Digestive System flashcards

What is the purpose of digestion?

To break down large, insoluble food molecules into smaller, soluble molecules that can be absorbed into the bloodstream for energy release or building new molecules.

What are the two types of digestion?

Mechanical and chemical

What is mechanical digestion?

The physical breakdown of food.

What is chemical digestion?

The breakdown using enzymes and acids

What happens in the mouth?

The teeth break food into smaller pieces to increase surface area. Amylase from saliva begins breaking down starch into maltose.

What is the function of the salivary gland?

To secrete saliva containing amylase which starts the digestion of carbohydrates.

What is the oesophagus?

A muscular tube connecting the mouth to a stomach where contractions push food down.

What happens in the stomach?

Food is churned and protease enzymes begin breaking down proteins

What does the liver do in digestion?

The liver produces bile which emulsifies fates and neutralises stomach acid.

What is the function of the gallbladder?

The gallbladder stores bile and reduces it into the small intestine.

What does the pancreas produce?

Amylase, protease and lipase enzymes.

What happens in the small intestine?

Enzymes complete digestion and bile neutralises the stomach acid. The villi absorb the nutrients.

What is absorbed in the large intestine?

Water is reabsorbed from remaining undigested material forming faeces.

What is the role of bacteria in the large intestine?

Bacteria form a microbial ecosystem that digest substances we can’t and it supplies nutrients.

What types of tissue are found in the stomach?

Glandular tissue which secretes enzymes , acid and mucus. Muscle tissue contracts for churning food. Epithelial tissue lines and protects the stomach wall.

What are enzymes?

Biological catalysts that speed up chemical reactions in living organisms without being used up.

What is the structure of an enzyme?

Proteins made up of amino acid chains are folded into specific shapes with an active site.

What is the lock and key theory?

The substrate acts as a key and fits into the enzymes active site (lock) where the reaction occurs.

How does temperature affect an activity of enzymes?

If the temperature is below optimum there is less kinetic energy so fewer collisions. If it is above optimum the enzyme denatures and the active site changes shape which means the substrate cannot lock.

How does pH affect enzymes?

Each enzyme has an optimum pH , extreme pH’s break bonds and the active site changes shape (denaturation)

What do Carbohydrases do?

Break down carbohydrates into simple sugar.

What do amylase do and where are they produced?

Break down starch into maltose. Amylase are made in the salivary glands, pancreas and the small intestine.

What does maltase do?

Breaks down maltose into glucose in the small intestine.

What do proteases and where are they produced?

Break down proteins into amino acids. Proteases are made in the stomach , pancreas and small intestine.

What do lipases do and where are they produced?

Break down lipids into glycerol and fatty acids. Lipases are produced in the pancreas.

What are the two main functions of bile?

Bile neutralises stomach acid and emulsifies fats.

How does emulsification help digestion?

Increases surface area so lipase enzymes can work more efficiently

What is glucose used for after digestion?

It’s used in respiration to release energy.

What are glycerol and fatty acids used for?

To build cell membranes , energy stores and some hormones.

What is a qualitative food test?

A test that shows if a certain type of molecules is present or absent based on a visible result.

How do you prepare a food sample?

Crush food with a pestle and mortar and mix with distilled water. Filter with filter paper.

What is the colour of a positive result in a Benedict’s test?

Brick red.

What is the colour of a positive result in an Iodine test?

Blue-black colour.

What is the colour of a positive result in a biuret test?

Purple/lilac colour.

What is the colour of a positive result in a test for lipids (emulsion test) ?

White/cloudy

What safety precautions are needed during food tests?

Wearing googles, avoiding skin contact and keep ethanol away from flames.

How do you test for sugars using Benedict’s solution?

Add food solution into the test tube and add an equal volume of Benedict’s solution , heat the mixture in a water bath for 5 minutes.

How do you test for starch using Iodine solution?

Add food solution into the test tube and add a few drops of iodine solution.

How do you test for protein using the Biuret test?

Add food solution to a test tube and add sodium hydroxide and few drops of copper sulphate and gently shake.

How do you test for lipids using the emulsion test?

Add food solution to a test tube, add ethanol and shake then add an equal volume of cold distilled water.

What does the duodenum do? (Small intestine)

It continues the digestion of carbohydrate and protein and starts the digestion of lipids.

What does the lleum do? (Small intestine)

Completes the digestion of carbohydrates and proteins into single sugars and amino acids, it absorbs the single sugars, amino acids and fatty acids and glycerol.