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UNIT B: Human Body Systems Chapter 8: Human Organization Chapter 9: Digestive System Chapter 10: Circulatory System and Lymphatic System Chapter 11: Respiratory System: Section 11.3 Chapter 12: Nervous System Chapter 13: Urinary System Chapter 14: Reproductive System

Chapter 11: Respiratory System UNIT B Chapter 11: Respiratory System Chapter 11: Respiratory System In this chapter, you will learn about the structure and function of the respiratory system. How would a narrowing and swelling of the airways affect the respiratory volumes? How do the typical treatments for asthma work to reduce the symptoms? Why is it so difficult to develop a cure for asthma? What are some of the normal defence mechanisms of the respiratory tract? Asthma is a disease in which the airways become constricted (narrowed) and inflamed (swollen), both of which can result in difficulty breathing. It is one of the most common chronic diseases in children. It is estimated that 10 to 15 percent of children in Canada have asthma. Chapter opener figure background: The incidence of asthma seems to be increasing rapidly. One hypothesis is that we may be “too clean,” in the sense that as children we are not exposed to enough common bacteria, viruses, and even worm parasites. As a result, our immune system may react to harmless material we inhale. Living next to a highway may be another significant factor. There are many harmful forms of air pollution, but scientists are becoming increasingly concerned about tiny “ultrafine” particles, which are produced at high levels by diesel engines. At no more than 0.1 micrometre (μm) across, these particles can bypass the normal defences of the upper respiratory tract and end up lodging deep in the lungs, with damaging effects. TO PREVIOUS SLIDE

11.3 Gas Exchanges in the Body UNIT B Chapter 11: Respiratory System Section 11.3 11.3 Gas Exchanges in the Body Respiration includes external respiration and internal respiration. External respiration: exchange of gases in the lungs Internal respiration: exchange of gases in the tissues Most of the oxygen carried in the blood is attached to the heme portion of hemoglobin (Hb), a protein found in red blood cells. hemoglobin (Hb): iron-containing respiratory pigment occurring in red blood cells TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 Figure 11.10 External and Internal respiration. During external respiration in the lungs, carbon dioxide (CO2) leaves the blood, and oxygen (O2) enters the blood. During internal respiration in the tissues, oxygen leaves the blood, and carbon dioxide enters the blood. TO PREVIOUS SLIDE

External Respiration UNIT B Chapter 11: Respiratory System Section 11.3 External Respiration External respiration is the exchange of gases between air in the alveoli and blood in the pulmonary capillaries. CO2 leaves the blood and O2 enters the blood. Blood in the pulmonary capillaries has a higher partial pressure of CO2 (PCO2) than atmospheric air CO2 diffuses out of the plasma into the lungs CO2 is carried in the plasma as bicarbonate ions (HCO3-) As CO2 diffuses out of the plasma, carbonic anhydrase speeds up the breakdown of carbonic acid (H2CO3), driving the reaction to the right: external respiration: the exchange of gases between air in the alveoli and blood in the pulmonary capillaries bicarbonate ions: the form in which most of the carbon dioxide is carried in the plasma carbonic anhydrase: an enzyme present in red blood cells that speeds the breakdown of carbonic acid during external respiration TO PREVIOUS SLIDE

UNIT B CO2 Exits the Blood Chapter 11: Respiratory System Section 11.3 TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 Blood returning from the systemic capillaries has a lower partial pressure of O2 (PO2) than the air in the alveoli O2 diffuses into plasma and then into red blood cells Hemoglobin has a higher affinity for O2 at lower temperatures and higher pH Hemoglobin takes up O2 and becomes oxyhemoglobin (HbO2) oxyhemoglobin (HbO2): compound formed when oxygen combines with hemoglobin TO PREVIOUS SLIDE

UNIT B O2 Enters the Blood Chapter 11: Respiratory System Section 11.3 TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 Figure 11.10 External respiration. During external respiration in the lungs, carbon dioxide (CO2) leaves the blood, and oxygen (O2) enters the blood. TO PREVIOUS SLIDE

Internal Respiration UNIT B Chapter 11: Respiratory System Section 11.3 Internal Respiration Internal respiration is the exchange of gases between the blood in systemic capillaries and the tissue fluid. In internal respiration, O2 leaves the blood, and CO2 enters the blood. Tissues have a higher temperature and lower pH, and the partial pressure of O2 (PO2) in tissue fluid is lower than in blood Therefore, oxyhemoglobin gives up O2, which diffuses out of the blood into the tissues: internal respiration: the exchange of gases between the blood in systemic capillaries and the tissue fluid TO PREVIOUS SLIDE

UNIT B O2 Exits the Blood Chapter 11: Respiratory System Section 11.3 TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 CO2 diffuses into the blood from the tissues because the PCO2 of tissue fluid is higher than in blood After CO2 diffuses into the blood, it enters red blood cells where about 10% is taken up by hemoglobin, forming carbaminohemoglobin (HbCO2) The remaining CO2 combines with water in the plasma, forming carbonic acid (H2CO3), which dissociates into hydrogen ions (H+) and bicarbonate ions (HCO3-). The increased concentration of CO2 in the blood drives the reaction to the right: carbanimohemoglobin (HbCO2): a compound formed when hemoglobin binds with carbon dioxide TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 The globin portion of hemoglobin combines with excess H+ to become reduced hemoglobin (HHb) Blood that leaves the systemic capillaries is dark maroon because red blood cells contain reduced hemoglobin When blood reaches the lungs, CO2 readily diffuses out of the blood and is exhaled Carbon monoxide (CO) poisoning occurs because it has a greater affinity for hemoglobin than O2 CO stays combined to hemoglobin for hours, making hemoglobin unavailable to O2 transport reduced hemoglobin (HHb): a compound formed when the globin portion of hemoglobin combines with excess hydrogen ions TO PREVIOUS SLIDE

UNIT B CO2 Enters the Blood Chapter 11: Respiratory System Section 11.3 CO2 Enters the Blood TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 Figure 11.10 Internal respiration. During internal respiration in the tissues, oxygen leaves the blood, and carbon dioxide enters the blood. TO PREVIOUS SLIDE

Check Your Progress UNIT B Explain the role of hemoglobin. Chapter 11: Respiratory System Section 11.3 Check Your Progress Explain the role of hemoglobin. Discuss why arterial blood is bright red in colour, but venous blood is darker. This being the case, why does blood oozing from a cut always appear to be bright red? Explain why carbon monoxide poisoning can be rapidly fatal. ANSWERS 1. Hemoglobin carries oxygen (as oxyhemoglobin) to the tissues, as well as a small amount of CO2 (as carbaminohemoglobin) and hydrogen ions (as reduced hemoglobin). Hemoglobin’s affinity for oxygen changes depending on temperature and pH. 2. Arterial blood is brighter red than venous blood, because the red blood cells in arterial blood contain large amounts of oxyhemoglobin, which is bright red compared to the red blood cells carrying reduced hemoglobin, which is darker. Blood from a cut appears bright red, because any hemoglobin exposed to O2 in the air, rapidly becomes the bright red oxyhemoglobin. 3. Carbon monoxide can quickly become fatal because the affinity of carbon monoxide with hemoglobin is very high. Carbon monoxide stays bound to the hemoglobin, thereby reducing the ability of blood to carry oxygen. If CO poisoning continues for a period of time, enough hemoglobin becomes unavailable that a person suffocates. TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 TO PREVIOUS SLIDE