Digestive System of the Pig: Anatomy and Function
Click here to learn about fighting cancer. The stomach is a muscular organ responsible for storage, initiating the breakdown of nutrients, and passing the digesta into the small intestine. Chickens fed only commercially prepared feed do not need grit. There's the flush we were talking about! PapayaPro also contains other immune boosting and important ingredients such as mangosteen powder that act synergistically with the papaya powder. In addition, the sodium bicarbonate serves a vital role to provide alkalinity so chyme can be transported though the small intestine without causing cell damage because of the low pH after leaving the stomach.
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An animal's body breaks down food through both mechanical and chemical means. Chemical action includes the release of digestive enzymes and fluids from various parts of the digestive system. After being released from food during digestion, nutrients are absorbed and distributed throughout the animal's body. The chicken has a typical avian digestive system. Figure 1 shows a chicken digestive tract, and Figure 2 shows the location of the digestive tract in the chicken's body.
As with most birds, a chicken obtains feed by using its beak. Food picked up by the beak enters the mouth. Chickens do not have teeth, so they cannot chew their food. However, the mouth contains glands that secrete saliva, which wets the feed to make it easier to swallow. The esophagus is a flexible tube that connects the mouth with the rest of the digestive tract. It carries food from the mouth to the crop and from the crop to the proventriculus.
The crop is an out-pocketing of the esophagus and is located just outside the body cavity in the neck region see Figure 3. Swallowed feed and water are stored in the crop until they are passed to the rest of the digestive tract. When the crop is empty or nearly empty, it sends hunger signals to the brain so that the chicken will eat more. Although the digestive enzymes secreted in the mouth began the digestion process, very little digestion takes place in the crop—it is simply a temporary storage pouch.
The crop evolved for birds that are typically hunted by other animals but need to move to the open to find feed. Occasionally, the crop becomes impacted, or backed up. This problem—called crop impaction, crop binding, or pendulous crop—can occur when a chicken goes a long time without feed and then eats too much too quickly when feed is available again. Crop impaction also can occur when a chicken free-ranges on a pasture of tough, fibrous vegetation or eats long pieces of string.
With crop impaction, even if a chicken continues to eat, the feed cannot pass the impacted crop. The swollen crop also can block the windpipe, causing the chicken to suffocate. The esophagus continues past the crop, connecting the crop to the proventriculus.
The proventriculus also known as the true stomach is the glandular stomach where digestion primarily begins. Hydrochloric acid and digestive enzymes, such as pepsin, are added to the feed here and begin to break it down more significantly than the enzymes secreted by the salivary glands.
Two views of the proventriculus and gizzard from a chicken digestive tract. Jacquie Jacob, University of Kentucky. Consumed feed and the digestive juices from the salivary glands and proventriculus pass into the gizzard for grinding, mixing, and mashing.
Inside of a chicken gizzard, with the internal lining removed. When allowed to free-range, chickens typically eat small stones. The stones remain in the gizzard until they are ground into pieces small enough to pass to the rest of the digestive tract.
Grit, a commercial product made up of small stones, can be used as a supplement to chicken feed. Chickens fed only commercially prepared feed do not need grit. Grit should not be confused with limestone or oystershell, which are given to laying hens as sources of calcium for their eggs' shells.
When a chicken eats a small, sharp object, such as a tack or staple, the object is likely to get stuck in the gizzard. Because of the strong grinding motion of the gizzard's muscles, such sharp objects can put holes in the gizzard wall. Chickens with damaged gizzards grow thin and eventually die.
Preventing this situation is a good reason to keep a poultry house free of nails, glass shards, bits of wire, and so on. The small intestine is made up of the duodenum also referred to as the duodenal loop and the lower small intestine.
The remainder of the digestion occurs in the duodenum, and the released nutrients are absorbed mainly in the lower small intestine. The duodenum receives digestive enzymes and bicarbonate to counter the hydrochloric acid from the proventriculus from the pancreas and bile from the liver via the gall bladder. The lower small intestine is composed of two parts, the jejunum and the ileum. The Meckel's diverticulum marks the end of the jejunum and the start of the ileum see Figure 6.
In the egg, the yolk sac supplies the nutrients needed for the embryo to develop and grow. Right before hatch, the yolk sac is taken into the navel cavity of the embryo. We have digestive juices that contain enzymes that speed up the chemical reactions in the body and break down food into nutrients.
There are also cells in the lining of the stomach and small intestine; these cells produce and release hormones that stimulate digestive juices and regulate our appetite. We also have nerves that control the digestive system. We have nerves within the GI tract that are triggered when there is food present, and this allows our digestive system to work properly. According to the ideas of Eastern medicine, exercise and a healthy diet can benefit the body only if the spleen is able to transmit nutrition and energy to the muscles, and a person with deficient spleen function will often experience weakness and fatigue.
It separates usable and unusable fluids that we consume daily. The spleen has the power to transform food and liquids into energy , which is then transported to our organs and enables the proper function of our entire body — this is why the spleen is seen as playing a central role in nourishing our bodies and promoting development.
When you swallow, your food pushes into the esophagus, the muscular tube that carries food and liquids from the mouth to the stomach. Once swallowing begins, it becomes involuntary and proceeds under the control of the esophagus and brain. Spleen — The spleen is a brown, flat, oval-shaped lymphatic organ that filters and stores blood to protect the body from infections and blood loss. It helps fight infection and keep body fluids in balance.
The spleen is in charge of cleaning impurities from the blood, destroying old red blood cells and storing blood in case of emergency, such as an injury.
Stomach — The stomach acts as a storage tank for food so that the body has time to digest large meals properly. This central organ not only holds the food, it also works as a mixer and grinder. The stomach contains hydrochloric acid and digestive enzymes that continue the digestion of food that began in the mouth. Enzymes and acids mix with the food that has already begun to break down in the mouth and esophagus, and it turns into a liquid called chyme.
Hydrochloric acid is a clear, colorless and highly pungent solution of hydrogen chloride in water. Liver — The liver is the second largest organ in the body, and it has many different functions. But the main function of the liver in digestion is the production of bile and its release into the small intestine. The liver makes and secretes bile, which helps enzymes in the body to break down fats into fatty acids.
After we absorb nutrients through our small intestines, it then enters the bloodstream. This blood is sent to the liver for filtering and detoxification. The liver has the amazing ability to break down and store amino acids, synthesize and metabolize fats and cholesterol, store glucose, detoxify the blood and regulate our internal functions.
The gallbladder sits just under the liver and stores bile that is made in the liver, which then travels to the gallbladder through a channel called the cystic duct. The gallbladder stores bile between meals, and when we eat, the gallbladder squeezes bile through the bile ducts, which connect the gallbladder and liver to the small intestine. Pancreas — The pancreas is a spongy, tube-shaped organ that is about six inches long.
It secretes digestive enzymes into the small intestine, and this completes the chemical digestion of foods. Pancreatic juice is capable of digesting lipids, carbohydrates creating energy , proteins creating amino acids for building and nucleic acids. Both enzymes and hormones are needed to keep the body and digestive system working properly.
The pancreas connects to the liver and the gallbladder with the common bile duct. As pancreatic juices are made, they flow into the main pancreatic duct, and then join the common duct — which allows the bile which helps to digest fat break down food before it reaches the small intestine. When the chyme our juices that are being digested leaves the stomach, it enters the small intestine through the pyloric sphincter — a muscle that serves as a valve and prevents the regurgitation of food from the intestine back into the stomach.
It transforms from an acidic environment to an alkaline one, which means that the acids are neutralized. The small intestine is lined with very small protrusions that increase the surface area of the intestinal wall, which creates a larger absorption area.
Each protrusion, called villi, is covered in smaller hair-like structures, which are called microvilli. Enzymes exist on the villi, helping further break down nutrients into a readily absorbable form. It is the job of the villi that help prevent leaky gut. Leaky gut is when the bowel lining is damaged.