Presentation of the Respiratory System

1. Respiratory System

3. The goblet cells of the nares produce mucus
The cilia 'waft' particles away from the lungs (towards the oesphagus).
Larynx
Known colloquially as the ‘Voice Box’, the larynx contains vocal cords that vibrate when sound is
made.
The vocal cords are also known as the ‘vocal folds’.
Forming the sounds that comprise speech.
Pharynx
The Naso-Pharynx is the junction of the nasal passage and the buccal cavity (i.e. the mouth).
A muscular tube lined with mucous membrane, that extends from the beginning of the
oesophagus (gullet) up to the base of the skull.
It is divided into the:
Nasopharynx
Oropharynx
Laryngopharynx
The pharynx acts as a passageway for food from the mouth to the oesophagus, and as an air
passage from the nasal cavity and mouth to the larynx. It also acts as a resonating chamber for
the sounds produced in the larynx.
Trachea
The windpipe, the part of the air-passage between the larynx and the main bronchi (i.e. from just
below the Adam’s Apple, passing behind the notch of the sternum). This is kept open by a ‘C’-
shaped ring of cartilage, the hyoid bone.
The upper part of the trachea lies just below the skin, except where the thyroid gland is wrapped
around it.
The lower part of the trachea divides into two bronchi (one for each lung). These lead to the upper
and lower bronchioles, and eventually the alveolar ducts.
Connects the external respiratory organs (nares and buccal cavities) with the lungs.
Bronchi

4. Bronchi
The bronchi are air passages beyond the trachea, which have cartilage and mucus glands in their
walls.
The trachea divides into two main bronchci, which divide successively into five lobar bronchi, 20
segmental bronchi, and two or three further divisions
Components essential for external respiration.
Broncioles
Bronchioles are subdivisions of the bronchial tree that do not contain cartilage or mucus glands
in their walls.
They (bronchioles) open from the 5th or 6th generation of bronchi and extend for up to 20 more
generations before reaching the terminal bronchioles. Each terminal bronchiole divides into a
number of respiratory bronchioles, from which the aveoli open.
Components essential for external respiration.
Each terminal bronchiole conducts air to an acinus in the lung.
Pleura
The covering of the lungs.
The covering consists of serous membrane, which has a smooth shiny moist surface due to the
secretion of small amounts of fluid. This fluid lubricates the opposing visceral and parietal
surfaces so that they can slide painlessly over each other during breathing.
Visceral
The covering of the lungs.
Parietal
The covering of the inner surface of the chest wall.
Pleural
The pleural cavity is the space between the visceral and parietal pleura, which is normally very
small as the pleural membranes are in close contact. The introduction of fluid (pleural effusion) or
gas separates the pleural surfaces and increases the volume of pleural space.

5. Alveoli
An alveolus in the lung is a blind-ended air sac of microscopic size.
About 30 alveoli open out of each alveolar duct, which leads from a respiratory bronchiole. The
alveolar walls, which separate alveoli contain capillaries. The alveoli are lined by a single layer of
pneumocytes, which thus form a very thin layer between air and blood so that exchange of oxygen
and carbon dioxide is normally rapid and complete.
Children are born with about 200 million alveoli.
The adult number of about 300 million is reached around the age of eight years.
Components essential for external respiration.
Diaphragm
The diaphragm is a thin musculomembranous dome-shaped muscle that separates the thoracic and
abdominal cavities.
It is attached to the lower ribs at each side, and to the breast bone and the backbone at the front
and back.
It bulges upwards against the heart and lungs, arching over the stomach, liver, and spleen.
There are openings in the diaphragm through which the oesophagus, blood vessels, and nerves
pass.
The diaphragm plays an important part in breathing. It contracts with each inspiration, becoming
flattened downwards and increasing the volume of the thoracic cavity. With each expiration the
diaphragm relaxes and is restored to its dome shape.

6. Alveoli
An alveolus in the lung is a blind-ended air sac of microscopic size.
About 30 alveoli open out of each alveolar duct, which leads from a respiratory bronchiole. The
alveolar walls, which separate alveoli contain capillaries. The alveoli are lined by a single layer of
pneumocytes, which thus form a very thin layer between air and blood so that exchange of oxygen
and carbon dioxide is normally rapid and complete.
Children are born with about 200 million alveoli.
The adult number of about 300 million is reached around the age of eight years.
Components essential for external respiration.
Diaphragm
The diaphragm is a thin musculomembranous dome-shaped muscle that separates the thoracic and
abdominal cavities.
It is attached to the lower ribs at each side, and to the breast bone and the backbone at the front
and back.
It bulges upwards against the heart and lungs, arching over the stomach, liver, and spleen.
There are openings in the diaphragm through which the oesophagus, blood vessels, and nerves
pass.
The diaphragm plays an important part in breathing. It contracts with each inspiration, becoming
flattened downwards and increasing the volume of the thoracic cavity. With each expiration the
diaphragm relaxes and is restored to its dome shape.