Digestive System of the human body is perhaps the most recognized part of all of the body systems as it entails knowledge about food intake – something we are all aware of. The digestive system consists of a group of organs which work together to convert food into energy and extract nutrients to feed the body as well as to excrete waste material.
The human body needs to digest food and use the energy so that it is able to function efficiently, repair itself and remain healthy.
The major physiology functions taking place within the digestive system are as follows:
Ingestion: This is quite simply the intake of food through the mouth. The amount of food in the mouth is an indication of how much the body can handle at any given time.
1. Secretion: About 7 litres of fluid is secreted by the body each day and include saliva (serves to moisten dry food), mucus (forms a protective barrier and lubricant within the GI tract), enzymes (breaks down protein, carbohydrates and lipids into smaller parts), bile (break down large lipids) and hydrochloric acid (digests food chemically and kills bacteria in the food).
2. Mixing and Movement: 3 main processes are used for this process.
A). Swallowing: The oral cavity including teeth and tongue are used to chew and push food through the pharynx and into the esophagus
B). Peristalsis: A muscular wave of movement helping to move partially digested food down the tract. This movement helps to move the food from the esophagus through the stomach and intestines.
C) Segmentation: This is the gentle squeezing movements of the small intestine to allow for increased absorption of nutrients.
4. Digestion: This is the entire method of breaking down food from the mouth right through the stomach and excretion at the end. In effect two processes are taking place simultaneously and that is the mechanical as well as the chemical breakdown of food. The whole process involves all the body organs are described in the anatomical section below.
5. Absorption: The absorption process takes place in the stomach. Substances which are absorbed directly into the blood stream include water and alcohol. After this the walls of the small intestine absorb much of the nutrients. Finally in the large intestine any remaining water and nutrients mainly vitamins B and K are absorbed before the remaining waste is excreted from the body.
6. Excretion: This is the final part of the digestive system and involves defecation of waste matter. The body needs to remove this waste matter to keep the gut clear from indigestible substances.
The anatomy of the Digestive System consists of the following components:
Another name for the mouth is oral cavity. To aid the intake of food the following parts help: teeth, tongue and the salivary glands. Once the teeth have cut the food into small chunks with the help of the moisture from the saliva, the tongue and together with other muscles help to push the food into the pharynx. The teeth are sharp and grinding and the tongue has taste buds which help to give food the taste and texture we deserve. There are 3 sets of salivary glands which also help with the digestion of carbohydrates. This lubrication is also used by the body throughout the mouth, pharynx and esophagus.
Better known as the throat, it has the responsibility of passing food from the back of the mouth down to the esophagus. The pharynx plays a vital part in the respiratory system and this is finely balanced between allowing air through the air valve and food through the other one. This is where the divider of the two known as the epiglottis acts as a switch between food valve and the air valve known as the larynx plays a vital role. Occasionally when we experience choking that is when the epiglottis has not made the switch effectively.
This serves as a connective tube between the pharynx and the stomach. It is constructed of a muscular tube. The role of the esophagus is to push the food into the stomach and the bottom part known as the cardiac sphincter keeps the esophagus closed thus preventing food from escaping the stomach.
The location of the stomach is on the left side of the abdominal cavity, near the diaphragm. As a muscular sac, the role of the stomach is to act much like a storage tank while the body has time to digest large meals properly. The hydrochloric acid combined with the digestive enzymes break down the food further within the stomach itself to help digestion.
In the form of a hose and taking up most of the physical space in the abdominal cavity, the small intestine forms part of the lower gastrointestinal tract. As a coiled long thin tube, but with the ridges and folds allowing for more area space, the role of this intestine is to maximize the absorption of nutrients in the food during this stage of digestion.
LIVER AND GALLBLADDER
Weighing 3 pounds and triangular in shape, the liver, located to the right of the stomach, has many different functions. As the second largest organ of the body its main function is to produce and secrete bile into the small intestine.
By comparison the smaller pear shaped gallbladder has the role of storing and recycling excess bile from the small intestine in order for reuse in the digestion of forthcoming meals.
The pancreas is connected to the duodenum from the head end and the tail end pointing to the abdominal cavity. In order to complete the chemical digestive process of food, the pancreas secretes digestive enzymes into the small intestine. The length is 6 inches and it is short and lumpy in appearance.
This is a longer and thicker tube than the small intestine and wraps around parts of the smaller intestine. This part of the digestive system contains symbiotic bacteria which helps the break-down of waste to help absorb the remainder of the nutrients. It also absorbs water. What is left is the waste called faeces which exits through the anal canal.
Digestive System Image Source: www.infovisual
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