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Unit L: Respiration

Unit L: Respiration. I Respiratory structures and functions:. Nasal Cavity: moistens, warms and cleans air. Nasal cavity. ii) Pharynx: joins mouth and nasal passages. iii) Larynx: Contains vocal chords for sounds. Pharynx. Larynx. iv) Trachea: passage way for air. Trachea.

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Unit L: Respiration

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  1. Unit L: Respiration

  2. I Respiratory structures and functions: • Nasal Cavity: moistens, warms and cleans air Nasal cavity ii) Pharynx: joins mouth and nasal passages iii) Larynx: Contains vocal chords for sounds Pharynx Larynx iv) Trachea: passage way for air. Trachea v) Lung: site of gas exchange Lung vi) Bronchus: divides trachea to each lung Bronchus vii) Bronchiole: takes air to alveoli Bronchiole Diaphragm viii) Diaphragm: Muscle for inhalation and exhalation

  3. Alveoli: Specialized structures for gas- exchange. • Millions of alveoli are found at end of bronchioles. • Alveoli are 1 cell thick to allow diffusion. • Covered with lipoprotein: acts as a surfactant to prevent walls sticking together. • Stretch receptors inside tell brain when they are full of air. • Moist to help gas diffusion. • Many capillaries on outside.

  4. II. Respiration is divided into three types: • External respiration: In the lungs: O2 is absorbed from the external atmosphere into the blood in capillaries. CO2 is removed from blood and moved into atmosphere. • Internal Respiration: In the body’s tissues: Blood releases O2 to the tissues and absorbs CO2 at the capillaries. • Cellular respiration:In the cell’s mitochondria. C6H12O6 + O2 CO2 + H2O and ATP’S!

  5. III. External Respiration: Inhalation • Inhalation requires the movement of the diaphragm downwards, intercostal muscles move ribs outwards. • The enlargement of the thoracic cavity causes a negative pressure to develop, air rushes in to fill the vacuum, inflating the lungs. • **The lungs DO NOT have their own muscles for inflation!**

  6. Exhalation: • Stretch receptors in alveoli indicate that they are full, sends a signal to brain to initiate the relaxing of muscles. • Diaphragm relaxes and moves upwards, rib cage moves down and inwards. • A positive air pressure develops, causing air to rush out of body. • CO2 detectors in medulla oblongata of brain detect rising levels and begin the inhalation process by activation of breathing muscles.

  7. External Respiration: gas exchange at alveoli. • Gas exchange occurs at the walls of the alveoli. Gases diffuse easily across the cell membranes: O2 into blood and RBC’s- binds to hemoglobin. CO2 out of plasma and through alveoli walls into bronchi passage for exhalation.

  8. V. Gas Exchange Reactions: • Oxygen is carried on hemoglobin, the human respiratory pigment: At the lungs: Hb + O2 HbO2 Hemoglobin + oxygen  oxyhemoglobin **Caused by pH= 7.4 and temp. = 37 C** At the tissues the reverse reaction: HbO2 Hb + O2 oxyhemoglobin Hemoglobin + oxygen **Caused by pH= 7.3 and temp. = 38 C**

  9. V. Gas Exchange cont’d • Carbon dioxide is carried in three important ways: 1) Small percentage dissolved as a gas in the plasma 2) Some reacts with free hemoglobin in RBC’s at tissues: CO2 + Hb  HbCO2. Carbon dioxide + hemoglobin  carbaminohemoglobin. • Most reacts with water to form bicarbonate, which is carried in the plasma. CO2 + H2O  H2CO3  H+ + HCO3-1 Carbon dioxide+watercarbonic acidhydrogen+bicarbonate This requires a special enzyme: carbonic anhydrase. • Extra H+ ions are reacted with hemoglobin & carried in RBC’s: H+ + Hb  HHb. Hydrogen ion + hemoglobin  Reduced hemoglobin (remember GER?)

  10. VI. Gas Reactions at Lungs are reversed… 1) The small percentage of CO2 dissolved as a gas in the plasma is released from blood to alveoli. 2) Hemoglobin releases CO2 due to changes in pH and T: HbCO2.  CO2 + Hb carbaminohemoglobin Carbon dioxide + hemoglobin 3) Hydrogen ions are released from Hemoglobin as well. HHb  Hb + H + The Hb can now pick up O2 coming into blood. 4) Bicarbonate is converted back to CO2 and H2O due the free H+ ions driving the reaction…. H+ + HCO3-1  H2CO3  CO2 + H2O This still requires a special enzyme: carbonic anhydrase.

  11. CO2 Reactions: O2 Reactions: HbCO2 Hb + CO2 Hb + O2HbO2 HHb  Hb + H+ pH= 7.4 T= 37 C H++ HCO3-H2O + CO2 Hb + CO2HbCO2 HbO2 Hb + O2 H2O + CO2  H++HCO3- pH= 7.3 T= 38 C Hb + H+ HHb

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