- 1.Human Anatomy,Second Edition McKinley & O'Loughlin
Chapter 25 Lecture Outline: Respiratory System 25-
2. Introduction
- Respiratory system is used for gas exchange: oxygen in and
carbon dioxide out
- Works closely with the cardiovascular system
25- 3. General Organization and Functions of the Respiratory
System
- Consists of anupperrespiratory tractand alower respiratory
tract .
- Conducting portion transports air .
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- From the nose to the bronchioles
- Respiratory portion carries out gas exchange .
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- composed of small airways called respiratory bronchioles and
alveolar ducts as well as air sacs called alveoli
25- 4. 5. Respiratory System Functions
- Breathing (pulmonary ventilation).
- Gas exchange,gas conditioning, sound production, olfaction,
regulation of blood pH, and defense.
25- 6. Cystic Fibrosis
- Most common serious genetic disease in Caucasians (1/3200
births - 5% are carriers)
- A missing chloride pump causes sodium and water to move from
the mucus back into the secretory cells, dehydrating the mucus
covering the epithelial surface
- Mucus becomes thick and sticky clogging lungs, and ducts of the
pancreas and salivary glands.
- Pulmonary infections and destruction of pancreas.
- In the skin, the chloride transport protein works in the
opposite direction making skin salty tasting.
- Treatment: break up mucus, replace pancreatic enzymes, etc.
Also insertion of healthy gene.
25- 7. Upper Respiratory Tract
- Composed of the nose and nasal cavity, paranasal sinuses,
pharynx (throat), and associated structures.
- All part of the conducting portion of the respiratory
system.
25- 8. Nose and Nasal Cavity
- Warms air, moistens, traps and moves gunk
- Resonating chamber for speech
- Pseudostratified ciliated columnar epithelium (cilia beat
toward the throat)
25- 9. 10. Paranasal Sinuses
- Four bones of the skull contain paired air spaces called the
paranasal sinuses.
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- decrease skull bone weight
- Named for the bones in which they are housed.
25- 11. 12. Pharynx (12 cm)
- Originates posterior to the nasal and oral cavities and extends
to the bifurcation of the larynx and esophagus.
- Common pathway for both air and food .
25- 13. Pharynx
- Walls are lined by a mucosa and contain skeletal muscles that
areprimarily used for swallowing .
- Flexible lateral walls are distensible in order to force
swallowed food into the esophagus.
25- 14. 15. Nasopharynx
- Posterior to the nasal cavity and superior to the soft palate
.
- Normally, only air passes through .
- Material from the oral cavity and oropharynx is typically
blocked from entering the nasopharynx by the soft palate, which
elevates whenwe swallow.
- In the lateral walls, paired auditory tubesconnect to the
middle ear.
- Posterior wall has a single pharyngeal tonsil (commonly called
the adenoids).
25- 16. Oropharynx
- Posterior to the oral cavity.
- Bounded by the edge of the soft palate superiorly and the hyoid
bone inferiorly.
- Common respiratory and digestive pathway .
- 2 pairs of muscular arches form the entrance from the oral
cavity.
- Lymphatic organs, tonsils, here provide the first line of
defense against ingested or inhaled foreign materials.
25- 17. Laryngopharynx
- Inferior, narrowed region of the pharynx.
- Extends inferiorly from the hyoid bone and is continuous with
the larynx and esophagus.
- Terminates at the superior border of the esophagus and is
equivalent to the inferior border of the cricoid cartilage in the
larynx.
- The larynx (voice box) forms the anterior wall
- Lined with a nonkeratinized stratified squamous epithelium
- Permits passage of both food and air.
25- 18. Lower Respiratory Tract
- Conducting airways(larynx, trachea, bronchi, bronchioles and
their associated structures).
- Respiratory portionof the respiratory system (respiratory
bronchioles, alveolar ducts, and alveoli).
25- 19. Larynx
- Voice boxis a short airway bounded posteriorly by
thelaryngopharynx and inferiorly by the trachea.
- Prevents swallowed materials from entering the lower
respiratory tract.
- Conducts air into the lower respiratory tract.
- Supported by a framework of nine pieces of cartilage thatare
held in place by ligaments and muscles.
- Pseudostratified ciliated columnar epithelium begins below the
vocal cords.
25- 20. Laryngeal Cartilages
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- epiglottis- covers the opening of the larynx when
swallowing
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- thyroid- has prominence called the Adams apple
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- cricoid- base of the others. Airway landmark for a
tracheostomy
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- arytenoid- attachment point for vocal cords
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- corniculate- attachment point for false vocal cords
25- 21. 22. Sound Production
- The inferior vocal ligaments,covered by a mucous membrane,are
called thevocal folds .
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- thetrue vocal cordsproduce sound when air passes between
them
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- attached to arytenoid cartilages
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- the tension, length,and position of the vocal folds determine
the quality of the sound.
- The superior vestibular ligaments, along with the mucosa
covering them, are called thevestibular folds .
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- thefalse vocal cordshave no function in sound production, but
protect the vocal folds.
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- attached to the corniculate cartilages .
25- 23. 24. 25. 26. Laryngitis
- Causes: virus, bacteria, overuse
- Symptoms: hoarse voice, sore throat, maybe fever
- Severe cases may spread to epiglottis
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- May dangerously obstruct airway in a child
25- 27. Trachea (12 cm x 2.5 cm)
- Anterior to the esophagus, inferior to the larynx, and superior
to the primary bronchi of the lungs.
- 15 to 20C-shaped tracheal cartilages.
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- reinforce and provide some rigidity to ensure that the trachea
remains open (patent) at all times
25- 28. 29. Trachea
- At the sternal angle (T5), the trachea bifurcatesinto the right
and left primary bronchi.
- Each primary bronchus projects laterally toward each lung.
- The most inferior tracheal cartilage separates the primary
bronchi at their origin and forms an internal ridge called the
carina.The carina is very sensitive and may initiate a cough
reflexif something lands there.
25- 30. Bronchial Tree
- A highly branched system of air-conducting passages that
originate from the bronchi and progressively branch before
terminating in terminal bronchioles.
- Incomplete rings of hyaline cartilage support the walls of the
primary bronchi to ensure that they remain open.
- Right primary bronchus is shorter, wider, and more vertically
orientedthan the left primary bronchus.
-
- Foreign particles are more likely to lodge in the right primary
bronchus.
25- 31. Bronchial Tree
- Theprimary bronchienter the hilum of each lung together with
the pulmonary vessels, lymphatic vessels, and nerves.
- Each primary bronchus then branches intosecondary bronchi (or
lobar bronchi).
- The left lung has two secondary bronchi since it has two
lobes.
- The right lung has three lobes and three secondary
bronchi.
- They further divide into tertiary bronchi.
- The right lung is supplied by 10 tertiary bronchi, and the left
lung is supplied by 8 to 10 tertiary bronchi.
- Each tertiary bronchus is called a segmental bronchusbecause it
supplies a part of the lung called a bronchopulmonarysegment.
25- 32. Bronchial Tree
- As branching occurs, several structural changes occur
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- Cartilage rings become cartilage plates and then cartilage
disappears
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- Pseudostratified ciliated columnar tissue becomes cuboidalin
the terminal bronchioles (need macrophages then) and finally simple
squamous in the respiratory bronchioles
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- As the cartilage decreases, there is an increase in the smooth
muscle which is affected by the ANS and chemicals such as histamine
and epinephrine
25- 33. 34. Bronchitis
- Causes: viruses, bacteria, chemicals, particulate matter,
cigarette smoke
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- Rapid development after an infection, e.g., a cold
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- Resolves usually in 10-14 days
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- Long-term exposure to irritants
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- Large amounts of mucus with a 3 mo. cough
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- Permanent damage may occur leading to increase chances of
bacterial infections and increased chance of pneumonia
25- 35. 36. 37. Respiratory Bronchioles, Alveolar Ducts, and
Alveoli
- Lungs contain small saccular outpocketings called alveoli.
- An alveolus is about 0.25 to 0.5 mm in diameter.
- Its thin wall is specialized to promote diffusion of gases
between the alveolus and the blood in the pulmonary
capillaries.
- Gas exchange can take place in the respiratory bronchioles and
alveolar ducts as well as in the lungs, which contain approximately
300400 million alveoli (70 m 2 ).
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- Alveoli are the major site for gas exchange.
- The spongy natureof the lung is due to the packing of millions
of alveoli together.
25- 38. Alveolar Cells
- Type 1 alveolar (squamous pulmonary epithelial) cells
- Type 2 alveolar (septal) cells produce surfactant which reduces
surface tension in the lungs preventing collapse of the air
sacs
- Alveolar macrophages or dust cells
25- 39. Hyaline Membrane Disease
- Respiratory distress syndrome
- Often in preemies(less than 7 months) or infants of diabetic
mothers
25- 40. 41. 42. Oxygen Transport
- 1.5% carried dissolved in the plasma
- 98.5% carried by the heme of Hb
- Normally, Hb gives up about 25% of the O 2to the tissues
- In active tissues, Hb gives up more O 2
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- The partial pressure gradient of O 2 ,pH, and temperature
affect the amount of O 2released by the Hb
25- 43. Carbon Monoxide Poisoning
- CO binds to heme 200x more tightly than oxygen .
- Symptoms: cherry pink, nausea, sleepiness
25- 44. Carbon Dioxide Transport
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- 7% dissolved in plasmaas CO 2
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- 23% binds to globinof Hb forming carbaminohemoglobin
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- 70% is converted to H 2 CO 3by carbonic anhydrase which then
quickly dissociates into H +and HCO 3 -(which quickly moves out of
the RBC and is carried in the plasma)
- In the lungs, the reverse occurs
25- 45. Pleura and Pleural Cavities
- The outer surface of each lung is tightly covered by the
visceral pleura, while the internal thoracic walls, the lateral
surfaces of the mediastinum, and the superior surface of the
diaphragm are lined by the parietal pleura.
- The parietal and visceral pleural layers are continuous at the
hilum of each lung.
- Thepleura are serous membranes , simple squamous on top of
connective tissue.
25- 46. Pleura and Pleural Cavities
- The potential space between these serous membrane layers is the
pleural cavity.
- The pleural membranes produce a thin, serous fluid that
circulates in the pleural cavity and acts as a lubricant.
25- 47. 48. Pneumothorax
- Free air in pleural cavityfrom an external injury or internally
(e.g., broken rib)
- Collapsed lung or part of lung results = atelectasis
- Large amount requires a tube for removal
- Dangerous type is tension pneumothorax where hole acts as a
one-way valve
- Fluids may accumulate in pleural cavity
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- Hydrothorax if serous fluid
25- 49. Pleurisy
- May get decreased pleural fluid leading to pain or
- May get increased pleural fluid leading to pressure on the
lungs
25- 50. Gross Anatomy of the Lungs
- Its base rests upon the diaphragm.
- Its apex projects superiorly to a point that is slightly
superior and posterior to the clavicle.
- Both lungs are bordered by the thoracic wall anteriorly,
laterally, and posteriorly, and supported by the rib cage.
- The lungs are separated from each other by the
mediastinum.
- Surface in contact with the thoracic wall is called the costal
surface of the lung.
25- 51. 52. 53. 54. 55. Segmental Resection
- Each segment is anautonomousunit.Therefore, a segment may be
removed if diseased leaving the other segments intact.
25- 56. Pneumonia
- Causes: viruses, bacteria, and sometimes fungi
- Tissue swelling and WBCs accumulate decreasing gas
exchange
- Symptoms: cough, fever, rapid breathing, sputum
- Treatment: antibiotics, respiratory support, and medications
for symptoms and possibly supplemental oxygen
25- 57. Blood Supply To and From the Lungs
- Pulmonary trunkand its branches carry deoxygenated blood
- Bronchial arteriesbring oxygenated blood from the systemic
circuit
- Two blood suppliescommunicateand most of the blood returns to
the heart through the pulmonary veins
25- 58. Lymphatic Drainage
- Lymph nodes and vessels are located within the connective
tissue of the lung as well as around the bronchi and pleura.
25- 59. 60. Pulmonary Ventilation
- Pulmonary ventilation or breathing
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- Exchange between atmosphere and lungs
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- About 500 ml of air exchanged/breath
- Pulmonary or external respiration
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- Exchange between lungs and blood
- Tissue respiration or internal respiration
- (Cellular respiration in mitochondria)
25- 61. Boyles Law
- The pressure of a gas decreases if the volume of the container
increases, and vice versa.
25- 62. Thoracic Wall Dimensional Changes During External
Respiration
- Elevation of the ribs increases the lateral dimensions of the
thoracic cavity, while depression of the ribs decreases the lateral
dimensionsof the thoracic cavity.
- Diaphragm actively moves down with inspiration and passively up
during normal expiration. Most important muscle for breathing.
25- 63. Muscles that Move the Ribs
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- The scalenes help increase thoracic cavity dimensions by
elevating the first and second ribs during forced inhalation.
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- The ribs elevate upon contraction of theexternal intercostals ,
thereby increasing the transverse dimensions of the thoracic cavity
during inhalation.
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- Contraction of theinternal intercostals depresses the ribs, but
this only occurs during forced exhalation .
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- Normal exhalation requires no active muscular effort.
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- A small transversus thoracis extends across the inner surface
of the thoracic cage and attaches to ribs 26. It helps depress the
ribs.
25- 64. Muscles that Move the Ribs
- Two posterior thorax muscles also assist with respiration.
- In addition, some accessory muscles assist with respiratory
activities.
25- 65. 66. 67. Factors InfluencingRespiratory Rate and
Depth
- Volition (conscious control)
- Chemical factors (most important)
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- Concentration of oxygen has little effect usually
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- Concentration of carbon dioxide has the most important
effect
25- 68. Factors InfluencingRespiratory Rate and Depth
- Concentration of carbon dioxide has the most important
effect
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- Increased arterial partial pressure of CO 2
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- Increases partial pressure of CO 2or decreases pH in CSF
stimulatecentral chemoreceptors in the medulla(70% of
response)
-
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- Stimulatesperipheral chemoreceptors in the carotid and aortic
bodiesmediate 30% of response
-
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- Afferent impulses go to medullary respiratory centers
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- Efferent impulses go to respiratory muscles
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- Increased ventilation (more CO 2exhaled)
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- Arterial pCO 2and pH return to normal
25- 69. Innervation of the Respiratory System
- The trachea, bronchial tree, and lungs are innervated by the
autonomic nervous system.
- The autonomic nerve fibers that innervatethe heart also send
branches to the respiratory structures.
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- Sympathetic innervation mainly causes bronchodilation
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- Parasympathetic innervation mainly causes
bronchoconstriction
- The involuntary, rhythmic activities that deliver and remove
respiratory gases are regulated in the brainstem.
25- 70. Ventilation Control by Respiratory Centers of the
Brain
- Regulatory respiratory centers are located within the reticular
formation through both the medulla oblongata and pons.
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- Medulla sets mainly the rate (basic rhythm)
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- Dorsal group is the inspiratory center
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- Ventral group is the expiratory center for forced
expiration
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- Apneustic center gives inspiratory drive
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- Pneumotaxic center inhibits apneustic center and limits the
length of inspiration and promotes expiration
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- Phrenic nerve serves the diaphragm
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- Intercostal nerves serve the external intercostals
25- 71. 72. Aging and the Respiratory System
- Less efficient with age due to structural changes.
- Decrease in elastic connective tissue in the lungs and the
thoracic cavity wall.
- Loss of elasticity reduces the amount of gas that can be
exchanged with each breath and results in a decrease in the
ventilation rate.
- Vital capacity of lung decreases by 35% by age 70.
- Emphysema may cause a loss of alveoli or their
functionality
- Reduced capacity for gas exchange can cause an older person to
become short of breath upon exertion.
- Carbon, dust, and pollution material gradually accumulate in
our lymph nodes and lungs (less macrophages and ciliary
function)
- Cardiovascular and respiratory systems affect each other.
- Increase in pulmonary disorders.
25- 73. Factors Influencing Gas Exchange
- Thickness of respiratory membrane
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- Ex., edema increases thickness
- Surface area of the respiratory membrane
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- Ex., emphysema and cancer decrease S.A.
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- Ex., less partial pressure at high altitude
25- 74. Chronic Obstructive Pulmonary Disease (COPD)
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- Smoking, difficult breathing, coughing and infections common,
most hypoxic, retain carbon dioxide so acidosis.
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- Disability and ultimately develop respiratory failure
(death)
25- 75. Chronic Obstructive Pulmonary Disease (COPD)
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- Alveoli enlarge.Inflammation leads to fibrosis and airways lose
elasticity.
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- Hard to exhale and leads to exhaustion
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- Overinflation leads to a barrel chest
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- Air retained - > pink puffers(cyanosis late)
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- Inflammation of mucosa of lower respiratory passages ->
increased mucus -> impaired ventilation and gas exchange->
increased risk of lung infection (e.g., pneumonia)
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- Hypoxia and carbon dioxide retention early in disease and
cyanosis is common ->blue bloaters
25- 76. Asthma
- A chronic condition characterized by episodes of
bronchoconstriction and wheezing, coughing, shortness of breath and
excess pulmonary mucus.
- Usually a sensitivity to an airborne agent.Upon reexposure, a
localized immune reaction occurs in the bronchi and
bronchioles.
- Usually lasts an hour or two.
- Eventually, the walls may become permanently thickened. Severe
attacks may be fatal.
- Treatment: inhaled steroids and bronchodilators.Important to
avoid triggering agent.Allergy shots may help some.
25- 77. Smoking and Lung Cancer
- Smoking increases the risk and severity of atherosclerosis and
is directly related to the development of cancers of the lung,
esophagus, stomach, and urinary bladder.Smoking also increases
wrinkling and impotency.
25- 78. Smoking and Lung Cancer
- Lung cancer: smoking causes 85%.
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- Paralyzes cilia and decreases macrophage activity
- Highly aggressive and frequently fatal .
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- 1/3 cancer deaths in U.S, 7% 5 year cure rate.
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- Detection is late and it spreads fast. Average 9 month survival
after diagnosis.
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- Resection is best if not too late
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- Chemotherapy and radiation may be the only options
25- 79. Lung Cancer
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- Squamous cell carcinoma most common type from transformed
epithelial cells.
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- Adenocarcinoma from mucin-producing glands.
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- Small-cell (oat-cell) carcinoma arises from the primary bronchi
and eventually invades the mediastinum. From neuroendocrine cells
and may produce hormones.Aggressive and early metastasis.
25- 80. Sudden Infant Death Syndrome (SIDS)
- Sudden and unexplained death of an infant younger than 1
year(usually 2-4 months old and 60% male)
- SIDS babies have trouble regulating and maintaining B.P.,
breathing and body temperature. Stress plus one or more of these
three factors appears to be involved.
- Back-to-sleep campaign has reduced incidence.
25- 81. Respiratory Changes at Birth
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- Powerful contractions of diaphragm and external intercostal
muscles cause inhalation
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- Rib cage expands and never returns to its former shape
(important forensically).We never completely empty our lungs after
birth.
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- More breaths increase inflation and surfactant helps prevent
collapse.
25-