Respiratory System 2015-1.ppsx

Respiratory System Chapter 15 Objectives        Discuss the mechanics involved in respiration Understand negative intrathoracic pressure Discuss terminology used to measure respiratory volume Review pulmonary circulation and discuss how it relates to respiration Describe diffusion of...

Respiratory System Chapter 15 Objectives        Discuss the mechanics involved in respiration Understand negative intrathoracic pressure Discuss terminology used to measure respiratory volume Review pulmonary circulation and discuss how it relates to respiration Describe diffusion of gases at the alveolar level Discuss the mechanisms used to control breathing Discuss the secondary functions of the Functions Primary Function  Respiration (exchange of O & CO ) 2 2   Internal (blood/cells of body) External (air/blood in lungs) Secondary Functions  Voice production (phonation)  Body temperature regulation  Acid-Base Balance regulation  Sense of smell (olfaction) Respiration    Requires effective movement of air into and out of the lungs Appropriate rate and volume to meet the body’s need at any given time Inspiration (inhalation)   Diaphragm / external intercostal muscles Expiration (exhalation)  Internal intercostal muscles / abdominal muscles Negative Intrathoracic Pressure      Pressure within the thorax is negative w/ respect to atmospheric pressure This partial vacuum pulls the lungs tightly against the thoracic walls Pleural fluid acts as a lubricant The lungs passively follow movements of the chest wall Negative pressure also aids in return of the blood to the heart Respiratory Volumes  Tidal volume = volume of air inspired and expired during one breath  Minute volume = volume of air inspired and expired during 1 minute (TV x RR = MV)  Residual volume = volume of air left in the lungs after maximum expiration Pulmonary Circulation = Blood supply to and from the lungs  Pulmonary artery to the lungs divides into right and left arteries  From there the blood vessels subdivide to coincide with the bronchial tree  At the capillary level there is a network of capillaries around the alveoli where exchange of oxygen and carbon dioxide takes place  The oxygen-enriched blood then enters the pulmonary venules which lead to larger veins & eventually to pulmonary Pulmonary Circulation  Pulmonary veins carry the oxygenenriched blood to the LA -> through left AV valve to LV & out through aorta -> systemic circulation to supply the body w/ oxygen (for internal respiration) Exchange of Gases in the Alveoli  Simple diffusion     From areas of high concentration to areas of low concentration Air in the alveoli of the lungs is only 2 thin epithelial layers away from blood in the capillaries around the alveolar sacs Because oxygen levels in the alveoli are high, oxygen simply diffuses across the alveolar and capillary walls into the blood where the oxygen concentration is low The same thing occurs with carbon Control of Breathing     Muscles used for respiration are voluntary, skeletal muscles but … Breathing does not require conscious effort Breathing is controlled by the respiratory center (RC) area in the medulla oblongata of the brainstem Individual control centers here send impulses out to the respiratory muscles at a subconscious level of the brain Control of Breathing Two main systems  Mechanical   stretch receptors in lung maintains normal, rhythmic resting breathing patterns  Chemical   receptors in carotid artery, aorta (carotid & aortic bodies) and in brainstem monitor blood pH and levels of CO2,and O2 W/ imbalance of any of these -> chemical control system signals RC to adjust the breathing process Chemical Control of Breathing   Increases in CO2 are linked with decreases in pH -> signals RC to increase rate & depth of respiration to eliminate more CO2 (opposite occurs also) Variations in O2 are not as clear cut   A slight lowering of the oxygen level in the blood can result in a condition called hypoxia & RC will increase rate & depth so more O2 is taken in but… If the oxygen level drops too low, the RC neurons become so depressed they can’t send the proper nerve impulses to respiratory Secondary Functions of Respiratory System    Phonation - two fibrous connective tissue bands (vocal folds) stretch across the lumen of the larynx and vibrate as air passes over them producing sound Body temperature – blood vessels under epithelium in nasal cavity warm inhaled air; panting cools blood via inc evaporation of fluid from nasal passages & mouth Olfaction – receptors for smell are in olfactory epithelium high in nasal cavity Review        Discuss the mechanics involved w/ respiration Define negative intrathoracic pressure Know the terminology used to describe respiratory volume measurements Review the pulmonary circulation and how it relates to respiration Describe diffusion of gases at alveolar level Describe the mechanisms used to control breathing Discuss the secondary functions of the