How are the nervous and endocrine systems organised?
The divisions of the nervous system: central and peripheral (somatic and autonomic). The function of the endocrine system: glands and hormones. The fight or flight response including the role of adrenaline.
Covers AQA 4.6 the nervous system (central and peripheral, somatic and autonomic), the endocrine system (glands and hormones) and the fight or flight response including adrenaline.
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What this dot point is asking
AQA wants you to describe the divisions of the nervous system, the endocrine system and the fight or flight response. The exam skill is to reproduce the nervous system hierarchy accurately and to trace the fight or flight response from stressor to adrenaline to physiological change.
Divisions of the nervous system
The nervous system is best learned as a branching hierarchy, because exam questions reward reproducing it in full. At the top it splits into the central nervous system (the brain, the centre of conscious awareness, and the spinal cord, which relays messages and controls reflexes) and the peripheral nervous system, which transmits messages via neurons to and from the rest of the body. The peripheral system then splits into the somatic nervous system, which governs voluntary skeletal movement and carries sensory information back to the CNS, and the autonomic nervous system, which governs vital involuntary functions such as heart rate, breathing and digestion without conscious control. The autonomic system itself has two opposing branches: the sympathetic branch, which arouses the body for action, and the parasympathetic branch, which calms it down and conserves energy (rest and digest). These two branches act antagonistically to keep the body in balance.
The endocrine system and fight or flight
The endocrine system works alongside the nervous system but more slowly, communicating through hormones released into the bloodstream by glands rather than through fast electrical impulses. The pituitary gland is the master gland because it controls the release of hormones from other glands. The fight or flight response shows the two systems working together. When a stressor is perceived, the hypothalamus signals the sympathetic branch of the autonomic nervous system, which stimulates the adrenal medulla to secrete adrenaline (and noradrenaline) into the blood. Adrenaline rapidly produces the bodily changes of arousal: a faster, stronger heartbeat and raised blood pressure to deliver oxygen and glucose to the muscles, faster breathing, dilated pupils, and the shutting down of non-essential functions such as digestion. This prepares the body either to confront the threat or to flee. When the danger passes, the parasympathetic branch acts as a brake, slowing the heart and restoring the resting (rest and digest) state. A useful evaluation point is that this acute response evolved for physical threats and may be maladaptive when triggered repeatedly by modern psychological stressors.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20184 marksOutline the divisions of the human nervous system.Show worked answer →
A 4-mark AO1 item. Markers want the hierarchy of divisions, ideally as a clear structure.
The nervous system divides first into the central nervous system (CNS), made up of the brain and spinal cord, and the peripheral nervous system (PNS), which carries messages between the CNS and the rest of the body. The PNS then divides into the somatic nervous system, which controls voluntary movement and carries sensory information to the CNS, and the autonomic nervous system, which controls involuntary functions such as heart rate. The autonomic system in turn divides into the sympathetic branch (arousing) and the parasympathetic branch (calming).
A full-mark answer gives the full hierarchy: CNS and PNS, then somatic and autonomic, then sympathetic and parasympathetic. Missing a level of the hierarchy is the common error.
AQA 20216 marksDescribe the fight or flight response and explain the role of adrenaline.Show worked answer →
A 6-mark item, roughly 4 AO1 and 2 AO2 (role of adrenaline).
When a stressor is perceived, the hypothalamus activates the sympathetic branch of the autonomic nervous system. This stimulates the adrenal medulla to release adrenaline into the bloodstream. Adrenaline produces the physiological changes of arousal: increased heart rate and blood pressure (delivering oxygen to muscles), faster breathing, dilated pupils, and the diversion of blood away from non-essential systems such as digestion. These changes prepare the body to either confront the threat (fight) or escape it (flight). Once the threat passes, the parasympathetic branch restores the body to its resting state (rest and digest).
Markers reward the sympathetic activation, the adrenal medulla releasing adrenaline, the specific physiological effects, and the parasympathetic return to rest.
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Sources & how we know this
- AQA A-level Psychology (7182) specification — AQA (2015)