Coordination and control – the nervous system

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Question 19
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The diagram shows the layout of the antagonistic circular and radial muscles within the iris of the human eye.

Diagram of iris muscles

When a person walks from a brightly lit lecture theatre into a dark room, their pupils dilate to allow more light to enter.

Which of the following correctly describes the nervous and muscular coordination of this response?

Autonomic pathway: Parasympathetic; Circular muscles: Contract; Radial muscles: Relax

Autonomic pathway: Sympathetic; Circular muscles: Contract; Radial muscles: Relax

Autonomic pathway: Parasympathetic; Circular muscles: Relax; Radial muscles: Contract

Autonomic pathway: Sympathetic; Circular muscles: Relax; Radial muscles: Contract

Coordination and control – the nervous system Questions

  1. GCSE
  2. /Biology
  3. /Coordination and control – the nervous system