The Digestive System Flashcards
Salivary amylase
Breaks down starch into simple sugars which is a chemical digestion
Bolus
As the bolus enters the esophagus the epiglottis covers the trachea ( windpipe )
Esophagus
The muscular portion of the GI tract through which peristalsis occurs
Peristalsis
Wave like muscular contractions which pushes the bolus down
Stomach
- can hold 2-4L of food, peristalsis is physical digestion in the stomach
- gastric juices mix with the food producing chyme
- gastric juices is made up of water , mucus and salts
Pepsin
Protein digesting enzyme found in the stomach
Why does the stomach not digest it’s own proteins
- It secretes littler gastric juice until food is present
- Some stomach cells produce mucus which prevents gastric jucies from harming the cells of the stomach lining
- Pepsin is produced in the form of pepsinogen that remains inactive until hydrochloric acid is present
Small intestine
Main function is to finish digestion of macromolecules and begin absorption of the subunits of macromolecules into the blood stream
- measures 7m in length
- segmentation is an example of physical digestion
Duodenum
- first segment, majority of digestion occurs here
- jejunum and ilium are the second and third segments of the small intestine
- when food reaches the small intestine is is covered in hydrochloric acid and pepsin
The small intestine protects itself from the acid by the following
- Acid entering the small intestine prosecretin to secretin
- Secretin is absorbed into the blood stream and is carried to the pancreas where bicarbonate ions are released
- By the way of the pancreatic duct, these ions raise the pH to 9
Villi and microvilli
Finger like projections which increase the surface area of the small intestines
The outer cell membranes of the cell are folded and these are the microvilli
Pancreas
Contain enzymes to break down proteins, carbs, and lipids
