pulmonary blood flow pt2

What is the flow of blood through the pulmonary circulation?

Right ventricle → Pulmonary arteries → Capillaries → Pulmonary veins → Left atrium

What percent of cardiac output goes to the lungs?

100% (all blood passes through lungs for gas exchange)

What is the main function of pulmonary circulation?

Gas exchange (O₂ uptake and CO₂ removal)

What are the two vascular systems of the lung?

Pulmonary circulation (gas exchange) and Bronchial circulation (nutrients for lung tissue)

Where does bronchial circulation arise from?

Systemic circulation (aorta

What structures does bronchial circulation supply?

Trachea

How much cardiac output is bronchial circulation?

~1–2%

What does bronchial venous drainage create?

What do pulmonary arteries carry?

Deoxygenated blood from right ventricle → lungs

What do pulmonary veins carry?

Oxygenated blood from lungs → left atrium (with some bronchial venous blood mixed in)

How do pulmonary vessels differ from systemic?

Thin-walled

What are normal pressures in systemic vs pulmonary circulation?

Systemic = high pressure/resistance; Pulmonary = low pressure/resistance

How are pulmonary pressures measured?

Pulmonary artery catheter (Swan-Ganz)

What pressures are measured with Swan-Ganz?

RAP (right atrial pressure)

What is PCWP and what does it reflect?

Pulmonary capillary wedge pressure

What is PVR?

Pulmonary vascular resistance = (MPAP − PCWP) ÷ Cardiac output

What lung volume has the lowest PVR?

Functional residual capacity (FRC)

How do lung volumes affect PVR?

Low lung volumes → vessel collapse ↑ PVR; High lung volumes → alveolar stretch ↑ PVR

What chemical factors increase PVR?

Thromboxane A2

What chemical factors decrease PVR?

Nitric oxide

How does exercise affect PVR?

Decreases PVR (recruitment & distension of pulmonary vessels)

How does body position affect PVR?

Supine → ↓ PVR

How does inspiration affect PVR?

More negative intrathoracic pressure can ↑ PVR

How does sympathetic vs parasympathetic tone affect PVR?

Sympathetic → vasoconstriction ↑ PVR; Parasympathetic → vasodilation ↓ PVR

How do blood viscosity & hematocrit affect PVR?

↑ viscosity or ↑ hematocrit → ↑ PVR

What effect does hypoxia have on pulmonary vessels?

Hypoxic pulmonary vasoconstriction (HPV) → shunts blood away from poorly ventilated areas

What happens with chronic hypoxia?

Persistent HPV → pulmonary hypertension

What are some pathological causes of ↑ PVR?

Pulmonary hypertension

How does Valsalva maneuver affect PVR?

Squeezes blood out of pulmonary circulation → ↑ PVR

How does left ventricular failure affect PVR?

Blood backs up into pulmonary circulation → distends vessels → ↓ PVR (but ↑ PAP)

What therapies lower PVR?

Vasodilators (prostacyclins

What is the clinical role of right heart catheterization?

Diagnose pulmonary hypertension