12. The Muscular System and Digestive System in Human Beings
Complete solutions to the Exercises. Maharashtra State Board (Balbharati), Grade Seven General Science.
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Exercises
(a) The process of digestion starts from the mouth. (stomach / mouth)
(b) Eyelids have voluntary muscles. (voluntary / involuntary)
(c) Production of blood cells is not a function of the muscular system. (Production of blood cells / Performing movements)
(d) Muscles of the heart are cardiac muscles. (ordinary muscles / cardiac muscles)
(e) Pushing forward the food that has been chewed is the function of the oesophagus. (stomach / oesophagus)
| Group ‘A’ | Group ‘B’ |
|---|---|
| (1) Cardiac muscles | (b) we never feel tired |
| (2) Are brought about by muscles | (d) chewing movements of jaws |
| (3) Pepsin | (e) enzyme of the gastric juice |
| (4) Cramps | (c) uncontrolled and painful contraction of muscles |
| (5) Skeletal muscles | (a) always function in pairs |
1. Tongue – My taste-buds can tell only a sweet taste. – Lie
Taste buds can tell sweet, salty, sour and bitter tastes.
2. Liver – I am the largest gland in the body. – True
The liver is the largest gland in the body.
3. Large intestine – I am 7.5 meter long. – Lie
The large intestine is about 1.5 m long.
4. Appendix – Digestion is impossible without me. – Lie
The appendix has no role in digestion in human beings.
5. Lung – I play an important role in excretion. – True
The lungs remove carbon dioxide from the body.
(1) Food becomes acidic in the stomach.
The walls of the stomach secrete gastric juice. Gastric juice contains hydrochloric acid. This acid mixes with the food. So the food becomes acidic. The acid also kills germs in the food.
(2) Cardiac muscles are said to be involuntary muscles.
Cardiac muscles make the heart beat continuously. This beating is not in our control. We cannot start or stop it as we wish. So cardiac muscles are called involuntary muscles.
(3) Intoxicating substances should not be consumed.
Tobacco, alcohol and smoking harm the digestive system. They cause vomiting and headache. Tobacco damages the teeth, gums and mouth. It can cause cancer. These substances are also addictive. So they should not be consumed.
(4) Your muscles should be strong and efficient.
Muscles help in all movements of the body. They give shape to the body. They help in beating of the heart, breathing and digestion. Only strong muscles can do this work well. So muscles should be strong and efficient.
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(a) How many types of muscles are there? Which are those types?
There are three types of muscles:
- Skeletal muscles: They are joined to bones. Example: muscles of hands and legs. They are voluntary.
- Cardiac muscles: They are found only in the heart. They are involuntary.
- Smooth muscles: They are found in internal organs like the stomach and intestine. They are involuntary.
(b) What causes the problem of acidity? What is its effect on the body?
Cause: Acidity occurs when the stomach secretes too much acid. This happens due to irregular meals, spicy and oily food, overeating, stress and lack of sleep.
Effects: It causes burning in the stomach and chest, sour belching, indigestion and headache.
(c) Name the different types of teeth. What is the function of each type?
- Incisors (8): for cutting and biting food.
- Canines (4): for tearing food.
- Premolars (8): for crushing food.
- Molars (12): for chewing and grinding food.
An adult has 32 teeth.
The human digestive system (simplified).
The digestive system has the alimentary canal and digestive glands. The alimentary canal is about 9 metres long.
- Mouth: Teeth chew the food. Saliva mixes with it. Digestion starts here.
- Oesophagus: It pushes the food down into the stomach.
- Stomach: Food is churned and mixed with gastric juice. Proteins are digested here.
- Small intestine: It is about 6 m long. Bile and pancreatic juice mix with food. Most digestion and absorption take place here.
- Large intestine: It is about 1.5 m long. Water is absorbed here.
- Rectum and anus: Undigested food is stored in the rectum. It is thrown out through the anus.
Digestive glands: Salivary glands secrete saliva. The liver secretes bile. The pancreas secretes pancreatic juice.
- Eat a balanced diet every day.
- Eat meals at fixed times. Chew food well.
- Exercise and play daily.
- Wash hands before eating. Brush teeth twice a day.
- Sleep for 8–9 hours.
- Say no to tobacco and alcohol.
Use pictures and short slogans on the charts.
- Title slide with your name and class.
- What is digestion?
- Labelled diagram of the digestive system.
- Mouth and types of teeth.
- Oesophagus and stomach.
- Small intestine and large intestine.
- Digestive glands.
- How to keep the digestive system healthy.