AQA · GCSE · Combined Science

    Course version: 8464 · Version from Sept 2018

    Adrenaline is produced by the adrenal glands in times of fear or stress.…

    Full specification wording

    Feedback systems (HT only): Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’.

    Adrenaline is a hormone secreted by the adrenal glands, which sit above the kidneys.

    Checked against the AQA 8464 specification (opens in a new tab) on .

    • Point 2 of 4
    • 3 key terms

    Study notes

    From the checked teaching notes for this specification point.

    The idea

    Adrenaline is a hormone secreted by the adrenal glands, which sit above the kidneys. When the brain detects fear or stress, nervous impulses travel to the adrenal glands, which release adrenaline into the blood. Adrenaline binds to receptors on the heart, causing an increase in heart rate, and also increases breathing rate and depth. It stimulates the liver to convert glycogen to glucose, so more glucose and oxygen reach the brain and muscles. These changes raise aerobic respiration, preparing the body for ‘flight or fight’ — either escaping danger or confronting it.

    What earns the marks

    • Adrenaline is produced by the adrenal glands, which are endocrine glands located above the kidneys.
    • Adrenaline increases heart rate, which raises blood flow and therefore the rate of oxygen and glucose delivery to the brain and muscles.
    • Adrenaline also increases breathing rate and stimulates the liver to release glucose, supporting increased aerobic respiration in muscle cells.
    • The overall effect is preparation for ‘flight or fight’, giving the body extra energy for rapid movement or a defensive response.

    Common mistakes and how to put them right

    • Saying adrenaline is a neurotransmitter released only at synapses.

      Put it right: Adrenaline is a hormone released by the adrenal glands into the blood, although its release is triggered by nervous impulses.

    • Claiming adrenaline lowers heart rate or reduces glucose delivery.

      Put it right: It increases heart rate and boosts oxygen and glucose delivery to the brain and muscles.

    • Confusing the adrenal glands with the thyroid gland.

      Put it right: The adrenal glands sit above the kidneys and secrete adrenaline, while the thyroid gland in the neck secretes thyroxine.

    Exam tips

    • Link each effect of adrenaline to its purpose: increased heart rate and breathing deliver more oxygen and glucose for respiration.
    • Use the phrase ‘flight or fight’ when explaining the response to fear or stress, and state that the effects are rapid and short-lived.
    • If asked to explain rather than describe, connect adrenaline release to the nervous system detecting stress and to increased aerobic respiration in muscles.

    Try the lesson

    The start of the Feedback systems (HT only): Adrenaline is produced by the adrenal glands in times of fear or stress. It increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles, preparing the body for ‘flight or fight’. lesson, made from checked teaching notes for this specification point.

    Have a go first

    What is the physiological effect of adrenaline on the body during times of fear or stress?

    Listen

    Adrenaline is a hormone secreted by the adrenal glands, which sit above the kidneys. When the brain detects fear or stress, nervous impulses travel to the adrenal glands, which release adrenaline into the blood. Adrenaline binds to receptors on the heart, causing an increase in heart rate, and also increases breathing rate and depth. It stimulates the liver to convert glycogen to glucose, so more glucose and oxygen reach the brain and muscles. These changes raise aerobic respiration, preparing the body for ‘flight or fight’ — either escaping danger or confronting it. A strong answer earns marks for these points. Adrenaline is produced by the adrenal glands, which are endocrine glands located above the kidneys. Adrenaline increases heart rate, which raises blood flow and therefore the rate of oxygen and glucose delivery to the brain and muscles. Adrenaline also increases breathing rate and stimulates the liver to release glucose, supporting increased aerobic respiration in muscle cells. The overall effect is preparation for ‘flight or fight’, giving the body extra energy for rapid movement or a defensive response. A common slip: Saying adrenaline is a neurotransmitter released only at synapses. Instead, adrenaline is a hormone released by the adrenal glands into the blood, although its release is triggered by nervous impulses. Exam tip: Link each effect of adrenaline to its purpose: increased heart rate and breathing deliver more oxygen and glucose for respiration.

    See it

    A top-down flowchart. The first box reads 'Fear or stress detected' and points to 'Nervous impulses travel to adrenal glands', which points to 'Adrenal glands release adrenaline into the blood'. From this box three arrows lead to three boxes: 'Heart rate increases', 'Breathing rate and depth increase', and 'Liver converts glycogen to glucose'. All three of these boxes point to 'More oxygen and glucose delivered to brain and muscles', which points to 'Aerobic respiration raised', which finally points to 'Body prepared for flight or fight'.
    It shows how fear or stress leads to adrenaline release and the changes that prepare the body for 'flight or fight'.

    Key words

    Say what each word means before you turn the card.

    Adrenaline

    Try answering aloud or in your head before turning the card.

    Adrenal glands

    Try answering aloud or in your head before turning the card.

    'Flight or fight'

    Try answering aloud or in your head before turning the card.

    See every definition
    Adrenaline
    A hormone produced by the adrenal glands in times of fear or stress, which increases the heart rate and boosts the delivery of oxygen and glucose to the brain and muscles.
    Adrenal glands
    Endocrine glands located above the kidneys that produce adrenaline in times of fear or stress.
    'Flight or fight'
    The preparation of the body for escaping danger or confronting it, brought about by adrenaline increasing the heart rate and boosting oxygen and glucose delivery.

    Label the diagram

    Some boxes have lost their names. Pick the right name for each number.

    The diagram again, with 3 boxes numbered instead of named. A top-down flowchart. The first box reads 'Fear or stress detected' and points to 'Nervous impulses travel to adrenal glands', which points to 'Adrenal glands release adrenaline into the blood'. From this box three arrows lead to three boxes: 'Heart rate increases', 'Breathing rate and depth increase', and 'Liver converts glycogen to glucose'. All three of these boxes point to 'More oxygen and glucose delivered to brain and muscles', which points to 'Aerobic respiration raised', which finally points to 'Body prepared for flight or fight'.

    • 1Box 1

    • 2Box 2

    • 3Box 3

    0 of 3 labelled

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