Intro to Respiratory - Trachte - W1

Question 1

What are the 4 major challenges to respiration?

Answer 1

1. Ventilation (getting air into and out of the lungs)
2. Diffusion (getting O2 and CO2 into and out of the BLOOD)
3. PERFUSION (gettting enough blood to lungs to accumulate O2 and excrete CO2)
4. Gas transport (how blood carries O2 and CO2)

Question 2

How do gases move across the blood-gas interface?

Which “direction” do they move?

Answer 2

• move across the interface by diffusion
• go from high pressure to low pressure
  
  • partial pressure of oxygen in air is 150mmHg and is 40mmHg in venous blood

Question 3

How do we calculate partial pressure of gases?

Answer 3

• NEED
  
  • normal atmospheric pressure = 760 mmHG
    
    • ​may be lower in denver since it’s higher up.
  • % of gas in atmosphere - O2 is 21%, nitrogen is 71%
• 760 x .21 = 160 mmHg (partial pressure of oxygen)

Question 4

What are 4 things that affect gases moving across a barrier?

Answer 4

1. cross sectional area of the barrier.
2. permeability of the barrier.
3. thickness of barrier - inversely proportional. More thick = less diffusion.
4. Pressure gradients across barrier.

Question 5

How do the lungs increase the surface area?

Answer 5

MANY ALVEOLI - capillaries wrap around them to really increase surface area

Question 6

What is a disease that can affect the thickness of the alveolar walls?

Answer 6

CHF - changes permeabiliity by adding a layer of water (thickness) which makes it harder for oxygen to get across

Question 7

What are the parts of the airway?

Answer 7

• Trachea
• Right and left bronchi
• lobar bronchi
• segmental bronchi
• terminal bronchioles
• respiratory bronchioles

Question 8

What is the part of the airway where particals tend to get stuck?

Answer 8

Terminal bronchioles

Question 9

which part of the airway has the greatest resistance and why?

Answer 9

• Resistance is GREATER near the main bronchus and segmental bronchi.
• Due to less cross sectional area, which makes resistance GREATER

Question 10

What makes up the conducting airways?

What is their job?

Answer 10

• trachea to terminal bronchioles
• conduct air - NOT INVOVLED IN GAS EXCHANGE

Question 11

What is the gas concentration in the conducting airways?

Answer 11

Similar to that of the atmosphere, except the air is more humid.

(High oxygen, low CO2)

Question 12

How much of a typical breath is “dead space”?

Answer 12

Typical breath is 500ml, and 30% is normally dead space.

~150mL of dead space.

Question 13

What is an ANIMAL and CLINICAL example of an increase or HIGH dead space

Answer 13

• Animal
  
  • giraffe has very long neck = high dead space
• Clinical
  
  • people on RESPIRATORS - increases the amount of dead space. A typical tidal volume of 500mL isn’t enough.

Question 14

What are the Respiratory zones of the airways?

Answer 14

• respiratory bronchioles - come off the terminal bornchioles
• alveolar ducts - come off the respiratory bronchioles
  
  • completely lined w/alveoli

Question 15

Explain the airflow of the lungs:

Answer 15

1. initated by expansion of the thoracic cavity
   
   1. diaphragm CONTRACTS - moves downward
   2. creates increased volume, but since no air is going in, it’s a lOWER PRESSURE
   3. Air can FLOW IN down to the terminal bronchioles.

Question 16

If dust enters the lungs, where does it accumulate? Why?

Answer 16

Accumulates in the terminal bronchioles.

The more distal sections of the lungs, the alveoli, rely on the diffusion of gases.

Question 17

What defines compliance of the lung?

Answer 17

Change in volume/change in pressure

(P=Fxr) –> V/FxR –> 500mL/(1L/sec x 2cm)

Resistance = 2cm water/L/sec

• We don’t have to change the pressure very much in the lungs to get them to expand.
• 3cm change in pressure = 500mL of air in.

Question 18

What is a disease that has something wrong with compliance? Explain.

Answer 18

COPD

Lungs expand too easily and won’t contract.

Question 19

Although there are thin walls (good for gas exchange) between alveoli and blood, they are easily susceptible to damage. What can cause the damage?

Answer 19

• Increased capillary pressure
  
  • pulmonary hypertension, hypoxia (emphysema, bronchitis), CHF)
• Increased alveolar pressure
  
  • positive pressure ventilator, which elevates pressure of breathing

Question 20

What are some things that cause increased capillary pressure?

Answer 20

• hypertension
• hypoxia
  
  • emphysema
  • bronchitis
• CHF

Question 21

What supplies the conducting airways?

Answer 21

Bronchial circulation from the systemic side (aorta)

Question 22

What is the equation for alveolar surface tension?

Answer 22

T = P*r / 2

Question 23

What is used to prevent surface tension and alveolar collapse?

Answer 23

Surfactant

Matters more in SMALLER alveoli

Question 24

What 3 things are used to prevent inhaled particles entering the lungs?

Answer 24

• Filtered in the nose w/nasal hairs
• moved toward the mouth with a mucous-ciliary elevator
  
  • smoking affects this
• engulfed by macrophages - occurs in alveoli

Question 25

What happens if there is no surfactant?

Answer 25

The H20-H20 bond in the alveoli will crush them. Surfacant affects this bond and prevents the crushing.