Respiratory System Lesson 2 - Part 2 PDF

Respiratory System Lesson 2 - Part 2 Mechanics of Breathing Exhalation For air to go out of the lungs, the pressure must be higher on the inside of the lungs than on the outside. Air moves from an area of high pressure to an area of low pressure. The high pressure area is created by...

Respiratory System Lesson 2 - Part 2 Mechanics of Breathing Exhalation For air to go out of the lungs, the pressure must be higher on the inside of the lungs than on the outside. Air moves from an area of high pressure to an area of low pressure. The high pressure area is created by quickly changing the volume of the thoracic cavity or the chest. If the volume is decreased, the air pressure increases inside the chest and air rushes out. Muscles of Exhalation External intercostal (chest) muscles ○ They relax, which causes the rib cage to move down and air to move out of the lungs. ○ These muscles are found between the ribs on the outside of the chest cavity. Muscles of Exhalation Diaphragm ○ A muscle between the abdominal and thoracic cavities. ○ It relaxes and moves up to its normal position, which causes air to move out of the lungs. Muscles of Exhalation Internal intercostal muscles ○ Can contract to increase the pressure on the chest and force exhalation with a little more power. ○ They are found between the ribs on the inside of the chest cavity. ○ They are used for forced breathing. Muscles of Exhalation Abdominal muscle ○ Can contract, which pushes the contents of the abdominal cavity towards the diaphragm causing air to move out of the lungs. ○ These muscles are also important for forced breathing. Inhalation Just before inhalation, the air pressure in the alveoli is the same as the atmospheric pressure. For air to go into the lungs, the pressure must be lower on the inside of the chest and higher on the outside. This means the air pressure must be actively decreased inside the chest. The low pressure area is created by quickly changing the volume of the thoracic cavity. Inhalation If the volume is increased, the air pressure decreases inside the chest. This is an active process and it requires the contraction of muscles. Your chest muscles pull your rib cage up and out. This is why breathing becomes difficult if there is pressure being placed against your rib cage. Muscles of Inhalation External intercostal muscles ○ Moves the rib cage up and out causing air to be sucked into the lungs. Diaphragm ○ Moves downward and flattens, which causes air to be sucked into the lungs. What causes hiccups? Transport of Oxygen Transport of Oxygen Oxygen is transported in 2 ways by the circulatory system. ○ Transport as a dissolved gas Oxygen dissolves directly into the plasma of oxygen-poor blood that circulates in the capillaries of alveoli. It does this because the oxygen in the alveoli exerts pressure in order to pass into the blood inside the capillaries. This accounts for 1% of the exchanged Transport of Oxygen Oxygen is transported in 2 ways by the circulatory system. ○ Transport by hemoglobin Oxygen easily combines with the red, iron- bearing heme of hemoglobin to produce oxyhemoglobin. This occurs inside the red blood cells and accounts for 99% of the oxygen transportation in the body. Oxygen is later released from the  Transport of Carbon Dioxide Transport of Carbon Dioxide CO2 is transported in the circulatory system in 3 ways. ○ Transport in the blood plasma Like oxygen, some of the CO2 dissolves under pressure in the blood plasma. The lungs are designed to release this pressurized gas into the atmosphere. Only 7% of the CO2 is transported this way. Transport of Carbon Dioxide CO2 is transported in the circulatory system in 3 ways. ○ Transport as hydrogen ions in red blood cells About 70% of the CO2 moves from the blood plasma into the cytoplasm of red blood cells. The CO2 breaks down as it mixes with water with the help of an enzyme called carbonic anhydrase. This allows CO2 to be transported disguised as hydrogen ions and bicarbonate ions. Transport of Carbon Dioxide CO2 is transported in the circulatory system in 3 ways. ○ Transport by hemoglobin About 23% of CO2 goes directly to the hemoglobin molecule, finds a spot on the outer protein (globin) portions, and hooks on for a ride to the lungs. This is called carbaminohemoglobin. Video