Frog Venous System

Main Components

Systemic Veins:

Two precaval veins (anterior venae cavae) and one postcaval vein (posterior vena cava) open into the sinus venosus, the collecting chamber just before the right atrium.​

Each precaval is formed from the union of three veins: external jugular (from tongue, floor of mouth), innominate (internal jugular from brain, subscapular from shoulder/back), and subclavian (brachial from forelimb, musculocutaneous from skin/muscles).​

The postcaval vein receives renal veins (from kidneys), genital veins (from gonads), and hepatic veins (from liver).​

Portal Vein Systems:

The renal portal system collects blood from the hind limbs (sciatic/femoral veins) via renal portal veins into the kidneys, providing a double filtration step before blood re-enters the main veins.​

The hepatic portal vein gathers blood from digestive organs (stomach, intestine, pancreas) and delivers it to the liver for nutrient processing before joining the postcaval.​

Pulmonary Veins:

Two pulmonary veins collect oxygenated blood from the lungs and drain it directly into the left atrium.​

Blood from the skin also joins systemic veins through musculocutaneous branches as frogs use their skin for respiration