Respiratory System- Physiology Review By Cj

Front 1

Respiratory System- Physiology Review by CJ

Back 1

Respiratory System- Physiology Review by CJ

Front 2

Name the site of respiration

Back 2

The mitochondrion in the cells! They are the ones that are consuming oxygen. Everything else is an elaborate delivery system. In order for the cells to continue to live, there needs to be a continuous supply of oxygen

Front 3

What are the three processes that are involved in determining the arterial P02

Back 3

Ventilation- Bringing in o2 from the atmosphere into the lungs and getting rid of Co2
Perfusion- distribution of the gas to the rest of the body
Diffusion- between the blood and the lung (and rest of the body); how the gas is transferred

Front 4

If you inspire 150mmHg the (PI02), then why do you only get 100mmHg to the alveoli? the circulation?

Back 4

There's a big drop because of ventilation from the inspiration to the alveoli. Some o2 is removed by the blood. So the alveolar o2 is dependent on the ratio of supply and removal.

After ventilation, there is diffusion, shunt and perfusion which creates tiny drops of o2 which finally gets to the arterial blood.

Front 5

How do you get high perfusion to the mitochondria?

Back 5

Keep the Po2 as high as possible because that gives a large gradient of diffusion to the mitochondria.

Front 6

What are the four main causes of hypoxemia?

Back 6

Hypoventilation, diffusion impairment, shunt, V/Q (ventilation/perfusion) inequality

These processes can be enhanced by disease.

Front 7

What is the A-a gradient?

Back 7

PAo2- Pao2 (alveolar minus arterial)

it's used to differentiate between causes of hypoxemia

from the equation, you can see that alveolar o2 is normally about 100

Front 8

Between LeBron and Justin, who is hyperventilating and why?

Back 8

Since Lebron's PCO2 is lower than Justin's, i'd say Justin is hypoventilating. If the PC02 is normal and they have hypoxemia, it can't be from hypoventilation. If the Pco2 is high and they have hypoxemia, it cane be due to a mechanism.

*you can't just look at the ventilatory rate since there are other issues

Front 9

What does hypoventilation do?

Back 9

Since you're reducing the rate of supply, so the overall amount in the alveoli decreases and the arterial o2 decreases.

However! The A-a gradient will stay the same! (assuming it's purely hypoventilation)

You will also see an increase in PaCO2.

Front 10

How does one calculate alveolar ventilation?

Back 10

depends on rate, tidal volume, and dead space...

Va=(Vt-Vd) x n

Vt is compliance. n are drugs like barbiturates that can slow ventilatory rate.

Front 11

What happens if you have a severe diffusion impairment?

Back 11

you have a increased A-a gradient. You have a normal PaCo2 (co2 diffuses faster than oxygen and the body ventilatory system responds to co2 primarily, so the body tried to reset the pco2 to compensate the diffusion impairment), decreased arterial po2 (only if it's really severe).

Front 12

What type of things cause a diffusion impairment?

Back 12

diffusion is dependent on fick's law (diffusion is proportional to the surface area, inversely prop. to the thickness and proportional to the partial pressure gradient)

Front 13

What happens if you have an increased thickness of the blood-gas barrier?

Back 13

you have a decreased rate of diffusion

Front 14

Why must it be a severe a severe case of hypoxemia to get diffusion impairment?

Back 14

the healthy lung has a huge reserve capacity for diffusion. normally the pulmonary arterial blood that's coming into the alveolus equilibrates with the oxygen very quickly (1/3 along the capillary at rest)

Front 15

So how can you get slow diffusion?

Back 15

if you combine it with other things. Like slow diffusion and exercising. or slow diffusion and high altitudes. This is when you get a lower gradient.

Front 16

how is o2 carried?

Back 16

dissolved in the plasma (doesnt carry much o2 because it's not very soluble in plasma. not enough for exercise)

hemoglobin- increases the amnt of o2 you carry in the blood. this allows more o2 to diffuse into the blood.

Front 17

Describe the 2 regions of the o2 dissociation curve in regards to Hb

Back 17

in the steep region, the Hb gives up o2 at a low tissue Po2. In the tissues there's a low po2 so it'll give up the o2 (that's good.)

At the plateau the Hb saturation maintained with drop in lung P02

Front 18

Predominant form of Co2 transportation?

Back 18

bicarbonate.some co2 is dissolved in the plasma, and some is carried by proteins (esp. Hb)

Front 19

What is the main facilitator of Co2 transport?

Back 19

red blood cells.

Front 20

Why does the V/Q inequality depress the Pa02?

Back 20

The alveolar po2 varies in the lung because of how ventilation and blood flow change in the lung. There's more o2 removal at the bottom of the lung (where there's more blood flow), so the alveolar po2 tends to be lower. But the overall Pa02 tends to be the value closer to the base bc more of the blood flow goes to the base of the lung.

Front 21

What is shunt?

Back 21

perfusion but no ventilation. it can be detected by giving pure oxygen. If the pt has shunt, the arterial po2 wont go up very much.

Front 22

What happens if you give someone pure oxygen? is the hypoxemia reversed?

Back 22

no. since we're already at the top of the o2 dissociation curve, we can get a large po2 change but we dont get a very big concentration change.

so when we give pure o2, the po2 doesnt go up in the case of shunt.

Front 23

How do you control respiration?

Back 23

Respiratory pattern generator in the medulla and pons, and these are modified by inputs in the brain and periphery. This controls the output of the lungs.

Central chemoreceptors in medulla (for Co2 only),

Peripheral chemoreceptors respond to oxygen