Physiology and Function 2: Upper GI Tract

Six Major Functions of the Digestive System:

● Ingestion
● Mechanical processing
● Digestion (which is our chemical processing)
● Secretion (another topic that has come up quite a bit on the Message Board)
● Absorption (which is the uptake of our nutrients)
● Excretion

*Ingestion occurs materials enter the digestive tract via the mouth.
Mechanical processing is the crushing and tearing of food that makes it easier to mobilize through and along the digestive tract. The function of mechanical processing is to increase the surface area of the food by breaking it down. This makes the food particles susceptible to enzyme reach or activity, some might call it more accessible to enzyme attack.

Four major Physiological Aspects of the Digestive System:

● the Cephalic Phase
● the Esophageal Phase
● the Gastric Phase
● the Intestinal Phase

Example of Mechanical Processing:

• Shearing and mashing with the teeth
• Compaction and squashing with the tongue
• Peristalsis in the esophagus
• Swirling, mixing, and churching in the stomach and the intestines
  

*Liquid Foods – need less mechanical processing than solid foods *

• These are all mechanical processes. They require the use of muscles
  

Digestion Function = Chemical as opposed to the mechanical breakdown of food.

• Chemical breakdown splits the food molecules into small organic fragments that are suitable for digestion
• Simple molecules can be absorbed in the bloodstream intact. Ie: glucose, amino acids, and fatty acids
• Molecules the size of proteins or peptides,(chains of amino acids) polysaccharides (long branches of sugar), and triglycerides (branches of fats attached to a glycerol molecule)
• These cannot be absorbed into the bloodstream intact
• Molecules from food must be chemically disassembled by digestive enzymes in order for absorption to take place.
  Example: Starches or sugars from a potato has no nutritional value until the enzymes in the mouth and small intestine (where carbohydrate digestion happens) have broken them down into simple sugars that the body can absorb and distribute to the cells
  

SECRETION FUNCTION = The release of several substances from the digestive tract and glandular organs. Substance that we secrete include:

• Water
• Acids
• Enzymes
• Buffers
• Salts
  

Water = a component of most foods we eat. Most abundant in plant foods.

Acids = Common in the stomach

Enzymes = Proteins that act like keys

Buffers = Compounds that stabilize the PH balance

Salts = Bile salts that are secreted by the liver and gall bladder

Absorption = Things that move from the outside world of the tube inside you and keep traveling through that tube into the bloodstream

*The major organ of absorption is the small intestine. The blood is continuously washing the exterior of the small intestine so that it can make more room for more nutrients. It sweeps those particles away to the liver for cleansing and cleaning

Nutrients are absorbed in 1 of 3 ways:

• Simple diffusion (like the fatty acids that pass through freely)
• Facilitated diffusion (such as the water-soluble vitamins that hitchhike onto a carrier to get transported into the bloodstream)
• Active transport for the glucose and amino acid molecules that require some energy for that facilitated diffusion to take place
  

*Electrolytes = ion that the ability to conduct electricity. They’re always present in the human body and their balance is essential for the normal function of our cells and organs.

Electrolytes:

• Minerals
• Sodium
• Potassium
• Chloride

NOTE: BEST NATURAL SOURCE OF ELECTROLYTES = COCONUT WATER

EXCRETION FUNCTION = Removal of waste products (what we don’t need)

• This happens through defecation in the form of feces or poop
• Elimination is the best way for your body to clean up
• Food poop = poop coloration caused by the foods we ate
• Mood poop = Any symptoms that arise throughout the day (From crankiness to stomach ate)
  

*ART of the Practice = Assess. Recommend. Track (Food, Mood, Poop Journal)

Two Other Functions of GI:

• Protection
• Transit Time
  

PROTECTION FUNCTION = Protecting against acids or enzymes from getting into the bloodstream. It protects the rest of the body from mechanical processes. It protects against bacteria that enters the body from the food we eat, and protects the cells also (see barrier systems)
NOTE: SIBO = Small Intestine Bacteria Overgrowth – when bacteria crosses the barrier into the small intestine and causes problems.

TRANSIT TIME FUNCTION = The time it takes foods to assimilate, digest, and be excreted (The time depends on the physiology)
Time Factors Include:

• Meal composition
• Psychological stress
• Gender
• Endocrine Status
• Medication Taken
  

Food Combining Example: Body Ecology Diet (BED)

• Foods that are not incompatible may pass through the system at differing times and need different resources