HOW THE SPUTUM IS FORMED WHEN WE COUGH
The involuntary expulsion of air from the lungs with a characteristic sound is called as cough. It is used to respond against the noxious substances and it is also used in maintaining the air passages in the respiratory tract.
Because of cough Expectoration or sputum production will take place and we will spit that material out of the respiratory tract. Whatever the mucosal substance in the respiratory tract accumulated is removed or expelled out by the formation of air flow from the lungs into the environment. Coughing is a voluntary reaction and it is a physiological reflex action. All these reflex actions are controlled by the reflex arc.
Because of cough Expectoration or sputum production will take place and we will spit that material out of the respiratory tract. Whatever the mucosal substance in the respiratory tract accumulated is removed or expelled out by the formation of air flow from the lungs into the environment. Coughing is a voluntary reaction and it is a physiological reflex action. All these reflex actions are controlled by the reflex arc.
It is made up of sensory receptors, afferent nerve fibers, a center, efferent nerve fibers, and effector muscles. Cough receptors are also known as irritant receptors and these nerve endings are more in the mucosa of the larynx, trachea, carina, bronchus and bronchioles which are stimulated by mechanical and chemical irritants. |
| These irritants are used to stimulate the nerve endings so that they produce a stimulus to the sensory receptor. The sensory receptor converts the chemical or mechanical stimuli into nerve impulse and initiates the afferent nerve fiber. The impulse is taken to the center or interneuron and is sent to efferent nerve fiber. From the efferent nerve fiber the impulse finally reaches to the effector organ to show its response according to the stimuli. |
Cough is most effective in clearing the secretions. The cough receptors are seen in other sites such as pharynx, peripheral airways, and other intra- or extra thoracic sites such as pleura, ear canals, tympanic membrane, and even the stomach. Vagus is the 10th cranial nerve which acts as an important afferent nerve. Along with vagus, the glossopharyngeal and trigeminal nerves may operate, depending on the receptors involved. In the brain, a medullary cough centre has been mentioned but there is no evidential proof for it. That means there is no evidential proof for the cough center but it is only assumed. This center is highly influenced by the higher nerve centers, which play a role in modifying or initiating the cough. As vagus is the afferent nerve for cough,
1. Vagi (recurrent laryngeals) - The recurrent (inferior) laryngeal nerve is a branch of the vagus that supplies motor function and sensation to voice box (larynx). It travels within the endoneurial sheath.
2. The phrenic nerves - The phrenic nerves contain motor, sensory, and sympathetic nerve fibers. These nerves provide the only motor supply to the diaphragm as well as sensation to the central tendon. In the thorax, each phrenic nerve supplies the mediastinal pleura and pericardium.
3. Spinal motor nerves of the expiratory muscles.
Tags:Cough, sputum, sputum formation, Vagus, Thoraic,larynx, trachea, carina, bronchus