Frog Internal Anatomy Quiz (Part 1)

Frog Internal Anatomy (Part 1)

• Viscera are the internal organs, located within the coelom (body cavity).
• The transverse septum is a connective tissue that divides the coelom into two cavities:
  • Pericardial Cavity - contains the heart
  • Pleuro-peritoneal Cavity - contains lungs, stomach, liver, and other viscera.
• Parietal Peritoneum - a thin, transparent membrane that lines the inner side of the muscular body wall.
• Mesentery - a double-walled connective tissue that anchors organs to the dorsal body wall (e.g., mesogaster of the stomach).
• Visceral Peritoneum - a mesentery or extension of the parietal peritoneum that encloses the visceral organs.
• Omentum - a double-walled connective tissue extension of the parietal peritoneum that connects an organ to another organ (e.g., gastro-duodenal omentum).

Buccal Cavity of the Frog

• The buccal cavity is found behind the mouth.
• Roof of the buccal cavity:
  • Median Subrostral Fossa - prominent depression at the anterior tip.
  • Pulvinar Rostrale - pair of low elevations on either side of the median fossa.
  • Lateral Subrostral Fossae - pair of depressions on either side of the pulvinar rostrale.
  • Sulcus Marginalis - pair of deep grooves on the inner margins of the upper jaw.
• Maxillary Teeth – small conical teeth in a row along the upper jaw.
• Vomerine Teeth - two small clusters of teeth on the vomer bones.
• Internal/Posterior Nares (Choanae) - slit-like openings leading into the buccal cavity, connecting to the outside through external nares.
• Eyeball Prominences - two large rounded bulges on the posterior half of the mouth; can be pulled into the buccal cavity during swallowing.
• Tuberculum Prelinguale - prominent median elevation on the anterior tip of the lower jaw, fitting into the median subrostral fossa.
• Prelingual Fossae – pair of tiny depressions on either side of the tuberculum prelinguale, where the pulvinar rostrale fits.
• Tongue - forked muscular structure occupying a large area of the buccal floor.

Back of the Buccal Cavity

• Openings of Eustachian Tubes - slit-like openings on the posterolateral side of the eyeballs.
• Opening of the Esophagus - wide transverse slit posterior to the laryngeal prominence; connecting the pharynx to the stomach.
• Laryngeal Prominence - small, hardened, oval-shaped elevation between the lateral forks of the tongue.
• Glottis - slit-like opening at the center of the laryngeal prominence; connecting the pharynx to the lungs.
• Openings of the Vocal Sacs - slit-like openings on the floor of the mouth, lateral to the posterior portion of the tongue (found only in males).

Digestive System of the Frog

• The digestive system converts ingested food into absorbable nutrients.
• Digestion involves:
  • Ingestion of food
  • Passage of food through the digestive tract
  • Release of hormones and enzymes to aid in the process
  • Egestion of undigested food.
• Digestive Tube - extends from the mouth to the anus, responsible for digestion, absorption, and elimination.
• Mouth - the anterior opening of the head for food ingestion.
• Buccal Cavity - area behind the mouth.

Pharynx, Stomach, Small Intestine, and Large Intestine

• Pharynx - posterior part of the buccal cavity.
• Esophagus - a short passageway connecting the pharynx to the stomach.
• Stomach - expanded, large, bag-shaped portion of the digestive tube; suspended from the dorsal body wall by the mesogaster.
• Pylorus - constricted region at the posterior end of the stomach; passageway to the intestines, controlled by the pyloric valve.
• Small Intestine - the longest portion; site of final digestion and absorption.
• Large Intestine - short-dilated tube; temporary storage of waste products.
• Rectum - first part of the large intestine, continuous with the jejuno-ileum.
• Cloaca - posterior end of the rectum, located within the pelvic girdle; common passageway for feces, urine, and reproductive cells.
• Anus or Vent - the terminal opening/elimination pathway for waste.

Digestive Glands (Liver, Gall Bladder, and Pancreas)

• Liver - large, reddish-brown gland, partially covering the stomach.
• Liver Lobes - right anterior, left anterior and posterior, and a median lobe.
• Gall Bladder - greenish sac on the ventral wall of the liver; temporary storage of bile.
• Bile Duct - conducts bile from the liver to the gall bladder.
• Cystic Duct - connects the gall bladder neck/bile duct.
• Pancreas - elongated, irregularly-shaped gland located between the duodenum and stomach, along the gastro-hepato-duodenal omentum.
• Pancreatic Ducts - tiny ducts; transport pancreatic juice.
• Common Bile Duct - formed by the union of hepatic, cystic, and pancreatic ducts; empties bile and pancreatic juice.
• Gastric and Intestinal Glands - found in the mucosa of the stomach and small intestine.

Frog Respiratory System

• The respiratory system takes in oxygen and releases carbon dioxide.
• Respiration includes:
  • External Respiration
  • Internal Respiration
• External Respiration - gas exchange between the blood and the environment occurs in the respiratory organs.
• Internal Respiration - gas exchange between the blood and the cells.
  • External Nares - outer respiratory openings.
  • Internal Nares - inner respiratory openings.
  • Olfactory Canal - pathway between internal and external nares,
  • Laryngeal Prominence - prominent structure with glottis.
  • Arytenoid Cartilages - valve-like cartilages guarding the glottis.
  • Cricoid Cartilage - ring-like cartilage surrounding the arytenoid.
  • Glottis - slit-like opening at the center of the laryngeal prominence.
  • Larynx - connects glottis to lungs.
  • Lungs - paired thin-walled sacs (alveoli).
• Functional units - alveoli increase the surface area for gas exchange.
• Pleura - surrounds the lungs, continuous with the parietal peritoneum.

Frog Urinary System

• The urinary system eliminates waste products.
• Kidneys - pair of reddish, elongated, flattened organs lined by the parietal peritoneum, located retroperitoneal (outside the abdominal cavity).
• Urinary Ducts / Tubules - carry urine to the cloaca.
• Urinary Bladder - storage organ for urine.
• Cloaca - posterior part of the large intestine, used for elimination.
• Anus or Vent - posterior opening for waste elimination.
• Nephro/Malpighian Body - structural functional unit in the kidneys
• Capillaries, glomerulus, Bowman's capsule - elements in the nephron

Frog Cardiovascular System

• The cardiovascular system includes the heart, blood vessels, blood.
• Heart - muscular organ that pumps blood throughout the body.
• Three chambers - two atria (right and left) and one ventricle.
• Conus Arteriosus/Bulbous Cordis - large tube on the ventral side of the right atrium that receives blood from the ventricle.
• Sinus Venosus - triangular structure where major veins empty (receiving blood from the rest of the body).
• Blood - Fluid component + cellular components (blood cells).
  • Erythrocytes/RBCs
  • Leukocytes/WBCs
  • Thrombocytes/platelets
• Blood Vessels - transport blood.
  • Arteries - carry oxygenated blood away from the heart
  • Veins - carry deoxygenated blood back to the heart
  • Capillaries - smallest vessels, site of gas exchange.

Branches of Circulatory System

• Precava (Superior Vena Cava) - receives blood from the head and forelimbs, draining into the sinus venosus.
• Postcava (Inferior Vena Cava) - gathers venous blood from the posterior trunk and hind limbs, flowing into the sinus venosus.
• Systemic veins - drain deoxygenated blood to the heart.
• Pulmonary Vein - carries oxygenated blood from the lungs to the heart.
• Portal veins - carry blood through capillaries to organs before entering the systemic circulation.
  • Hepatic Portal Vein
  • Renal Portal Vein

Frog Reproductive Systems (Male and Female)

• Male Reproductive System:
  • Testes - pair of elongated, yellowish structures on the ventral surface of the kidney
  • Mesorchium - suspensory membrane of the testes from the kidney.
  • Vasa Efferentia - small tubules carrying sperm from testes to kidney.
  • Seminal Receptacle - expanded posterior end of the mesonephric duct ; temporary storage of sperm
  • Vestigial Oviduct - lateral to the mesonephric duct in males, reduced in size and function.
• Female Reproductive System:
  • Ovaries - pair of lobulated, saccular organs attached to the dorsal body wall (mesovarium).
  • Mullerian Ducts/ Oviducts - convoluted tubes on each side of the ovary.
  • Ostium - funnel-shaped opening of the oviduct, near the oesophagus.
  • Oviduct Proper - elongated portion of the oviduct
  • Uterine Enlargement - posterior, enlarged, highly distensible sac connected to cloaca
  • Corpora Adiposa/Fat Bodies - yellowish structures attached to the ovaries; store reserve food.

Test your knowledge about the internal anatomy of frogs, focusing on the structure and function of various organs and their locations within the coelom. This quiz covers key concepts such as the pericardial cavity, mesentery, and the buccal cavity. Perfect for students studying amphibian biology or anatomy.