→ 2 lungs in the thorax and the air passages leading to them.
→ air passages consist of nasal passages, pharynx, larynx, trachea, bronchi, bronchioles.
→ thoracic cavity, ribs, diaphragm, and related muscles - also vital parts of the gas exchange system.
The Nose
Air → usually enters body through 2 external nostrils → walls of nostrils bear a fringe of hairs. → nostrils lead into 2 nasal passages - that are lined with a moist mucous membrane
Advantages of breathing through nose:
- dust and foreign particles → including bacteria in air → are trapped by the hair in the nostrils as well as by the mucous on the mucous membrane.
- As air passes through nasal passages → it is warmed and moistened
- harmful chemicals may be detected by small sensory glands in the mucous membrane.
Nose to Trachea
air in nasal passages enters the pharynx from pharynx - air passes into your larynx and then into the trachea through an opening.
Trachea
Trachea (windpipe) is supported by C-Shaped rings of cartillage → cartilage keeps the lumen of the trachea open. membrane next to the lumen is the epithelium.
Lower end of the trachea divides into 2 bronchi (one to each Lungs)
- Right bronchus - divides into 3 bronchial tubes (1 to each lobe)
- Left bronchus - divides into 2 bronchial tubes
Epithelium consists of 2 types of: Gland Cells: secrete mucus to trap dust particles and bacteria Ciliated Cells: have hair like structures called cilia on their surfaces. cilia sweep the dust trapped mucus up the trachea.
Lungs
Diaphragm
- dome shaped sheet of muscle and elastic tissue
- diaphragm muscle contracts - diaphragm flattens downwards
- diaphragm muscles relax - diaphragm arches upwards. *
Ribs
supports the chest wall
- attached to backbone dorsally in a way that they can move up and down
- 10/12 pairs of the ribs are attached to the sternum
- 2 sets of muscles; internal intercostal muscles and external intercostal muscles - which operate in tandem (and antagonistically) → they can be found between the ribs.
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