Notes For All Chapters – General Science Class 7
The Muscular System and Digestive System in Human Beings
1. Introduction
- The human body is made up of different systems that perform specific functions.
- Two important systems are:
- The Muscular System – Helps in body movement.
- The Digestive System – Helps in digestion and absorption of food.
2. The Muscular System
- The muscular system consists of muscles that help in movement, posture, and various body functions.
- Muscles work by contracting and relaxing to move different parts of the body.
Types of Muscles
| Type of Muscle | Location | Function | Voluntary/Involuntary |
|---|---|---|---|
| Skeletal Muscles | Attached to bones | Help in movement (walking, running) | Voluntary (we control them) |
| Smooth Muscles | Internal organs (stomach, intestines) | Help in digestion and blood flow | Involuntary (work automatically) |
| Cardiac Muscles | Heart | Pump blood throughout the body | Involuntary (work continuously) |
3. Functions of the Muscular System
✔ Helps in body movement (walking, running, holding objects).
✔ Supports posture and keeps the body stable.
✔ Helps in digestion (muscles push food through the digestive tract).
✔ Cardiac muscles keep the heart beating and blood flowing.
4. The Digestive System
- The digestive system breaks down food into simpler substances so that the body can absorb nutrients.
- Digestion occurs in different stages, involving various organs.
Main Parts of the Digestive System and Their Functions
| Organ | Function |
|---|---|
| Mouth | Chews food and mixes it with saliva. |
| Salivary Glands | Produce saliva, which contains enzymes to break down food. |
| Oesophagus | A tube that carries food from the mouth to the stomach. |
| Stomach | Produces gastric juices (acid and enzymes) to digest food. |
| Liver | Produces bile, which helps in digestion of fats. |
| Pancreas | Produces digestive enzymes to break down carbohydrates, proteins, and fats. |
| Small Intestine | Absorbs nutrients from food into the bloodstream. |
| Large Intestine | Absorbs water and removes waste. |
| Rectum & Anus | Store and remove undigested food as waste. |
5. Digestion Process
1️⃣ Ingestion – Food is taken into the mouth and chewed.
2️⃣ Digestion – Enzymes break down food in the mouth, stomach, and intestines.
3️⃣ Absorption – Nutrients from digested food enter the blood through the small intestine.
4️⃣ Assimilation – The body uses these nutrients for energy, growth, and repair.
5️⃣ Egestion – Waste products are removed from the body through the anus.
6. Importance of a Healthy Digestive System
✔ Eating fiber-rich foods (fruits, vegetables, grains) helps digestion.
✔ Drinking water improves digestion and prevents constipation.
✔ Chewing food properly makes digestion easier.
✔ Avoiding junk food and eating balanced meals keeps the digestive system healthy.
7. Harmful Effects of Tobacco and Alcohol on Digestion
✘ Tobacco damages the mouth, stomach, and intestines, leading to ulcers and cancer.
✘ Alcohol harms the liver, causing liver diseases and digestive problems.
✘ Both can weaken the immune system and cause long-term health issues.
8. Problems Related to Digestion
| Problem | Cause | Effects |
|---|---|---|
| Acidity | Excess stomach acid | Burning sensation in the stomach and throat |
| Constipation | Lack of fiber and water | Difficulty in passing stool |
| Diarrhea | Infection or bad food | Frequent watery stools, dehydration |
| Food Poisoning | Eating contaminated food | Stomach pain, vomiting, fever |
9. Importance of Teeth in Digestion
- Teeth help break food into smaller pieces for easy digestion.
- There are four types of teeth:
| Type of Tooth | Function |
|---|---|
| Incisors | Cutting food |
| Canines | Tearing food |
| Premolars | Crushing food |
| Molars | Grinding food |
- Brushing teeth twice a day and avoiding sugary food prevents cavities.
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