2 17 Biology Notes Fig 33 2 The human respiratory system can be divided into 2 parts The conducting portion a series of passageways that carry air into and out of the gas exchange portion of the respiratory system The gas exchange portion where gases are exchanged with the blood in tiny space within the lungs Conducting portion air is inhaled actively and exhaled passively occurs in 2 stages Inhalation when air is drawn into the lungs ing the negative pressure system Inhalation occurs when the chest cavity is enlarges The lower boundary of the chest cavity is formed by the diaphragm which domes upward when relaxed During inhalation the diaphragm is contracted which pulls it downward and the rib muscles contract lift ribs up and outward Inhaled air travels past the larynx into the trachea reinforced with semicircular bands os stiff cartilage The trachea splits into two bronchi one going to each lung inside the lung each bronchus branches repeatedly into small tubes bronchioles thick walls Bronchioles lead to microscopic alveoli where gas exchange occurs membrane is thin Exhalation when air is expelled from the lungs Fig 33 11 Gas Exchange portion Gas exchange occurs in the alveoli Alveoli cluster around the end of each bronchiole like a bunch of grapes providing a large surface area 1500 sq feet A network of capillaries covers most of the alveolar surface The walls of the alveoli consist of a single thin layer of epithelial cells How does the blood carry oxygen and carbon dioxide Oxygen and carbon dioxide are transported in blood using different mechanisms Q Which location would be expected to have the highest level of Oxygen A Lungs starts with breathing in sets gradients based on amount of material we have Oxygen Transport hemoglobin Nearly all about 90 of the Oxygen carried by the blood is bound to A large protein that gives red blood cells their color Each hemoglobin molecule can carry up to 4 oxygen molecules As oxygen binds hemoglobin the protein changes its shape which alters its affinity for oxygen its color Q What color is oxygen poor blood A blue maroon Q What color is oxygen rich blood A red How do the following impact Oxygen transport Anemia Sickle cell Anemia small amount of red blood cells by lack of iron in diet change in structure hemoglobin molecules clump together causes shape doesn t bind oxygen the same Q What location would be expected to have the highest levels of carbon dioxide A muscle capillaries Carbon dioxide transport Carbon dioxide is transported in the blood in 3 ways As bicarbonate ions 70 Bound to hemoglobin 20 Dissolved in plasma as carbon dioxide 10 Plasma has about 80 of CO2 because bicarbonate ions are in there Bicarbonate ions HCO3 are formed in red blood cells when carbon dioxide combines with water CO2 H2O H2CO3 H HCO3 These reactions are always reversible
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