the human digestive system

digestion

The process by which the body breaks down food into smaller components that can be absorbed and utilized for energy, growth, and cell repair.

what enzymes are present in the saliva?

the enzyme amylase breaks down starch into sugars

the oesophagus

The oesophagus moves food from the mouth to the stomach using peristalsis (muscular contractions).

What does the stomach do in digestion?

The stomach produces gastric juices that contain hydrochloric acid and enzymes like pepsin to break down proteins.

Why is hydrochloric acid important in the stomach?

It provides an acidic environment (pH 1-2) for pepsin to work and kills harmful bacteria.

What happens in the small intestine?

The majority of digestion and absorption of nutrients happens in the small intestine. Enzymes from the pancreas and bile from the liver help break down food.

What is the role of the pancreas in digestion?

The pancreas produces digestive enzymes (like amylase, lipase, and protease) and bicarbonate to neutralize stomach acid entering the small intestine.

What is the role of the liver in digestion?

The liver produces bile, which is stored in the gall bladder and released into the small intestine to emulsify fats (break them into smaller droplets).

What happens in the large intestine?

The large intestine absorbs water and minerals from undigested food, turning it into solid waste. It also contains bacteria that help break down remaining food.

What are enzymes and why are they important in digestion?

Enzymes are biological catalysts that speed up chemical reactions. In digestion, they break down large food molecules into smaller, absorbable molecules.

Name some key digestive enzymes.

• Amylase (breaks down starch into sugars)

• Protease (breaks down proteins into amino acids)

• Lipase (breaks down fats into fatty acids and glycerol)

What is the active site of an enzyme?

The active site is the specific region of an enzyme where the substrate (the substance being acted upon) binds and the chemical reaction takes place.

Why is the shape of the enzyme important?

The shape of the enzyme’s active site is specific to the substrate it binds to. This is known as the lock and key model, where the enzyme is the lock and the substrate is the key.

What happens if the enzyme's active site is changed?

If the enzyme's shape is altered (e.g., due to extreme temperature or pH), the enzyme may no longer fit the substrate, causing it to lose its ability to function (denaturation).