General Science Solutions Solutions for Class 7 Science Chapter 12 The Muscular System And Digestive System In Human Beings are provided here with simple step-by-step explanations. These solutions for The Muscular System And Digestive System In Human Beings are extremely popular among Class 7 students for Science The Muscular System And Digestive System In Human Beings Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the General Science Solutions Book of Class 7 Science Chapter 12 are provided here for you for free. You will also love the ad-free experience on Meritnation’s General Science Solutions Solutions. All General Science Solutions Solutions for class Class 7 Science are prepared by experts and are 100% accurate.

Page No 87:

Question 1:

Fill in the blanks with the right word from the brackets.
(a) The process of digestion starts from the ............. . (stomach / mouth)
(b) Eyelids have ............. muscles (voluntary / involuntary)
(c) ............ is not a function of the muscular system. (production of blood cells / Performing movements)
(d) Muscles of the heart are .............. (ordinary muscles / cardiac muscles)
(e) Pushing forward the food that has been chewed is the function of the ............. . (stomach / oesophagus).

Answer:

(a) The process of digestion starts from the mouth.
(b) Eyelids have voluntary muscles.
(c) Production of blood cells is not a function of the muscular system. 
(d) Muscles of the heart are cardiac muscles.
(e) Pushing forward the food that has been chewed is the function of the oesophagus.​
 

Page No 87:

Question 2:

Find a match for me.

Group 'A' Group 'B'
(1) Cardiac muscles (a) always function
(2) Are brought about
by muscles
(b) we never feel tired.
(3) Pepsin (c) uncontrolled and painful contraction of muscles.
(4) Cramps (d) chewing movements of jaws.
(5) Skeletal muscles (e) enzyme of the gastric juice.

Answer:

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

Page No 87:

Question 3:

Who is telling a lie ?

Organ Statement
1. Tongue My taste-buds can tell only a sweet taste.
2. Liver I am the largest gland in the body.
3. Large intestine I am 7.5 meter long.
4. Appendix Digestion is impossible without me.
5. Lung I play an important role in excretion.

Answer:

The tongue, large intestine, appendix and lungs are lying.

1. Tongue can taste salt, sweet and bitter tastes.
2. Large intestine is 1.5 meter long.
3. Appendix is not required for digestion.
4. Kidneys play an important role in excretion.

Page No 87:

Question 4:

Give reasons.
(1) Food becomes acidic in the stomach.
(2) Cardiac muscles are said to be involuntary muscles.
(3) Intoxicating substances should not be consumed.
(4) Your muscles should be strong and efficient.

Answer:

a. Food becomes acidic in stomach because of the presence of hydrochloric acid in the stomach. As the food reaches the stomach, it gets mixed with the hydrochloric acid present there. The hydrochloric acid plays the following roles in digestion:

1. It initiates protein digestion by activating the conversion of pepsinogen to pepsin.

2. It provides acidic medium for the activity of pepsin and other enzymes present in gastric juice.

b. Cardiac muscles are said to be involuntary because they are not controlled by our will. These muscles are found in heart and are the only muscles which work throughout the life without getting tired or fatigue.

c. Intoxicating substances should not be consumed because they harm the body directly or indirectly. Substances such as alcohol cause damage to the nervous system and the digestive system as well. Liver is the main organ which is affected by alcohol. Tobacco is one of the leading causes of oral cancer. Smoking has a direct effect on the respiratory system of an individual and can lead to lung cancer as well.

d. Our muscles should be strong and efficient because they carry out various vital functions in our body. From helping us to breath, digest food to helping us in walking and lifting weights, muscles play an important role. If our muscles are not strong enough we would get tired easily and feel fatigue. It is required to keep them in a healthy state by regular exercising and taking proper diet. 

Page No 87:

Question 5:

Answer the following.
(a) How many types of muscles are there? Which are those types?
(b) What causes the problem of acidity? What is its effect on the body?
(c) Name the different types of teeth. What is the function of each type?

Answer:

a. There are 3 types of muscles:

  • Skeletal muscle fibre: They are found attached to the skeletal bones and are voluntary. Skeletal muscle fibres are striated and are bundled together in a parallel manner by a sheath of tough connective tissues.

  • Smooth muscle fibres: They are present in the walls of internal organs such as blood vessels, stomach, etc., and are involuntary. Smooth muscle fibres are fusiform (taper at both ends) and non- striated. They are held together by cell junctions and are bundled together in a sheath of connective tissues.

  • Cardiac muscle fibres: This is the only type of muscle present in the heart. They are contractile in nature and are involuntary. Plasma membranes of cardiac cells are fused together by cell junctions, and hence, the cells stick together. Communication junctions present as intercalated discs facilitate the contraction of cardiac cells as a unit.


b. Stomach contains special cells called oxyntic or parietal cells which secrete hydrochloric acid in stomach. It plays two important roles like:

1. It initiates protein digestion by activating the conversion of pepsinogen to pepsin.

2. It provides acidic medium for the activity of pepsin and other enzymes present in gastric juice.

However, if the level of this HCl exceeds its normal levels, it results in acidity/acid reflux. Higher levels of HCl can result in the following effects on the body:

  1. burning sensation in the stomach
  2. burning sensation in the throat and heart
  3. difficulty in swallowing
  4. regurgitation
  5. restlessness
  6. belching
  7. nausea
  8. prolonged sour taste in the mouth
  9. indigestion
Exposure to higher levels of HCl for longer durations can also result in the development of peptic ulcers/ulcers in the stomach. 


c. There are 4 types of teeth which are found in humans:

1. Incisors are the teeth present at the front portion of the mouth. There are four incisors in each jaw. They are used for biting and cutting food.
2. Canines are located next to the incisors. There are two canines in each jaw. They are used for tearing and piercing food.
3. Premolars lie next to the canines. There are four premolars in each jaw. They are used for chewing and grinding food.
4. Molars lie next to the premolars at the end of the jaw. There are six molars in each jaw. They are also used for chewing and grinding food.

Page No 87:

Question 6:

Sketch and label a diagram of the digestive system and describe it in your own words.

Answer:

Major constituent organs of the human digestive system are: buccal cavity, oesophagus, stomach, small intestine, large intestine, rectum and anus.

Buccal cavity − It includes the teeth, saliva and tongue. The teeth break down the food. Digestion of food begins in the mouth. The tongue helps in the chewing and swallowing of food.

Oesophagus − The food passes from the mouth, down the oesophagus, into the stomach, as a result of the movement of the walls of the oesophagus.

Stomach − It mixes the food received from the oesophagus with digestive juices.

Small intestine − The food from the stomach moves into the small intestine, which receives intestinal juices from two glands − liver and pancreas. These juices help in the further digestion of food.

Large intestine − Water is absorbed in the large intestine.

Rectum and anus − Undigested food particles are thrown out with the help of the rectum and anus.



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