Presentation on theme: "F ‘08 P. Andrews, Instructor. Respiration Exchange of gases between an organism and it’s environment Pulmonary (external) respiration Occurs in."— Presentation transcript:
Respiration Exchange of gases between an organism and it’s environment Pulmonary (external) respiration Occurs in lungs Cellular (internal) respiration Occurs in peripheral capillaries Is the exchange of respiratory gases between RBCs and tissue Produces CO2 Ventilation The mechanical process that moves air into and out of lungs
The thorax Moves air in and out Oxygen and CO 2 are exchanged Also contains heart, major vessels, trachea, bronchi, lungs, mediastinum
Ventilations are controlled by a series of centers in the brain and blood vessels Main control center – medulla oblongata Connected to respiratory muscles via VAGUS NERVE Additional control center – pons Apneustic center Pneumotoxic center
In the medulla and carotid bodies and arch of the aorta Stimulated by changes in O 2 and CO 2 as well as pH
Hyoxemia is a profound stimulus of respiration in a normal person People with COPD retain CO 2 – have chronically elevated PaCO 2 Peripheral chemoreceptors become used to this; CNS stops using PaCO 2 to regulate. A default mechanism – HYPOXIC DRIVE – is activated Increased respiratory stimulation when PaO 2 falls; inhibited respiratory stimulation when PaO 2 climbs
Sternocleidomastoid muscles raise upper rib and sternum Intercostal muscles contract elevate ribs and increase anterior-posterior dimension Diaphragm is the primary muscle of respiration – it contracts and flattens increases volume of cavity. Pressure in cavity becomes less than atmospheric air rushes in to alveoli to equalize pressure
Muscles relax… Diaphragm moves upward Ribs and sternum move inferiorly Ribs move closer together in inferior and posterior position Thoracic volume decreases Intrathoracic pressure increases
Changing volume and pressure of thoracic cage also helps with Pumping blood to and return from systemic circulation Affects BP and pulse strength Normally, systolic BP and pulse strength fall during inspiration, rise during exhalation
Adults – 12 – 24 breaths per min. Children – 18 – 24 breaths per min. Infants – 40 – 60 breaths per min.
Total lung capacity – TLC ~ 6 L Tidal Volume – V T ~ 500 ml (5 – 7 ml/kg) Dead space volume – V D ~ 150 ml Alveolar Volume – V A ~ 350 ml Minute volume - V min
Your consent to our cookies if you continue to use this website.