediately move his hand away.

a) state the effector in this reflex reaction (1 mark)

b) Describe the pathway of the reflex from stimulus to effector (4 marks)

Answer 17

a) Muscle (1 mark)

b) The heat stimulus is detected by receptors in the hand (1 mark), which send impulses along a sensory neurone to the CNS (1 mark). The impulses are transferred to a relay neurons (1 mark). They are then transferred to a motor neurone and travel along it to the effector/muscle (1 mark).