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35 Cards in this Set
- Front
- Back
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Pulmonary tree of lower respiratory tract
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Trachea-high velocity, small x-section
-divides into R/L primary bronchi & continues to divide into smaller & smaller divisions (generations) *23 generations |
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R/L primary bronchi
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-bifurcation @ sternal angle (carina)
-enters the hilum (roots of the lungs, blood vessels, lymph vessels & nerves accompany) |
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Divisions of the bronchi:
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1-lobar bronchi (3 on R, 2 on L)
2-segmental bronchi (10): "surgical lobes" 3-eventually divide until they terminate & become respiratory bronchioles |
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Acinus
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where the tracheal tree terminates, region of gas exchange
composed of 3 structures: 1-respiratory bronchiole 2-alveolar ducts 3-alveoli |
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Functions of the Pulmonary System
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1-respiration vis ventilation (gas exchange)
2-phonation-production of sounds by movement of air thru vocal cords 3-acid-base balance-regulation/compensation by removing CO2 from blood stream 4-pulmonary defense mechanism-air conditioning & olfaction |
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Metabolic function of the Pulmonary System
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*homeostasis
-many vasoactive substances are removed or inactivated by the lungs Ex: -prostaglandins E & F removed -leukotrienes -seratonin (85-95% removed) -norepinephrine (30%) [NOT epinephrine] -bradykinin (80% inactivated) -angiotensin I (produce ACE to convert angiotensin I to II) -ATP & AMP (40-90% removed) |
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Filtration & Removal of Particles/Microorganisms
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inhaled particles/microorganisms are "blocked" from reaching the distal end of the tracheal tree
2 mechanisms of defense: 1-particles trapped in mucous cheath lining the tubules 2-particles removed by ciliary action & reflex mechanisms |
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Mucociliary Escalator
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*ciliary action
-lining of respiratory tract produces mucous -mucous is propelled away from the alveoli via cilia -particels become trapped in the mucus & transported up to the pharynx (coughing) -removed via swallowing or blowing nose |
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Irritant receptors
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*reflexes in the airway that produce sneezing & coughing
sneeze-receptors in nasopharynx cough-receptors in trachea |
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2 regions of the airway
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1-conducting zone
2-respiratory zone |
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Conducting Zone (airway)
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Location: URT to terminal bronchioles, NO alveoli found in conducting zone, first 16 generations of tracheal tree
Function: provide passage for air into & out of gas-exchange area of lung, NO gas exchange Air flow: fast thru trachea, progressively slower as air travels down divisions of tracheal tree *anatomical dead space-air that never reaches the respiratory zone Defense: mucociliary escalator & reflexes |
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Respiratory Zone (airway)
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*transitional/respiratory sections
Location: respiratory bronchioles to alveolar sacs -alveoli found starting @ 17-19 generations -completely line 20-22 generations -sac represents 23rd generation |
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Respiratory bronchioles
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1st site of gas exchange
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Alveolar ducts
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portion that is surrounded by grape-like cluster of the alveoli
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Alveolar sacs
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clusters of individual alveoli (grape-like)
Pores of Kohn - allow adjacent alveoli to exchnage air btwn each other |
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Alveoli
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*adults have approx. 300 million, primary gas exchange
Structure: alveolar septa - 2 layers: 1-Epithelial layer consists of 2 cell types type I alveolar cells (provide physical sturcture) type II alveolar cells (produce surfactant) 2-basement layer: thin elastic layer which allows gas exchange Defense: alveolar phagocytes/macrophages -ingest & remove foreign particles/bacteria -removed thru lymphatics in terminal bronchioles (migrate up to terminals) -NO cough reflex this deep |
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Wall & Lining of Airway
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Trachea:
anterior/lateral - C shaped cartilage posterior - smooth muscle Larger to smaller bronchi: cartilage continues to surround but progressively diminishs into distal airways Bronchioles: cartilage disappears @ this point in the tracheal tree Tracheal tree: inner layer - epithelial lining middle layer - smooth muscle layer outer layer - connective tissue |
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Epithelial lining of tracheal tree
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-entire tract lined by mucus producing cells & ciliated cells
EXCEPT: respirtaory bronchiole anterior 1/3 of nose portions of pharynx Composed of: ciliated cells mucus producing/secreting cells mucus glands |
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Ciliated cells
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"beat" constantly (600-900 betas/min) to produce "waves" to provide physical movement for mucociliary elevator
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Mucus producing/secreting cells
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single exocrine cells distributed btwn the numerous ciliated cells (secrete "outside" body)
2 types: Goblet cells: located proximal to bronchioles Clara cells: located in the terminal bronchioles |
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Mucus glands
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located througout respiratory tract & also produce/secrete mucus
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Clinical pathological conditions of mucus producing/secreting cells
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Chronic bronchitis - hypertrophy of mucus producing cells produce too much mucus & obstruct airway
Intubation - continue to produce mucus but removal mechanisms are impaired Cystic fibrosis - genetic disease of many organs causing excessive mucous, sweat & digestive juice production *mucus accumulation in lungs promotes infection |
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Pulmonary circulation
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"un-oxygenated" blood flow from R ventricle travels to pulmonary capillaries for gas exchange
Function: -faciliates gas exchnage -acts as a reservoir for L ventricle -acts as a filter system to remove particles/emboli |
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Bronchial circulation
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"oxygenated" blood flow from L ventricle supplies structures of pulmonary system
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Pressure & flow dynamics of pulmonary circulation
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LOW PRESSURE system (10-20 mmHg) but same stroke volume as L side of heart
-only 1/3 pulmonary blood vessels filled (perfused) @ any moment which accomodates increased stroke vol w/o increasing pressures |
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Pulmonary capillaries
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-surround each alveolar sac
-density of capillaries allows a lot of blood to be exposed to gas in the alveoli |
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Alveolocapillary membrane
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alveolar & capillary walls "merge together" to form gas exchange membrane
Composed of: 1-alveolar epithelium & basement membrane 2-intersitial space 3-capillary basement membrane & epithelium Damage: plasma/blood can leak into alveolar space, impair gas exchange |
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Ratio of blood to surface area in the alveolocapillary membrane
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100ml of blood in the capillaries is spread across 70-100 m sq of alveolocapillary membrane
(1/10 can of soda spread over 10mx10m=Great SA!) |
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Hypoxic Vasoconstriction
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*unique to lungs
if damage to partial pressure of O2 drops, arterioles direct blood AWAY from the site |
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Bronchial circulation
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DOES NOT participate in gas exchange, part of systemic circulation where bronchial arteries supply the structure of the lungs
Function: 1- supply nutrients to the structures of the lungs 2- some bronchial veins create functional "right to left" shunt of blood flow: -bronchial capillaries (deoxygenated) drain into pulmonary veins (oxygenated) -unoxygenated blood passes into oxygenated circulation |
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Lymphatic drainage
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lymphatic capillaries drain all structures of the lungs EXCEPT acinus
-located throughout tracheal tree to the terminal bronchioles *No lymphatics at site of gas exchange! -accumulated fluid in the alveoli & alveolar macrophages migrate up to the terminal bronchioles & drain into lymphatics system @ level of terminal bronchioles |
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Chest wall
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ribs & intercostal musculature
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Pleura
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"double folded" serous membrane
visceral pleura (lines the lungs) parietal pleura (lines the chest wall) |
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Pleural Cavity (pleural space)
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potential space created btwn the visceral & parietal layers
pleural fluid: thin layer secreted by the pleura, provides lubricant to create "frictionless" movement btwn visceral pleura & parietal pleura Pressure: low (negative): -4 to -10 mmHg allows lungs to expand & "suck-in" outside air |
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Pheumothorax
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an abnormal collection of air or gas in the pleural space that separates the lung from the chest wall and may interfere with normal breathing
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