Digestive System Flashcards
How much of our bodies are composed of water?
65%
What percent of water makes up the composition of certain tissues and organs
60%-90%
List four functions of water
1) dilutes waste substances and transports them out of bodies
2) Acts as an important dissolving agent or solvent, so that substances can be transported within bodies and through cell membranes
3) functions as a lubricant (saliva, mucous)
4) acts as a temperature regulator (as perspiration evaporates from the skin)
List four ways that water can enter the body.
1) absorbing it
2) drinking it
3) entering bodies from the food of a plant or animal
4) dehydration synthesis
What is ingestion?
The process of taking in nutrients into a body.
What is the first stage of digestion?
Physical or Mechanical
What happens during the first stage of digestion?
-chewing or grinding of food is done to make a smaller form
What do the churning and grinding actions of the stomach or gizzard do?
Help breakdown further (phase 1)
What is phase two of digestion?
Chemical
What is the main component of chemical breakdown (phase two)?
Enzymes
What are hormones used for in the second stage of digestion?
To stimulate the enzyme secreting glands to help in digestion.
What are the three main functions of the human digestive system?
1) Injest food
2) break food down so nutrients can be ansorbed
3) eliminate what cannot be digested
What do we digest?
- proteins
- carbs
- lipids
What happens when we digest proteins?
Amino acids are absorbed through the what and carried into the what?
- Proteins are broken down into component amino acids in the stomach and small intestines
- Amino acids absorbed into blood stream through small intestine and carried to various body cells
What happens when we digest carbs?
Where are simple carbs absorbed?
- Complex carbs are broken down into simple carbs in the stomach, small intestine, and mouth
- Simple carbs are absorbed in the small intestine and circulated throughout the body by the blood
What happens when we digest lipids?
Where are lipids digested?
Fatty acids are absorbed in the what?
Fatty acids are broken down where?
- Digested in the small intestine into fatty acids and glycerol
- Fatty acids are absorbed in the small intestine and circulated in the blood throughout the body.
- Fatty acids are broken down in the liver to acetic acid
What is acetic acid?
Source of fuel for liver-produces acetone as byproduct.
What is acetic acid?
Acitic acid is a source of fuel for liver. Produces acetone as byproduct.
What parts of the mouth begin mechanical digestion? How do they do this?
- The tongue and the teeth
- They crush the food into smaller pieces
What glands supply saliva and mucous? Where are they located? What is the purpose of the saliva and mucous?
- The salivary glands and mucous glands
- They are located along the cheeks
- The mucous and saliva helps moisten and break up food
What enzyme does saliva have? What does this enzyme begin?
- Amylase
- Begins the chemical digestion of starches
What takes place after the food is broken up?
-Swallowing
What happens once food is in the esophagus?
-Muscular movements called peristalsis moves the bolus downward through the cardioesopjageal sphincter into the stomach.
What is stage one of digestion?
The mouth
What is stage two of digestion?
The stomach
What happens in the stomach?
-Both physical and chemical digestion occur
How many muscle layers make up the stomach walls?
three muscle layer
What are these muscles called?
- circular
- longitudinal
- oblique
What do the muslces that line the stomach wall do?
Cause rhythmic contractions along the stomach’s length resulting in the mixing of food, mucous, acid, and enzymes.
What is the pH in the stomach?
2
What do the glands in the stomach do?
Secret chemicals called gastric juices due to neural and hormonal factors.