Ch 14 - Human Digestive System Flashcards
Why do we need carbohydrates?
They provide our body with energy.
What are sources of carbohydrates?
- starch (rice, bread, cereal)
- sugars (glucose in fruit, sucrose in sweets)
Why do we need protein?
- grow and repair damaged tissues in our body
- provide energy
What are sources of protein?
- animal - fish, meat, egg white, cheese
- plant - soya beans, nuts
Why do we need fats?
- provide our body with energy
- keep our body warm
What are sources of fats?
- butter, margarine
- cooking oil
- coconut
Why does food need to be digested?
- Molecules of nutrients (starch, protein fats) are too large to pass through the cell membrane.
- Must first be broken down into small molecules.
What is digestion?
The breaking down of large, insoluble and complex food molecules into smaller, simpler and soluble molecules in the body.
The digestion of food begins in the…
MOUTH 👄
What is the starting and ending point for digestion?
start: mouth
end: small intestine
What is physical digestion?
It involves mechanical break up of food into smaller particles.
What are two types of physical digestion?
- chewing
- churning action
What is chemical digestion?
It involves break down of large molecules into small soluble molecules that can be absorbed.
What are enzymes?
Biological catalysts that speed up chemical reactions without changing itself at the end of the reactions.
Enzymes only react with…
substances that have a complementary shape to their molecules.
What are substances that react with enzymes called?
substrates
Lipase is effective in removing what type of dirt?
grease dirt
Protease is effective in renoving what type of dirt?
protein dirt
What are the organs in the alimentary canal?
- mouth
- esophagus
- stomach
- small intestine
- large intestine
- anus
What organs help in digestion (but are not in the alimentary canal)?
- liver
- gall bladder
- pancreas
Describe the physical digestion in the mouth?
The teet cut and grind food into smaller pieces –> increases surface area for digestion
Describe the chemical digestion in the mouth.
Salivary amylase digests starch into maltose.
What can be digested in the mouth?
carbohydratess (only)
Are enzymes present in the oesophagus?
NOPE 🙅 NUH UH
Describe the chemical digestion in the oesophagus.
Salivary amylase continues to digest starch into maltose.
What does gastric juice contain?
hydrochloric acid & protease
What does hydrochloric acid do?
- kills microorganisms
- provide an acidic environment for protease to work effectively
Describe the chemical digestion in the stomach.
Protease digests large protein molecules into polypeptides.
Describe the physical digestion in the stomach.
When the stomach churns, it helps to break down the food into smaller pieces.
What can be digested in the stomach?
protein
What enzymes are released in the small intestine?
- small intestine releases intestinal juice
- pancreas releases pancreatic juice
What substance is released in small intestine.
(SIMONE) BILE[s] 🩵
What is bile?
- substance made in the liver
- stored in gall bladder before being released
Describe the chemical digestion of carbohydrates in the small intestine.
- amylase digests remaining starch into maltose
- maltase digests maltose into glucose
Which one is more acidic/alkaline?
gastric juice OR intestinal/pancreatic juice
- more acidic: gastric juice
- more alkaline: intestinal/pancreatic juice
Describe the chemical digestion of proteins in the small intestine.
- protease digests remaining protein into polypeptides
- protease digests polypeptides into amino acids
Describe the digestion of fats in the small intestine.
- bile emulsify fats into small fat droplets (physical)
- lipase digest small fat droplets into glycerol and fatty acids (chemical)
What can be digested in the small intestine?
- carbohydrates
- proteins
- fats
What reaches the large intestine?
Food that cannot be digested.
As food passes through the large intestine…
some of the remaining water and mineral salts are absorbed
What is stored in the rectum?
the undigestible material (faeces)
What can be digested in the large intestine?
NOTHING 😔
What is the use of glucose in the body?
To provide energy during cellular respiration.
What is the use of amino acids in the body?
To grow new cells, to repair damaged tissues.
What is the use of fatty acids and glycerol in the body?
To make fats and keep u warm.
