Pulmonary Ventilation

LUNG PATHOLOGY

Oxygen (2)

• Purpose: To supply the body with oxygen and dispose of carbon dioxide

• Body process requiring oxygen: Electron transport system of cellular respiration

Source of carbon dioxide

Krebs cycle of cellular respiration

Krebs Cycle (5)

• Involves the aerobic oxidation of glucose within living organisms

• The first step of utilizing glucose is glycolysis, where glucose is split into pyruvate, which is then converted to acetyl CoA

• Within the mitochondria

  • It converts acetyl CoA into CO2

  • Releases energy in the form of ATP, NADH, and FADH2

Breathing

Gas exchange between the atmosphere and the alveoli

Driving Airflow

The alternate contraction and relaxation of respiratory muscles generate a pressure difference between the atmosphere and the lungs, driving airflow

Inspiration (6)

• For air to enter the lungs, the pressure inside the alveoli must be lower than atmospheric pressure (760 mmHg or 1 atm)

• Lowering the intraalveolar pressure is achieved by increasing lung volume

• Increasing lung volume by lung expansion lowers the pressure below 1 atm

• The first step involves the contraction of the diaphragm, which expands the thoracic cavity

• As the overall size of the thoracic cavity increases, the pressure within the alveoli (intraalveolar pressure) drops below 1 atm

• This allows air to flow from the atmosphere into the alveoli, following a high-to-low pressure gradient

Boyle’s Law

an inverse relationship between the pressure of a gas in a closed container and its volume

Contraction of the diaphragm (3)

• expands the thoracic cavity

• The contraction is innervated by the phrenic nerve (C3/4/5)

• The diaphragm flattens upon contraction, increasing the vertical dimensions of the thoracic cavity

Pulmonary Ventilation

The process of moving air into and out of the lungs

Alveolar Ventilation

The air that actually reaches the alveolar membranes, where gas exchange occurs

External Respiration

The gas exchange between the lungs and the bloodstream, involving the transfer of oxygen into the blood and carbon dioxide out of the blood

Internal Respiration

The gas exchange between systemic blood vessels and tissues, where oxygen is delivered to tissues and carbon dioxide is removed