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45 Cards in this Set
- Front
- Back
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Pleural Pressure
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Always negative due to elastic properties. Chest wall always wants to go out & lungs want to collapse in.
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Alveolar Pressure
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Can be negative or positive compared to pressure outside
If - air moves in If + air moves out |
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Pneumothorax
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Hole in the chest wall, air in the pleural space
Lungs will collapse and chest goes out |
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Mechanism of normal inspiraton
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Contract diaphragm-->pulls down, increased volume of chest cavity, decrease in pressure
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Mechanism of increased inspiration
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Contract external intercostal muscles -->pulls the chest wall up & out
Contract accessory muscles in neck Increased volume, decrease in pressure-->Air moves IN |
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Mechanism of normal expiration
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Passive
Diaphragm relaxes and moves back up -->decrease in volume, increase in pressure |
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Mechanism of increased expiration
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Contract internal intercostal muscles -->pulls the chest wall down & in
Decrease in volume and increase in pressure --Air moves IN |
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Amount of air moved during each breath
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~0.5L
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Vital Capacity
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Total amount of air that canbe moved
Typically ~ 5L |
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Total Lunch Capacity
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Vital + Residual = 6L
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Asthma
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Airway Constriction
Primarily an obstructive disorder |
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Obstructive Disorders
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Emphysema, Asthma
FVC=3L RV=3L Can't get air out due to loss of alveoli and elastic recoil |
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Restrictive Disorders
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Edema
FVC=3L RV=1L Can't get air in |
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Anatomic Dead Space
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Air in the conducting zone (no gas xchange)
~150ml |
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Total Ventilation
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amount of air moved/minute
=tidal volume x frequency of breathing ~6L/min |
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Alveolar Ventilation
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amount of air moved that is involved in gas exchange/minute
=(tidal volume - anatomic dead space) x frequency of breathing ~4.2L/min |
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Deep and Slow v. Rapid and Shallow
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Deep & Slow breaths are much more efficient
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Airway Resistance
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R=1/r^4
Increase radius-->drastic decrease in resistance The greatest R is @ the bronchi The most important R is @ the bronchioles due to the amount of smooth muscle |
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Parasympathetic NS control of airway resistance
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Para releases Ach-->muscarinic receptors-->airway constriction
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Sympathetic NS control of airway resistance
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Sympathetic releases NE/Epi-->B2 receptors -->airway dilation
Tx of Asthma: B2 agonist |
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Compliance
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How easy it is to inflate the lungs
C=V/P |
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Increased compliance
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Large change in volume for a change in pressure
Ex. Emphysema: easy to inflate lungs but hard to get it out |
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Decreased compliance
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Small change in volume for a change in pressure
Ex. Restrictive disorders: hard to inflate lungs |
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Surfactant
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Causes a decrease in surface tension by getting b/t water molecules and decreasing surface tension which prevents alveoli from collapsing
Secreted by Type II alveolar cells |
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Perfusion limited Diffusion
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diffusing capacity is limited by blood flow
Must increase blood flow to get more O2 in blood |
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Diffusion Limited
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Diffusing capacity is limited by rate of diffusion
Need to increase rate of diffusion to get more O2 into the blood *If you double the rate of diffusion for O2 you DON'T increase transfer of O2 because its limited by hemoglobin |
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Pulmonary circulation problem with Left Congestive Heart failure
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Failure of left ventricle
Blood backs up into pulmonary circulation Increase in pulmonary capillary pressure -->filtration Pulmonary edema -->poor gas exchange -->DEATH! |
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3 Benefits of Recruitment/Distension of capillaries
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Decrease in resistance-->decrease in pressure-->no edema
Decreased velocity of blood flow-->increase in gas exchange Increased surface area for gas exchange |
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Effect of autonomic nervous system on regulation of pulmonary vascular resistance
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Not an important regulator
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Hypoxia
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Low Oxygen levels
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Effect of hypoxia on surround vessels
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Low O2 in blood-->vasoconstriction
Low CO2 in blood-->airway constriction |
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Affintity of Oxygen binding to hemoglobin
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As O2 binds to Hb, it increases the affininity of Hb for more O2
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O2-Hb Curve
Shift Left |
In the lungs
More O2 binds to Hb Causes: Decreased CO2, Decreased H+, Decreased temperature, Decreased DPG |
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O2-Hb Curve
Shift Right |
More O2 leaves Hb
Causes: Increased CO2, Increased H+, Increased temperature, Increased DPG |
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Bohr Effect
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If shift is caused by increased CO2 or Increased H+
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Causes of Hypoxia
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Diffusion Impairment (ie. Pulmonary Edema)
Decreased atmospheric Po2 (ie. High Altitude) Both Result in Decreased P02 in arterial blood-->Chemoreceptors will detect this and stimulate breathing Anemia: Less Hb, less O2 bound to Hb CO Poisoning: CO binds to Hb with very high affinity and O2 can't bind to Hb. The same amount of O2 is dissolved in the blood-->normal PO2 so therefore NOT detected by chemoreceptors-->DEATH! |
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Transport of CO2
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Dissolved in plasma (10%)
Bound to proteins, mainly Hb (30%) Bicarbonate ions (60%) |
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Haldane Effect
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Occurs in the lungs
When O2 binds to Hb, less CO2 will bind to Hb |
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Peripheral Chemoreceptors
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Detect changes required for respiratory adjustments
Detect increased CO2 and H+ and decreased O2 |
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Inhibitors of Inspiration
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Pulmonary stretch receptors
Other brain centers |
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Stimulators of Inspiration
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Chemoreceptors
Pulmonary Irritant Receptors |
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Central Chemoreceptors
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Stimulated by increased PCo2 and increased H+ in CSF
NOT STIMULATED by decreased P02 or increased H+ in blood |
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Pulmonary Receptors
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Slowly adapting receptors (Pulmonary stretch receptors)
Found in lungs in the smooth muscle of the bronchioles |
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Hering-Breur Reflex
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Stops inspiration when the lungs are being overinflated, a protective reflex
(NOT involved in stopping normal inspiration) |
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Pulmonary Irritant Receptors
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Respond to Irritants
Produces complex effects like cough and a general stimulus to inspire |
