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Chapter 7 Respiration Chapter 7 The Respiratory System Why do we need to breath? Oxygen in air is vital to cellular respiration (energy) and the carbon dioxide produced must be removed from the body. Remember C6H12O6 + O2 CO2 + H2O Read pages 245 to 247. Structures 1 Chapter 7 Respiration AIR TRAVELS FROM THE NASAL PASSAGES INTO THE PHARYNX AND PASSES THROUGH WHAT OPENING INTO THE TRACHEA? GLOTTIS DURING A COOL EVENING YOU DECIDE TO GO FOR A WALK OUTSIDE, WHAT ARE THE BENEFITS OF BREATHING THROUGH YOUR NOSE RATHER THAN YOUR MOUTH? 1. LESS HEATING OF COOL AIR AND MOISTENING 2. NO CILIA IN YOUR MOUTH TO TRAP FOREIGN PARTICLES 2 Chapter 7 Respiration LUNG HEART pulmonary arteriole high CO2 low O2 pulmonary venule high O2 low CO2 Stages in Respiration Breathing involves two basic processes: 1﴿ inspiration ﴾breathing in, or inhaling﴿ AIR MOVING FROM EXT. ENVIRO TO LUNGS 2﴿ expiration ﴾breathing out, or exhaling﴿. AIR MOVING FROM LUNGS TO EXT. ENVIRO TWO FORMS OF RESPIRATION 1﴿ External respiration is the exchange of oxygen and carbon dioxide between the air and the blood. OCCURS AT THE ALVEOLI 2﴿ Internal respiration is the exchange of oxygen and carbon dioxide between the body’s tissue cells and the blood. OCCURS BETWEEN CAPILLARIES AND CELLS Pressure How does pressure play a role in getting air into your lungs? Consider the relationship between pressure and volume. 3 Chapter 7 Respiration Mechanics of Breathing Breathing is based around changes in air pressures Same amount of gas: Increase the volume = decreased pressure (molecules have less collisions) Decrease the volume = increased pressure (molecules collide rapidly) Breathing is controlled by two muscular structures 1) Diaphragm 2) Intercostal (rib) muscles They are responsible for the changes in thoracic pressure 1. intercostal ribs contract lifting ribs up and out at the same time diaphragm contracts and flattens 2. Air pressure within the lungs is less than external environment 3. Air from environment moves into lungs Tidal volume is the volume of air that is inhaled and exhaled in a normal breathing movement when the body is at rest. Inspiratory reserve volume is the additional volume of air that can be taken into the lungs, beyond a regular, or tidal, inhalation. Expiratory reserve volume is the additional volume of air that can be forced out of the lungs, beyond a regular, or tidal, inhalation. Vital capacity, or total lung volume capacity, is the total volume of gas that can be moved into or out of the lungs. It can be calculated as tidal volume + inspiratory reserve volume + expiratory reserve volume. Residual volume is the amount of gas that remains in the lungs and the passageways of the respiratory system even after a full exhalation. This gas never leaves the respiratory system; if it did, the lungs and respiratory passageways would collapse. The residual volume has little value for gas exchange because it is not exchanged with air from the external environment. 4 Chapter 7 Respiration Gas Exchange and External Respiration Takes place in the lungs as gases are exchanged between the alveoli and the blood in the capillaries. Gas exchange via DIFFUSION with the help of FACILITATED DIFFUSION During Inhalation: Alveoli has higher concentration of O2 than capillaries Diagram BBC alveoli Capillaries have higher concentration of CO2 Diagram In facilitated diffusion, proteinbased molecules in the wall of the alveoli facilitate diffusion by “carrying” oxygen across the cell membranes ﴾no energy required﴿. 5 Chapter 7 Respiration Two main requirements for EXTERNAL respiration: • surface are large enough for the exchange of oxygen and carbon dioxide. • a moist environment for the dissolving of the gases in water. Gas Exchange and Internal Respiration Internal Respiration takes place between the body tissue cells and the blood. Oxygen transport to cells Approx. 99 percent of the O2 is carried by an oxygen transporting molecule called hemoglobin, which is only in red blood cells. The rest is dissolved in the blood plasma. Carbon dioxide transport to lungs 70% bicarbonate ion (HCO3) 23% hemoglobin 7% plasma CO2 + H2O Carbonic acid (H2CO3) The carbonic acid quickly dissociates (breaks down) into a H+ and HCO3. This reaction occurs in the red blood cells. The H+ then combines with hemoglobin, and the HCO3 diffuse out of the red blood cells into the plasma, which is carried to the lungs. When the blood reaches the lungs, the whole process reverses to reform carbon dioxide and water. The carbon dioxide then diffuses into the air in the alveoli and is exhaled. 6 Chapter 7 Respiration Pneumothorax A pneumothorax is commonly known as a collapsed lung. Normally, the outer surface of the lung sits next to the inner surface of the chest wall. The lung and the chest wall are covered by thin membranes called pleura ﴾pleural membranes﴿. A collapsed lung occurs when air escapes from the lungs or leaks through the chest wall and enters the space between the two membranes ﴾pleural cavity﴿. As air builds up, it causes the nearby lung to collapse. A collapsed lung can result from blunt force trauma, rib fractures, or a foreign object entering through the thoracic cavity and into the lung. Upper respiratory tract Read about tonsillitis and laryngitis p. 256 then answer Q 9 Lower respiratory tract Bronchitis caused by bacterial infection can be treated with antibiotics alveoli pneumonia what happens? pleurisy inflammation of pleura p. 256 Q 9 12 emphysema what happens? asthma inflammation the bronchi and bronchioles chronic obstructive lung disease 7
