Question

the respiratory system and what its parts do in detail?

Answer 1

The respiratory system in humans includes following structures: I) The lungs

II) oral and nasal cavities, that's the conducting airways.

III) The nervous control respiration, respiratory centers in the CNS.

IV) Respiratory muscles: Intercostal muscles, abdominal muscles; rib cage, diaphragm.

The main functions of respiratory system are to provide oxygen to the blood and tissues and remove carbon dioxide.

The lungs: There are two lungs for respiration, each one is divided into lobes. The right lung is divided into three lobes and the left lung is divided into two lobes. The covering membrane of lungs is called the pleura. Pleural cavity is present between visceral and parietal pleura and is filled with pleural fluid in it. This helps the lungs to glide smoothly during inspiration and expiration.

Airways: The air is distributed to the lungs by the way of the trachea, bronchi, and bronchioles.

The trachea branches into two main bronchi, which further branch into lobar bronchi that connect each love. The lobar bronchi further branch into segmental bronchi and into smaller branches, then reach to the terminal bronchioles, they are the smallest airways without any alveoli attached. These all airways are known as the 'conducting zones', they don't participate in gas exchange.

The terminal bronchioles then divided into respiratory bronchioles, which have alveoli attached to their walls. The respiratory bronchioles lead to the alveolar ducts and finally to the alveoli, where gas exchange takes place and called the 'respiratory zone'.

Respiratory unit: The respiratory unit is composed of a respiratory bronchiole, alveolar ducts, and alveoli. About 300 million alveoli present in the two lungs. The alveolar walls are extremely thin thus alveolar gases are in very close proximity to the blood. The gas exchange between the alveolar air and the pulmonary blood occurs through the respiratory membranes of all the terminal portions of the lungs.

Respiratory muscles:

Inspiratory muscles:-

• Diaphragm: It is a dome- shaped muscle that separates the thoracic cavity from the abdominal cavity. It is the main inspiratory muscle. During inspiration diaphragm contract and during expiration diaphragm relax.
• External intercostal muscles: During inspiration this muscles are contracted. It is the most important muscle that raise the rib cage, but other accessory inspiratory muscles are, a) sternocleidomastoid muscles, that lift upward on the sternum; b) anterior serrati, that lift many of ribs; c) scaleni, that lift the first two ribs; d) alaenasi, causes flaring of the nostrils.

Expiratory muscles:-

The muscles that pulls the rib cage downward during expiration are, a) Rectus abdominis, b) Internal intercostal muscles.

There are central and peripheral chemoreceptors in the brain, which regulates respiratory system.