Chapter 14 - Digestive Systems Flashcards
Why do we need a digestive system?
As undigested food is too large & insoluble, it needs to broken down so that the nutrients in it can be absorbed by our body and used by our body cells.
What nutrients does food contain?
Carbohydrates, proteins, fats.
What is the function of carbohydrates?
It provides an immediate source of energy and helps with the formation of faeces.
What is the function of proteins?
It repairs worn-out cells and makes new cells for body growth.
What is the function of fats?
It keeps the body warm against heat less and stores our energy.
Where does the human digestive system start and end?
It starts from the mouth and ends at the anus.
What happens when food moves down the digestive tract?
It is broken down into small soluble molecules by a combination of physical and chemical processes.
What is the physical process of digestion?
Food is broken down into smaller pieces by physical or mechanical means such as crushing, grinding and mixing.
What is the chemical process of digestion?
Food is broken down into small molecules through enzymes.
What are enzymes
Enzymes are biological molecules produced by the digestion system which speed up the breakdown of large food molecules into smaller molecules.
What are the three types of enzymes?
Carbohydrases, proteases, lipases
What is the function of carbohydrase?
They speed up the breakdown of carbohydrates into simple sugars (also knowns as glucose).
What is the function of protease?
They speed up the breakdown of proteins into amino acids.
What is the function of lipase?
They speed up the breakdown of fats (also known as lipids) into fatty acids or glycerol.
Where does all digestion end?
Small intestine
What happens when molecules get broken down?
They get broken down into smaller molecules to be absorbed.
How does the mouth go through digestion ?
Physical digestion - The strong teeth and jaw muscles cut and crush the food in smaller pieces.
Chemical digestion - As saliva in the mouth contains carbohydrases, partial digestion of starch begins in the mouth.
What are other functions of the mouth when undergoing digestion?
Saliva softens and lubricates the food for easier swallowing.
How does the gullet go through digestion?
Although the gullet does not release any digestive juice, starch from the mouth continues to be digested by carbohydrases that are mixed with the food.
The muscles of the gullet push food towards the stomach.
How does the stomach undergo digestion?
Physical digestion: The stomach churns food into smaller pieces.
Chemical digestion: Stomach releases gastric juice that contains proteases to digest proteins.
What is the function of gastric juice in the stomach?
It contains hydrochloric acid which kills harmful microorganisms to provide proteases the right condition to act.
What is the function of the stomach’s layer of mucus?
The stomach has a thick layer of mucus to protect it’s tissue from damage caused by hydrochloric acid and proteases in gastric juice.
What do the muscles at both end of the stomach control?
The muscles at both ends of the stomach control the food entering and leaving the stomach.
How does the small intestine undergo digestion?
It doesn’t go through physical digestion but chemical digestion.
Fats are first digested due to presence of lipases in digestive juices.
Carbohydrates, proteins and fats are fully digested here.
