Anatomy & Physiology I and II

Anatomy & Physiology Study Guide

©2018 Achieve Test Prep Page 166 of 367 During development, distinct connections form between particular neurons that create innate reflexes. These reflexes perform in a predictable sequence, from the simplest reflex responses to more complex motor patterns. The neural connections responsible for the basic motor patterns of an innate reflex are genetically or developmentally programmed. The reflexive removal of a hand from a hot stove top and blinking when the eyelashes are touched are two examples. Acquired reflexes consist of complex, learned motor patterns. An experienced driver hit the brakes when trouble appears ahead; a professional skier must make quick adjustments in body position while racing. These motor responses are rapid and automatic, but they were learned rather than pre-established, and thus, these reflexes are enhanced by repetition. The Reflex Arc The “wiring” of a specific reflex is called a reflex arc. Sending communication from a receptor to a peripheral effector, a reflex arc may stimulate a response at a muscle fiber or a gland cell. A reflex response removes or opposes the original stimulus. In the example of touching a sharp object, the contracting muscle pulls the hand away from the painful stimulus before the conscious indication of the pain. This reflex arc is, therefore, an example of negative feedback. Reflexes play a significant role in maintaining homeostasis through opposing harmful changes. The immediate reflex response is not the only response to a stimulus. However, the other responses, which are directed by the brain, involve multiple synapses and take longer to organize and coordinate. Classification of Reflexes The categorization of reflexes is determined by their development, the complexity of the neural circuit involved, the nature of the resulting motor response, or the site of information processing. Development of Reflexes