Respiratory System PDF

Which two structures does the trachea lead to in the lungs? The bronchi The bronchioles The pleural membranes What are the tiny air sacs in the lungs called? Bronchioles Alveoli Capillaries When we inhale (breathe in), what happens to the pressure in the thorax? It increases It stays the same It...

Which two structures does the trachea lead to in the lungs? The bronchi The bronchioles The pleural membranes What are the tiny air sacs in the lungs called? Bronchioles Alveoli Capillaries When we inhale (breathe in), what happens to the pressure in the thorax? It increases It stays the same It decreases What happens during gas exchange in the lungs? Oxygen passes into the blood and carbon dioxide passes out of the blood Oxygen passes out of the blood and carbon dioxide passes into the blood Oxygen and carbon dioxide pass into the blood Which of the following is the correct pathway through which air travels in the human respiratory system? nose, lungs, pharynx, trachea nose, pharynx, trachea, lungs pharynx, nose, trachea, lungs Which of the following is responsible for preventing food from entering the trachea? epiglottis glottis larynx Which of the following is responsible for preventing food from entering the trachea? epiglottis glottis Larynx Approximately how many alveoli are found in the human lungs? 10,000 300 million 500,000 Mechanisms of respiration By Dr. Eman Ibrahim El-gizawy Assitant proffesseur of medical physiology department ,faculty of medicine ,menoufia university  Regulation of pulmonary blood flow 1. Cardiacoutput: pulmonary blood flow is directly proportional to cardiac output Cardiac output affected by (venous return -force of contraction-rate of contraction -peripheral resistance) 2. Vascular resistance: pulmonary blood flow is inversely proportional to vascular resistance. During inspiration pulmonary blood vessels are the distended because of decreased intrathoracic Pressure. During exercise vascular resistance decrease and pulmonary blood flow increase 3. Nervous factor: sympathetic nervous system cause vasoconstriction (b2) 4. chemical factors: Excess carbon dioxide and the lack of oxygen cause vasoconstriction. 5. Gravity and hydrostatic pressure: normally in a standing position blood pressure in lower extremities of the body is very high and in parts above the heart Is low Apical portion: Zone 1: Pulmonary capillary pressure is almost the same is alveolar pressure so there is no gas exchange in this zone.has zero blood flow. Mid portion zone 2: Pressure in in the alveoli is less than pulmonary systolic pressure and more than Pulmonary diastolic pressure. So Blood flow increase during systole and decrease during the diastole (area of intermittent blood flow ). lower portion zone 3 :pulmonary arterial pressure is high and more than alveolar pressure In systole and diastole so it’s the area of continuous blood flow.  Mechanisms of respiration Respiratory movements: § respiratory muscles (inspiratory muscle and expiratory muscles) Inspiratory muscles: diaphragm - external intercostal muscles - sternocleidomastoid Expiratory muscles: internal intercostal muscle - Abdominal muscles § Movement of the lung: during inspiration enlargement of the thoracic cage. negative pressure increased in thoracic cavity. causes expansion of the lung during expiration the thoracic cavity decrease in size and compress lungs, so air expelled outside it.  Collapsing tendency of the lungs Factors causing: o Elastic property of the lung tissue o Surface tension of fluid secreted over alveolar epithelium Factors preventing: o Intrapleural pressure: always -ve o Surfactant: Substance secreted in the alveolar epithelium. it's reduced the surface tension and prevent tendency collapsing tendency  Surfactant: surface acting material (lipoprotein complex) responsible for lowering surface tension of fluid lining pulmonary surfactant Secret by type II alveolar epithelial cells § Respiratory pressures: Two types of pressures are exerted in the thoracic cavity and lung during the process of respiration 1. intrapleural pressure (intrathoracic pressure) 2. intra alveolar pressure (intrapulmonary pressures)  Interpleural pressure is the pressure present in the pleural cavity in between visceral and parietal layer of the pleura Normal values: At the end of normal inspiration: -6 mmHg (760- 6 ) 754mmHg At the end of normal expiration: -2 mmHg (760- 2 ) 758mmHg At the end of forced inspiration: -30 mmHg At the end of forced inspiration with closed glottis (Muller maneuver): - 70 mmHg At the end of forced expiration with closed glottis (Valsalva maneuver): + 50 mmHg intrapleural always -ve expect Valsalva maneuver and pathological condition pneumothorax, hemothorax and pyothorax Signifance: keep lung always inflated. Functions: ü Prevent collapsing of the lungs ü Act like suction pump and pulls venous return up from lower part o Intra alvelor pressure: pressure in the alveloi of the lungs o Normal values: - At the end of normal inspiration: -1 mmHg (760- 1 ) 759 mmHg - At the end of normal expiration: +1 mmHg (760 + 1 ) 760 mmHg - At the end of inspiration and expiration: equal to the atmospheric pressure - At the end of forced inspiration with closed glottis (Muller maneuver): - 80 mmHg - At the end of forced expiration with closed glottis (Valsalva maneuver): + 100 mmHg Signifance: flow of air in and out alveloi & gases exchanges between alvelor air and the blood o Transplumonary pressure Difference between intraalvelor pressure and intrapleural pressure Practical session  Lung function tests arer two types: 1. Static lung function tests 2. dynamic lung function tests Static lung function tests : Are based on volume of air that flow in and out of the lung. These tests don't depend on rate at which air flows. Static lung function tests include static lung volumes and the capacities Dynamic lung function tests : Are based on time varied at which air flows into or out of the lungs these tests. useful in determining the severity of obstructive and restrictive lung diseases Lung volumes: Tidal volume: Is the volume of air breathed in and out of the lungs in single normal quiet respiration tidal volume signifies the normal depth of breathing normal value: 500 ml Inspiratory reserve volume: is an additional volume of air that can be inspired forcefully after the end of normal insperation normal value: 3300 ml Expiratory reserve volume; is the additional volume of air that can be expelled out forcefully after normal expiration normal value: 1000 ml Residual volume Is the volume of air remaining in lungs even after forces expiration significance of residual volume: 1.It helps to a year till blood in between breathing and during expiration 2. It maintains the contour of the lungs Normal value : 1,200 ml