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Details

Respiratory Apparatus
Physio Final
37
Veterinary Medicine
Professional
12/01/2009

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Cards

Term
What does the slope of a compliance curve represent?
Definition
  • The change in volume for the change in pressure
  • The steeper the slope, the greater the compliance
Term
What does it mean if a lung is highly compliant?
Definition
It doesn't take much force (pressure) to create a change in volume
Term
What does it mean if a lung is not very compliant?
Definition
It would take a lot of force (pressure) to create a change in volume
Term
What type of ventilation pressure can you use after an animal is intubated?
Definition
Positive pressure intubation
Term
What is the elastic recoil pressure?
Definition
The pressure measured inside when the air flow into the elastic sphere (lung) is zero
Term
Why is the compliance curve for a normal lung not a straight line?
Definition

It takes more pressure when you begin to inflate the lung than after a little bit and then it again take a lot of pressure when the lung is very filled

(think of blowing up a balloon)

Term
What would emphysema do to the lungs?
Definition
  • Compliance would increase b/c less tissue to resist the pressure
  • With the increased compliance, there is decreased elasticity
    • This is why the problem with emphysema is really during exhalation
Term
What would pneumonia do to the lungs?
Definition
  • Adding junk to the lungs would:
    • Decrease in compliance
    • Increase in elasticity
Term
How does negative pressure ventilation work?
Definition
  • You pull back on a plunger to create a negative pressure in the intrapleural space to inflate the lung (pull airs into alveoli)
  • Plot an increased negative pressure over a change volume
Term
What can intrapleural pressure accomplish?
Definition
  1. Overcome the elastic recoil pressure
  2. Create air flow
Term
What kind of pressure are the lungs always exerting?
Definition
  • Elastic recoil pressure
Term
What keeps the lungs from moving air?
Definition
  • Pressure in the intrapleural space has to be just negative enough to offset the elastic recoil pressure to keep the lungs from moving air
Term
What change allows the lungs to move air?
Definition
  • The intrapleural space has to become more negative for air flow
  • Causes flow pressure
Term
What happens to flow pressure when you inhale rapidly, and what does this cause?
Definition
  • Flow pressure increases
  • Causes an increase in flow & its velocity
Term
What determines the rate of airflow into the lungs?
Definition
  • The rate of muscular contractions of inspiratory muscles
Term
What determines the amount of pressure that is required for air flow?
Definition
  • Rate of air flow
Term
What is the measurement for the volume in the lungs?
Definition
  • Liters
Term
What is the measurement for elastic pressure in the lungs?
Definition
  • cmH2O
Term
What is the measurement for air flow in the lungs?
Definition
  • L/sec
Term
What is the measurement for alveolar pressure in the lungs?
Definition
  • cmH2O
Term
What is the measuement for intrapleural pressure in the lungs?
Definition
  • cmH2O
Term
How do you determine elastic recoil pressure?
Definition
  • Take the difference in pressure across the wall of the lung
Term
Is intrapleural pressure positive or negative?
Definition
  • Always negative
  • Increases in negativity during inspiration
Term
What happens to the different pressures during inspiration?
Definition
  • Intrapleural pressure becomes more negative
  • Air flows into the lungs
  • Air volume in the lungs increases
  • Elastic recoil pressure increases
  • Alveolar pressure becomes more negative
  • At peak inspiration, things reverse
Term
What happens to the different pressures during expiration?
Definition
  • Air volume decreases
  • Elastic recoil pressure decreases
  • Air flow occurs
  • Alveolar pressure becomes more positive to clear air out down a pressure gradient
  • Intrapleural pressure becomes less negative so the lungs can deflate themselves
Term
What happens to fluid-filled lungs?
Definition
  • Become more compliant
Term
Why are fluid-filled lungs more compliant?
Definition
  • Surfactant coats the alveolus
  • A liquid-liquid interface has a lower elasticity, & therefore greater compliance, than a liquid-air interface
Term
What makes up the elasticity of the lung?
Definition
  • Together:
    • The interface (liquid-air, liquid-liquid, etc)
      • Surfactant-air interface is responsible for most of the lung's elasticity
    • The elasticity of the tissue itself
Term
What is surfactant?
Definition
  • Produced by type 2 alveolar cells
  • Not like water or plasma (which would have a greater elasticity)
  • Reduces surface tension
Term
Where does surface tension occur and why?
Definition
  • Occurs at the interface of water & air
  • Why? unequal attraction of water molecules for each other as compared to the air
Term
What does surface tension do, and what can reduce it?
Definition
  • Surface tension acts at the plane of the surface as elastic tension
  • Surfactant decreases surface tension, and thus decreases elastic tension
    • Surfactant-air interface has a lower elasticity than water-air interface
Term
How does surfactant keep alveoli open?
Definition
  • Surface tension of surfactant changes with surface area
    • Decreases surface tension as surface area decreases
    • Law of Laplass Pressure= 2T/r
  • Keeps smaller alveoli from dumping its contents into bigger ones
  • Not true of water or detergent
Term
What is pneumothorax
Definition
  • Usually caused by puncture wound
  • The negative pressure in the intrapleural space is lost, causing atelectasis (collapse of lungs)
  • When chest expands in volume from inspiratory muscles, the puncture wound will suck air in through it
    • If the hole is small, then air will get in, but will be trapped
Term
What is tension pneumothorax?
Definition
  • Caused by lesion on lung tissue that ruptures alveoi into the intrapleural space
  • Air gets into the intrapleural space & is trapped, causing atelectasis
Term
What is the relationship between basal oxygen requirements and body weight?
Definition
  • Direct relationship
  • Increased body weight requires more oxygen
Term
What is the relationship between total alveolar surface area and metabolic rate (O2 consumption)?
Definition
  • Direct relationship
Term
What is the relationship between high metabolic rate and alveolar size?
Definition
  • Inverse relationship
  • Small animals w/ high metabolic rates increase internal diffusing area by increasing the # of alveoli, so they have to be smaller to fit more in
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