20.1 General characteristics of the respiratory system
20.2 Respiratory cycle
20.3 Pulmonary and alveolar ventilation
20.4 Methods of assessing external respiration
20.5 Work done while breathing
20.6 Respiratory tract function
20.7 Gas exchange in lungs
20.8 Transport of gases by blood
20.9 Assessment of gas composition of blood
20.10 Gas exchange between blood and tissues
20.11 Tissue respiration
20.12 Protective respiratory reflexes
20.13 Non-gas exchange pulmonary functions Profile materials
Control questions Situational tasks
20.1. General characteristics of the respiratory system
The respiratory system is a physiological system that manages the intake of O2 into the body, its delivery and utilization in tissues, as well as elimination of CO2, the final product of breathing, from the body. Functional significance for the body Direct metabolic effect of О2. Oxygen is an acceptor of electrons in a respiratory chain of mitochondria, there-
fore it provides oxidative phosphorylation and synthesis of the main bulk of ATP in the body. Mitochondria als release products of incomplete restoration of О2 - free radicals (superoxide anion, hydrogen peroxide, hydrox-yl radical, etc.). They affect the viscosity and fluidity of membranes, vascular tone, proliferation of lymphocytes, participate in phagocytosis.
Physiological effects of О2 and CO2. О2 and CO2 tension are important factors of regulating vascular tone, the acid-base state, erythropoiesis, and the respiratory function.
The lungs participate in regulation of acid-base state, thermoregulation and perform other non-gas exchange functions.
Basic stages of respiration. There are five distinct stages of breathing: 1) pulmonary ventilation; 2) exchange of gases in lungs; 3) transport of gases by blood; 4) exchange of gases between blood and tissues; 5) tissue respiration. Pulmonary ventilation is aeration of lungs with exchange of gases between atmospheric and alveolar air, ensuring renewal of alveolar air and maintaining the partial pressure of oxygen and carbon dioxide in alveolar air at a level necessary for normal gas exchange.