Copyright 2010, John Wiley & Sons, Inc. Chapter 18 The Respiratory System

Copyright 2010, John Wiley & Sons, Inc. Respiration: Three Major Steps 1.Pulmonary ventilation  Moving air in and out of lungs 2.External respiration  Gas exchange between alveoli and blood 3.Internal respiration  Gas exchange between blood and cells

Copyright 2010, John Wiley & Sons, Inc. Organs of the Respiratory System Upper respiratory system  Nose and pharynx Lower respiratory system  Trachea, larynx, bronchi, alveoli, and lungs “Conducting zone” consists of  All airways that carry air to lungs: Nose, pharynx, trachea, larynx, bronchi, bronchioles, and terminal bronchioles “Respiratory zone”  Sites within lungs where gas exchange occurs Respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

Copyright 2010, John Wiley & Sons, Inc. Organs of the Respiratory System

Copyright 2010, John Wiley & Sons, Inc. Upper Respiratory System: Nose Structure  Nostril openings – nares  Septum – pperating the nostrils. Rich in blood supply… nosebleeds (epitaxis) result from septum contusion.  Vestibule – area just inside the nostril. Covered with vibrissae (course hairs to catch microbes and chemical scents.  Nasal mucosa – this portion of the nose begins in the respiratory portion of the nasal passage. Air passes over this area carrying across the olfactory epithelium.

 Sinuses – air filled cavities lines with respiratory mucosa that drains into the nose.  Cleft palate – bone separating the roof of the mouth from the base of the nose.  Cribiform plate – bone separating the roof of the nose from the base of the cranial cavitiy. Copyright 2010, John Wiley & Sons, Inc.

Nose Functions  Warm, humidify, filter/trap dust and microbes Mucus and cilia of epithelial cells lining nose  Detect olfactory stimuli  Modify vocal sounds  If obstructed, air can bypass the nose and go in and out of the mouth. Copyright 2010, John Wiley & Sons, Inc.

Upper Respiratory System: Pharynx Known as the “throat” Structure  Tubelike structure about 5” in length extending from the base of the skull to esophogus. Three regions (with tonsils in the upper two)  Upper: nasopharynx; posterior to nose Adenoids and openings of auditory (Eustachian) tubes  Middle: oropharynx; posterior to mouth Palatine and lingual tonsils are here  Lower: laryngopharynx Connects with both esophagus and larynx: food and air

Copyright 2010, John Wiley & Sons, Inc. Respiratory System: Head and Neck

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Larynx “Voice box” – located between the base of the tongue and upper end of the trachea Made largely of cartilage  Thyroid cartilage: gives triangular shape to anterior wall. “Adam's apple”: projects more anteriorly in males Vocal cords “strung” here (lining juts inward and forms folds)  Epiglottis: leaf-shaped piece; covers airway During swallowing, larynx moves up so epiglottis covers opening into trachea

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Larynx

Copyright 2010, John Wiley & Sons, Inc. Voice Production Mucous membrane of larynx forms two pairs of folds  Upper = false vocal cords  Lower = true vocal cords Contain elastic ligaments When muscles pull elastic ligaments tight, vocal cords vibrate  sounds in upper airways Pitch adjusted by tension of true vocal cords Lower pitch of male voice  Vocal cords longer and thicker; vibrate more slowly

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Trachea “Windpipe” Location  Anterior to esophagus and thoracic vertebrae  Extends from end of larynx to primary bronchi Structure  C-shaped rings of cartilage support trachea, keep lumen open during exhalation Tracheostomy: opening in trachea for tube – this is permanent

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Bronchi, Bronchioles Structure of bronchial tree  Bronchi contain cartilage rings  Primary bronchi enter the lungs medially  In lungs, branching  secondary bronchi One for each lobe of lung: 3 in right, 2 in left These smaller airways  Have less cartilage, more smooth muscle. In asthma, these airways can close.  Can be bronchodilated by sympathetic nerves, epinephrine, or related medications.

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Alveoli Alveoli: composed of three types of cells  Lined with thin alveolar cells (simple squamous); sites of gas exchange  Scattered surfactant-secreting cells. Surfactant: Prevents the alveoli from “sticking shut” as air moves in and out Humidifies (keeps alveoli from drying out) Surfactant is the last thing to develop at the end of gestation Respiratory membrane: alveoli + capillary  Gases diffuse across these thin epithelial layers: air  blood

Copyright 2010, John Wiley & Sons, Inc. Lower Respiratory System: Lungs Two lungs: left and right  Right lung has 3 lobes  Left lung has 2 lobes and cardiac notch Function  Air distribution to the alveoli  Gas exchange between the air and blood

Copyright 2010, John Wiley & Sons, Inc. Lung Lobes

Copyright 2010, John Wiley & Sons, Inc. Lobule of the Lung

Copyright 2010, John Wiley & Sons, Inc. Lobule of the Lung

Copyright 2010, John Wiley & Sons, Inc. Respiration Step: 1. Pulmonary Ventilation Air flows: atmosphere   lungs due to difference in pressure related to lung volume  Lung volume changes due to respiratory muscles Inhalation (AKA inspiration): diaphragm + external intercostals  Diaphragm contracts (moves downward)   lung volume Cohesion between parietal-visceral pleura   lung volume as thorax volume .

Copyright 2010, John Wiley & Sons, Inc. Exhalation Exhalation (expiration) is normally passive process due to muscle relaxation  Diaphragm relaxes and rises   lung volume  External intercostals relax   lung volume Active exhalation: exhale forcefully  Example: playing wind instrument  Uses additional muscles: internal intercostals, abdominal muscles

Copyright 2010, John Wiley & Sons, Inc. Muscles of Inhalation and Exhalation

Copyright 2010, John Wiley & Sons, Inc. Muscles of Inhalation and Exhalation

Copyright 2010, John Wiley & Sons, Inc. Volume-Pressure Changes in Lungs Volume and pressure are inversely related  As  lung volume   alveolar pressure  As  lung volume   alveolar pressure Contraction of diaphragm  lowers diaphragm   lung volume   alveolar pressure so it is < atmospheric pressure  air enters lungs = inhalation Relaxation of diaphragm  raises diaphragm   lung volume   alveolar pressure so it is > atmospheric pressure  air leaves lungs = exhalation

Copyright 2010, John Wiley & Sons, Inc. Volume-Pressure Changes in Lungs

Copyright 2010, John Wiley & Sons, Inc. Air Flow Terms Frequency = breaths/min; normal: 12 Tidal volume (TV) = volume moved in one breath. Normal ~ 500 ml  About 70% of TV reaches alveoli (350 ml)  Only this amount is involved in gas exchange  30% in airways = anatomic dead space Minute ventilation (MV) = f x TV = 6000 mL/min

Copyright 2010, John Wiley & Sons, Inc. Lung Volumes Measured by spirometer  Inspiratory reserve volume (ERV) = volume of air that can be inhaled beyond tidal volume (TV)  Expiratory reserve volume (IRV) = volume of air that can be exhaled beyond TV  Air remaining in lungs after a maximum expiration = residual volume (RV)

Copyright 2010, John Wiley & Sons, Inc. Lung Capacities Inspiratory capacity = TV + IRV Functional residual capacity (FRC) = RV + ERV Vital capacity (VC) = IRV + TV + ERV (typical is 4L at rest) Total lung capacity (TLC) = VC + RV

Copyright 2010, John Wiley & Sons, Inc. Lung Capacities

Copyright 2010, John Wiley & Sons, Inc. Types of Breathing Eupnea - normal breathing Hypernea - increased breathing that is regulated to meet an increased demand for the body for oxygen (ex: during exercise) Dyspnea – difficulty breathing Apnea – temporary cessation of breathing (happens during sleep in some people) Respiratory arrest – failure to resume breathing following a period of apnea

Copyright 2010, John Wiley & Sons, Inc. Reflexes Cough – stimulated by foreign matter in the trachea or bronchi. The epiglottis closes which increases the air pressure in the lungs. This pressure explodes (cough) which opens the epiglottis suddenly forcing the foreign matter upwards. Sneeze – stimulated by foreign matter in the nasal cavity. Burst of air is forced through the nose which forces the contaminant out.

Copyright 2010, John Wiley & Sons, Inc. Reflexes Hiccup – spasmodic contraction of the diaphragm usually at the beginning of the inspiration. Soreness results because the diaphragm is a muscle and when it contracts for a length of time it causes soreness. Certain nerve and brain disorders can cause chronic hiccups. Yawn – slow, deep inspiration. There are many theories, but no confirmed reason for yawning.

Copyright 2010, John Wiley & Sons, Inc. Control of Respiration

Copyright 2010, John Wiley & Sons, Inc. Control of Respiration

Copyright 2010, John Wiley & Sons, Inc. Other Regulatory Factors of Respiration Respiration can be stimulated by  Limbic system: anticipation of activity, emotion  Proprioception as activity is started  Increase of body temperature Sudden pain can  apnea: stop breathing  Prolonged somatic pain can increase rate Inflation reflex  Bronchi wall stretch receptors inhibit inspiration  Prevents overinflation

Copyright 2010, John Wiley & Sons, Inc. Aging and the Respiratory System Lungs lose elasticity/ability to recoil  more rigid; leads to  Decrease in vital capacity  Decreased blood P O2 level  Decreased exercise capacity Decreased macrophage activity and ciliary action   Increased susceptibility to pneumonia, bronchitis and other disorders

Heimlich Maneuver Do not perform if person can talk or cough. Universal sign of choking is hands to neck. Placing arms around the person, make a fist with one hand and place it just below the xyphoid process of the sternum, clasp the other hand on top of the fist and push hands in an upward motion toward the heart. This forces the thoracic cavity to shrink and the lungs to force air out, removing the object. Copyright 2010, John Wiley & Sons, Inc.

Respiratory Acidosis Condition that occurs when breathing slows down, which in turn causes CO2 of the blood to then be dissolved as carbonic acid, which in turn raises the acidity of the blood. This causes the heart to speed up, eventually causing a heart attack. This was the final stage of Christ on the cross following hypovolemic shock. Copyright 2010, John Wiley & Sons, Inc.