The Human
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In humans, the most evolved species on earth, the digestive tract is around 5 meters – 9 meters and is composed of upper and lower digestive tract. The path of food through the alimentary canal is as follows:-
Mouth → Food pipe or esophagus → stomach → small intestine → large intestine → excreted
The above path can be divided into three parts:-
Digestion: complex molecules of food are broken down to simpler ones by the saliva, gastric juice, bile and pancreatic juice.
Absorption: Essential and needed components of the food are absorbed from it in the small intestine
Excretion: The waste food not containing nutrients is excreted away.
Components of Digestive System
In view of the diverse metabolic requirement of human body the digestive system is at its highest anatomical order. The flow of the food from mouth to the intestine in a proper and systematic manner is due to the proper arrangement of components in digestive system.
The digestive system is split as Upper and Lower gastrointestinal tract to understand in a better way. The upper gastrointestinal tract is composed of mouth cavity, pharynx, esophagus, stomach, and duodenum. The lower digestive tract is mainly with intestine and anus. The lower digestive system composed of intestine is the key component in the alimentary canal and is responsible for assimilation and absorption of the food that is digested in stomach. It is also responsible for secretion of intestinal juices which are poured into stomach to enhance the digestion.
It includes the following
Small Intestine: Includes 3 parts such as Duodenum, jejunum and ileum.
Large Intestine: Also includes 3 parts: Cecum, Colon, and Rectum.
Mouth → Food pipe or esophagus → stomach → small intestine → large intestine → excreted
The above path can be divided into three parts:-
Digestion: complex molecules of food are broken down to simpler ones by the saliva, gastric juice, bile and pancreatic juice.
Absorption: Essential and needed components of the food are absorbed from it in the small intestine
Excretion: The waste food not containing nutrients is excreted away.
Components of Digestive System
In view of the diverse metabolic requirement of human body the digestive system is at its highest anatomical order. The flow of the food from mouth to the intestine in a proper and systematic manner is due to the proper arrangement of components in digestive system.
The digestive system is split as Upper and Lower gastrointestinal tract to understand in a better way. The upper gastrointestinal tract is composed of mouth cavity, pharynx, esophagus, stomach, and duodenum. The lower digestive tract is mainly with intestine and anus. The lower digestive system composed of intestine is the key component in the alimentary canal and is responsible for assimilation and absorption of the food that is digested in stomach. It is also responsible for secretion of intestinal juices which are poured into stomach to enhance the digestion.
It includes the following
Small Intestine: Includes 3 parts such as Duodenum, jejunum and ileum.
Large Intestine: Also includes 3 parts: Cecum, Colon, and Rectum.
The Cat
![Picture](/uploads/1/1/5/0/11503558/109171767.jpg)
Cats are carnivores (meat eaters) and have become highly adapted predators. Domestic cats are well evolved for hunting small prey such as birds and small mammals like mice, although the occasional adventurous cat may try to hunt larger prey such as young rabbits.
The digestive system is responsible for the processing of food by the body, breaking it down and absorbing all the nutrients before expelling indigestible elements and other waste products. Digestion starts in the mouth, where cats take in food and begin to chew. Their teeth are specially adapted to their role as hunter. The large, sharp canines are used for grabbing prey and biting, whilst the sharp molars are adapted for tearing meat. The liver and pancreas are also part of this system, with a role in producing factors required to digest food as well as many other vital jobs.
The digestive system is responsible for the processing of food by the body, breaking it down and absorbing all the nutrients before expelling indigestible elements and other waste products. Digestion starts in the mouth, where cats take in food and begin to chew. Their teeth are specially adapted to their role as hunter. The large, sharp canines are used for grabbing prey and biting, whilst the sharp molars are adapted for tearing meat. The liver and pancreas are also part of this system, with a role in producing factors required to digest food as well as many other vital jobs.
The Bird
![Picture](/uploads/1/1/5/0/11503558/582513748.jpg)
The digestive process is as follows: The food taken into the mouth is swallowed and passes through the oesophagus into the stomach, assisted in its descent by the secretions of the salivary and mucous glands. When there is a Crop, it is therein mixed with saliva and water, and assisted by the heat of the body is softened and acted upon in a preliminary way. It then enters the stomach, where it meets with the secretions of the proventricular or gastric glands. But besides being acted upon chemically it is crushed and triturated in the gizzard, especially in graminivorous and granivorous birds, which possess a strong muscular stomach. Thus comminuted it is known as "chyme," and passes through the pylorus into the small intestine, in the first loop of which, the "duodenum," it is mixed with the bile and pancreatic juice, these two fluids being the secretions of the liver and the pancreas. Their principal action is to convert its soluble parts into "peptones", which are to be conveyed into the Lymphatic System, and so into the blood. Their absorption as chyle is effected by numerous "villi" or projections which line the walls of the whole Canal from the pylorus to the cloaca. At the beginning of the rectum the caeca, when such are functional, receive the remaining chyme, and it is probable that in them certain hitherto undissolved matter, as cellulose and possibly chitin, is acted upon by methane, so as to extract as much nutrition as possible from the food. After remaining a due time in the caeca, their contents return to the rectum, and are finally ejected through the cloaca as faeces.