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7.2 – Breathing and Respiration

7.2 – Breathing and Respiration. Pages 249 - 254. The Structures. The diaphragm and the intercostal muscles (rib muscles) control the movement of air in and out of the lungs. Diaphragm – domed shaped layer of muscle that separates the thoracic and abdominal cavity.

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7.2 – Breathing and Respiration

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  1. 7.2 – Breathing and Respiration Pages 249 - 254

  2. The Structures The diaphragm and the intercostal muscles (rib muscles) control the movement of air in and out of the lungs. Diaphragm – domed shaped layer of muscle that separates the thoracic and abdominal cavity. Rib muscles – are found between and along the inside of the ribs.

  3. The Mechanics of Breathing Inhalation: External rib muscles and the diaphragm contract. Rib cage expands upward and outward. The volume of the thoracic cavity increases. The density of gas in the cavity decreases – air pressure in the cavity decreases. Air moves from areas of high to low pressure (outside the lungs to inside the lungs) Air rushes into the lungs.

  4. Exhalation: External rib muscles and the diaphragm relax. The volume of the thoracic cavity decreases. The density of gas in the cavity increases – air pressure in the cavity increases. Air moves from areas of high to low pressure (inside the lungs to outside the lungs) Air rushes out of the lungs.

  5. Respiratory Volume Under normal circumstances your regular breathing does not use your full lung capacity. When your body needs more oxygen the volume of your lungs can increase. A spirograph is used to represent the amount of air that moves into and out of the lungs with each breath.

  6. The following terms are used in a spirograph: Tidal volume – volume of air that is inhaled and exhaled in a normal breathing movement when the body is at rest. Inspiratory volume – the additional volume of air that can be taken into the lungs, beyond a regular breath. Expiratory reserve volume – the additional volume of air that can be forced out of the lungs, beyond a regular breath.

  7. Vital capacity – the total lung capacity; the total volume of gas that can be moved into or out of the lungs. • Vital capacity = tidal volume + inspiratory reserve + expiratory reserve volume • Residual volume – the amount of air that remains in the lungs and the passageways even after a full exhalation. If this gas left the system, the lungs and passageways would collapse. • The residual volume has little value for gas exchange because it is not exchanged with the external environment.

  8. The Spirograph

  9. 2. The typical tidal volume for humans is 500 mL. 3. The typical expiratory reserve volume for humans is 1200 mL. 4. The typical vital capacity for humans is 4800 mL.

  10. External Respiration External respiration takes place in the lungs. During external respiration, gases are exchanged between the alveoli and the blood in the capillaries. The walls of the alveoli and capillaries are each one cell thick. Gases easily diffuse through these membranes.

  11. Diffusion occurs from high  low concentration. The air entering the alveoli have a higher oxygen concentration than the blood in the capillaries, oxygen diffuses from the alveoli into the capillaries. 30% of the oxygen gas is aided by “helper” proteins in the membranes in facilitated diffusion. (does not required additional energy)

  12. The blood in the capillaries has a higher concentration of carbon dioxide because it is returning from body tissues. The carbon dioxide diffuses from the capillaries into the alveoli. The carbon dioxide is then exhaled into the air.

  13. Internal Respiration Once oxygen and carbon dioxide have been exchanged, the blood moves through the heart and back to the body tissues. Oxygen and carbon dioxide are transported differently. 99% of oxygen is carried by the hemoglobin molecule. Hemoglobin is only present on red blood cells. 1% is dissolved in the blood plasma

  14. Carbon dioxide is carried via: • 23% by hemoglobin. • 7% in the plasma. • 70% is dissolved and carried in the blood as bicarbonate ion (HCO3-) • The carbon dioxide reacts with water in the red blood cell to form carbonic acid. • The reaction is reversed once the carbonic acid reaches the lung tissues. • CO2 +H2O  H2CO3  CO2 +H2O Carbon dioxide is carried via: 23% by hemoglobin. 7% in the plasma. 70% is dissolved and carried in the blood as bicarbonate ion (HCO3-) The carbon dioxide reacts with water in the red blood cell to form carbonic acid. The reaction is reversed once the carbonic acid reaches the lung tissues. CO2 +H2O  H2CO3  CO2 +H2O

  15. What to do Answer the following questions on page 254 of the text: 1- 4 a,c, 6, 8.

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