Reflex action

Cranial Nerves The somatic nerves that extend from the brain are known as cranial nerves and are located on the back of the head and neck . There are 12 pairs of cranial nerves in total, each of which splits to carry signals between both sides of the brain and body. These nerves are often involved in neuromuscular disorders. Spinal Nerves The somatic nerves that extend from the spinal column are known as spinal nerves. There are 31 pairs of spinal nerves. Eight come from the cervical portion of the spine, 12 are in the thoracic region, both the lumbar and sacral regions have five spinal nerves, and one is near the tailbone. A disease or injury in any of these areas can result in a loss of sensation and function below that area. • Movement control: The somatic nervous system plays a vital role in initiating and controlling the movements of your body. This system is responsible for nearly all voluntary muscle movements. • Sensory input: The somatic system is also responsible for processing sensory information that arrives via external stimuli. It processes the senses of An example of a somatic system function is if you are out for a jog in the park one brisk winter morning and as you run, you step on a patch of slick ice. Once your foot starts to slip, your somatic nervous system carries a message to the muscles in your legs, enabling you to catch yourself and avoid a fall. • Brachial plexus neuropathy, or damage to nerves in the upper shoulder, resulting in pain in the shou...

\( \newcommand\) • • • • • • • Autonomic reflexes are unconscious motor reflexes relayed from the organs and glands to the CNS through visceral afferent signaling. Key Points • While the unconscious reflex arcs are normally undetectable, in certain instances they may trigger pain, typically masked as referred pain. • The sympathetic nervous system is a quick-response, mobilizing system while the parasympathetic system is a more slowly activated, dampening system—but there are exceptions, such as in sexual arousal and orgasm where both systems play a role. • Within the brain, the ANS is located in the medulla oblongata in the lower brainstem. The medulla’s major ANS functions include respiration, cardiac regulation, vasomotor activity, and certain reflex actions (such as coughing, sneezing, vomiting, and swallowing). Key Terms • reflex arc: A neural pathway that controls an action reflex. There are two types of reflex arcs: the autonomic reflex arc that affects the inner organs, and the somatic reflex arc that affects muscles. • referred pain: Pain perceived at a location other than the site of the painful stimulus. • somatic: Part of, or relating to, the body of an organism. The Autonomic Nervous System The autonomic nervous system (ANS, visceral nervous system, or involuntary nervous system) is the part of the peripheral nervous system that acts as a control system. It functions largely below the level of consciousness, and controls visceral functions. The ANS affects hea...

\( \newcommand\) • • • • • A reflex arc defines the pathway by which a reflex travels—from the stimulus to sensory neuron to motor neuron to reflex muscle movement. Key Points • Reflexes, or reflex actions, are involuntary, almost instantaneous movements in response to a specific stimulus. • 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. • sensory neuron: These are typically classified as the neurons responsible for converting various external stimuli that come from the environment into corresponding internal stimuli. • reflex arc: A neural pathway that controls an action reflex. In higher animals, most sensory neurons do not pass directly into the brain, but synapse in the spinal cord. This characteristic allows reflex actions to occur relatively quickly by activating spinal motor neurons without the delay of routing signals through the brain, although the brain will receive sensory input while the reflex action occurs. There are two types of reflex arcs: autonomic reflex arc (affecting inner organs) an...

A reflex is an involuntary and rapid response to the stimulus. It is a crucial component of the famed survival instinct. Depending on our previous experiences and understanding, we all have different instincts. A reflex is a response that is triggered by an instinct. Sometimes we don't know if the pan is hot or not until it's too late. To put it another way, reflex has little to do with instinct. In this article, you will understand reflex action, types of reflex action, the significance of reflex action, and some FAQs. So, let us start by understanding reflex action in the coming section. What is Reflex Action? An involuntary or instantaneous action by the human body parts in response to a stimulus is called reflex action. It is because of numerous neural pathways that are known as reflex arcs that act on an impulse before it reaches the brain. Reflex action doesn’t need any conscious thought or awareness about the automatic response. What happens in Reflex Action? When a specialized tissue receives a stimulus, it may either directly/indirectly alter the relation of other tissues or also the whole individual to the (Image will be uploaded soon) Types of Reflex Action To understand reflex action, we should understand all parts of the reflex arc responsible to cause a reflex action. Types of reflex action can be myotatic reflexes, tendon reflexes, or reflexes observed only in human infants such as sucking reflexes, and other reflexes such as abdominal reflexes or cough refl...

Every time you accidentally touch a hot surface, your hand withdraws itself immediately. It is like an automated action that happens without you having to think about it. In scientific terms, this action is called reflex action. Such Actions occur because of numerous neural pathways that are known as reflex arcs that act on an impulse before it reaches the brain. These actions can be inherited from parents or are learned throughout their lifetime. Read the article to explore more about the physiology and significance of reflex action. What is Reflex Action? Reflex action refers to the simplest form of response in the nervous system, which may be defined as the spontaneous, automatic and mechanical response to a stimulus acting on a specific receptor without conscious effort or thought and requires the involvement of a part of the central nervous system. Physiology of Reflex Action i. Reflex action is a rapid, simple, automatic response to a stimulus that is not under the voluntary control of the brain. ii. It is an involuntary action. iii. It takes very less time, about a few milliseconds, to show response during reflex action. iv. Reflex action generally involves the spinal cord for quick response to a specific stimulus. Such reflexes are termed spinal reflexes. Then information input goes on to the brain, where the thinking process occurs later. v. Reflexes maintain balance & posture. E.g. Spinal reflexes – control trunk and limb muscles. vi. Reflex actions that involve ...

Overview What is hyporeflexia? Hyporeflexia happens when your A reflex is an involuntary (automatic) action your body does in response to something. Reflexes protect your body from things that can harm it. Hyporeflexia results from any interruption of the reflex arc, which has a sensory part, a central part ( Hyporeflexia is the opposite of Hyporeflexia is just a physical sign that’s very useful for a How is hyporeflexia diagnosed? Healthcare providers use the deep tendon reflex (DTR) examination to check for hyporeflexia or hyperreflexia as part of a The DTR exam involves a healthcare provider tapping your knee with a rubber hammer (it shouldn’t hurt). This tap stretches your patellar Normally, your spinal cord (via motor neurons) very quickly sends a message back to the muscle telling it to contract. The contraction causes your lower leg to kick out. If you have hyporeflexia, your leg will kick only weakly or won’t kick out at all. For effective and reliable results for the DTR exam, you need to be as relaxed as possible. If you’re thinking about the test or have a rigid posture, the results might not be accurate. Your provider may try to distract you with a question or some other method as they tap on your knee to prevent this. Aside from your knee, your provider may also check reflexes: • Along the outside of your elbows. • In the crooks of your arms. • At your wrists and ankles. • At your chin. Possible Causes What are the causes of hyporeflexia? Damage anywhere along...

Reflex actions are involuntary and instantaneous movements in response to stimuli. What is a reflex action? A reflex or a reflex action is an instant movement in response to a stimulus. Some natural pathways called reflex arcs act in an impulse before the impulse reaches the brain, and this makes a reflex or a reflex action. For example; What if a ball comes flying at your face? Your eyelids blink shut quickly and you may even scrunch up your eyes or bring your hands up to your face for extra protection. These quick movements are called reflexes and they protect your body from harm without you even having to think about it. Sequence of a reflex action You don’t need to think for a reflex action to happen. What is your reaction if you touch something hot or sharp? You automatically pull your hand away. This is a withdrawal reflex. This type of a movement happens even before your brain has received information from the sense organs that there is a problem. What is your reaction if you touch something hot or sharp? How does a reflex action work? Many reflexes are controlled by the spinal cord. Signals travel to the spinal cord along nerves from the receptors of the sense organs. But, even before the information reaches the brain, a signal zaps back out from the spinal cord that tells the effectors, which is the muscles to move. This overall sequence is called the reflex arc. How does a reflex action work – Diagram of Reflex Arc Next we are going to learn about the reflex arc ...