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Flashcards in (12) Mechanics of Breathing Deck (14):

(Exhalation - Exceptions to Elastic Recoil)

There are 2 general examples - what are they?

Then 3 in different species.... what are they?

1) exercise - active phase with exertion

2) disease - active phase with disease


1) horse - active phase even at rest

2) neonates - compliance -> atelectasis (if born early for example)

3) small mammals - compliance -> atelectasis


I think this was in last lecture...


Think this was in last lecture too....

What animals have these curves been adapted for?

- horse and cat


What are the three major muscles of inhalation?

What are some conditions where we might see diaphragmatic failure (he just asked the class this - wasn't in the slides)

1) diaphragm (the major one)

2) external intercostal muscle

3) upper airway abductor muscle (prevents collapse during inhalation)


 - skeletal muscle diseases, myasthenia gravis (nicotinic receptor of skeletal muscle fucked up - antibody binds the receptor and blocks the neurotransmitter) - Cushing's disease (excess cortisol - adrenal glands hypertrophy and undergo hyperplasia - too much cotrisol has a deleterious effect of skeletal muscle)


What are the Three muscles of exhalation?

1) Elastic Recoil - lungs and muscles

2) internal intercostal muscles

3) abdominal muscles (rectus abdominus, external obliques)


(Pressure, Resistance, and Airflow)

learn stuff in image


Factors That Influence the Airway Resistance

1) Which of these terms has a profound effect of flow?

2) what is it inversely releated to?

3) When the radius of an airway decreases by one-half, resistance of airflow thorugh that airway increases by what fold?

4) What are the major mechanisms for influencing resistance to airflow?

1) radius - cause of the 4

2) (8* the viscosity * the length of the tube)

3) 16 fold

4) broncho-constriction and -dilation


What can cause esophagitis in animals during surgery?

What's in gastric fluid?

How does this cause Esophageal stricture (thinning)?

- Anasthesia - it has a relaxing effect on the muscles of the GI tract, the vascular system, the urinary tract - sphincter relaxes and acid gets in

2) acids, pepsin

3) esophagus repairs itself but builds up fibrous tissue in the process which thins the airway


(Changes in Airway Resistance Due to Changes in Airway Resistance)

Smooth Muscle Relaxation and Bronchodilation:

1) What two things cause this?

A Little Review...

2) What type of receptor and NT are at ganglion of PS and sympathetic?

3) receptor and NT at end of sympathetic?

4) at end of PS?

5) Drug example?

6) Why do we activate sympathetic to widen airways rather than inhibiting PS function (which constricts)?

1) sympathetic activation & beta-adrenergic receptor agonists

2) Ach and nicotinic

3) NE and alpha and beta receptors

4) Ach and muscaranic

5) Albuterol

6) inhibiting PS function has side effects


(Changes in Airway Resistance)

Smooth muscle contraction and Bronchoconstriction presents as what in cats and horses?

Also - What does each do in response?

cats - asthma (mouth breathing)

horses - heaves (flare nares)



(Velocity of Airflow and Lung Sounds)

1. What is a dimensionless unit that represents the ratio of intertial to viscous forces?

2. What produces the lung sounds heard during auscultation (listening to the internal sounds of the body)

3. What are these normal noises exaggerated with?


1. The Reynold's number (R ~ velocity/viscosity)

2. The high velocity of airflow in the trachea and bronchea causing turbulent flow

3. airway inflammation

(Similarly, physiologic flow murmurs associated with anemia are due to high velocity and low viscosity which raises the Reynold's number - causes turbulence)

(Anemia is a condition in which the body does not have enough healthy red blood cells)


(Effect of surfactant on collapsing pressure)

1) Smaller alveoli increase or decrease surface area for gas exchange?

2) Alveoli are governed by what law?

3) What does P equal in this law/equation?

4) What works to reduce the surface tension on alveoli so that they don't collapse?

5) What produces the things mentioned above?

1) increase

2) Law of LaPlace (P=2T/r)

3) collapsing pressure, pressure required to keep alveolus open, = 2T/r (and smaller alevoli tend to collapse)

4) surfactant - lines the alveoli and reduces surface tension

5) phospholipids produced by type II alveolar cells


What can happen in premature births with regards to alveoli problems?

Usually happens in what species?

- they have incomplete synthesis of surfactant and therefore their airways collapse (and atelectasis - collapse of part of the lung)

- humans and horses


What does the influenza virus do to affect alveoli?

- causes change in phoshoplipid components of pulmonary surfactant that decrease its abiliity to decrease surface tension