Lecture 13: Cardiac Pathologies; The Breath Cycle

Clinical Application

• In _______: insufficient blood flow (____) to the heart

coronary artery disease (CAD); ischemia

What is CAD?

insufficient blood flow (ischemia) to the heart

What is the result of CAD?

result may be myocardial damage in the affected region, or even death of that portion of the heart — a myocardial infarction, or heart attack

Site of gas exchange

Alveoli

Types of Alveoli

Type I alveolar cells: gas exchange

Type II alveolar cells: produce (detergent-like substance) surfactant

The total alveolar-capillary surface area is very large —→

permits the rapid exchange of large quantities of O2 & CO2 by diffusion

Steps of Respiration

1. Ventilation: exchange of air b/w atmosphere and alveoli

2. exchange of O2 & CO2 b/w alveolar air & blood in lung capillaries by diffusion

3. transport of O2 and CO2 thru pulmonary and systemic circulation

4. exchange of O2 and CO2 b/w blood in tissue capillaries and cells in tissues by diffusion

5. Cellular utilization of O2 and production of CO2

Ventilation

exchange of air b/w atmosphere and alveoli

F = ΔP/R

Flow (F) is proportional to the pressure difference (ΔP) b/w 2 points and inversely proportional to the resistance (R)

Steps of respiration

1. ventilation

2. gas exchange

3. gas transport

4. gas exchange

5. cellular respiration

Mechanics of Breathing

Pulmonary ventilation: 2 Phases

Inspiration: gases flow into lungs

Expiration: gases exit lungs

Atmospheric Pressure (Patm)

• pressure exerted by air surrounding the body

Respiratory pressures described relative to Patm

• negative respiratory pressure: less than Patm

  

• positive respiratory pressure: greater than Patm

• zero respiratory pressure: equal to Patm