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SCIENCE

The document provides an overview of the digestive system, detailing its functions, major steps in digestion, and the organs involved. It outlines the processes of ingestion, digestion, absorption, assimilation, and elimination, along with the roles of accessory organs like the liver and pancreas. Additionally, it summarizes common digestive diseases, their symptoms, and treatments.

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32 views4 pages

SCIENCE

The document provides an overview of the digestive system, detailing its functions, major steps in digestion, and the organs involved. It outlines the processes of ingestion, digestion, absorption, assimilation, and elimination, along with the roles of accessory organs like the liver and pancreas. Additionally, it summarizes common digestive diseases, their symptoms, and treatments.

Uploaded by

roselector15
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as DOCX, PDF, TXT or read online on Scribd
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Digestive System and Nutrition – Grade 8 Science Reviewer

Digestive System Overview


The digestive system is a group of organs that work together to process food, extract
nutrients, and eliminate waste. It involves mechanical and chemical processes to convert
food into energy and body-building substances.

Five Major Steps in Digestion


 1. Ingestion – Intake of food through the mouth.
 2. Digestion – Breaking food into simpler substances (mechanically and chemically).
 3. Absorption – Nutrients are absorbed mainly in the small intestine.
 4. Assimilation – Nutrients are used by cells for energy, growth, and repair.
 5. Elimination – Waste is removed through the anus.

Organs of the Digestive System


A. Alimentary Canal (Digestive Tract)
 Mouth
 Mechanical digestion: Chewing
 Chemical digestion: Saliva with amylase breaks down starch

 Salivary Glands

 Produce saliva to moisten food


 Amylase breaks down carbohydrates

 Pharynx

 Connects mouth to esophagus

 Esophagus

 Muscular tube that transports food via peristalsis

 Stomach

 Stores and digests food


 Secretes gastric juices with acid and enzymes
 Protected by mucous lining

 Small Intestine

 About 10 feet long


 Main site for digestion and nutrient absorption

 Large Intestine (Colon)

 Absorbs water and minerals


 Forms and stores feces
 Aids in bacterial fermentation

 Rectum and Anus

 Rectum stores feces


 Anus expels waste

B. Accessory Organs
 Liver

 Produces bile to digest fatsq

 Gallbladder

 Stores and concentrates bile

 Pancreas

 Releases enzymes for digestion of starch, proteins, and fats


Digestive Process – Movement and Enzymes
Peristalsis – Wave-like muscle contractions to push food

Segmentation – Mixing food with digestive juices

Enzymes – Break down food into absorbable forms

Digestive System Diseases – Summary


Gastrointestinal (GI) diseases are disorders affecting the digestive organs. They may
interfere with digestion, absorption, or waste removal. Causes include infection, poor
diet, genetics, or lifestyle.

Common Digestive Diseases:


 Diarrhea

 Definition: Frequent, watery bowel movements


 Relief: Drink fluids to avoid dehydration

 Constipation

 Definition: Hard or infrequent bowel movements


 Cause: Low fiber, dehydration

 Hepatitis

 Hepatitis A: Spread via contaminated food/water


 Hepatitis B: Spread via infected blood/body fluids
 Symptoms: Jaundice, fatigue

 Gallstones

 Definition: Hard crystals from too much cholesterol


 Detection: Found through ultrasound
 Treatment:
 - Small stones: Treated with medicine
 - Large stones: May need gallbladder surgery

 Appendicitis

 Definition: Inflammation of the appendix


 Symptoms: Pain in the lower right abdomen, fever
 Treatment: Requires immediate surgery (appendectomy)

 Peptic Ulcer

 Types: Gastric, Esophageal, Duodenal


 Cause: Bacteria (H. pylori) or medications
 Diagnosis: Endoscopy – uses a thin tube with a camera
 Hemorrhoids

 Definition: Swollen veins in the anus or rectum


 Symptoms: Pain, itching, bloody feces
 Prevention: Eat fiber-rich foods and stay hydrated

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