What Is a Reflex Action?

The Universal College of Learning defines reflex action as a rapid involuntary or automatic reaction to a specific situation or stimulus. Autonomic reflex actions are those that involve the autonomic nervous system, cardiac muscle, smooth muscle and glands, while somatic reflex actions involve the somatic nervous system and skeletal muscles. The impulses that produce a reflex action are transmitted within a nervous circuit called a reflex arc.

MedicaLook explains that reflex actions begin with sensory reception followed by sensory transmission along sensory neurons to the central nervous system. The sensory stimulus is then analyzed or integrated within the central nervous system, causing motor transmission to effector organs for a reflex response. A majority of simple reflexes are analyzed and interpreted within the spinal cord without the involvement of the brain. A reflex action is so rapid that the brain gets a message about the stimulus after the response has already occurred. The speed of reflex reaction varies from one individual to another, with some people demonstrating faster reflexes than others. The speed of reflex action response slows with age. Reflex actions are important because they protect the body from harm. The knee jerk reflex is a common example of a reflex action, which occurs when the pattelar ligament is tapped.

Babies are born with several reflex actions that disappear over time but serve a vital function early in life. The rooting reflex causes a baby to open his mouth when his cheek is touched. This reflex encourages the baby to take to the breast for nourishment. The sucking reflex is also present from birth to help the baby understand how to eat. Other such reflexes involve grasping, startling and stepping.