Advertisement Upgrade to remove ads

Anatomical flow through the GI tract

Mouth, espohagus, stomach, small intestine (pancreas, gall bladder & liver dump into sm int), and large intestine

Four accessory organs to the GI tract

Salivary glands, pancreas, liver, gallbladder

Three main functions of the GI tract

Digestion, absorption, elimination


Breakdown of lg food molecules to smaller by the means of
Physical (mechanical) and chemical


Process of taking digested products through the intestinal wall into the intestinal cell and then releasing into the body


Undigested portions of food and waste products are removed from the body

Chemical digestion

Breakdown of nutrients by digestive enzymes

Chemical digestion requirement

Emzymes and water for hydrolysis to breakdown the different macronutrients (bonds)

Breaks down food to create increased surface area


Control center for the digestive process

Brain and CNS

Enzymes are....

Macronutrient specific


Lipid enzyme

Carbohydrase (amylase)

CHO enzyme


Protein enzyme

Function of sphincters

Control the flow of food from one digestive organ to the next.
Circular muscles that close off one digestive organ from another


Wave like muscular contractions that propel digesting food forward through the GI tract


Muscular action causing physical digestion of food by breaking down into smaller pieces


Segmentations in the colon that contract sluggishly to move contents

Mass movement

Occurs in large intestine to move waste towards the rectum


Physiological equilibrium or stability - normal body function

Regulates feelings of hunger and fullness / digestive system



Physiological desire (need) for food - non specific (any food will do)


Desire to consume specific foods - due to smells, stress eating, sensoral or emotional need for food


Need for food yet no appetite


Sensation of fullness from eating - satisfied need for hunger and appetite


Hormone produced by the stomach to stimulate gastric acid production to reach a pH of 1.5


Hormone produced by sm intestine and released into the blood in response to presence of acidic chyme

Stimulates production and secretion of pancreatic fluids



Hormone produced by the small intestine and released into the blood in response to fat and proteins

Stimulates the secretion of bile from the gall bladder and digestive fluids from the pancreas while slowing GI mobility


Digestive steps that occur in the mouth

Physical - chewing & tongue mixes saliva and food
Chemical - Salivary amylase digests complex CHO (grains, veggies, beans, nuts and seeds)

Food that is chewed up, moist and ready to swallow


Digestive steps in the stomach

Physical - Muscles churn bolus into chyme
Chemical 1 - HCL denatures protein
Chemical 2 - Pepsin digest protein into smaller chains

Food in the stomach that is digested and ready to move to the small intestine


Protective secretion in stomach that protects against HCL

Mucus layer and production of bicarbonate

Digestive steps of small intestion

P - Segmentation
C 1 - Pancreatic bicarbonate to neutralize HCL
C 2 - Bile emulsifies (mixes) fat and water (liver & gall bladder)
C 3 - Pancreatic enzymes digest macronutrients
C 4 - Small intestinal cells produce disaccarides & peptisases

Pancreatic enzymes

Lipase, amylase and protease


Fat bus


Fat pad around abdominal wall

What organ receives fat first


Digestive steps in the large intestine

P - Stool digestion
C - Gut bacteria (digest soluble fiber)


Process of taking molecules across a cell membrane and into cells of the body

What part of the GI tract is responsible for the greatest amount of absorption

Small intestine / duodenum - due to its structure

Small intestine folds that increase absorption and surface area


Form brush border which increases surface area more


Three mechanisms of absorption

Diffusion, Facilitated diffusion and Active absorption


Requires no energy and has no transporter - inefficient absorption of nutrients

Facilitated diffusion

Requires no energy but has a transporter - more efficient than diffusion

Active absorption

Requires ATP and has a transporter for nutrient - most effective
(glucose and amino acids)

Water soluble macronutrients

CHO and protein

Water soluble micronutrients

B Vits and Vit C

Water soluble nutrient path as leave intestine and released to body cells

Bloodstream and taken to liver via portal vein then heart

Fat soluble macronutrients

Lipids and triglycerides

Fat soluble micronutrients

Vits A, D, K, and E

Fat soluble nutrient path as leaves intestine and released to body cells

Transported through the lymph, bypasses liver and directly to heart and then ultimately the blood

Fat soluble nutrients are transported

Packaged into chylomicrons and released into the lymph

Water soluble nutrients are transported

Freely or bound to a carrier in the blood

Cells use nutrients for a....

Functional or structural purpose

Protects from HCL backflow

Gastro-esophageal sphincter

Prevents HCL from entering into the small intestive

Pyloric Sphincter

Primary systems responsible for regulating digestion and absorption

Nervous - provide sensory info - distention and muscle action
Endocrine - hormonal regulation of digestion by GI & brain (hypotha)

In brain above pituitary gland


Cephalic phase

Starts before 1st bite - hunger feeling/ body ready to receive food, thoughts of food stimulate release digestive enzymes, olfactory receptors detect aroma and trigger organs to be ready to receive food

Highest satiation value


Enzyme that breaks down starches

Salivary amylase

Gastric juices contain

HCL (denature protein & activates pepsin), pepsin (digest protein), gastric liapase (digest fat), and intrinsic factor

Intrinsic factor

Protein to absorb vitamin B 12


End product of stomach digestion

Produces bile


Stores bile

Gall bladder

Cholescytokinin (CCK)

Stimulates the gallbladder to release bile and the liver to produce more bile

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording