Frog Circulatory System Short Notes | Free Biology Notes

In this article we will discuss about the frog circulatory system

Frog Circulatory System

• The distribution of the digested food and oxygen to various parts of the body through blood is called circulation
• The frog circulatory system are responsible for circulation
• The frog circulatory system consists of blood vascular system and lymphatic system.
• Blood vascular system consists of blood, heart, and blood vessels

Blood

• It is a liquid connective tissue containing fluid plasma and blood cells
• Plasma composed of 90% water and 10% of organic and inorganic substances
• Three type of blood cells are present in it
  • RBC: RBC are oval or biconvex in shape and nucleated. It contains haemoglobin which carry the oxygen.
  • WBC: This cell provide protection or immunity.
  • Thrombocytes: This cell prevent loss of blood by forming thrombus or clots on the bleeding site.

Heart

• The heart is muscular and triangular pumping organs
• A thin, transparent, two-layered pericardium encloses the heart.
• The frog consists of three chambered heart
• Upper two chambers are called auricle and lower one chamber is called ventricle

Auricles

• There are two auricles, left and right
• The left auricle is smaller than the right
• Sinus venosus opens into dorsal wall of the right auricle through the sinu auricular aperture
• The common pulmonary vein opens into left auricle
• Both auricles open into ventricles by a common large auriculo ventricular aperture

Ventricle

• The ventricle has thick muscular and spongy wall
• The opening of ventricle into truncus anteriosus is guarded by three semilunar values, which prevent the back flow of blood from truncus arterious into ventricle
• On contraction of the ventricle blood flow from the ventricle into truncus anteriosus
• Truncus anteriosus divided into two trunks called ventral aorta
• Each ventral aorta further divided into a carotid arch, systemic arch and a pulmocutaneous arch

• The hearts of frog have two additional chambers: truncus arteriosus and sinus venosus.

Truncus arteriosus

• Tube shaped structure that arises from the right side of the ventricle.
• Anterior end of these structures, there is a division into two trunks called ventral aorta
• The spiral valves in amphibians are present within the truncus arteriosus

Sinus venosus

• Thin walled and triangular chamber
• Three veins open into sinus venosus: right precaval, left precaval and post caval veins
• Sinus venosus open in the right auricle
• Impure blood from all body parts is poured into the sinus venosus
• It further pours this impure blood into the right auricle

Blood vessels (arterial system)

• Arteries carry blood away from the heart
• Arterial system starts with truncus arteriosus
• The truncus divides into left and right branches and each of these branches subdivide into three major vessels or aortic arches
  1. Common carotid artery to head
  2. Systemic artery to body and viscera
  3. Pulmocutaneous artery to lung and skin

How Circulatory System Works In Frog?

• Sinus venosus contracts, its impure blood is pumped into the right auricle through sinu auricular aperture
• At the same time the left auricle receives blood from the lungs via pulmonary veins.
• Both auricles contract almost simultaneously driving blood into the ventricle through the auriculo ventricular aperture
• Completely mixed blood in ventricle
• The truncus which flows simultaneously through the three pairs of arches to all parts of the body