Human Nutrition: Digestion & Related Systems – Grade 11 Review

A comprehensive set of question-and-answer flashcards covering mechanical and chemical digestion, enzymes, digestive organs and their functions, tooth structure and decay, nutrient absorption, the roles of the liver and pancreas, and common malnutrition disorders.

What is digestion?

The process of breaking large, complex food molecules into smaller, soluble ones that can be absorbed into the bloodstream.

Name the two main types of digestion.

Mechanical digestion and chemical digestion.

What is mechanical digestion?

The physical breakdown of food into smaller pieces without changing its chemical structure.

Give two examples of mechanical actions in the mouth.

Chewing by the teeth and rolling food into a bolus by the tongue.

Which muscular process moves food down the oesophagus?

Peristalsis.

Why does mechanical digestion increase enzyme efficiency?

It increases the surface area of food for enzymes to act on during chemical digestion.

List one reason dietary roughage (fiber) is important.

It speeds up movement of food, stimulates peristalsis, absorbs water and excess fats, and decreases constipation.

What is chemical digestion?

The enzymatic breakdown of large molecules such as starch, proteins, and fats into smaller, soluble molecules.

Which enzyme begins carbohydrate digestion in the mouth?

Salivary amylase.

What substrate does salivary amylase act on, and what is the product?

Starch → Maltose.

Name the main protease active in the stomach.

Pepsin.

What activates pepsin in the stomach?

Hydrochloric acid (HCl).

Besides activating pepsin, give another role of HCl in the stomach.

It kills bacteria present in food.

Which hormone stimulates secretion of gastric juice?

Gastrin.

What is the function of mucin (mucus) in the stomach?

It protects the stomach lining from acid and digestive enzymes.

Name three digestive enzymes produced by the pancreas.

Pancreatic amylase, proteases (e.g., trypsin), and lipase.

What does pancreatic lipase break down and into what products?

Lipids (fats) → Fatty acids and glycerol.

What is the role of bile in digestion?

It emulsifies fats, mechanically breaking them into smaller droplets to aid enzyme action.

Where is bile produced and where is it stored?

Produced in the liver; stored in the gallbladder.

What valve controls food entry from the oesophagus to the stomach?

The cardiac sphincter (cardiac valve).

Which valve regulates chyme release from the stomach to the duodenum?

The pyloric sphincter.

Name the first section of the small intestine.

Duodenum.

Which section of the small intestine is the main site of nutrient absorption?

Jejunum.

Which section of the small intestine absorbs vitamins and bile salts?

Ileum.

What structural features of the small intestine increase surface area for absorption?

Folds, villi, and microvilli (brush border).

What nutrient types enter the lacteals of villi?

Fatty acids and glycerol (fats).

Which blood vessel carries nutrient-rich blood from the small intestine to the liver?

The hepatic portal vein.

Define assimilation.

The process by which absorbed nutrients are taken up by body cells for use or storage.

Give one way the liver helps regulate blood glucose levels.

Converts glucose to glycogen for storage (glycogenesis) or converts glycogen back to glucose (glycogenolysis).

What toxic substance is produced when the liver breaks down excess amino acids?

Urea.

Name two vitamins stored in the liver.

Any two of: Vitamins A, D, E, K, or B12.

What are the two main endocrine hormones of the pancreas and their basic functions?

Insulin lowers blood glucose; glucagon raises blood glucose.

Which cells of the pancreas secrete insulin?

Beta cells of the Islets of Langerhans.

What is peristalsis?

Rhythmic contractions of the muscular walls of the digestive tract that propel food forward.

Which teeth are specialized for cutting and biting food?

Incisors.

How many premolars does an adult typically have?

Eight.

What is the hardest substance in the human body that covers the tooth crown?

Enamel.

What causes tooth decay (dental caries)?

Acid produced by bacteria feeding on sugars dissolves enamel, creating cavities.

Give one method to prevent tooth decay.

Brush with fluoride toothpaste, floss regularly, limit sugary foods, visit the dentist, or eat calcium-rich foods.

What is the role of the epiglottis during swallowing?

It prevents food from entering the trachea (windpipe).

Which part of the large intestine stores faeces before elimination?

Rectum.

What vitamin is commonly produced by bacteria in the large intestine?

Vitamin K (also some B vitamins).

Define malnutrition.

A condition resulting from a diet lacking the right quantity or balance of nutrients, including undernutrition and overnutrition.

Which deficiency disease is caused by lack of vitamin D?

Rickets.

Name the protein-deficiency disease characterized by a swollen belly in children.

Kwashiorkor.

Which mineral deficiency leads to anaemia?

Iron deficiency.

What hormone does the stomach release that increases acid secretion and motility?

Gastrin.

Which digestive organ secretes bicarbonate to neutralize stomach acid entering the duodenum?

Pancreas.

What is the main mechanical function of bile despite not being an enzyme?

Emulsification of fats to increase surface area.

Which enzyme converts maltose to glucose in the small intestine?

Maltase.

What is the primary function of salivary glands?

Produce saliva that moistens food and begins starch digestion with amylase.

Which muscular tube connects the throat to the stomach?

Oesophagus.

Name the finger-like projections inside the small intestine that contain capillaries and lacteals.

Villi.

What term describes the mixture of food and gastric juice in the stomach?

Chyme.

List one function of the pancreas as an exocrine gland.

Secretes pancreatic juice containing digestive enzymes into the duodenum.

How does insulin lower blood glucose?

It promotes uptake of glucose by body cells and stimulates storage of glucose as glycogen in the liver.

Which part of the colon moves waste horizontally across the abdomen?

Transverse colon.

What is the role of mucus in saliva?

Lubricates food for easier chewing and swallowing.

What nutrient deficiency causes scurvy?

Vitamin C deficiency.

Which valve prevents acid reflux by closing after food enters the stomach?

Cardiac sphincter.