Inspiration: Active Phase UNIT B Chapter 11: Respiratory System Section 11.2 Inspiration: Active Phase Diaphragm: contracts and lowers Creates Negative Pressure Intercostal muscles: contract Rib cage: moves up and out Pleura – two membranes Parietal – adheres to rib cage and diaphragm Visceral pleura - lungs Lungs are enclosed by two pleural membranes – one lines chest, inner lines lung. Fluid in between makes for air tight seal. Breathing is powered by the diaphragm:Diaphragm contracts (pulls down), increasing volume in thoracic cavity, creating negative pressure (vacuum), air rushes in. Intercostal muscles (attached to ribs) also contract when you breathe in. Ribs pull up and out, further increasing the space within the thoracic cavity. As the thoracic volume increases, the lung volume increases, and air pressure in alveoli decreases Alveolar pressure is lower than atmospheric pressure outside lungs, causing air to flow into airways Pleura- separated by small amount of fluid. Intrapleural pressure is lower than atmosphereic pressure by 4mm Hg. If air enters this space, lung collapses. Pleurisy – infection of pleura TO PREVIOUS SLIDE

Expiration - passive phase UNIT B Chapter 11: Respiratory System Section 11.2 Expiration - passive phase Diaphragm: relaxes and moves up Intercostal muscles: relax Rib cage: moves down and in Thoracic volume decreases lung volume decreases  air pressure in alveoli increases Alveolar pressure is higher than atmospheric pressure outside lungs, causing air to be pushed out expiration: passive phase of breathing in which air is expelled from the body TO PREVIOUS SLIDE

Nervous Control of Breathing UNIT B Chapter 11: Respiratory System Section 11.2 Nervous Control of Breathing Ventilation is controlled by a respiratory centre in the medulla oblongata of the brain. Sends impulse to diaphragm and intercostal muscles Alveoli expand and stretch Signal sent to brain to inhibit Medula Oblongata Diaphragm relaxes Expiration occcurs respiratory centre: located in the medulla oblongata Stimulates inspiration by automatically sending impulses to the diaphragm through the phrenic nerve, and to the intercostal muscles through the intercostal nerve Diaph contracts and lowers, while rib cags moves up air flows into aveolialveolar walls expand and stretch stretch receptors in alveoli walls detect stretchingnerves in alveoli send signal to brain to inhibit Med. Ob from seding its message to diap and rib. They stop contracting. After forced inhalation, stretch receptors send inhibitory nerve impulses to the respiratory centre via the vagus nerve. Usually, expiration automatically occurs because of the lack of stimulation from the respiratory centre to the diaphragm and intercostal muscles. When the respiratory centre stops sending signals to the diaphragm and rib cage, the diaphragm relaxes and expiration occurs Following inhalation, stretch receptors in the alveolar walls send inhibitory nerve impulses via the vagus nerve to the respiratory centre, which inhibits the respiratory centre from sending impulses, diap relaxes, moves upward, rib cage relaxes and moves downward and inward. Air forced out. TO PREVIOUS SLIDE

Control of Breathing UNIT B Chemical Input: Chapter 11: Respiratory System Section 11.2 Control of Breathing Chemical Input: When Carbon dioxide levels and hydrogen ions in the blood increase  respiratory centre increases rate and depth of breathing Carotid bodies and aortic bodies When [O2] decreases signal the respiratory centre to increase rate and depth of breathing Chemical Input The respiratory centre is also sensitive to levels of carbon dioxide and hydrogen ions in the blood When carbon dioxide or hydrogen ion concentrations increase, the respiratory centre increases rate and depth of breathing Respiration rate is also influenced by cells called carotid bodies and aortic bodies Chemoreceptors sensitive to levels of O2.. When concentration of blood oxygen decreases, these bodies signal the respiratory centre to increase rate and depth of breathing carotid bodes: a group of cells located in the carotid arteries that are sensitive to blood oxygen levels and influence respiration rate aortic bodies: a group of cells located in the aorta that are sensitive to blood oxygen levels and influence respiration rate TO PREVIOUS SLIDE

Control of Breathing: Conscious Vital Capacity

Heimlich manoeuvre is a first aid procedure used to treat upper airway obstructions (or choking) by foreign objects. The term Heimlich maneuver is named after Dr. Henry Heimlich, who first described it in 1974

Gas Exchanges in the Body UNIT B Chapter 11: Respiratory System Section 11.3 Gas Exchanges in the Body Respiration includes: External respiration: exchange of gases in the lungs Internal respiration: exchange of gases in the tissues 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 cellshemoglobin (Hb): iron-containing respiratory pigment occurring in red blood cells TO PREVIOUS SLIDE

UNIT B Chapter 11: Respiratory System Section 11.3 External and Internal respiration. Exchange bt air (at alveoli) and blood (in pulmonary capillaries). Both ave and cap walls are one cell thick. Gas exchange is by diffusion alone 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: 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 Chapter 11: Respiratory System Section 11.3 CO2 Exits the Blood TO PREVIOUS SLIDE

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

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 is an iron-containing respiratory pigment found within RBCs. About 20 million Hb molec/RBC

UNIT B Chapter 11: Respiratory System Section 11.3 O2 Enters the Blood 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. O2 leaves the blood, and CO2 enters the blood. internal respiration: the exchange of gases between the blood in systemic capillaries and the tissue fluid 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: TO PREVIOUS SLIDE

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

UNIT B Chapter 11: Respiratory System Section 11.3 About 10% CO2 is taken up by hemoglobin = carbaminohemoglobin (HbCO2) 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) Carbon monoxide (CO) poisoning occurs because it has a greater affinity for hemoglobin than O2 reduced hemoglobin (HHb): a compound formed when the globin portion of hemoglobin combines with excess hydrogen ions 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 TO PREVIOUS SLIDE

UNIT B 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

Saturation of Hb relative to temperature temperature The partial pressure of oxygen (PO2) in pulmonary capillaries is about 98-100 mm Hg, but in tissue capillaries is only about 40 mm Hg. Hemoglobin is about 98% saturated in the lungs because of PO2, and also because the temperature is cooler (and pH is higher in the lungs). On the other hand, hemoglobin is only about 60% saturated in the tissues because of PO2, and also because the temperature is warmer (and pH is lower) in the tissues.

Saturation of Hb relative to pH Hemoglobin is about 98% saturated in the lungs because of PO2, and also because pH is higher in the lungs (and temperature is cooler). On the other hand, hemoglobin is only about 60% saturated in the tissues because of PO2, and also because the pH is lower (and temperature is warmer) in the tissues.

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.

Respiration and Health