What do reflexes involve

It's because of your reflex. A reflex is an involuntary say: in-VAHL-un-ter-ee , or automatic, action that your body does in response to something — without you even having to think about it. You don't decide to kick your leg, it just kicks. There are many types of reflexes and every healthy person has them. In fact, we're born with most of them. Reflexes protect your body from things that can harm it. For example, if you put your hand on a hot stove, a reflex causes you to immediately remove your hand before a "Hey, this is hot!

A reflex is just like a relay race, but in a reflex, it is the action potential that moves between neurons rather than a baton and runner along parts of the track Figure 3. In the above example of a monosynaptic reflex, the interneuron is not used. It is easy to add an interneuron; just add another runner and baton, but this runner travels a very short distance.

In our body, interneurons are in the spinal cord. So, when an interneuron participates in a reflex, there is more than one synapse, and these reflexes are then called complex reflexes. There are many different reflexes in the body. Some of them are complicated and involve multiple interneurons and many synapses.

These reflexes, just like the simple monosynaptic reflex, exist in living beings, especially humans, to keep us safe! Sometimes reflexes create more than one action.

Imagine removing your foot from something sharp—like a Lego piece that was left on the floor. So, the withdrawal reflex to remove your foot works with a reflex on the other side of the body telling you to put your other foot down. That reflex is called the crossed extensor reflex. These actions are all done without you thinking or planning, but your brain helps to assess the situation as an afterthought.

Who left the Lego there? Did you notice how the brain was not on the five-part list of what makes up a reflex? Well, reflexes are functions of the nervous system, which coordinates our actions.

The nervous system is the network of neurons that transmits the action potentials. The sensor and neurons are outside the spinal cord, in what is called the peripheral nervous system PNS. The other part of the system is called the central nervous system CNS , and it consists of the brain and spinal cord.

The CNS is used to think, plan, and learn. Remember the earlier examples when you ducked down in response to a loud noise or lifted your foot after stepping on the Lego? In those examples, the CNS is what helped you understand what the noise was or why you moved automatically. It did not create the initial movement, but the CNS allowed you to understand why you ducked down or that you stepped on a Lego.

The CNS also plans the voluntary movements that come after the initial involuntary reflex. Reflexes are a unique category of responses because they do not require the higher centers used for conscious or voluntary responses. Instead reflexes are involuntary, stereotyped they are repeatable under the same stimulus conditions responses that occur quickly.

Reflexes can either be visceral or somatic. 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. They utilize neurons of the autonomic nervous system to elicit their actions. Visceral reflexes have been more fully discussed in the section on the autonomic nervous system.

In contrast, somatic reflexes involve unconscious skeletal muscle motor responses. In doing so, these reflexes utilize some of the same lower motor neurons alpha motor neurons used to control skeletal muscle during conscious movement. Because reflexes are quick, it makes sense that somatic reflexes are often meant to protect us from injury. As examples, reflexes contribute to the maintenance of balance and rapid withdrawal of the hand or foot from damaging stimuli.

Somatic reflexes can either be intrinsic present at birth or learned. Reflex arcs that contain only two neurons, a sensory and a motor neuron, are considered monosynaptic. Examples of monosynaptic reflex arcs in humans include the patellar reflex and the Achilles reflex.

Most reflex arcs are polysynaptic, meaning multiple interneurons also called relay neurons interface between the sensory and motor neurons in the reflex pathway. Key Terms motor neuron : A neuron located in the central nervous system that projects its axon outside the CNS and directly or indirectly control muscles.

There are two types of reflex arcs: autonomic reflex arc affecting inner organs and somatic reflex arc affecting muscles. Spinal Reflexes Spinal reflexes include the stretch reflex, the Golgi tendon reflex, the crossed extensor reflex, and the withdrawal reflex. Learning Objectives Distinguish between the types of spinal reflexes. Key Takeaways Key Points The stretch reflex is a monosynaptic reflex that regulates muscle length through neuronal stimulation at the muscle spindle.

The alpha motor neurons resist stretching by causing contraction, and the gamma motor neurons control the sensitivity of the reflex.

The stretch and Golgi tendon reflexes work in tandem to control muscle length and tension. Both are examples of ipsilateral reflexes, meaning the reflex occurs on the same side of the body as the stimulus. The crossed extensor reflex is a contralateral reflex that allows the body to compensate on one side for a stimulus on the other.

The withdrawal reflex and the more-specific pain withdrawal reflex involve withdrawal in response to a stimulus or pain. When pain receptors, called nociceptors, are stimulated, reciprocal innervations stimulate the flexors to withdraw and inhibit the extensors to ensure they are unable to prevent flexion and withdrawal.

Key Terms golgi tendon reflex : A normal component of the reflex arc of the peripheral nervous system. In this reflex, a skeletal muscle contraction causes the agonist muscle to simultaneously lengthen and relax. This reflex is also called the inverse myotatic reflex because it is the inverse of the stretch reflex. Although muscle tension is increasing during the contraction, the alpha motor neurons in the spinal cord that supply the muscle are inhibited. However, antagonistic muscles are activated.

They innervate the extrafusal muscle fibers of skeletal muscle and are directly responsible for initiating their contraction.