Tag: respiratory system in humans

The respiratory system terminates in the alveoli which are sac-like structures and are enveloped by the capillary network for the exchange of gases.

Alveoli are the air sacs of the lungs. They have thin walls surrounded by blood capillaries (another layer of simple squamous epithelium). Gas exchange occurs in the alveoli. During inhalation, oxygen gas is in higher concentration in the alveoli than in the blood and so it diffuses into the blood through this thin layer of cells. During exhalation, carbon dioxide is in higher concentration in the blood than in the alveoli and so it diffuses into the alveoli through this thin layer of cells.

The two large branches of the airway that lead off the trachea at the tracheal bifurcation are the bronchi. They act as the main passageway into the lungs. Each bronchus enters one of the two (either the left or the right lung). Within the lungs, the bronchi branch off into smaller and smaller passageways, the smallest of which are called bronchioles and at the end of the bronchioles are tiny air sacs that are known as the alveoli. The re-oxygenized blood is sent through meta venules to the pulmonary vein. So, the correct option is 'bronchi'.

Alveoli are tiny balloon shaped structures in the respiratory system. The alveoli are only one cell thick and are surrounded by blood capillaries. This allows the relatively easy passage of oxygen and carbon dioxide (CO2) between the alveoli and the blood. Alveoli are therefore the site of gaseous exchange in the respiratory system. So, the correct option is 'alveoli'.

The trachea or the windpipe is an airway that is a cartilaginous tube that connects the pharynx and larynx to the lungs, allowing the passage of air. It connects the nose and the mouth with the pharynx and larynx. So, the correct option is 'pharynx; larynx'.

The trachea is also known as the windpipe and is part of the passageway that supplies air to the lungs, it is about 4.5 inches long. The trachea branches into the bronchi that act as the passageways that enter the lungs. The larynx connects the nasal and oropharynx with the trachea and functions in air conduction and vocalization. The pharynx is the part of the throat behind the mouth and nasal cavity. The trachea connects the pharynx and the larynx to the lungs. So, the correct option is 'trachea'.

Even after the most forcible expiration possible some amount of air remains in the lungs. This is known as the residual volume and is about 1200 ml. So, the correct option is 'False'.

In humans, gas exchange occurs in the lungs between the alveoli and the capillaries located on the walls of the alveoli. The inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli. So, the correct option is 'alveolar sacs'.

Even after the most forcible expiration possible some amount of air remains in the lungs. This is known as the residual volume and is about 1200 ml. This keeps the alveoli open as some air is always present inside the lung alveoli even during expiration. So, the correct option is 'true'.