The Human Respiratory Tract

1.nostrils: opening to the nasal passages 2. nasal passages: lined with a mucus membrane bearing cilia (warms, moistens, and filters incoming air) 3. pharynx (throat)--cavity in back of mouth

4. glottis: windpipe or trachea opening epiglottis--muscular flap covering the glottis- -prevents food from entering the windpipe 5. larynx (voice box) upper part of the windpipe containing sound producing vocal cords 6. trachea: (windpipe)--about 4 inches long & 1 inch in diameter --supported by rings of cartilage --lined with a ciliated mucus membrane which filters incoming air

7. bronchi: two main branches of trachea which enter lungs --lined with cartilage and ciliated 8. bronchioles: smallest air tubes which end at the alveoli or air sacs --cartilage ring support "fades out” from this point on 9. alveoli (air sacs): site of respiratory gas exchange by diffusion --resemble bunches of grapes --moist surface aids exchange--each alveolus is surrounded by capillaries & gas exchange occurs with them (oxygen in-- carbon dioxide out)

Ventilation

Gas Exchange Diffusion

Cellular Respiration

Compare the areas of the alveolus.

Purpose and Function of the System The purpose of getting in oxygen is to get it through our bloodstream to the cells of our body. At our cells it combines with glucose food to form usable ATP energy (cell respiration).

** The capillaries which surround the alveoli are involved in gas exchange between the blood and the alveoli. In the blood, oxygen is carried by the red blood cell as oxyhemoglobin. Oxygen, which is loosely bound to the hemoglobin, diffuses into the cells where it is used during aerobic cellular respiration.

** The end products of aerobic cellular respiration, water and carbon dioxide diffuse into the blood. Then these waste gases are released from the lungs.

diaphragm: sheet of muscle separating the thoracic (chest) cavity from the abdominal cavity Breathing - the mechanical part of respiration... involves both the diaphragm and rib cage muscles

What happens when… We breathe in? -diaphragm moves downward, creates a “low pressure” in our thoracic cavity. -air is forced into (we don’t suck it into) our lungs, filling any available empty space. We breathe out? -diaphragm pushes upwards, creating a high pressure in our thoracic cavity. -air is forced out through our nose and mouth, leaving a “low” that can be refilled (hopefully immediately)

6.4.2 Explain the need for a ventilation system. Unicellular organisms and small multicellular organisms have few problems in gaseous exchange. The required gases will easily diffuse in and out of the system. For larger organisms this is not possible due to their smaller surface area over volume ratio.

The decrease of the surface area over volume ratio is quite rapid as the size of an organisms. Surface lost. No volume lost

Small cube Surface area 6 x 1 x 1= 6cm2 Volume 1 x 1 x 1 = 1 cm3 Surface area ratio 6/1 =6 Large cube Surface area 6 x 10 x 10cm2 = 600cm2 Volume 10 x 10 x 10 = 1000 cm3 Surface area ratio 600/1000 =0.6

The smaller cube has 6cm2 of surface for every cm3 of volume, where the larger cube has 0.6cm2 of surface for every cm3 of volume.

When organisms become larger, there is simply not enough surface for gaseous exchange. An added problem is that the oxygen, once inside the organism, has to travel a long way to reach some cells. Since diffusion in liquids is a fairly slow process, this is unsatisfactory. The same principle applies to other organs that exchange material with the internal or external environments e.g. intestine and kidney.

3000ml 500 ml 1200ml

Some Respiratory System Malfunctions

pneumonia: alveoli fill with fluids and mucus resulting in coughing and breathing difficulties

asthma: allergic reaction in which bronchiole contractions create breathing difficulties

emphysema: air sacs lose their elasticity and breakdown resulting in a loss of respiratory surface in the lungs --shortness of breath is the chief symptom (smoking frequently leads to this disorder)