Science 8 – Digestive System (Quarter 1 Module 1)

This set of question-and-answer flashcards reviews the structure, organs, and key functions of the human digestive system for Science 8, Quarter 1 Module 1.

What is the overall function of the digestive system?

To convert food and liquids into energy and basic nutrients for the body while eliminating waste.

Which three main processes make up digestion?

Breaking down food, absorbing nutrients, and eliminating waste.

What two major groupings make up the digestive system?

The alimentary canal (GI tract) and the accessory organs.

Name the accessory digestive organs.

Salivary glands, liver, gallbladder, and pancreas.

List, in order, the parts of the alimentary canal from mouth to anus.

Mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, anus.

How do the teeth and tongue contribute to digestion in the mouth?

Teeth mechanically break food into small pieces; the tongue mixes food with saliva.

Which enzyme in saliva begins starch digestion?

Amylase.

What is the role of the epiglottis during swallowing?

It closes over the trachea to prevent food from entering the windpipe.

Approximately how long is the esophagus, and what motion moves food through it?

About 20 cm long; food is moved by peristalsis.

What common discomfort results when stomach acid enters the esophagus?

Heartburn.

Describe two main functions of the stomach.

Stores ingested food and mixes it with digestive juices containing enzymes and hydrochloric acid.

What is the semi-liquid mixture of food and gastric juice called?

Chyme.

What is the function of the cardiac (lower esophageal) sphincter?

It prevents acidic stomach contents from flowing back into the esophagus.

What is the function of the pyloric sphincter?

It controls the passage of chyme from the stomach into the duodenum.

Roughly how long is the small intestine?

About 7 meters.

What structures increase the small intestine’s surface area for absorption?

Villi and microscopic microvilli on the intestinal lining.

About what percentage of ingested water is absorbed in the small intestine?

Approximately 80 %.

What are the three sections of the small intestine, and which performs most chemical digestion?

Duodenum (most digestion), jejunum (absorption of nutrients and water), ileum (absorption of nutrients and water).

List at least four substances absorbed across the small-intestinal wall.

Vitamins, minerals, carbohydrates, proteins, lipids, and most water.

Approximately how long is the large intestine?

About 1.5 meters.

State two major functions of the large intestine.

Absorbs additional water and salts; houses bacteria that ferment carbohydrates and form feces.

Give the correct sequence of colon segments through which material travels before defecation.

Ascending colon → transverse colon → descending colon → sigmoid colon.

What is the primary function of the rectum?

Short-term storage of feces before they are excreted.

What is the function of the anus?

It is the terminal opening of the digestive tract through which feces exit the body.

Why do feces become more solid as they move along the colon?

Because of reabsorption of excess water by the colon.

What digestive fluid does the liver produce, and what is its role?

Bile, which emulsifies and aids in the digestion of fats.

Besides producing bile, how does the liver protect the body?

It filters out toxins, drugs, alcohol, and other poisons from the blood.

What is the primary role of the gallbladder?

To store bile from the liver and release it into the small intestine.

What condition can result from fatty diets affecting the gallbladder?

Gallstones.

Name two key functions of the pancreas in digestion and metabolism.

Produces digestive enzymes for fats, carbohydrates, and proteins; regulates blood sugar by producing insulin.

Define peristalsis.

Wavelike muscular contractions that propel food along the alimentary canal.