K325 / 2027

Lesson 7 of 7 / Nutrition in humans

Alcohol, the brain and the liver

How can a slower response become a wider social risk?

I can connect alcohol's effects on the brain and liver to immediate, long-term and social consequences.

  • I can explain the specified nutrient-processing, bile and breakdown roles of the liver.Syllabus

    Syllabus K325, Topic 4(f). Explain the specified nutrient-processing, bile and breakdown roles of the liver.

  • I can explain alcohol effects on the brain, long-term damage and social consequences.Syllabus

    Syllabus K325, Topic 4(g). Explain alcohol effects on the brain, long-term damage and social consequences.

About 5 min

Make a guess. You are not marked.

After a few drinks, a driver says they feel more alert. What has most likely happened to their reaction time?

  1. It is unchanged, because they feel fine.
  2. It has decreased, so they react faster.
  3. It has increased, so they react later.
Show the answer

It has increased, so they react later.

Alcohol slows the brain. A longer reaction time means the car travels further before braking starts.

The key idea

Alcohol can slow responses and reduce self-control. Repeated excessive consumption can damage the liver and brain, with consequences for the person and others.

Reaction time is the time between a stimulus and the response to it. A longer reaction time means responding more slowly, not more quickly.

Explore the idea

Connect a body effect to a consequence

Reaction time: a possible causal chainBrain response slows; Response begins later; Injury risk can rise. In this original example, a 0.5 s extra delay at 10 m/s adds 5 m travelled before a response begins. This is not an alcohol-dose prediction.Brain response slowsResponse begins laterInjury risk can rise

In this original example, a 0.5 s extra delay at 10 m/s adds 5 m travelled before a response begins. This is not an alcohol-dose prediction.

Original cause-and-effect model. It separates an immediate biological effect from a possible consequence; it does not predict an individual's response or specify an alcohol dose.

Explanation

Alcohol affects brain function. It can increase reaction time, so a person takes longer to respond to a signal or hazard. It can also reduce self-control and impair judgement and coordination. Feeling more confident does not mean that responses have become more accurate.

Slower responses and poorer decisions can increase the risk of injury, including road accidents. A delay between seeing a hazard and beginning to react lets a moving vehicle travel further before braking starts. This is a consequence of response delay, not a change in the vehicle's brakes.

The liver breaks down alcohol, but this capacity is limited. Long-term excessive consumption can cause liver disease, including scarring that interferes with liver function, and can damage the brain. Acute effects on decisions and coordination are different from damage that develops over time.

The effects can extend to other people. Injuries may affect passengers or pedestrians; impaired decisions can strain relationships, study or work; dependence and illness can create financial and care burdens. Explain these links without assuming that every individual experiences the same outcome.

Step by step
  1. 1

    Name the biological effect

    For example, increased reaction time, reduced self-control or liver damage after excessive long-term consumption.

  2. 2

    Explain the consequence

    A slower response to a hazard can increase injury risk. Reduced self-control can affect decisions.

  3. 3

    Connect to others

    Show how a particular consequence can affect family, other road users, work or health services.

Worked example

Extra distance before a response

In an illustrative example, a vehicle travels at 10 m/s. A driver's reaction time increases from 0.3 s to 0.8 s. How much further does it travel before the driver begins to respond?

One way to explain it

The extra delay is 0.5 s. At 10 m/s the vehicle travels an additional 10 x 0.5 = 5 m before the response begins. This illustrates why an increased reaction time can increase risk; it is not a measurement of any particular alcohol dose.

Why this answer works
  • Subtract the two reaction times.
  • Multiply speed by the extra delay.
  • Distinguish distance before responding from braking distance.

Watch out for this

A student says: "Increased reaction time means a person reacts faster." What is wrong with this?

Show the answer

Reaction time is a duration. An increase means the response starts later, which can leave less time to avoid a hazard.

Check your understanding

Which chain correctly links a brain effect of alcohol to a possible social consequence?

  1. Reduced judgement can lead to risky decisions that injure other people.
  2. The liver breaks down alcohol, so no harm can occur.
  3. Alcohol speeds up reaction time, so a driver brakes sooner and has fewer collisions.
Show the answer

Reduced judgement can lead to risky decisions that injure other people.

This links a biological effect to a possible behavioural and social consequence without claiming that the same outcome always occurs.

Quick recall

Card 1 of 3. Answer in your head, then check.

How can a slower response become a wider social risk?

You can return to this lesson any time.