Veterinary Anatomy and Physiology: Respiratory Anatomy and Physiology Notes
Overview of Respiratory Anatomy and Physiology
Pulmonary Blood Flow
Pulmonary Vascular Resistance (PVR): Resistance where the right ventricle cardiac ejects blood against.
Low resistance in pulmonary blood vessels.
Influenced by recruitment of vessels and distension.
Capillaries provide most resistance in pulmonary circulation unlike systemic circulation.
Transmural Pressure
Transmural Pressure: Difference in pressure inside vs. outside vessel.
Increased volume leads to vasodilation.
Vascular Smooth Muscle
Factors affecting smooth muscle contraction/relaxation:
Amount of smooth muscle (species variance).
Initial vascular tone.
Neural and humoral influences play key roles.
Alveolar Hypoxia
Poorly ventilated alveolus induces vasoconstriction in pulmonary arteries, redirecting flow to better-ventilated areas.
Example: Llamas have minimal hypoxic response due to high-altitude adaptation.
Gas Exchange Mechanisms
Alveolar Gas Composition: Determined by ventilation, CO2 exchange, and partial pressures
PO2: PO2 = BP imes fO2
O2 and CO2 Exchange
Diffusion occurs between the alveolus and capillary blood, dependent on gas properties, surface area, barrier thickness, and pressure gradient.
VO2 Equation: VO2 = D imes A imes rac{(PAO2 - PcapO2)}{x}
Hemoglobin Functionality
Hemoglobin binds O2 through heme and globin components.
Affinity for O2 is influenced by temperature, CO2 levels (Bohr effect), pH, and phosphates.
Carbon Dioxide Transport
CO2 is mostly converted to bicarbonate and transported in the plasma.
Defense Mechanisms of the Respiratory System
Protects against pollutants and pathogens through:
Mucociliary system (clears foreign particles).
Immune response (immediate and delayed).
Nonrespiratory Functions of the Lung
Fluid Exchange: Continuous lymph production and hormone metabolism for homeostasis.
Metabolic Functions: Removal/inactivation of hormones and toxins.