The key difference between rat and human digestive system is that rat digestive system does not have a gallbladder, but it has an enlarged large intestine while human digestive system has a gallbladder.
Since both human and rat are mammals, their digestive systems exhibit many similarities and very few dissimilarities. However, a deep analysis of the both would reveal the existing difference between rat and human digestive system. Obviously, humans have a physically larger system, being the larger animal.
CONTENTS
1. Overview and Key Difference
2. What is Rat Digestive System
3. What is Human Digestive System
4. Similarities Between Rat and Human Digestive System
5. Side by Side Comparison – Rat vs Human Digestive System in Tabular Form
6. Summary
What is Rat Digestive System?
Rats are predominantly seed eaters; hence, their digestive system shows special adaptations to digest seeds. As most of the seeds contain cellulose, the rat digestive tract is capable of digesting long polysaccharides efficiently. Therefore, there is a specialized chamber in the rat digestive system in order to rot the seeds to digest the hard cellulose chains through fermentation. The enlarged large intestine or caecum with microorganisms works as the fermentation chamber of the digestive system of rats.
Figure 01: Rat Digestive System
Interestingly, there is no gall bladder in the rat digestive system. Usually, the enzymes secreted from the gall bladder are responsible for the digestion of animal fats. But rats are mostly neither carnivorous nor omnivorous. Therefore, they do not need to digest animal fats, and there is no need for a gall bladder. Other than these exceptions, rats have a digestive tract that starts with the small oral cavity with salivary glands and ends with the posterior opening.
What is Human Digestive System?
Humans are omnivorous and have a generalized food habit, which means there is no specific food type that is particularly essential to maintain the life of a human. Therefore, the digestive system is not essentially specialized, but it is a simple tract with necessary accessory glands. It starts with the simple oral cavity containing salivary glands, tongue, and teeth to taste and start the digestion of food. The oesophagus, stomach, small intestine with three parts, large intestine, and anus are the main parts of the digestive system, performing essential functions in food digestion, absorption, and elimination.
Figure 02: Human Digestive System
Moreover, the accessory glands play an invaluable role in the food digestion as humans consume a variety of foods containing various nutrients. As humans are omnivorous, there are a lot of proteins and fats being ingested, and these will have to be digested properly. The presence of gall bladder facilitates the digestion of animal fats from the food. In addition, humans do not feed on many seeds, unless it is tasty or prepared by softening the hard cellulose parts. Thus, there is no adaptation in the human digestive tract to breakdown cellulose.
What are the Similarities Between Rat and Human Digestive System?
- Both rat and human digestive systems have three main parts: salivary glands, oral cavity, and abdominal cavity.
- Since both rats and humans are omnivores, their digestive systems can digest both plants and animal foods.
- They are the same in size, proportionally to their respective body sizes.
What is the Difference Between Rat and Human Digestive System?
The key difference between rat and human digestive system is that rat digestive system does not have a gallbladder while human digestive system has a gallbladder. Another difference between rat and human digestive system is the fermentation chamber to digest seeds containing cellulose. Rats have a fermentation chamber to digest cellulose while humans do not have a fermentation chamber. Moreover, the human digestive system is physically large compared to the systems in rats. Rats have a specialized digestive system, whereas humans have a simple system. This is another important difference between rat and human digestive system.
Summary – Rat vs Human Digestive System
Rat digestive system does not have a gallbladder while human digestive system has. On the other hand, rat digestive system has a fermentation chamber to digest cellulose while human digestive system does not have a fermentation chamber. This is the key difference between rat and human digestive system. Other than these two differences, there is a difference in size as well since human digestive system is larger than the rat digestive system.
Reference:
1. Dworken, Harvey J., et al. “Human Digestive System.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 29 Nov. 2018, Available here.
Image Courtesy:
1. “41529” (CC0) via Pixabay
2. “Wistar rat digestive system” By Museum of Veterinary Anatomy FMVZ USP / name of the photographer when stated (CC BY-SA 4.0) via Commons Wikimedia