The Human Nervous System (AQA GCSE Biology)

Nerve tissues that communicate with muscles contain a receptor called the nicotinic acetylcholine receptor.

Figure 1 shows how a nerve impulse passing along neurone X causes an impulse to be passed along a motor neurone.

The motor neurone in Figure 1 is connected to the diaphragm, a muscle involved in breathing.

Figure 1

Name the type of neurone labelled X.

Describe the series of events that would result in the diaphragm contracting, from X onwards.

Refer to Figure 1 in your answer.

Anatoxin is a neurotoxin that is also known as ‘Very Fast Death Factor’ because when it was injected into mice it induced paralysis and death within a few minutes.

Anatoxin is similar in shape to the neurotransmitter that usually binds to the nicotinic acetylcholine receptor.

Suggest how anatoxin can lead to death.

Higher Tier Only

When cycling, a cyclist's body temperature increases.

Describe how body temperature is monitored by the brain.

The skin surface temperature and core body temperature of a cyclist were monitored before, during and after a race, as shown in Figure 1.

Figure 1

Core body temperature rises during exercise. When an individual stops exercising, their core body temperature starts to decrease.

How long did it take for the cyclist’s temperature to recover after the race?

Describe and explain the changes that occurred during the race to both the cyclist’s core body temperature and skin temperature.

Figure 1 shows the human eye in two different conditions: bright light and dim light.

Figure 1

Describe the changes in the pupil and iris going from A to B.

Explain how these changes occur, referring to changes in light level.

Figure 2 shows light entering the eye of an individual with blurred vision, and how this condition can be corrected with glasses.

Figure 2

Explain how glasses correct the blurred vision.

Figure 3 shows a ball flying towards an eye.

Figure 3

In the blink reflex light from the ball is detected by light-sensitive cells in the eye. The muscles in the eyelid shut the eye before the ball hits it.

Describe the pathway taken by the nerve impulse in this blink reflex.

The nerve pathway linking the light receptors in the retina of the eye to the eyelid muscle is about 0.5 m metres in length.

It would take a nervous impulse 0.006 seconds to travel this distance along neurones.

However it takes about 0.3 seconds for the blink reflex response to the ball to occur.

Explain the difference.

Figure 1 shows the front part of two eyes.

Figure 1

Name the process of changing the shape of the lens to focus on near or distant objects.

Name the part of the eye where the light rays form an image and outline how the structure of this part of the eye relates to its function.

The change in the shape of the lens of a patient was measured by an eye specialist.

The test involved the patient reading a chart from 15 metres away and when reading a book.

The results are shown in Figure 2.

Figure 2

Write the letter A on Figure 2 to show a time when the patient was reading a book.

Describe and explain the changes that occur in the eye to change the shape of the lens during the time marked 'B' on Figure 2.

Neuroscientists have been able to study individuals with brain damage to map different regions of the brain to particular functions.

Name the part of the brain responsible for controlling unconscious functions in the body, such as breathing and heart rate.

Higher Tier Only

A patient is found to have a tumour in the cerebrum of her brain following an MRI scan.

Evaluate whether the patient should have surgery to remove the tumour.

Name the three different types of neurone.

Give two examples of effectors.

Which type of cells detect stimuli?

On a warm day it usually feels hotter when the humidity (how much water vapour is in the air) is high.

The heat index shown in Table 1, is an index that combines air temperature and relative humidity, it indicates the human-perceived ambient temperature.

Table 1

Endurance athletes such as marathon runners need to be careful when competing in hot humid conditions as their bodies can overheat causing heatstroke, which can be fatal.

Explain how temperature regulation can fail in endurance athletes, leading to overheating in hot, humid conditions.

A person is playing a game tennis and hits the ball back over the net with their racket.

Suggest what the stimulus, receptors and effectors are in this action.

The CNS is termed a coordination centre.

Describe what a coordination centre is.

Figure 1 represents a pathway of how the nervous system responds during a voluntary response.

Figure 1

Complete Figure 1 by listing the correct order of events during a voluntary response.

This should include some structures through which impulses pass between the stimulus and the response. 

Figure 2 shows a synapse (in two states) connecting two neurones

Figure 2

Name substance X.

Neurones pass information around the body.

Explain how information is passed from one neurone to another.

Reflex actions help to protect the body from damage.

Figure 3 represents the nervous pathway for a reflex action when a person accidentally steps on a sharp pin.

Figure 3

Describe and explain how the impulse is transmitted to the effector when the person stands on the sharp pin.

Table 2 shows some pathways around the nervous system. 

Table 2

Complete Table 2

A student carried out an investigation to see if playing computer games improves reaction time.

The test consisted of pressing the 'return key' on a keyboard every time an image appeared on the screen.

The student tested two groups of five people. One group were Gamers (experienced players of computer games) and the other group were people who do not play computer games.

Table 3 shows the results.

Table 3

The student concluded:

"Playing computer games improves reaction time"

Calculate the value Y and suggest why this may not be an accurate statement.

Figure 5 shows a human brain with four regions labelled A - C.

Figure 5

Identify regions A - C and give an example of a role of each region.

Higher Tier Only

Neuroscientists have been able to study the brain and map out the function of different regions. For example they have been able to identify which parts of the cerebrum are involved in vision, hearing or language.

Describe how neuroscientists have been able to achieve this.

The human body has to keep its core temperature at around 37 ^•C which is the optimum temperature for enzymes in the body.

Explain how body temperature is controlled via negative feedback.

Figure 6 shows a cross section of the human eye.

Figure 6

Label the parts of the eye which refract light in Figure 6.

Figure 7 shows the path of light entering the front part of the eye of a person with normal vision, whilst looking at a close object.

Figure 7

As people get older (typically 40+), their lenses lose flexibility and can't spring back into a round shape when looking at close objects.

Explain what effect a less flexible lens would have on the path of light. 

Explain the changes that occur in the normal human eye to focus on near and distant objects.

Explain why long-sighted people are unable to focus on near objects and how this can be corrected using glasses.

As people age, their vision tends to deteriorate. The majority of adults choose to wear glasses to correct their vision as shown in Figure 8.

Figure 8

Explain how laser eye surgery can correct a person's eyesight and suggest a reason why it is not as popular as other methods of vision correction.