Comparative Anatomy of Internal Organs

Comparative Anatomy of Internal Organs in Domestic Animals

• Comparative anatomy studies similarities and differences in organ anatomy across species.
• Stomach: The dilated part of the digestive tract where digestion begins.
• Significant diversity in stomach form and function among mammals, primarily due to dietary differences.
• The stomach (ventriculus) receives food from the esophagus, holding it before release into the small intestine.
• Dog's stomach: Has a relatively modest capacity, differing based on breed, comprising four parts (cardia, fundus, body, and pylorus).
• Esophagus opens at the cardia, and the pylorus connects to the duodenum.
• The cardia is distensible, rapidly expanding to accommodate meals; the pylorus remains relatively constant.
• Stomach structure varies among species (dog, pig, human, horse).
• Diagrams display various species' stomachs' internal structures and features, such as the diverticulum ventriculus and saccus cecus in the pig, and the simple/composite types in different animals.
• Stomach types show differences, such as simple vs. compound, based on the diet (carnivores, herbivores, ruminants).
• Ruminants have a multi-chambered stomach like the rumen, omasum, reticulum, and abomasum.
• Stomach pH values vary depending on animal type (carnivores vs ruminants vs pigs vs horse and humans.)
• Stomach capacity varies: Carnivores 60-70% of GIT volume; Herbivores below 30%; Omnivores 60-70%.
• Small intestine: The duodenum, jejunum, and ileum make up the small intestine.
• Small intestine length relative to body length differs across species: Carnivores (3-6 times); Herbivores (10-12 times); Omnivores (4-6 times).
• Large intestine variations exist across species regarding its structure and positioning relative to other organs.

Liver

• The liver (hepar) is the largest gland, found in the cranial abdomen behind the diaphragm.
• Functions: Bile production, protein, carbohydrate, and fat metabolism.
• Located primarily on the right side in most species (though with some variation in asymmetry).
• The gall bladder is absent in horses.
• Lobation and position of the liver vary across species (i.e., ruminants, pigs, dogs, horses). Specific lobe names and their relative positions are documented in further detailed drawings comparing different species.

Pancreas

• The pancreas is a small gland near the duodenum, with a body and two lobes (especially in canines).
• Its cellular structure and shape resemble the salivary glands, though it has a softer texture.
• It performs both exocrine and endocrine functions.
• The exocrine function produces digestive juices that flow into the duodenum.
• These juices contain enzymes that break down protein, carbohydrates, and fats.
• The endocrine component (pancreatic islets) produces insulin, glucagon, and gastrin.
• Variation in pancreatic duct system is documented for various species (cat, dog, pig, ruminants (ox), sheep, goats, horse).

Explore the fascinating world of comparative anatomy focusing on the internal organs in domestic animals. This quiz delves into the structure and function of the stomach and other digestive organs across different species, including dogs, pigs, humans, and horses. Test your knowledge on the anatomical differences and similarities that contribute to diverse dietary needs.