1. The Respiratory System
Chapter 22
The Respiratory System

2. Functions and Divisions of the Respiratory System
Ventilation - breathing (external respiration) (bold - internal respiration)
Gas exchange - between air and blood in lungs and blood and other tissues
Oxygen utilization - Energy-liberating reactions of cell respiration
Divisions
Conducting division all structures which conduct air to the respiratory system
Respiratory division - alveoli of lungs - where gas exchange occurs

4. Organs of the Conducting System
Nose - nasal bones and cartilages - where air enters the respiratory system
Pharynx - funnel-shaped passageway that connects the oral and nasal cavities
Larynx - composed of several cartilages and keeps the passageway to the trachea open for breathing
closed for swallowing - voice box
Trachea - rigid tube - supported by rings of cartilage - connects larynx and bronchiole tubes
Bronchial tree - right and left primary bronchus, secondary bronchi (3 on right, 2 on left), tertiary bronchi and bronchioles.

11. Organs of the Respiratory Division
Lungs - Right and Left lungs - separated by mediastinum - 3 lobes on right, 2 lobes on left
Alveoli - functional unit of lungs - where gas exchange occurs
Serous Tissues
Visceral Pleura- covers lungs
Parietal Pleura- lines thoracic cavity

17. Respiratory Physiology
Intrapleural pressure - pressure outside the lungs- always less than intrapulmonary pressure - subatmospheric - less than atmospheric pressure
Intrapulmonary pressure - pressure inside the lungs - falls below atmospheric pressure during inspiration and rises above atmospheric pressure during expiration
Transpulmonary pressure - the difference between the intrapulmonary and intrapleural
Acts to expand the lungs as the thoracic volume increases during inspiration
Boyle’s Law= the pressure of a gas is inversely proportional to its volume

19. Pulmonary Ventilation
inspiration - Diaphragm and external intercostal and internal intercostal muscles contract - increase volume of lungs
expiration - These muscles relax - elastic recoil of lung an thorax - decrease in volume of lungs
Lungs are stuck to the wall of the thorax because - interpulmonary pressure is greater than intrapleural pressure.

20. Respiratory Volumes
tidal volume - amount of air inspired or expired in each unforced respiratory cycle (quiet breath)
inspiratory reserve volume - maximum volume of gas inspired during forced respiratory cycle in addition to tidal volume
expiratory reserve volume - maximum volume of gas that can be expired during forced breathing in addition to tidal volume
vital capacity - maximum amount of air that can be forcefully exhaled after a maximum inhalation sum of inspiratory reserve volume and expiratory reserve volume

21. Respiratory Volumes
residual volume - volume of gas remaining in the lungs and after a maximum expiration
total lung capacity - Total amount of gas in the lungs at the end of a maximum inspiration
dead spaces -
anatomical - conducting zone, of the respiratory system- where no gas exchange takes place
physiological - anatomical dead space plus underventilated or underperfused alveoli that do not contribute normally to blood-gas exchange

23. Regulation of Breating
aspects of breathing -
voluntary (cerebral cortex controlled) and
involuntary (medulla oblongota controlled) - influenced by sensory feedback from receptors sensitive to partial pressure of carbon dioxide (PCO2), pH, and PO2 of arterial blood.
portions of the brain stem
rhythmicity center -(in medulla oblongata)- controls automatic breathing
I neurons stimulate spinal motor neurons which innervate respiratory muscles during inspiration.
E neurons inhibit I neurons
apneustic center - (in pons) - promote inspiration - stimulate I neurons
pneumotaxic center- (in pons) antagonize apneustic- center - inhibits inspiration

25. Regulation of Respiration
chemoreceptors
central chemoreceptors - in medulla oblongata
peripheral chemoreceptors - aortic and the carotid bodies - not aortic and carotid sinuses
pressure/stretch receptors -
Hering-Breuer reflex - stimulated by pulmonary stretch receptors - inhibits inspiration
control of normal ventilation in newborns - exercise ventilation in adults
irritant receptors - stimulate reflex constriction of bronchioles in response to smog or smoke
sneezing, sniffing, and coughing - stimulated by irritant receptors in nose, larynx, and trachea
hyperventilation - excessive ventilation - results from abnormally low blood CO2

28. Respiratory Disorders
Asthma - dyspnea, wheezing, etc.. - obstruction of air flow through the bronchioles - caused by inflammation and increased mucus secretion and bronchoconstriction - stimulated by leukotrienes and histamine released by mast cells and leukocytes - provoked by allergic reaction or by release of acetylcholine from parasympathetic nerve endings
Chronic obstructive pulmonary diseases -
Emphysema - Characterized by destroyed alveolar tissue - fewer, but larger alveoli - reduces surface area and decreased ability of bronchioles to remain open during expiration - bronchioles close during expiration and cause “air trapping” which further decreases the efficiency of gas exchange in the alveoli
Chronic bronchitis - inflammation of the bronchioles

30. Respiratory Infections
Pneumonia - acute infection and inflammation of the lung tissue - accompanied by accumulation of fluid (exudation).
Tuberculosis - inflammatory disease of lungs caused by presence of tubercle bacilli - leads to ulceration of lung tissue
Pleurisy - inflammation of the pleura - usually associated with other respiratory diseases

31. The End.