reflex actions

Try the Reflex actions test once you have read this page.

Remember an effector makes the animal carry out a response, it can be a muscle or a gland.

Reflex Actions

Reflex actions are simple forms of behaviour designed to keep the animal safe. They involve only a few neurones (nerve cells). A sensory neurone

Most have a relay neurone (but not all, the knee jerk reflex does not). and a motor neurone.

These neurones are linked.

Examples of reflex actions

Reflex action	Stimulus	Receptors	Response
Pupil reflex	Light intensity	Rods and cones	Iris muscles adjust pupil diameter, wide in dim light, narrow in bright light.
Knee jerk	Tapping patellar tendon	Proprioceptors/ . tendon stretch receptors	Lower leg kicks forwards due to sudden contraction of front thigh muscles
Sweating	Increased body temperature	Thermoreceptors	Increased sweat release to cool body surface down.
Coughing and sneezing.	Irritant material on mucosa of airways	Chemoreceptors	Sudden contraction of diaphragm and internal intercostal muscles causing a violent expiration to blow irritant material out.