The Respiratory System Group Members: Abby Ridley-Kerr Lia Kato Sasha Yovanovich Shelby LaRosa

The Relationship of the Respiratory Surface and the Transport System The respiratory system collects O 2 and pumps it throughout the body. Then it expels the remaining CO 2 left over after gas exchange.

Characteristics of a Respiratory Surface Thin and has a large surface area. All living cells bathed in water maintaining plasma membranes. To supply O 2 and expel CO 2. Gills, Tracheae, and Lungs are the most common respiratory surfaces.

Terrestrial Animals and Internal Surfaces Terrestrial animals have internal respiratory systems because they are more complex animals which cannot supply enough O 2 by merely using external cells.

Countercurrent Exchange in Fish Countercurrent exchange is evidenced in fish. The blood gains oxygen as it moves through the capillary. It simultaneously obtains water allowing for a greater transfer of oxygen.

How is countercurrent in fish an adaptive value? The fish has adapted to its aqueous habitat by using both the surrounding water and blood flow to gain oxygen.

Features of Tracheal Tubes and Lungs Lungs are adapted for gas exchange because they have a large surface area and a dense network of capillaries The trachea is adapted for gas exchange because it has C-shaped rings of cartilage that maintain its shape. Also, it forks into two bronchi, one leading to each lung.

Human Respiratory System

Alveoli Alveoli- are air sacs at the tip of the bronchioles; they are sufficient enough to carry out gas exchange for the entire body

Partial Pressure and Gas Exchange A gas always diffuses from a region of higher partial pressure to a region of lower partial pressure. 1. Blood arriving at the lungs via the pulmonary arteries has a lower P O 2 and a higher P CO 2 than the air in the alveoli. As blood enters capillaries, CO 2 diffuses from the blood to the air in the alveoli. O 2 in the air dissolves in the fluid that coats the epithelium and diffuses into the blood. 2. When the blood leaves the lungs in the pulmonary veins, its P O 2 has been raised and its P CO 2 has been lowered. After returning to the heart, this blood is pumped through the systemic circuit. 3. In the tissue capillaries, gradients of partial pressure favor the diffusion of O 2 favor the diffusion of O 2 out of the blood and CO 2 into the blood. This is because cellular respiration removes O 2 from and adds CO 2 to the interstitial fluid. 4. After the blood unloads O 2 and loads CO 2, it is returned to the heart and pumped to the lungs again, where it exchanges gases with air in the alveoli.

Breathing Regulation Breathing is regulated by automatic mechanisms which insures that the work of the respiratory system in coordinated with the cardiovascular system and metabolic demands for gas exchange. These automatic mechanisms include, the medulla, pH levels, carotid arteries, the aorta, and the diaphragm.

Breathing Regulation

Medulla The medulla sets the basic breathing rhythm, sends impulses to the diaphragm and rib muscles to stimulate contraction

pH Level Changes in pH trigger either increased depth and rate of breathing or decreased rate of breathing

Carotid Arteries Carotid arteries detect changes in blood pH and send nerve impulses to the medulla It also detects changes in oxygen levels in the blood

Aorta The aorta detects changes in blood pH and CO 2 levels

Diaphragm The diaphragm contracts and causes inhalation

Adaptive Values of Hemoglobin Hemoglobin is an iron containing protein in red blood cells that reversibly binds oxygen. It can bind not only to oxygen but also to nitric oxide. The nitric acid relaxes the capillary walls and allows them to expand, aiding in the deliver of oxygen to all cells.

Dissociation Curves of Hemoglobin Hydrogen ions affect the conformation of hemoglobin—a drop in pH shifts the oxygen dissociation curve toward the right. At a given PO2, hemoglobin gives up more O2 at pH 7.2 than at pH 7.4, the normal pH of human blood. The pH decreases in very active tissues because the CO2 produced by respiration reacts with water, forming carbonic acid. Hemoglobin then releases more O2, which supports the increased cellular respiration in the active tissues.

Oxygen Circulation and Hemoglobin When the tissues rest, the body is at normal metabolism. So when O 2 is consumed in cellular respiration it causes a relatively large increase in the amount of O 2 the blood unloads.

pH Reduction and Oxygen Release

Path of CO 2 1. Carbon dioxide produced by body tissues diffuses into the interstitial fluid and the plasma. 2.Over 90% of the CO2 diffuses into red blood cells, leaving only 7% in the plasma as dissolved CO2. 3.Some CO2 is picked up and transported by hemoglobin. 4.However, most CO2 reacts with water in red blood cells, forming carbonic acid (H2CO3), a reaction catalyzed by carbonic anhydrase contained within red blood cells. 5.Carbonic acid dissociated into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). 6.Hemoglobin binds most of the H+ from H2CO3, preventing the H+ from acidifying the blood and thus preventing the Bohr shift. 7.Most of the HCO3- diffuses into the plasma where it is carried in the bloodstream to the lungs. 8.In the lungs, HCO3- diffuses from the plasma into red blood cells, combining with H+ releasing from the bloodstream and forming H2CO3. 9.Carbonic acid is converted back into CO2 and water. 10.CO2 formed from H2CO3 is unloaded from hemoglobin and diffuses into the interstitial fluid. 11.CO2 diffuses into the alveolar space, from which it is expelled during exhalation. The reduction of CO2 concentration in the plasma drives the breakdown of H2CO3 into CO2 and water in the red blood cells (see step 9), a reversal of the reaction that occurs in the tissues (see step 4).

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