Download PHYL1007 (SAMPLE) RESPIRATION

PHYL1007
(SAMPLE)
RESPIRATION
The respiratory system is involved in the following functions:
1 – It allows gas exchange between the air and the blood
2 – It is needed for speech
3 – It is needed for smell
4 – It is necessary in maintaining blood pH balance
Note that a small change of blood pH has a large impact on the cells and enzymes in the body.
The vena cava is the largest vein and it connects directly into the right atrium.
The nasal cavity (nasal fossa) is a large air-filled space above and behind the nose in the middle of
the face.
The pharynx is the cavity behind the nose and mouth that connects to the oesophagus.
The epiglottis is a flap of cartilage behind the root of the tongue that is depressed during
swallowing to cover the opening of the trachea. This prevents food from entering the trachea.
The trachea (wind pipe) is a membranous tube with rings of cartilage around it. It connects the
larynx to the lungs.
The larynx is a hollow muscular organ on the top of the trachea. The larynx houses the vocal cords.
The lungs themselves are NOT muscles. However, they are connected to the thoracic cage. As the
diaphragm contracts and relaxes (the diaphragm IS a muscle), it causes the thoracic cavity, inside of
which sit the lungs, to increase and decrease in size. Essentially, the lungs are connected to the
thoracic cage so when the diaphragm contracts, the lungs are forced to expand and air enters.
The thoracic cage is made up of the sternum, ribs and thoracic vertebrae.
The lungs are surrounded by a fluid filled pleural sac. This keeps the lungs protected and prevent
friction with the chest wall. The pleural sac encloses each lung individually and entirely.
The parietal pleura is stuck in between of the thoracic cage and the pleural sac. It is like a
membrane.
The visceral pleura is stuck in between of the pleural sac and the lung itself. It is also like a
membrane.
So from interior to exterior it is as follows: lungs, visceral pleura, pleural sac, parietal pleura,
thoracic cage.
The intercostal muscles are several groups of muscles that run between the ribs, and help form and
move the thoracic cavity. These muscle help in expanding and shrinking the size of the thoracic
cavity to facilitate breathing.