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.