Department of medical physiology 5 th week

Transcription

1 Department of medical physiology 5 th week Semester: winter Study program: Dental medicine Lecture: RNDr. Soňa Grešová, PhD. Department of medical physiology Faculty of Medicine PJŠU

2 Department of medical physiology 5 th week 1. Pressures in the pulmonary system 2. Transport of the respiratory gases by blood 3. Respiratory gases exchange 4. Blood flow through the lungs and ventilationperfusion ratio

3 1. Pressures in the Pulmonary System The systolic pressure in the right ventricle about 25 mm Hg, and the diastolic pressure averages about 0 to 1 mm Hg During systole, the pressure in the pulmonary artery is essentially equal to the pressure in the right ventricle about 25 mm Hg, the diastolic pulmonary arterial pressure is about 8 mm Hg, and the mean pulmonary arterial pressure is 15 mm Hg. The mean pulmonary capillary pressure, is about 7 mm Hg The mean pressure in the left atrium and the major pulmonary veins averages about 2 mm Hg (varying from as low as 1 mm Hg to as high as 5 mm Hg) Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

4 1. Pressures in the pulmonary system Pulmonary capillaries Mean BP =7 mmhg Pulmonary arteries BP=25 mm Hg/8mmHg (Mean BP= 15 mmhg) Right ventricle BP= 25 mm Hg/0-1 mmhg The major pulmonary veins and the left atrium Mean BP= 5 mmhg The left ventricle BP= 120mmHg/0mmHg The systemic arteries Mean BP= 100 mmhg Calculation of mean arterial blood pressure (MAP) MAP = DBP (SBP-DBP)

5 1. Pulmonary Capillary Dynamics Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

6 2. Transport of Oxygen O 2 transport Transported two ways: 1) Dissolved in blood (3%) partial pressure of oxygen (Po 2 ) 2) In chemical combination with Hb (97%) oxyhemoglobin

7 2. Uptake of Oxygen by pulmonary The alveolus Po 2 = 104 mmhg the venous blood entering the pulmonary capillary Po 2 = 40 mmhg blood and Po 2 Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

8 2. Transport of oxygen in the arterial Blood is mixed with pulmonary shunt blood blood and Po 2 the bronchial circulation (2%) venous admixture of blood Po 2 falls = 95 mmhg Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

9 2. Diffusion of oxygen from the peripheral capillaries into the tissue fluid and Po 2 the arterial blood Po 2 = 95 mmhg the interstitial fluid Po 2 = 40 mmhg the blood leaving the tissue capillaries and entering the systemic veins Po 2 = 40 mmhg Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

10 2. Effect of blood flow and rate of oxygen consumption on tissue P O2 Effect of rate of blood flow on interstitial fluid P O2 points A, B, C Effect of rate of tissue metabolism on interstitial fluid P O2 curves O 2 consumption Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

11 2. Transport of carbon dioxide CO 2 transport Transported three ways: 1) Dissolved in blood (7%) partial pressure of carbon dioxide (Pco 2 ) 2) In the form of bicarbonate ion (70%) 3) In combination with Hb (23%) carbaminohemoglobin

12 2. Diffusion of Carbon Dioxide and Pco 2 Intracellular Pco 2, = 46 mm Hg Interstitial Pco 2, = 45 mm Hg The arterial blood entering the tissues Pco 2 = 40 mm Hg The venous blood leaving the tissues Pco 2 = 45 mm Hg Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

13 2. Diffusion of Carbon Dioxide and the blood entering the pulmonary capillaries at the arterial end Pco2 = 45 mmhg Pco2 of the alveolar air = 40 mm Hg Pco 2 Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

14 2. Effect of blood flow and metabolic rate on peripheral tissue Pco 2 Effect of rate of blood flow on interstitial fluid Pco 2 points A, B, C Effect of rate of tissue metabolism on interstitial fluid Pco 2 curves of metabolic rate Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

15 3. Exchange of O 2 and CO 2 in pulmonary capillaries

16 3. Exchange of O 2 and CO 2 in systemic capillaries

17 Oxygen-hemoglobin dissociation curve. The Bohr effect Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

18 Carbon dioxide dissociation curve. The Haldane effect Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

19 Transport of the respiratory gases by blood VCO 2 = 4ml/100ml VO 2 = 5ml/100ml VO 2 = 15ml/100ml VCO 2 = 52ml/100ml PCO 2 = 45 mmhg PO 2 = 40 mmhg ph=7,36 Hg saturation =75% VO 2 = 20ml/100ml VCO 2 = 48ml/100ml PCO 2 = 40 mmhg PO 2 = 95 mmhg ph= 7,4 Hg saturation =97% VO 2 = 5ml/100ml VCO 2 = 4ml/100ml

20 Zone 1: 4. Blood flow through the lungs no blood flow during all portions of the cardiac cycle and its distribution Zone 2: intermittent blood flow Zone 3: continuous blood flow Normally, the lungs have only zones 2 and 3 blood flow zone 2 (intermittent flow) in the apices, and zone 3 (continuous flow) in all the lower areas. Copyright: Hall, J. E., & Guyton, A. C. (2006). Guyton and Hall textbook of medical physiology. Philadelphia, PA: Saunders Elsevier.

21 Lung Ventilation/Perfusion ratio Alveoli at apex are underperfused (overventilated) V=more than 4000ml/min Q=less than 5000ml/min (V/Q >0,8) Alveoli at the base are underventilated (overperfused) V=less than 4000ml/min Q=more than 5000ml/min (V/Q<0,8) V/Q

22 Ventilation Perfusion Mismatching Blood goes to parts of the lung that do not have oxygen to give it Obstruction of airways (regulation-constriction of vessels) Blood does not go to parts of the lung that have oxygen Thrombus (regulation-bronchoconstriction) Copyright: