Lecture 13: Cardiac Pathologies and The Breath Cycle

What is coronary artery disease?

it is insufficient blood flow (ischemia) to the heart

What is ischemia?

not enough blood flow to a tissue

What are the complications of coronary artery disease?

CAD may result is myocardial damage in the affected region that may cause the death of that portion

• ie. myocardial infarction or heart attack

Which type of alveoli is the site of gas exchange?

Type I alveolar cells (pneumocytes)

What are pneumocytes?

they are cells that line the alveoli

What is the function of Type II alveolar cells?

they produce a detergent-like (lipid-protein) substance called surfactant

What are the five steps of respiration?

1) Ventilation: exchange of air between atmosphere and alveoli

2) Exchange of O2 and CO2 between alveolar air and blood in lung capillaries by diffusion

3) Transport of O2 and CO2 through pulmonary and systemic circulation

4) Exchange O2 and CO2 between blood in tissue capillaries and cells in tissues by diffusion

5) cellular utilization of O2 and production of CO2

What are the two phases of pulmonary ventilation? What occurs during these phases?

1) Inspiration: gases flow into lungs

2) Expiration: gases exit lungs

What is the formula for flow?

flow = pressure / resistance

What is atmospheric pressure (Patm)?

pressure exerted by air surrounding the body

What are the three respiratory pressures that are described relative to atmospheric pressure (Patm)? What do they mean?

• negative respiratory pressure= respiratory pressure is less that atmospheric pressure

• positive respiratory pressure= respiratory pressure is greater that atmospheric pressure

• zero respiratory pressure= respiratory pressure is equal to atmospheric pressure

What is intrapulmonary or intraalveolar pressure (Palv)?

the pressure in the alveoli

What is intrapleural pressure (Pip)? What is special about intrapleural pressure?

pressure in the pleural cavity

• it is always a negative pressure and less than atmospheric and alveolar pressure

What is transpulmonary pressure? What is the equation?

it is the pressure that keeps the lung spaces open and keeps the lungs from collapsing

intrapulmonary/intraalveolar pressure - intrapleural pressure

At what situation do Pip, Palv, and Patm have to be at to cause the lungs to collapse?

Pip = Palv

or

Pip = Patm

At what pressure much Pip be at to keep the lung from deflating?

it must be maintained at a negative pressure

What is atelectasis?

lungs collapse due to plugged bronchioles or pneumothorax

What is a pneumothorax? When does it occur? How is it treated and why is this the treatment?

it is a collapsed lung when air get into the pleural space

• occurs when there is a wound in the parietal pleura or a rupture of visceral pleura

• treated by removing air with chest tubes

  • volume changes which changes the pressure and the change in pressure leads to a flow of gases to equalize pressure

What is Boyle’s Law?

the relationship between pressure and volume of a gas

P1V1=P2V2

you know this

What is inspiration?

it is the active process involving inspiratory muscles

What are the inspiratory muscles?

diaphragm and external intercostals

What happens to the diaphragm when it contracts?

it moves inferiorly and flattens out and then there is an increase in thoracic volume

What happens when the intercostal muscles contract?

the rib cage is lifted up and out and then there is an increase in thoracic volume

What is the thoracic volume?

it is the amount of space inside the chest cavity

What happens as the thoracic cavity increases?

lungs are stretched as they are pulled out with the thoracic cage

During inspiration what pressures change until they equalize?

there is a difference between atmospheric and intrapulmonary/intraalveolar pressure until they equalize

When do forced (deep) inspirations occur? What is the purpose?

They occur during times of vigorous exercise or in people with COPD

• increase in the thoracic cage size in comparison to the normal range causes a larger pressure gradient so more ait is drawn in

What are the types of expiration? What are the differences?

• Quiet expiration= normally is passive process

• Forced Expiration= is an active process that uses abdominal muscles and internal intercostal muscles

What occurs to inspiratory muscles, thoracic cavity volume, and lungs, during quiet expiration?

inspiratory muscles relax, thoracic cavity volume decreases, and lungs recoil

What are the levels of the pressures during quiet expiration? To reach what?

intraalveolar/intrapulmonary pressure > atmospheric pressure so air flows out of the lungs until they reach equilibrium