Coordination and Response (Nervous and Endocrine Systems)
What this domain tests
Questions compare nervous and endocrine control, test reflex-arc ordering, brain regions, and matching hormones to glands, target organs and disorders.
Core rules
- Neuron: dendrites receive, cell body integrates, axon conducts; the myelinated sheath speeds conduction; the synapse releases a neurotransmitter (acetylcholine) across the gap.
- Reflex arc: receptor → sensory neuron → spinal cord (relay) → motor neuron → effector. Thinking is bypassed for speed.
- Brain: cerebrum for thought, memory and voluntary action; cerebellum for balance and muscle coordination; medulla oblongata for heart rate, breathing and swallowing; hypothalamus links nervous and endocrine systems and controls body temperature and thirst.
- Cerebrospinal fluid cushions the CNS.
- Autonomic system: sympathetic for fight-or-flight, parasympathetic for rest-and-digest.
- Key hormones: insulin (beta cells of pancreas) lowers blood glucose; glucagon raises it; thyroxine needs iodine and controls metabolic rate; adrenaline from the adrenal medulla raises heart rate and glucose; growth hormone from the anterior pituitary; ADH from the posterior pituitary; testosterone and oestrogen from gonads.
- Negative feedback keeps hormone levels stable.
Worked example
A child touches a hot pan and withdraws the hand before feeling pain. Reasoning: heat receptors fire, impulses travel through the sensory neuron to the spinal cord, which immediately signals a motor neuron to the biceps - the withdrawal happens without waiting for the cerebrum. Pain is perceived later when impulses reach the cerebral cortex.
Traps that cost marks
Reversing insulin and glucagon effects; naming the pituitary as the source of thyroxine; saying reflexes are decided by the cerebrum; confusing diabetes insipidus (ADH) with diabetes mellitus (insulin); forgetting iodine is essential for thyroxine.