Anatomy of Frog

Anatomy of Frog

The anatomy of a frog encompasses various organ systems: 

1. Body Structure:

  • Frogs have a head and trunk, lacking a neck and tail.
  • The body skin is smooth and slimy due to mucus, kept moist to facilitate respiration.
  • Dorsal skin is typically olive green with dark spots, while the ventral side is pale yellow.
  • Frogs maintain moisture balance through skin absorption.
  • Sexual dimorphism is present, with males having vocal sacs and copulatory pads on the first digit of the forelimbs.

 2. Digestive System:

  • Frogs are carnivores, so their alimentary canal is short.
  • The mouth leads to the buccal cavity, then the oesophagus, stomach, intestine, and rectum.
  • The liver secretes bile stored in the gall bladder.
  • The pancreas produces pancreatic juice.
  • Food digestion occurs through HCl and gastric juices in the stomach.
  • Chyme, partially digested food, moves to the duodenum, where it receives bile from the gall bladder and pancreatic juices.
  • Bile emulsifies fat, while pancreatic juices digest carbohydrates and proteins.
  • The final digestion takes place in the intestine, where absorption occurs through villi and microvilli.
  •  Undigested waste exits through the cloaca.



3. Respiratory System:

  • Frogs respire in both water and on land.
  • The skin serves as an aquatic respiratory organ through cutaneous respiration.
  • On land, frogs use buccal cavity, skin, and lungs for pulmonary respiration.
  • The lungs are elongated, sac-like structures in the thorax.
  • During aestivation and hibernation, skin facilitates gaseous exchange.

 4. Circulatory System:

  • Frogs have a closed circulatory system with a well-developed heart.
  • The heart has three chambers (two atria and one ventricle) and is covered by the pericardium.
  • Blood is carried by arteries to various body parts and returned to the heart via veins.
  • Special venous connections exist between the liver and intestine and the kidney and lower body parts.
  • The blood consists of plasma, RBCs (nucleated with haemoglobin), WBCs, and platelets.
  • Frogs also have a lymphatic system.

 5. Excretory System:

  • The excretory system includes kidneys, ureters, cloaca, and urinary bladder.
  • Two ureters emerge from the kidneys in males (females have separate openings for oviducts and ureters).
  • Frogs are ureotelic, excreting urea.
  • Excretory wastes are carried by the blood to the kidneys, separated, and excreted.

 6. Nervous System:

  • Frogs possess both a neural system and endocrine glands.
  • The brain is divided into forebrain, midbrain, and hindbrain.
  • The central nervous system includes the brain and spinal cord, with peripheral and autonomic nervous systems.
  • Frogs have well-developed sense organs for touch, taste, smell, vision, and hearing.

 7. Reproductive System:

  • Males have paired testes and vasa efferentia that open into the urinogenital duct.
  • The female reproductive system includes paired ovaries and separate oviducts.
  • Fertilization is external in water, with development involving a tadpole stage that undergoes metamorphosis into an adult frog.