In this reflex, when a skeletal muscle is stretched, a muscle spindle in the belly of the muscle is activated. One of the simplest reflexes is a stretch reflex. Reflexes can also be categorized by the number of synapses they involve (monosynaptic reflex versus polysynaptic reflex) or the relative position of the sensory receptors to the responding muscles (ipsilateral = same side of the body, contralateral = opposite sides of the body).Įxamples of Somatic Reflexes Stretch Reflex Learned reflexes are much more complicated in their anatomical structure and result from repetitive actions, such as athletic training. We will be focusing on intrinsic reflexes, which occur as the result of normal human development. Somatic reflexes can either be intrinsic (present at birth) or learned. As examples, reflexes contribute to the maintenance of balance and rapid withdrawal of the hand or foot from damaging stimuli. Because reflexes are quick, it makes sense that somatic reflexes are often meant to protect us from injury. In doing so, these reflexes utilize some of the same lower motor neurons (alpha motor neurons) used to control skeletal muscle during conscious movement. In contrast, somatic reflexes involve unconscious skeletal muscle motor responses. Visceral reflexes have been more fully discussed in the section on the autonomic nervous system. They utilize neurons of the autonomic nervous system to elicit their actions. Visceral reflexes involve a glandular or non-skeletal muscular response carried out in internal organs such as the heart, blood vessels, or structures of the GI tract. Reflexes can either be visceral or somatic. Instead reflexes are involuntary, stereotyped (they are repeatable under the same stimulus conditions) responses that occur quickly. Reflexes are a unique category of responses because they do not require the higher centers used for conscious or voluntary responses. You might recognize this as the same model used to maintain homeostasis. In a reflex, sensory information activates a receptor that sends information to the CNS via a sensory neuron, some level of processing occurs in the integration center, and then the response is communicated to the effector target via the motor neurons. A reflex arc is a neural pathway involved in a reflex. A reflex is an unlearned, rapid, involuntary and predictable response. The other option is to use this sensory information to initiate a pre-programmed reflex.
MOVE UP AND DOWN IN ESSENTIAL ANATOMY 3 HOW TO
One option is to make conscious decisions about how to react to the information, such as deciding how to change our behavior if we are cold or hungry. Now let’s consider what the central nervous system might do with the information it is receiving from the afferent division of the PNS. So far we have discussed the CNS and PNS. Define monosynaptic and polysynaptic reflexes.
Compare and contrast somatic and visceral reflexes.
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