Respiratory Physiology 2024-2025 PDF

RESPIRATORY PHYSIOLOGY Department of Physiology Clinical Nutrition 2024-2025  Objectives of the lecture Definition and concept of respiration Types of respiration Exchange and transport of gases Transport of oxygen and hypoxia Textbook/readings: Sherwood,...

RESPIRATORY PHYSIOLOGY Department of Physiology Clinical Nutrition 2024-2025  Objectives of the lecture Definition and concept of respiration Types of respiration Exchange and transport of gases Transport of oxygen and hypoxia Textbook/readings: Sherwood, L. (2015). Human physiology: from cells to systems. Cengage learning. Chapter 13  What is Respiration? Process of obtaining O2 for use by the body cells and eliminate CO2 produced by the cells  Respiration Internal External respiration respiration Refers to Refers to the intracellular the entire sequence metabolic processes of events involved in the carried out within the exchange of O2 and CO2 mitochondria, which between the external use O2 and produce environment and the CO2 cells of the body  External Respiration Entire sequence of events involved in the exchange of O2 and CO2 between the external environment and the cells of the body. It involves 4 steps: Pulmonary ventilation: Inflow and outflow of air between atmosphere and alveoli. Exchange of O2 and CO2 between air in alveoli and blood within pulmonary capillaries. Transport of O2 and CO2 by the blood between lungs and tissues. Exchange of O2 and CO2 between the blood in systemic capillaries and the tissue cells.  O2 CO2 1 Gas exchange between the atmosphere and the alveoli O2 CO2 Alveoli 2 Exchange of O2 and CO2 between air in the alveoli and the blood Pulmonary circulation 3 Transport of O2 and CO2 between the lungs Heart and the tissues Systemic circulation 4 Exchange of O2 and CO2 between the blood and the tissues Tissues O2 CO2  Respiratory System STRUCTUREOFTHELUNGSANDTHORACICCAVITY 1. Air conducting (a)Therespiratorysystem parts Pharynx Tongue Nasalcavity 2. Gas exchange Vocalcords Upper respiratory zone: ( alveoli ) Esophagus system Larynx Trachea Rightlung Leftlung Lower respiratory Left system Right bronchus bronchus Diaphragm Mechanism of Pulmonary Ventilation: inspiration and expiration.  Breathing Breathing, or pulmonary ventilation, consists of two phases – Inspiration – air flows into the lungs – Expiration – gases exit the lungs Muscles of Respiration Atmospheric pressure Alveolar pressure intrapleural pressure The flow of the air into and out of the lungs occurs because of changes in the intra-alveolar pressure Exchange and Transport of gases  Diffusion Of Gas Through Alveolar Membrane Diffusion rate of gas through alveolar membrane is affected by : – Thickness of membrane ( inc. thickness >> dec. diffusion rate ) – Surface area (inc. Surface area >> inc. diffusion rate ) – Gas solubility ( inc. gas solubility>> inc. diffusion rate ) – Pressure difference ( inc. pressure difference >> inc. diffusion rate )  Factors effecting diffusion through respiratory membrane Pulmonary edema – Pulmonary edema….increased thickness of membrane…..decreased gas exchange. Emphysema – Emphysema…..damage to alveolar walls….decreased surface area of respiratory membrane……decreased gas exchange. Lung fibrosis – Lung fibrosis i.e in tuberculosis….increased thickness of respiratory membrane…..decreased gas exchange  Exchange of O2 and CO2 and Normal partial pressures of oxygen and carbon dioxide  O2 transport in the blood Dissolved in Bound to plasma hemoglobin 1.5 % 98.5 %  Transport of CO2 in blood Physically Bound to As dissolved Hemoglobin bicarbonate 10 30 60 % % % CO2 +H2O…………….. H2CO3………………H+ + HCO3- HYPOXIA  Factors determining tissue oxygenation Arterial PO2 Blood flow Hb  Hypoxia (Insufficient O2 at the cellular level) Hypoxic Circulatory hypoxia hypoxia Anemic Histotoxic hypoxia hypoxia  Hypoxic hypoxia arterial PO2 with inadequate Hb saturation Oxygen content Examples Respiratory malfunction Exposure to High altitude  CASE SCENARIO FOR HYPOXIC HYPOXIA A 5 years old child was a known case of bronchial asthma and was observed of being allergic to the peanuts. His parents always avoid him from taking any peanut or peanut made foods. One day he shared a peanut butter sandwich with his friend, after which he developed status asthmaticus (severe attack of asthma characterized by breathlessness and in extreme cases cyanosis). He was rushed to the hospital where emergency care was provided and a blood sample was also taken for blood gas analysis. What findings do you expect in the blood gas analysis of this child? Comment on the Hb saturation in this child. What type of hypoxia is expected in this child? Explain the physiological basis of this type of hypoxia.  What findings do you expect in the blood gas analysis of this child? Oxygen levels will be decreased. Co2 levels will be increased. Comment on the Hb saturation in this child. Hb saturation…. Decreased due to decreased oxygen. What type of hypoxia is expected in this child? Explain the physiological basis of this type of hypoxia. Hypoxic hypoxia.  Anemic hypoxia ¯O2 carrying capacity of the blood ¯(decreased Hb saturation) but normal PO2 Oxygen content Examples circulating red blood cells Hb CO poisoning  CASE SCENARIO FOR ANEMIC HYPOXIA A mother of three years old child visited to the clinical nutritionist. She was worried about the general health condition of the child. She indicated that the child is lethargic most of the times and becomes exhausted even after a minor physical activity. She also had the report of blood CP(Complete picture), which was showing that the child is suffering from microcytic hypochromic anemia. The nutritionist asked her about the diet of child, she told that her child is very fond of milk and most of the times he is relying on milk rather than on any solid diet. The nutritionist counseled the mother about changing the diet habits of the child. She advised the mother to add solid foods especially dates, guava, apples,  CASE SCENARIO FOR ANEMIC HYPOXIA What is the cause of lethargy and easy fatigability in the child? Which type of hypoxia can be associated with microcytic hypochromic anemia? Would this type of hypoxia be associated with a decrease in the number of circulating RBCS? Comment on arterial pressures of oxygen and carbon dioxide in this child. Why did the nutritionist advised a change in the dietary habits and a gap between the intake of the milk and solids. Explain the physiological basis of improvement of general health condition of this child.  What is the cause of lethargy and easy fatigability in this child? Anemic hypoxia…so enough oxygen is not reaching the tissues. Which type of hypoxia can be associated with with microcytic hypochromic anemia? Anemic hypoxia. Would this type of hypoxia be associated with a decrease in the number of circulating RBCS? Yes Comment on arterial pressures of oxygen and carbon dioxide in this child. po2 would be normal because of normal amount of physically dissolved oxygen. O2=100mmHg CO2=40mmHg Why did the nutritionist advised a change in the dietary habits and a gap between the intake of the milk and solids. To treat anemia Explain the physiological basis of improvement of general health condition of this child. Increased Hb levels, increased Hb saturation, increased oxygen content, increased oxygen reaching the tissue.  Circulatory hypoxia Little oxygenated blood reaches the cell But Normal arterial PO2, Normal HB Saturation and Normal O2 content of the blood Examples Congestive heart failure Circulatory shock  Histotoxic hypoxia Cells unable to use O2 But Normal arterial PO2, Normal HB Saturation and Normal O2 content of the blood Examples Cyanide poisoning  CASE SCENARIO FOR HISTOTIC HYPOXIA A group of students of clinical nutrition were being taught about a few foods which can be poisonous for the human body, if ingested in excess. These include: Almonds in raw form almonds of apricot seeds of apple and some forms of mushrooms Students were than given an assignment to find out the  CASE SCENARIO FOR HISTOTIC HYPOXIA Answer the following questions on the basis of above mentioned facts: How can you relate acute cyanide poisoning with hypoxia? What would be the effects of cyanide poisoning on oxygen content and arterial pressure of oxygen. Can acute cyanide poisoning have any effects on respiration? If yes explain the mechanism. How can you relate acute cyanide poisoning with hypoxia? Histotic hypoxia…cells are not able to use oxygen. What would be the effects of cyanide poisoning on oxygen content and arterial pressure of oxygen. None Can acute cyanide poisoning have any effects on respiration? If yes explain the mechanism. The problem is in the cells. As lungs are normal and blood also have normal levels of oxygen and carbon dioxide but the cells are unable to use this oxygen.  Hypoxia Decreased oxygen delivered to tissues Hypoxic hypoxia Decreased PO2 Decreased O2 content Anemic hypoxia Normal PO2 Decreased O2 content Circulatory hypoxia Normal PO2 Normal O2 content Histotoxic hypoxia Normal PO2 Normal O2 content THANK YOU