Term
| what is the function of the respiratory system? |
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Definition
Function: obtain O2 /eliminate CO2
Two separate, related processes
Internal (cellular) respiration
Metabolism within mitochondria, O2 /CO2, with nutrient use
Respiratory quotient (RQ = CO2/O2)
External respiration (exchange of O2/CO2) at lungs, tissues (4 steps)
Ventilation – movement of air in/out lungs
O2 and CO2 exchange between air/blood at pulmonary capillaries
Blood transports O2/CO2 between lungs and tissues
O2/CO2 exchange between tissues/blood at systemic capillaries |
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Term
| what are some non-respiratory functions of the nervous system? |
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Definition
Route for water loss and heat elimination
Enhances venous return
Helps maintain normal acid-base balance
Enables speech, singing, and other vocalizations
Defends against inhaled foreign matter
Removes, modifies, activates, or inactivates various materials passing through the pulmonary circulation
Nose - organ of smell |
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Term
| what are the conducting zones and respiratory zones? |
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Definition
Conducting zone
Nasal passages (nose)
Pharynx (common passage)
Trachea (windpipe)
Larynx (voice box)
Right and left bronchi
Bronchioles
Respiratory zone
Air sacs at end of terminals exchange gases b/t air & blood; Lung acinus/alveoli
Alveoli (air sacs at ends of terminal bronchioles |
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Term
| wwhat are some differences between trachea/large bronchi vs bronchioles? |
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Definition
Trachea and larger bronchi
Fairly rigid, nonmuscular tubes
Rings of cartilage prevent collapse
Bronchioles
No cartilage to hold them open
Walls contain smooth muscle innervated by autonomic nervous system
Sensitive to certain hormones and local chemicals |
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Term
| what are some properties of alveoli? |
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Definition
Thin-walled inflatable sacs
Function in gas exchange
Walls consist of a single layer of flattened Type I alveolar cells
Pulmonary capillaries encircle each alveolus
Type II alveolar cells secrete pulmonary surfactant
Alveolar macrophages guard lumen |
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Term
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Definition
Double-walled, closed sac, separates lungs from thoracic wall
Pleural cavity – interior plural sac
Intrapleural fluid
Secreted by surfaces of pleura
Lubricates pleural surfaces |
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Term
| repiratory mechanics generally has 3 factors. what are they? |
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Definition
Atmospheric pressure (Patm)
Intra-alveolar pressure (Palv)
Intrapleural pressure |
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Term
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Definition
| Collapse of inflated lung - dyspnea, chest pain, loss of consciousness, cyanosis |
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Term
| what is resorption atelectasis? |
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Definition
Resorption
obstructing conducting airway (e.g. mucus plugs, foreign bodies)
Air in distal parenchyma slowly resorbed |
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Term
| what is compression atelectasis? |
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Definition
Compression
Compression of parenchyma by a solid, liquid, or gas within the pleural space
Pneumothorax/Hemothorax |
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Term
| what is contraction (fibrosis) atelectasis? |
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Definition
Contraction (fibrosis)
Limits expansion (focal or diffuse)
Initial causes: radiation, infection, toxic injury, or systemic disease – not reversible |
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Term
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Definition
| pressure exerted by a gas varies inversely with the volume of a gas. P ~ 1/V |
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Term
| why is the intrapleural pressure always negative? |
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Definition
| its like a vaccuum always keeping the lungs open. without this, they would collapse. |
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Term
| what are some secondary inspiratory muscles? |
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Definition
| external intercostals, sternocleidomastoid, scalenes. |
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Term
| what are some qualities of expiration? |
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Definition
Normal Expiration
Relaxation of inspiratory muscles
Passive recoil
Elastic tissue around entire lung – rebound forces
Alveolar surface tension -contractive tendency of liquid surface
Surfactant lines alveoli
reduces surface tension/recoil, maintains lung stability
Damage to elastic layers (emphysema) = forced expiration
Forced expiration
Abdominal wall muscles
Internal intercostal muscles |
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Term
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Definition
Flow = Pressure/Resistance
Pressures – lung inflation/deflation
Resistance – airway diameter (radius)
ANS = bronchoconstriction or bronchodilation
Local control: CO2 in alveoli, decreases resistance
O2 in alveoli, increase pulmonary vasdilation
Altered with specific diseases (“obstructive”) |
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Term
Working of breathing (3-5% of total energy expenditure)
Lungs normally operate “half full”, increases w/exercise
Increased with increased resistance, decreased recoil
Decreased pulmonary compliance (effort to stretch/distend lungs) - restrictive lung diseases - increase work of breathing. |
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Definition
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Term
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Definition
| normal breathing volume of air in one breath. (~500 ml) |
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Term
| what is inspiratory capacity? |
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Definition
| as much as you can inspire in one breath starts at bottom of tidal volume. (~3500ml) (IRV + TV) |
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Term
| what is expiratory reserve? |
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Definition
| starting at the bottom of tidal volume, you then expire as much as as you possibly can. |
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Term
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Definition
| Minimum volume of air remaining in the lungs even after a maximal expiration |
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Term
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Definition
| Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV) |
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Term
| what is forced expiratory volume in one second? |
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Definition
| Volume of air that can be expired during the first second of expiration in a VC determination |
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Term
| what happens in the conducting (nonalveaolar) zone when you inhale? |
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Definition
the air is warmed (V~T, so volume increase). the air is humidified (takes up a % of partial pressure)
It is filtered by pseudostratified ciliiated lining. goblet cell secrete mucous. |
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Term
| how is pulmonary vs alveolar ventilation different? |
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Definition
minute ventilation = VE; ml/min)= tidal volume (TV; ml/breath) x respiratory rate (RR; breathes/min). usually 6L-8L per minute.
Alveolar ventilation = VA. VA is always less than VE. Volume of air exchanged between atm and alveloi per minute
VA< VE - anatomic dead space (Vd-air in conducting zone)
150 ml in adults
VA = (TV – dead space) x RR |
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Term
| what are the partial pressure gradients for O2 and CO2 |
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Definition
total pressure x % gas
760 mmg x 21% O2
760 mmHg x 0.03% CO2 |
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Term
| what are some additional factors affecting gas exchange? |
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Definition
surface area
barrier thickness
diffusivity |
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Term
if PO2 = 160 mmHg
PCO2 = 0.3 mmHg in the atmosphere, then
why does PO2 at alveoli = 100 mmHg, PCO2 = 40 mmHg? |
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Definition
| you are mixing atm air with your dead space air, and water vapor takes up some of the partial pressure |
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Term
Partial pressure in alveolar capillaries
PO2 = 40 mmHg, PCO2 = 45 mmHg
Diffusion allows rapid equilibration |
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Definition
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Term
| how does exercise affect our gas exchange? |
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Definition
| the blood is moving so fast through the lungs, it doesnt have enough time for the gases to exchange, so that can be a limiting factor. |
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Term
| how does gas exchange work AT the tissues/capillaries? |
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Definition
Blood arriving at tissues
PO2 = 100 mmHg,
PCO2 = 40 mmHg
Partial pressure in systemic tissues
PO2 = 40 mmHg, PCO2 = 45 mmHg
Concentrations altered depending on local tissue metabolism
Diffusion allows rapid equilibration |
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Term
| can you explain what is happening in the oxygen-hemoglobin dissociation curve? |
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Definition
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Term
| what things shift the O2-hemoglobin curve to the right (unloading)? |
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Definition
Increased temp
Increased 2-3 DPG
Increased H+
(at the tissues/exercise) |
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Term
| what things shift the O2-hemoglobin curve to the left (loading lungs) |
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Definition
Decreased temp
Decreased 2-3 DPG
Decreased H+
(lungs rest loading, shifts it LEFT and UP) |
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Term
| how is carbon dioxide carried in the body? |
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Definition
60% CO2 dissolved
CO2 + H20 = H2CO3 = H + + HCO3-
Facilitated by carbonic anhydrase
H+ favored at systemic level, CO2 favored at lungs
Chlroide shift – Cl- and HCO3- shift in/out of cells
30% CO2 bound to hemoglobin in the blood (globin) – carboamino Hb
10% CO2 dissolved in plasma |
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Term
| what are some abnormalities in arterial oxygen or CO2 concentration? |
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Definition
Hypoxia - insufficient O2 at the cell level
Hypoxic hypoxia - not enough air in lungs
Anemic hypoxia
Circulatory hypoxia- not enough blood flow to tissue
Hyperoxia - above-normal arterial PO2
Can only occur when breathing supplemental O2. Can be dangerous (free radicals)
Hypercapnia - excess CO2 in arterial blood (hypoventilation)
Hypocapnia - lower arterial PCO2 levels (hyperventilation via anxiety, fever, aspirin poisoning) |
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Term
| what centers in the brain control respiration? |
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Definition
Medullary respiratory center
Dorsal respiratory group (DRG) - Mostly inspiratory neurons
Ventral respiratory group (VRG) – Inspiratory and expiratory |
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Term
| what part of the brain generates respiratory rhythm? |
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Definition
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Term
| what reflex prevents lung overinflation? |
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Definition
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Term
| what is the pneumotaxic center? |
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Definition
Sends impulses to DRG, “switch off” inspiratory neurons
Dominates over apneustic center
Prevents inspiratory neurons from being switched off
Provides boost to inspiratory drive
damage to this pneumotaxic center would give you ....? |
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Term
| decreased PO2 - sensed by chemoreceptors in carotid bodies and aortic bodies. These are only active when your PO2 is below 60 mmHg - increases tidal volumes, however centrally hypoxia will depress the respiratory center (very dangerous levels) |
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Definition
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Term
| what happens when you have hypercapnia peripherally? centrally? |
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Definition
peripherally - weak effects
centrally - dissociates to H+ - strong stimulation, increased breathing RATE. |
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Term
| what happens when you have acidosis peripherally vs centrally? |
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Definition
Peripheral – strong stimulation, important in acid-base balance
Central – cannot directly bass BBB, CO2 has main effect |
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Term
Reflexes originating from body movement
passive or active movement
Integration/collateral signaling from ascending fibers to respiratory centers.
increases breathing rate. |
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Definition
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Term
| what happens to ventilation with an increase in body temperature? |
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Definition
Indirect - increased metabolism influences VE
Direct – direct effects on CNS, respiratory centers |
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Term
| epinephrine release has what affect on ventilation? |
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Definition
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Term
| how do commands from the cerebral cortex affect ventilation? |
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Definition
Voluntary – control to primary/accessary resp muscles
Automatic – increased VE with exercise |
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Term
| what are some factors that influence ventilation that are unrelated to the need for gas exchange? |
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Definition
Protective reflexes - sneezing and coughing
Inhalation of noxious agents - trigger immediate cessation of breathing
Pain anywhere in body - reflexively stimulates respiratory center
Involuntary modification of breathing occurs during expression of various emotional states
Respiratory center is reflexively inhibited during swallowing |
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Term
| what is the difference between a respiratory obstructive vs restrictive diseases. |
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Definition
Obstructive - narrowing of respiratory passage ways
blockage by secretions (normal defenses)
increased resistance = increased energy for single breath
Impaired FEV1 (maximal airflow rate)
Restrictive inability to expand thoracic cavity/lungs
scarring, fibrotic changes; orthopedic or neuromuscular issues
no change in resistance, but need increased rate of breathing
Impaired VC
(ALS, MS, Stroke, broken rib, scoliosis) |
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Term
| how would a "breathing graph" change for restrictive vs obstuctive lung disease? |
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Definition
Vital Capacity (VC) – reduced in restrictive diseases
pleurisy
neuromuscular, musculoskeletal diseases
fibrosis/interstitial diseases
FEV1 –Forced Expiratory Volume and Forced Vital Capacity (FEV1/FVC)- reduced in obstructive disease
Asthma
Bronchitis /COPD |
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Term
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Definition
| inflammation of the pleura |
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Term
| What is the major symptoms of COPD? |
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Definition
dyspnea with chronic or recurrent obstruction to airflow within the lung.
incidence increased dramatically in past few decades |
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Term
| what is the pathophysiology of Bronchitis? |
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Definition
Incidence: cigarette smokers/urban dwellers, 40-65 yrs
Dx on clinical presentation.
Persistent productive cough > 3 consecutive months in > 2 consecutive years.
Forms:
Simple chronic - productive cough, minimal obstruction
Chronic asthmatic - hypersensitivity
Chronic obstructive bronchitis (smokers – w/emphysema)
Pathogenesis – Mucus-hypersecretion
Morphology
enlargement mucus-secreting glands
increased number of goblet cells
loss of ciliated epithelial cells, squamous metaplasia,
dysplastic changes and bronchogenic carcinoma.
Inflammation, fibrosis and narrowing of bronchioles
acute – viral origin? |
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Term
| what is the pathophysiology of emphysema? |
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Definition
destruction, enlargement of alveolar tissue
collapse of smaller airways
breakdown of walls
destructive enzyme release with irritants
macrophage responses
overwhelming protective mechanisms (alpha-1-anti-trypsin ; elastases)
Genetic predisposition for those with alpha-1-anti-trypsin deficiency
bronchiolar inflammation
so less passive recoil of the lungs.
permanent enlargement of the airspaces distal to the terminal bronchioles
destruction of their walls, without obvious fibrosis.
Over inflation |
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Term
| what are the 4 types of emphysema? |
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Definition
Types
1. Centriacinar (20x)
2. Panacinar
3. Distal acinar
4. Irregular |
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Term
| Centriacinar (centrilobular) emphysema |
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Definition
Incidence: potentially large % population on autopsy (50%?); pulmonary disease resp for ~7%
Centriainar
central, proximal acini affected, distal alveoli are spared
heavy smoker in association with chronic bronchitis |
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Term
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Definition
Occurs in 1-anti-trypsin deficiency.
Acini uniformly enlarged from respiratory bronchioles to terminal alveoli (lower lung zones) |
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Term
| what are some differences in people with pure chronic bronchitis vs pure emphysema? |
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Definition
pure bronchitis: large airways - mucus hypersecretion, inflammation. small airways - peribronchioloar fibrosis, airway obstruction.
pure emphysema: acinus (refers to any cluster of cells that resembles a many-lobed "berry")(respiratory bronchiole alveolar ducts, and alveoli) loss of esastic recoil |
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Term
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Definition
people with sever emphysema with less bronchitis. Oxygenated, “pink face and pursed lips”
Barrel-chested
Dyspnea – particularly during expiration
Cough/wheezing, weight loss
Death – respiratory acidosis, hypoxia, coma, R-sided cardiac failure |
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Term
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Definition
people with sever bronchitis with less emphysema. De-oxygenated
Barrel-chested
Typically obese
Increase sputum |
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Term
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Definition
Chronic relapsing inflammation
hyperactive airways - episodic, reversible bronchoconstriction
increased responsiveness of the tracheobronchial tree to various stimuli |
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Term
| what is the difference between extrinsic vs intrinsic asthma? |
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Definition
Extrinsic asthma – type 1 hypersensitivity reaction
Intrinsic asthma – diverse, non-immune mechanisms (exercise/stress, cold, inhaled irritant) |
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Term
| what is the respiratory pathophysiology of extrinsic asthma? |
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Definition
Atopic (allergic) asthma - most common form, begins in childhood (other allergic signs – urticaria, rhinitis)
Skin test with antigen - immediate “wheal and flare” reaction (like + TB sign)
Serum IgE, eosinophil recruitment, later TH cells
IgE-mediated reaction elicits acute (minutes) and late phase reaction (4-8 hours)
acute response (30-60 min)
Mast cells activated on mucusol surface
Mediators (leukotrienes, prostaglandins, histamine)
Bronchospasm
Increased vascular permability/dilation
Increased mucus production
late phase reaction (~4-8 hours)
Mast cell initiated – cytokine, chemotactic factor release
Eosinophil/TH cell recruited, Also B cells, macrophages
Greater epithelial damage without additional antigen |
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Term
| what is the pathogenesis of instrinsic asthma? |
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Definition
Non-atopic asthma- upper respiratory infection; hyper-reactivity in vagal receptors to irritants
Drug induced asthma- aspirin most documented; associated with recurrent rhinitis and nasal polyps
Occupational asthma- induced by chemical fumes, dust, solvents, and gases
Exercise or cold-induced asthma –
cold or un-warmed air (mouth-breathing) may cause bronchoconstriction and/or vasodilation/edema to compress bronchioles
other possible causes (alveolar hypercapnia, low humidity/dehydrated airways) |
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Term
| common presentation of asthma? |
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Definition
Clinical presentation
wheezing,
difficulty breathing (shortness of breath)
chronic cough
Pathological findings
Lung over-distended
Occlusion of bronchi/bronchioles with thick mucus
Bronchiolar hypertrophy
Increased mucus glands |
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Term
| What is the pathophysiology of bronchiectasis? |
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Definition
Chronic necrotizing bronchi/bronchiolar infection - Abnormal airway dilation
Bronchial obstruction
Localized - tumor, foreign bodies, mucous
Generalized (asthma or bronchitis)
Changes irreversible or obstruction persists/added infection
Congenital/hereditary conditions:
Congenital - e.g. Cystic fibrosis
Immunodeficiency status (lupus, RA)
Necrotizing pneumonia - TB, staphylococci mixed infection |
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Term
| what is the pathophysiology of cystic fibrosis? |
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Definition
abnormality in single Cl- channel (Cl- not secreted in mucus)
decreased watery secretions
impaired ciliary escalator
accumulation of concentrated, viscous secretions
airway obstruction → secondary infections
damaging to liver, pancreas, salivary glands |
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