Tag: respiratory system in humans

Breathing involves expansion and contraction off lungs to adjust the partial pressure of relative gases for exchange. The process of inhalation occurs due to an increase in the lung volume (diaphragm contraction and chest wall expansion) which results in a decrease in lung pressure in comparison to the atmosphere. Thus, air rushes in the airway. The process of exhalation occurs due to an elastic recoil of the lung tissue which causes a decrease in volume, resulting in increased pressure in comparison to the atmosphere. Thus, air rushes out of the airway. 

A bronchus, also known as a main or primary bronchus, is a passage of airway in the respiratory tract that conducts air into the lungs. There is a right bronchus and a left bronchus and these bronchi branch into smaller secondary and tertiary bronchi which branch into smaller tubes, known as bronchioles. No gas exchange takes place in the bronchi. The trachea (windpipe) divides into two main or primary bronchi, the left and the right, at the level of the sternal angle and of the fifth thoracic vertebra or up to two vertebrae higher or lower, depending on breathing, at the anatomical point the carina of trachea. An alveolus is an anatomical structure that has the form of a hollow cavity. Thus, option B is correct.

The vertebral column, also known as the backbone or spine, is a bony skeletal structure found in vertebrates. Skull is present in head. The rib cage is formed by the vertebral column, ribs, and sternum and encloses the heart and lungs. In humans, the rib cage, also known as the thoracic cage, is a bony and cartilaginous structure which surrounds the thoracic cavity and supports the pectoral girdle (shoulder girdle).

A trachea is a connects the larynx and the lungs. It is made up of cartilaginous rings which prevent it from collapsing. It divides into bronchi which further separates to form bronchioles and terminates into air filled lobes known as alveoli.

• The process of breathing ) is divided into two distinct phases, inspiration and expiration occur simultaneously.
  
• Inspiration can occur if the pressure within the lungs (intra-pulmonary pressure) is less than the atmospheric pressure,
•  Inspiration is initiated by the contraction of a diaphragm which increases the volume of the thoracic chamber in the anteroposterior axis. The contraction of external inter-costal muscles lifts up the ribs and the sternum causing an increase in the volume of the thoracic chamber in the dorsoventral axis.
• The overall increase in the thoracic volume causes a similar increase in pulmonary volume. An increase in pulmonary volume decreases the intrapulmonary pressure to less than the atmospheric pressure which forces the air from outside to move into the lungs. Hence, When the pressure of air within the lungs is less than the atmospheric pressure, air will not flow out of the lungs.
  

• Carbon dioxide is the waste gas that is produced when carbon is combined with oxygen as part of the body's energy-making processes.
• The lungs and respiratory system allow oxygen in the air to be taken into the body, it also helps the body to get rid of carbon dioxide in the air breathed out.
• When the blood from the heart flows through the capillaries and collects oxygen from the alveoli. At the same time, carbon dioxide passes out of the capillaries and into the alveoli. These blood brings oxygen to the body cells and takes away their carbon dioxide.  Hence, the circulatory system and respiratory system eliminates carbon dioxide from the body.