Process of breaking down foods to a form the body can use
Uptake of nutrients to the blood or lymph.
Innermost layer of the GI tract, lumen
Second inner most layer of GI tract, has blood vessels carrying nutrients
Muscle (GI tract)
Third layer in GI tract, moves food forward
Outermost layer in GI tract, protects the tract
Lower Espoghagial Spincter
prevents backflow of stomach to espoghagus
controls flow of stomach acid into small intestine
Spincter of Oddi
Controls flow of bile from common bile duct into small intestine
Prevents contents in large intestine from re entering small intestine
Prevents defecation until person chooses to
Contractions to move matter along the tract
Produced in the mouth, helps swallow, lubrication to mouth
Originates in mouth, stomach, small, large intestine. Helps protect GI tract and lubricates food.
Enzymes ex Amylase and Lipase
Happen in mouth, stomach, small intestine, pancreas. Help digest carbs, fats and proteins.
Acid ex HCl
introduced in the stomach, helps digest proteins and destroys microorganisms, and helps digest minerals.
Made in liver, stored in gall bladder, digests fat.
In the pancreas and small intestine, helps eliminate stomach acid for the small intestine
Hormones (digestion secretions)
Stomach and small intestine, helps digest and absorb nutrients
Saliva is composed of three things...
- lysozomes: break down bacteria
- mucus: lubricates and holds bolus together
- Amylase: breaks down starch
- olfactory (smell)
Gastric Inhibitory Peptide
slows release of chyme into small intestine and regulates pyloric spincter
What do Parietal Cells secrete into stomach?
What do chief cells secrete into stomach?
Gastic lipase and pepsinogen
What does Gastrin Do?
Hormone that controls the release of HCl and pepsinogen, releases when we think about food
What does Mucus secrete into stomach?
Mucus protects stomach from digesting itself
What does HCl do?
- inactivates protein
- destroys bacteria and virus
- converts pepsinogen into pepsin
- absorbs minerals
What does pepsinogen do?
Helps digest proteins (enzyme)
pH Scales examples
- Acids: lemon juice, vinegar, HCl, urine
- neutral: pure tears
- basic: NaOH, oven cleaner, Pancreatic juices
What is stomach acid stimulated by?
- Gastrin, a hormone
- stomach distention
- histamine, a regulator
- thoughts of food
- food itself
What does the liver do?
Produces bile, circulates and recycles bile
What does gall bladder do?
What does Pancreas do?
Produces bicarbonate, lipases, amylase
What do digestive enzymes do?
- speed up chemical reactions
- each has a specific function
- controlled by hormones and nerves
- released as needed
Order of digestion in the small intestine
- 1. enzymes secreted from pancreas
- 2. sugar break down from sacchrides to mono, microvilli brush the border
- 3. bile from the gall bladder, bicarbonate ions and enzymes from pancreas enter
- 4. segmentation mixes food with juices
- 5. 3-10 hrs later, food moves out. (95% digested)
What are the hormones of the GI Tract?
What are the types of absorption in the small intestine?
- Passive: fat, no energy, high to low conc, permeable wall
- Facilitated: carrier brings nutrients to cell, no energy, vitamins, high to low
- Active: ATP, energy required, glucose
- Endocytosis: phagocytosis
What do beneficial bacteria do in large intestine?
control pathogens, synthesize vitamin K and biotin, aid in lactose digestion and fermentation