vertebrate digestive system
Quick Summary
The vertebrate digestive system is a complex pathway responsible for breaking down food into absorbable nutrients and eliminating waste. It begins with the mouth, where food is ingested and mechanically broken down by teeth and mixed with saliva. From there, it travels through the pharynx and esophagus to the stomach.1
The stomach, a saclike organ, stores food and begins chemical digestion, particularly of proteins and fats, by secreting enzymes and hydrochloric acid. In humans, the stomach is divided into four regions: fundus, body, antrum, and pylorus, each with sphincters to control food passage. The stomach churns food into a semi-fluid mixture called chyme.2
Following the stomach, food enters the small intestine, the primary site for digestion and nutrient absorption. The small intestine is further divided into the duodenum, jejunum, and ileum. Accessory organs like the pancreas and liver (with its gallbladder) contribute digestive juices to the duodenum. The remaining undigested material moves into the large intestine, where water is absorbed, and waste is formed before elimination through the anus. Different vertebrates exhibit variations in their digestive systems, such as multi-chambered stomachs in ruminants or gizzards in birds, adapted to their specific diets.312
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birdMuscles and organsThe avian digestive system shows adaptations for a high metabolic rate and flight. Enlargements of the esophagus, collectively called the crop, permit the temporary storage of food prior to digestion. The stomach is typically divided into a glandular proventriculus and a muscular gizzard, the latter lying near…
Read MoreThe avian digestive system shows adaptations for a high metabolic rate and flight. Enlargements of the esophagus, collectively called the crop, permit the temporary storage of food prior to digestion. The stomach is typically divided into a glandular proventriculus and a muscular gizzard, the latter lying near…
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anseriformPhysiology…known about the physiology of digestion in waterfowl. It appears that, despite being almost entirely grazers, geese lack the ability to digest cellulose, either by the secretion of enzymes or by the symbiotic activities of microorganisms in the gut. Such inefficient digestion is probably correlated with the extraordinarily rapid passage…
Read More…known about the physiology of digestion in waterfowl. It appears that, despite being almost entirely grazers, geese lack the ability to digest cellulose, either by the secretion of enzymes or by the symbiotic activities of microorganisms in the gut. Such inefficient digestion is probably correlated with the extraordinarily rapid passage…
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dogDigestive systemDogs rarely chew their food. Once the food is taken into the mouth, it is gulped or swallowed and passed through the esophagus into the stomach, where digestive enzymes begin to break it down. Most of the digestion and absorption of food takes…
Read MoreDogs rarely chew their food. Once the food is taken into the mouth, it is gulped or swallowed and passed through the esophagus into the stomach, where digestive enzymes begin to break it down. Most of the digestion and absorption of food takes…
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feeding behaviourRegulation of food intakeSecondly, the capacity of the digestive system may set a limit on nutrient supply to the body. There is evidence that this is so in the minute filter-feeding crustacean Daphnia magna. Such limitations are known to play a role in human feeding behaviour.
Read MoreSecondly, the capacity of the digestive system may set a limit on nutrient supply to the body. There is evidence that this is so in the minute filter-feeding crustacean Daphnia magna. Such limitations are known to play a role in human feeding behaviour.
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giant pandaNatural history…giant panda has retained the digestive system of its carnivore ancestry and is therefore unable to digest cellulose, a main constituent of bamboo. Pandas solve this problem by rapidly passing prodigious quantities of the grass through their digestive tracts on a daily basis. As much as 16 out of every…
Read More…giant panda has retained the digestive system of its carnivore ancestry and is therefore unable to digest cellulose, a main constituent of bamboo. Pandas solve this problem by rapidly passing prodigious quantities of the grass through their digestive tracts on a daily basis. As much as 16 out of every…
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reptileDigestive and urogenital systemsThe digestive system of modern reptiles is similar in general plan to that of all higher vertebrates. It includes the mouth and its salivary glands, the esophagus, the stomach, and the intestine and ends in a cloaca. Of the few specializations…
Read MoreThe digestive system of modern reptiles is similar in general plan to that of all higher vertebrates. It includes the mouth and its salivary glands, the esophagus, the stomach, and the intestine and ends in a cloaca. Of the few specializations…
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