Define Gastrointestinal tract & their roles?

The gastrointestinal tract, also known as the digestive system, is a series of organs that work together to break down food, absorb nutrients, and eliminate waste from the body. The main organs of the gastrointestinal tract include the mouth, esophagus, stomach, small intestine, large intestine, and anus.

The roles of the gastrointestinal tract include:

1. Ingestion: The process of taking in food through the mouth.

2. Digestion: The breakdown of food into smaller molecules that can be absorbed by the body. This process is carried out by enzymes in the stomach and small intestine.

3. Absorption: The process of absorbing nutrients, such as carbohydrates, proteins, fats, vitamins, and minerals, from the digested food into the bloodstream.

4. Motility: The movement of food through the gastrointestinal tract, which is facilitated by muscle contractions.

5. Secretion: The release of digestive enzymes, acids, and other substances that aid in the digestion and absorption of food.

6. Elimination: The removal of waste products from the body through the rectum and anus in the form of feces.

Overall, the gastrointestinal tract plays a crucial role in maintaining the body's energy levels, supporting growth and development, and promoting overall health and well-being.

Definition:

The gastrointestinal (GI) tract is a series of organs that work together to digest food, absorb nutrients, and eliminate waste.

Organs and Roles:

1. Mouth:

- Entry point for food
- Initial chewing and saliva secretion
- Begins chemical digestion with salivary enzymes (amylase)

2. Esophagus:

- Muscular tube that transports food to the stomach
- Impedes reflux with its lower esophageal sphincter

3. Stomach:

- Muscular sac that stores and churns food
- Produces gastric juices (hydrochloric acid and pepsin) that break down proteins and kill bacteria
- Controls passage of food to the small intestine

4. Small Intestine:

- Longest part of the GI tract, coiled in the abdomen
- Primary site of nutrient absorption
- Lined with villi (microscopic finger-like projections) that increase surface area for absorption

a. Duodenum:
- Receives food from the stomach
- Neutralizes stomach acid with secretions from pancreas and liver
- Contains enzymes (trypsin, chymotrypsin) that break down proteins

b. Jejunum:
- Main site of nutrient absorption
- Specialized cells transport glucose, amino acids, and fatty acids into the bloodstream

c. Ileum:
- Completes absorption of nutrients and water
- Prepares undigested material for elimination

5. Large Intestine (Colon):

- Absorbs water and electrolytes from undigested food
- Forms and stores waste (feces)
- Contains beneficial bacteria that aid in digestion and produce vitamins

6. Rectum:

- Stores feces until it is ready to be expelled
- Controlled by anal sphincters

7. Anus:

- Final opening of the GI tract
- Passageway for elimination of waste