Bleeding in the Gastrointestinal tract
Once food has been reduced to its building blocks, it is ready for the body to absorb. Absorption begins in the stomach with simple molecules like water and alcohol being absorbed directly into the bloodstream. Most absorption takes place in the walls of the small intestine, which are densely folded to maximize the surface area in contact with digested food.
The large pouch-shaped cecum marks the beginning of the colon. Attached near the cecum bottom is the vermiform (worm-like) appendix. The appendix contains lymphoid tissue and intercepts pathogenic microorganisms that enter the digestive tract. Sometimes, fecal matter may become trapped in the appendix, resulting in appendicitis (infection and inflammation). From the esophagus, the bolus passes through a sphincter (muscular ring) into the stomach.
Table 3 provides an overview of the basic functions of the digestive organs. Lipids are digested mainly in the small intestine by bile salts through the process of emulsification, which allows lipases to divide lipids into fatty acids and monoglycerides. In order for nutrients (carbohydrates, lipids, vitamins) to be absorbed for energy, food must undergo chemical and mechanical digestion.
The undigested food material enters the colon, where most of the water is reabsorbed. Recall that the colon is also home to the microflora called â€œintestinal floraâ€ that aid in the digestion process. The semi-solid waste is moved through the colon by peristaltic movements of the muscle and is stored in the rectum. As the rectum expands in response to storage of fecal matter, it triggers the neural signals required to set up the urge to eliminate. The solid waste is eliminated through the anus using peristaltic movements of the rectum.
Large, complex molecules of proteins, polysaccharides, and lipids must be reduced to simpler particles before they can be absorbed by the digestive epithelial cells. Different organs play specific roles in the digestive process. The animal diet needs carbohydrates, protein, and fat, as well as vitamins and inorganic components for nutritional balance. The digestive system ingests and digests food, absorbs released nutrients, and excretes food components that are indigestible. The six activities involved in this process are ingestion, motility, mechanical digestion, chemical digestion, absorption, and defecation.
The digestive system consists of the alimentary canal along which the food passes after eating to where the residual wastes are eliminated from the body, together with the liver and the pancreas. The digestive system is responsible for the ingestion of food, its breakdown into its constituent nutrients and their absorption into the blood stream, and the elimination of wastes from this process. The digestive system in the domestic fowl is very simple but efficient when compared to many other species, such as cattle. In the process of evolution, those avian species that developed simple but effective digestive systems were more able to fly and hence survive, as the simple digestive system would be lighter in weight. It is necessary that the diet provided to fowls be of high quality and easily digestible due to the simplicity in the structure and function of their digestive system.
The partially digested food enters the duodenum as a thick semi-liquid chyme. In the small intestine, the larger part of digestion takes place and this is helped by the secretions of bile, pancreatic juice and intestinal juice. An earthworm’s digestive system consists of a mouth, pharynx, esophagus, crop, gizzard, and intestine. The mouth is surrounded by strong lips, which act like a hand to grab pieces of dead grass, leaves, and weeds, with bits of soil to help chew.
Feces in the large intestine exit the body through the anal canal. Indigestible food delivered from the small intestine to the large intestine flows into the appendix and is forced out by contraction of the muscular walls of the appendix. A blockage in the opening where the appendix attaches to the large intestine can lead to inflammation of the appendix, known as appendicitis. This can cause acute pain, fever, nausea, vomiting and loss of appetite, but can be cured easily by removing the appendix. After the food moves through the small intestine it enters the large intestine.
Egestion – the removal of undigested food materials
This latter system enters the liver via two veins (one for each lobe). The two blood supply systems join together inside the organ.