60 lines
2.9 KiB
Markdown
60 lines
2.9 KiB
Markdown
The primary roles of the digestive system are:
|
|
- breakdown of food into nutrients
|
|
- absorption of nutrients
|
|
- elimination of solid waste products
|
|
Digestion is the process of breaking down large food molecules into nutrients that the body can use
|
|
Absorption is the uptake and removal of nutrients from the digestive tract.
|
|
- The digestive tract is also called the gastrointestinal tract (GI), alimentary canal, or gut
|
|
# The GI tract
|
|
## Order
|
|
1. Mouth
|
|
1. Digestion starts here for carbohydrates and fats (not proteins)
|
|
2. Salivary glands are structures that produce saliva and secrete the fluid in the oral cavity
|
|
3. Saliva is the watery fluid that contains mucus and enzymes
|
|
1. Lysozyme - Destroys some bacteria that are in the food or mouth
|
|
2. Salivary Amolase
|
|
3. Lingual Lipase
|
|
4. Taste buds have specialized cells that help distinguish five basic tastes
|
|
5. You lose taste buds as we age. Older people have fewer taste buds than younger people.
|
|
2. Esophagus*
|
|
1. The esophagus is a flap of tough tissue that prevents the food from entering the larynx and the trachea
|
|
2. **Peristalsis** is the wave of muscular contraction that helps move material through most of the digestive tract. It's an involuntary response to swallowing
|
|
3. By relaxing and contracting, the muscles can mix substances, in the lumen and control movement through the tract
|
|
3. Stomach*
|
|
1. The stomach is a muscular sac that stores and mixes food
|
|
2. Gastric glands located in the stomach synthesize and secrete gastric juice
|
|
1. Gastric juice is a mix of mucus, hydrochloric acid, intrinsic factor, and digestive enzymes
|
|
4. Small intestine (DJI)
|
|
1. Duodenum
|
|
2. Jejunum
|
|
3. ileum*
|
|
5. Large intestine
|
|
6. Rectum
|
|
7. Anus
|
|
## Sphincters
|
|
Sphincters are thickened regions of circular muscle that control the flow of contents at various points in the GI tract.
|
|
- Contracted:
|
|
- Passageway closed
|
|
- Flow is restricted
|
|
- Essential for normal digestion and absorption
|
|
There are 3 main sphincters associated with digestion:
|
|
1. Gastroesophageal/lower esophageal/cardiac - connects the esophagus to the stomach
|
|
2. Pyloric - connects the stomach to the duodenum (small intestine)
|
|
3. ileocecal valve - Connects the small intestine to the large intestine
|
|
The upper esophageal sphincter is at the top of the esophagus (not as important).
|
|
|
|
# Digestion
|
|
**Mechanical digestion refers to the physical treatment that food undergoes** while it is in the intestinal tract
|
|
|
|
Chemical digestion refers to the breakdown of large molecules in food into smaller components, primarily by the action of **enzymes**.
|
|
- Enzymes are a protein that speeds up the rate of a chemical reaction without being altered in the process.
|
|
- Enzymes usually end in -ase and begin with the name of whatever they are working to digest:
|
|
- Amylase digests amylose
|
|
- Maltase digests maltose
|
|
|
|
|
|
# Definitions
|
|
| Phrase | Definition |
|
|
| ------ | --------------------------------------------- |
|
|
| Lumen | The open space inside of the digestive system |
|