The Digestive System

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The Digestive System by Mind Map: The Digestive System

1. Brief Description :

1.1. Absorbs nutrients and digests the food we eat The small intestine in an adult human measures on average 6 meters and is 2.5-3 meters wide. It is divided into three structural parts: -Duodenum -Jejunum -Iluem

2. Digestion

2.1. Digestive enzymes are secreted from the pancreas which are used to digest food

2.2. Proteins degrade into amino acids which are then split by enzymes.

2.3. Fats are degraded into fatty acids and glycerol.

2.4. Some carbohydrates are degraded into simple sugars while other carbohydrates pass undigested into the large intestine and further handling by intestinal bacterial.

2.5. Mechanical / Physical Digestion

2.6. Chemical Digestion

3. Absorption

3.1. The digested food come into contact with the many small blood vessels which surround the small intestine.

3.2. This blood then leaves the small intestine, carrying away nutrients, water electrolytes, vitamins, minerals, fats and medications to the entire body.

3.3. It can take 3-6 hours for a meal to pass through the small intestine.

4. Duodenum

4.1. A hollow jointed tube about 10–12 inch long connecting the stomach to the jejunum.

4.2. The duodenum is responsible for the breakdown of food in the small intestine, using enzymes.

4.3. Brunner's glands, which secrete mucus, are found in here.

4.4. It also regulates the rate of emptying of the stomach via hormonal pathways.

5. Jejunum

5.1. The inner surface of the jejunum is covered with villi, which increase the surface area of tissue available to absorb nutrients from the digested food.

5.2. Once the food is soaked into the villi, they are transported by the blood stream to the rest of the body.

5.3. The transport of nutrients includes the transport of sugar fructose, amino acids, small peptides, vitamins and glucose.

6. Ileum

6.1. The function of the ileum is mainly to absorb products of digestion that were not absorbed by the jejunum.

6.2. The wall of the ileum is made up of folds, each of which has many villi on its surface.

6.3. The ileum has an extremely large surface area both for the adsorption (attachment) of enzymes and for the absorption of products of digestion.

6.4. Undigested food are sent to the colon.

7. Steps of digestion

7.1. Ingestion – this is the consumption of or taking in of nutrients.

7.2. Digestion – the chemical breakdown of large organic molecules into smaller components by enzymes.

7.3. Absorption – the transport or delivery of digested nutrients to body tissues.

7.4. Assimilation-the conversion of absorbed food into the substance of the body.

7.5. Egestion – the elimination of food waste materials from the body.

8. Accessory Organs

8.1. Salivary gland

8.1.1. parotid glands - produce a serous, watery secretion.

8.1.2. submaxillary (mandibular) glands - produce a mixed serous and mucous secretion.

8.1.3. sublingual glands - secrete a saliva that is predominantly mucous in character.

8.2. Liver

8.2.1. The liver is a large accessory organ of the digestive system that is constantly producing a fluid known as bile.

8.2.2. Bile is stored in the gall bladder until it is needed in the small intestine.

8.3. gall bladder

8.3.1. The presence of lipids in the small intestine trigger the release of the hormone cholecystokinin (CCK) which triggers the release of bile from the gall bladder.

8.3.2. Bile contains bile salts that emulsifies fats which means it breaks them into smaller droplets so they can be digested.

8.4. Pancreas

8.4.1. The pancreas is an accessory organ of the digestive system. It releases chemicals to aid in digestion.

8.4.2. Secretin will stimulate the pancreas to release a solution containing bicarbonate ion into the small intestine where it will neutralize the acidic chyme and raise the pH from 2.5 to 9.0. This inactivates the pepsin.

9. Large intestine

9.1. About 5 feet long Accepts what small intestines don’t absorb Rectum (short term storage which holds feces before it is expelled).