Module 4 - Digestion and Elimination

Question 1

what are the 6 digestive functions?

Answer 1

1. Ingestion – Intake of food
2. Secretion – Water, acid, buffers, enzymes
3. Mixing/Propulsion – Moving the food
   through the GI tract
4. Digestion – Breakdown of food
5. Absorption – Passage of nutrients into the
   blood and lymph
6. Defecation – Elimination of the “leftovers”

Question 2

what are the big ideas of digestion?

Answer 2

1. Digestion is a north to south process.
2. The big three organs from a nutritional
   standpoint are:
   - Stomach
   - Pancreas
   - Gallbladder
3. Digestion is fundamental to nutritional
   therapy.
   **Every cell that makes up every tissue that makes up every organ depends on the body’s Digestive System to provide the nutrients it needs to keep on functioning.

Question 3

describe how digestion starts north

Answer 3

1. Digestion begins in the brain.
   – The sight and smell of food triggers the
   salivary glands to begin producing saliva.
2. The mouth is the physical gateway to the digestive system.
   – Mechanical and chemical breakdown
   of the food begins.

Question 4

describe how digestion works in the mouth

Answer 4

1. The teeth physically break down food into smaller parts (mastication).
2. The salivary glands secrete saliva to moisten the food and help with
   swallowing.
   – Saliva = 99.5% water + 0.5% solutes
   – One solute is the enzyme, salivary amylase, which begins the chemical breakdown of carbohydrates.

Question 5

describe how digestion continues south from the mouth to the stomach

Answer 5

1. When you swallow, bolus enters the esophagus for passage to the stomach.
   – The cardiac sphincter at the bottom of the esophagus opens to allow the bolus to pass into the stomach.
2. The stomach continues the mechanical
   breakdown of food, along with a number of
   chemical activities.

Question 6

describe digestion in the stomach

Answer 6

1. Bolus enters the stomach.
2. Gastric juice is secreted from millions of tiny gastric glands located in the mucosal lining of the stomach.
   – Mucous
   – Pepsinogen/Pepsin
   – Hydrochloric Acid (HCl)
3. HCl and pepsinogen begin breaking down proteins into peptides (smaller strings of amino acids).
4. HCl triggers gastrin to be released into the bloodstream.

Question 7

describe how digestion travels from the stomach to the small intestines

Answer 7

1. After the stomach churns the bolus and
   mixes it with gastric juice, the food breaks
   down even more into a paste called chyme
   (very acidic).
2. Chyme is released into the upper part of
   small intestine (duodenum) through the pyloric sphincter.

Question 8

describe digestion in the small intestine

Answer 8

1. Chyme enters the duodenum.
2. The acidic pH (1.5-3.0) of the chyme
   triggers the small intestine to secrete mucous.
3. The small intestine has a dual role as a digestive organ and a gland.
4. At the same time the intestinal walls are
   secreting mucous, they are also secreting two hormones into the bloodstream:
   – Secretin
   – Cholecystokinin (CCK)
5. Secretin stimulates the pancreas to release bicarbonate and pancreatic
   juice, and CCK stimulates the gallbladder to release bile.
   – Bile is necessary to emulsify and absorb fats.
   – As part of the pancreatic juice, the pancreas first releases sodium bicarbonate to help raise the pH of the chyme to neutral (7.0).
   – Once the chyme pH reaches neutral, the enzyme portion of the pancreatic juice is released to complete the chemical digestion of carbohydrates, proteins, and fats.
6. By the time chyme leaves the duodenum, it is almost totally digested:
   – Carbohydrates are broken down into glucose molecules.
   – Proteins are broken down into amino acids and polypeptides.
   – Fats are broken down into fatty acids and glycerol molecules.
7. Peristalsis moves these absorbable molecules into the jejunum.
8. Millions of villi and macrovilli absorb the nutrient molecules into the bloodstream, where they are carried to the entire
   body:
   – Glucose, amino acids, and short-chain fatty acids are carried by the villi to the
   capillaries and into the liver.
   – Long-chain fatty acids require bile for proper absorption and end up in the lymphatic system.

Question 9

describe how digestion goes from the small to large intestine

Answer 9

The leftover chyme from the small intestine
(indigestible fibers, bile, water, sloughed off cells) gets passed on to the large intestine
through the ileocecal valve.

Question 10

describe digestion in the large intestine

Answer 10

The large intestine:
– Recycles the water
– Recycles the waste material, which nourishes the colon cells
– Captures any lost nutrients that are still
available (with the help of the bowel flora) and converts the nutrients to Vitamins K/B1/B2/B12 and butyric acid.
– Forms and expels feces.