Presentation on theme: "The Respiratory System"— Presentation transcript:
1 The Respiratory System Chapter 23(6th edition chapter 22)
2 Functions of the Respiratory System Supply oxygen to the circulatory system for delivery to the tissuesRemove CO2 (and some other wastes) from blood.
3 There are 4 processes that we call “respiration”. Pulmonary ventilation - Movement of air into and out of the lungs(also referred to as “breathing”).2. External respiration - Gas exchange in the lungs between the bloodof the capillaries and the spaces in the air sacs (alveoli)Transport - The movement of gases by the circulatory systemStrictly speaking, a function of the blood.Internal respiration - Gas exchange between the blood and thetissues of the body
22 Respiratory Physiology: Dalton’s Law of Partial Pressures The total pressure of a mixture of gases is the sum of the partialpressures exerted independently by each gas in the mixture.LocationAtmosphere at sea levelAlveoli of lungsGasApproximate %Partial pressure in mmHgN278.659774.9569O220.915913.7104CO20.040.35.240H2O0.463.76.247Total100.0760
23 Partial pressure relationships: Movement of gases between the lungs and the tissues
24 Most soluble Least soluble Solubility: Differential solubility of gases contributes to the balance of gas exchangeMost soluble Least solubleCO2 >>>>>>>>>>>>>>>>> O2 >>>>>>>>>>>>>>>>>>> N2CO2 is 20 times more soluble than O2N2 is about half as soluble as O2
25 Ventilation-Perfusion Coupling Breathing and blood flow are matched to the partial pressure of alveolar gases
26 Respiratory Gas Transport Oxygen - about 98.5% is bound to hemoglobin (Hb) and 1.5% in solution.The affinity of O2 for hemoglobin is influenced by partial pressure
29 BPG (2,3-bisphosphoglycerate) The Bohr EffectDecreased pH that results from increased Pco2 lowers the bindingaffinity between O2 and Hb. The result is that, under acidosis, Hbsaturates at a lower Po2. This allows more oxygen to be unloaded at thewhere it is needed.BPG (2,3-bisphosphoglycerate)This compound is produced during glycolysis, anaerobic means ofproducing energy from glucose. BPG binds to Hb and decreases O2affinity. This results in a right-shifted O2 - Hb dissociation curve,Like we see in the Bohr effect
30 CO2 Transport 7 - 10% dissolved in the plasma ~ 20% bound to the amine groups of the Hb molecule ascarbaminohemoglobin~ 70% as bicarbonate ion in the plasma
35 Medullary Respiratory centers Neural and chemicalinfluences
36 Pco2 & pH are the primary regulators of ventilation by means of negative feedback
37 Pathology and clinical considerations Common homeostatic imbalances:COPD (chronic obstructive pulmonary disease)AsthmaTuberculosisLung cancer
38 COPD: EmphysemaResults: Loss of lung elasticity, hypoxia, lung fibrosis, cyanosis.Common causes: Industrial exposure, cigarette smoking.
39 Tuberculosis At the beginning of the 20th century a third of all deaths in peoplewere from TB.Antibiotic-resistant strainsof Mycobaterium tuberculosisare a growing problem at thebeginning of the 21st century.