Part |
Description |
Function(s) |
The Nose |
The technical medical term for ‘nose’ is ‘nares’.
It
contains ciliated cells and goblet cells
(see below).
|
|
Note about Smoking: Smoke paralyses the
cilia and continued smoking destroys the
cilia
/ ciliated cells, which are then replaced
by
goblet cells. This causes the accumulation
of excess mucus in the lungs - together with
particles, tar, and carcinogens. |
|
1. |
Moistens air |
2. |
Filters air |
3. |
Warms air |
4. |
Senses/detects odours |
5. |
The goblet cells of the nares produce
mucus |
6. |
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. |
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 |
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. |
|
|
|
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 oesaphagus, 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. |
