Important Topic of Biology: Reflex Action

When there is an action there will be an immediate reaction in biology, the same thing applied but in different terms. Our body reacts to many actions – when we place our foot on a sharp object or hand on a heated object or another. When we encounter these types of incidents, we will give a response in seconds unknowingly. 

So what do you do when things happen without your knowledge? How do we respond to it? What do we call this process? How does it work? Reflex action is the reason behind all this. It is an involuntary response to stimuli. When we encounter the incidents, as discussed above, we will give involuntary quick reflex actions to it. It is also known as a survival instinct. When we touch a hot pan in our absence of mind, we will react to it and quickly move our hands far from it. So, let’s learn more in detail about reflex action.

Reflex Action Definition

Reflex action is an involuntary action and instantaneous movement in response to a stimulus. A reflex that is made by a neural pathway is known as a reflex arc which acts on impulse before it reaches the brain. It is an automatic response to a stimulus that doesn’t need consciousness. We will call it an involuntary function when the brain’s permission is needed in doing it. Reflex is a Latin word, whose meaning is a reflection and was introduced by Marshall Hall in the 19th century.

The reflex arc is an anatomical pathway of a reflex. It has afferent or sensory nerves and efferent which is also known as motor nerves or secretory nerves or secretomotor nerves. Reflexes are having several synapses where stretch reflex is not having an interneuron in the arc and has only one synapse between efferent and afferent nerve fiber.

Reflex Action Body Parts

The parts of the reflex arc or the parts which help in this reflex action are described below.

• Reflex Arc – it is a neural pathway that controls the reflexes and gives instantaneous reactions. There are two types of reflex arc:
• Autonomic reflex arc – affects the functioning of inner organs.
• Somatic reflex arc – affects the functioning of muscles.

The further reflex arc consists of the following parts:-

• Receptor – The receptor does detect the stimulus. It is highly sensitive to any kind of internal or external change in the result of the stimulus.
• Sensory neuron – It transfers sensory information to the brain or spinal cord. Its function is to transmit nerve impulses from the receptors into the spinal cord or brain.
• Motor neuron – It transmits nerve impulses from the brain or spinal cord to an effector. It conducts motor output to the periphery.
• Effector – Effectors act in response to the stimulus by motor neurons and produce instantaneous or involuntary reflexes.
• Interneuron – Intern neuron which is also known as relay neuron serves as a processing center and conducts nerve impulses from the sensory neurons to motor neurons. They are responsible for communication between the sensory and central nervous systems.

Pathway

1. Receptors detect the stimulus or a sudden change in our surroundings where instinct action takes place. The sensory organ receives the stimulus.
2. Sensory organs send the signal to relay neurons.
3. The relay neuron sends the signal to the motor neuron.
4. It is followed by a motor neuron sending signals to the effector’s nerves.
5. Further effector produces an involuntary or instantaneous response.

Types of Reflex Actions in Humans

• Myotic reflexes
• Tendon reflexes

And there are some reflexes that we will observe in only infants. They are:

• Sucking reflexes
• Abdominal reflexes
• Rooting reflexes
• Asymmetric and symmetric tonic neck reflexes etc.

Examples of Reflex Action

• One of the best-known examples of reflex action is the pupillary light reflex. When our eyes see bright light it automatically blinks for a sec. Due to the flashing of light pupils of both eyes get contracted.
• Another example is coughing and sneezing. When our trachea has irritation, an involuntary action occurs.
• The first reflex of humans starts in the mother’s womb. By seven and half weeks we can observe reflection in the fetus. By birth, the child will have sucking and swallowing reflexes. When anything touches the baby’s or infant’s lips they tend to suck and when anything touches the back of their throat they tend to swallow it. These are the reflexes that are developed in infants.

Importance of this chapter in NEET

The Paper will definitely have a question or multiple questions from this area. They can ask about the reflex arc or the part of the reflex arc including their functions or nerves which are included in this process with their function. It’s an important chapter and you just need to understand the process and the functions of every part with some examples. You can score marks when you encounter questions related to this area or topic. If you want to get good marks easily then you should not avoid topics like these which give you marks easily by understanding the little things.

In this article, we have discussed reflex action which is involuntary action to stimuli, it process like how the ratio is going to come without involving the brain, the parts which are involved in this reflex action with their functions are also being discussed and we have also discussed the type of reflexes even there are some reflexes which occur in infants only. Some of them are sucking and swallowing reflexes; these are also known as first reflexes in humans. At last, we have discussed some examples of reflex action.