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Copyright 2010, John Wiley & Sons, Inc.
Chapter 18
The Respiratory System
Copyright 2010, John Wiley & Sons, Inc.
Respiration: Three Major Steps1. 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.
Copyright 2010, John Wiley & Sons, Inc.
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 PO2 level Decreased exercise capacity
Decreased macrophage activity and ciliary action Increased susceptibility to pneumonia, bronchitis
and other disorders
Copyright 2010, John Wiley & Sons, Inc.
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.