The Digestive System
What 2 things have happened by the time Chyme are ready to leave the Small Intestine?
1. Complex organic molecules have been digested and absorbed 2. Only water, cellulose, and other undigestible substances are left behind
What 2 things do the Gastric Glands in the lining of the Stomach release?
1. Hydrochloric Acid 2. Pepsin
Which teeth cut and tear the food?(3)
1. Incisors 2. Cuspids 3. Bicuspids
In what 4 phases is food processed through the Digestive System?
1. Ingestion 2. Digestion 3. Absorption 4. Elimination
What 3 functions does the Pancreas serve?
1. It produces hormones that regulate blood sugar levels 2. It produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids 3. It produces sodium bicarbonate
Which 4 enzymes are in the small intestine?
1. Maltese 2. Sucrase 3. Lactase 4. Peptidase
In what 2 ways is food broken down to be absorbed?
1. Mechanical Digestion 2. Chemical Digestion
Which 3 Enzymes are released from the pancreas into the small intestine?
1. Pancreatic Amylase 2. Trypsin 3. Lipase
What 2 things can be absorbed across the stomach?
1. Water 2. Alcohol
What is the Alimentary Canal?
A 1-way tube which passes through the body
What is Sodium Bicarbonate?
A base that quickly neutralizes stomach acid as chyme enters the duodenum
What is a Bolus?
A clump of food made by the tongue and throat muscles which is pushed down the esophagus
What is the Epiglottis?
A flap of connective tissue
What is Bile?
A fluid loaded with lipids and salt which helps break down fat
What is Mucus?
A fluid produced by a stomach gland which lubricates and protects the stomach wall from pepsin
What is the stomach
A large muscular sac which continues chemical and mechanical digestion of food
What is Pepsin?
A protease enzyme that breaks down proteins and that works best in acidic conditions
What is the Cardiac Sphincter?
A thick ring of muscle which closes the esophagus after food passes through so the contents of the stomach don't come flowing back
What happens if the Mucus layer fails?
Acids may erode the stomach lining and cause a peptic ulcer
What is the digestive enzyme in Saliva?
Amylase
What is Lysosome?
An enzyme in saliva that fights infection by digesting the cell walls of many bacteria that enter the mouth with food
Why is the large intestine large?
Because of its diameter, not length
What begins the process of Mechanical and Chemical Digestion?
Chewing
What is Peristalsis?
Contractions of smooth muscles which provide the force that moves food through the esophagus toward the stomach
What are Villi?
Fingerlike projections that cover the small intestine
What happens during Digestion?
Food travels through the mouth, esophagus, stomach and small intestine
What is the result of stomach acid flowing back into the Esophagus?
Heartburn
Which bacteria usually causes Peptic Ulcers?
Helicobacter pylori
What hormones do the Pancreas produce?
Insulin
What does the Large Intestine do?
It absorbs water and several vitamins and prepares waste for elimination from the body
What does the liver do?
It assists the pancreas in fat digestion and produces bile
What does Amylase do?
It breaks down carbohydrates into simple sugars
What does Peptidase do?
It breaks down do peptides into amino acids
What does Lipase do?
It breaks down fat
What does Hydrochloric Acid do?
It breaks down food
What does Bile do to fat?
It breaks up the globs of fat into smaller droplets and breaks them down through mechanical digestion
What does Trypsin do?
It continues the breakdown of protein
What does Pancreatic Amylase do?
It continues the breakdown of starch
What does the Digestive System do?
It converts food into small molecules that can be used by the cells of the body
What does Saliva do?
It helps to moisten the food and make it easier to chew
What does Chewing do to the surface area of food?
It increases the surface area
What does Chyme do in the Duodenum?
It mixes with enzymes and digestive fluids from the pancreas, the liver, and the lining of the duodenum
What does the Chyme do after it passes through the Duodenum?
It moves along the rest of the small intestine as a rich mixture of small and medium sized nutrient rich molecules that are ready to be absorbed
How does Feces leave the body?
It passes through the rectum and is eliminated from the body through the anus
Why does the Epiglottis cover the Trachea?
It prevents food from moving into the air passageways to the lungs as it passes through the pharynx and into the esophagus
What does the Appendix do?
It processes cellulose and other materials
What teeth grind and crush food?
Molars
What is the Pyloric Sphincter?
The 'gateway' between the stomach and small intestine which allows the chyme to pass through after 1-2 hours
How does the Bolus travel down the throat?
The Bolus enters the pharynx as the epiglottis closes over the trachea so the bolus can travel down the esophagus and into the stomach
Where does the Chyme go after it passes the Pyloric Sphincter?
The Duodenum
What controls the Salivary Glands?
The Nervous System
What is the Digestive System built around?
The alimentary canal
What do materials pass from the small to the large intestines?
The appendix
What is the Pharynx?
The area at the back of the throat
Where are the products of Carbohydrate and Protein digestion?
The capillaries of the villi
What is Feces?
The concentrated waste material that remains after most of the water has been removed
How does Chemical Digestion begin?
The digestive enzymes in saliva start the breakdown of complex carbohydrates into smaller molecules
Why does Elimination occur?
The digestive system cannot digest and absorb all food products that enter the body
What is the Duodenum?
The first of 3 parts of the small intestine where all the digestive enzymes enter the intestine
Where is Bile stored?
The gallbladder
Where does Chyme go when it leaves the small intestine?
The large intestine, or colon
Where are fats and fatty acids absorbed?
The lymph vessels
What happens after food is absorbed through the Small Intestine?
The molecules enter the circulatory system, which transports them throughout the body.
What is Chyme?
The oatmeal-like substance made from swallowed food
What is Mechanical Digestion?
The physical breakdown of large pieces of food into smaller pieces
What is Ingestion?
The process of putting food into your mouth
Where does Absorption occur?
The small intestine
What does the tongue do?
The tongue moves food around so it comes in contact with your teeth
Why is there cartilage in the Trachea but not the Esophagus?
The trachea needs to stay open at all times where the esophagus needs to contract
What is the Trachea?
The windpipe
What do alternating stomach contractions allow?
They allow enzymes greater access to the food and churn and mix the swallowed food
What do Maltase, Sucrase, and Lactase do?
They break down remaining disaccharides into monosaccharides
What do the Salivary Glands do?
They secrete saliva
How is Nutrients absorbed?
Through the walls of the small intestine
What are Microvilli?
Tiny projections that cover the villi which provide enormous surface area for absorption of nutrient molecules
What is the primary function of the Large Intestine?
To remove/absorb water from the undigested material that is left
What is Chemical Digestion?
When enzymes break down food into small molecules the body can use
What is Elimination?
When some materials travel through the large intestine and are eliminated from the body as feces
When does the Gallbladder release Bile?
When there is fat in the duodenum bile is released though a duct in the small intestine
What happens if too much water is absorbed by the large intestine?
constipation
What happens if not enough water is absorbed by the large intestine?
diarrhea
