Digestive System

Day 2 Notes

ingestion

the act of taking food and drink into the body by the mouth

digestion

the process of breaking down food into individual molecules small enough to be absorbed through the intestinal wall

absorption

the process of moving nutrients from the gastrointestinal (GI) tract into the bloodstream

transport

the process of moving absorbed nutrients throughout the body through the circulatory and lymph systems

elimination

the removal of undigested and unabsorbed food through the feces

stomach

What does -gastro mean?

gastrointestinal tract

* a 23-foot-long muscular tube comprised of the organs of the digestive tract
* extends from the mouth through the esophagus, stomach, and small and large intestines to the anus

sphincter

a ring of muscle surrounding and serving to guard or close an opening or tube, such as the anus or the opening of the stomach

saliva

dissolves small food particles

salivary amylase

enzyme in saliva which begins to break down carbohydrates

enzymes

biological catalysts that speed up chemical reactions in the body

epiglottis

the flap which covers the trachea so food and water don’t enter the windpipe

peristalsis

rhythmic contractions/waves of the GI tract

bolus

a ball-like moisture of food and saliva that forms in the mouth during the process of chewing

stomach

muscular bag that stores the food you eat and breaks it down even further into tiny pieces

5 hours

How long can the digestive process last in the stomach?

Proteins

What are the only macromolecules pepsin chemically breaks down in the stomach?

hydrochloric acid (HCI) and pepsin

What two things are released by the stomach during the digestive process?

chyme

food in the stomach right before it enters the small intestine

duodenum

the first part of the small intestine immediately beyond the stomach

small intestine

Where does the majority of digestion and nutrient absorption occur?

duodenum, jejunum, ileum

List the three sections of the small intestine

3-10 hours

About how long does it take for food to traverse the small intestine?

amylase

breaks starch/carbs down into glucose

protease

breaks proteins down into amino acids

lipase

breaks lipids/fats down into 3 fatty acids and 1 glycerol

villi

increase intestinal absorptive surface area approximately 30-fold providing exceptionally efficient absorption of nutrients in the lumen (surface area of the small intestine)

large intestine

site of water reabsorption

diarrhea

What does too little water reabsorption performed by the large intestine result in?

constipation

What does too much water reabsorption performed by the large intestine result in?

rectum

stores waste before it is released from the body

anus

relaxes to release waste from the body

liver

* manufactures bile that is used to digest fats/lipids
* the sight of alcohol and drug metabolism
* removes toxins
* produces cholesterol
* filters your blood

gallbladder

* receives bile
* releases bile into the small intestine

pancreas

* releases hormones to maintain blood glucose levels
* secretes digestive enzymes into the small intestine