12
– The Muscular System and Digestive System in Human Beings
Q 1.
Fill in the blanks.
Ans.
(1) mouth (2) voluntary (3) Production of blood cells (4) cardiac muscles (5)
oesophagus
Q. 2.
Who is telling a lie?
Ans. (1) Tongue is lying. It can sense all the
different tastes.
(2)
Liver is telling the truth.
(3)
Large intestine is lying. Its length is 1.5 meter long.
(4)
Appendix is lying. It does not perform any function in human body.
(5)
Lung is telling a partial lie. It can perform function of excretion. But not as
important
role as performed by kidney.
Q. 3.
Find a match for me
Ans
(1)
Cardiac muscles – we never feel tired
(2)
Are brought about by muscles - Chewing movements of jaws
(3)
Pepsin - Enzyme of gastric juice
(4)
Cramps - uncontrolled and painful contraction of muscles
(5)
Skeletal muscles - always function in pairs
Q 4. Give
reasons :
1.Food
becomes acidic in the stomach.
Ans.
The wall of the stomach has gastric glands that produce mild hydrochloric acid.
Due to this the food become acidic
in the stomach.
(2) Cardiac muscles
are said to be involuntary muscles.
Ans.
The muscles of heart do not function
according to our will. They continuously work throughout the life time by
involuntary, smooth muscles.
(3) Intoxicating
substances should not be consumed.
Ans Consuming intoxicating addictive substances
can cause harm to our health. Tobacco
smoking
cigarettes, consuming alcohol are bad addictive habits. Some of these also
cause cancer of various organs. The functioning of the systems of the body is
disturbed due to such habits. Therefore, intoxicating substances should not be
consumed.
(4)
Your muscles should be strong and efficient.
Ans.
The muscles of the body become strong and healthy due to proper proteinaceous
diet and exercise. With such muscles, we can perform many activities. If the
muscles are not healthy, there can be various painful problems therefore the
muscles should be strong and efficient.
Q. 5.
Answer the following questions in short:
(1)How
many types of muscles are there? Which are those types?
Ans.
The muscles are of three
main types, viz. (1) Skeletal or voluntary muscles (2) Cardiac muscles (3)
Smooth or involuntary muscles.
(2) What causes the problem of acidity? What
is its effect on the body?
Ans.
Acid is produced by stomach. It is mild 0.5 % HCl. If excess of acid is
produced it causes headache, heart burns, vomiting or skin rashes.
(3)
Name the different types of teeth. What is the function of each type?
Ans.
There are main four types of teeth. These are incisors, canines, premolars and molars.
Incisors help in biting, breaking something into a piece or for peeling.
Canines are not well developed in herbivorous animals and man. They are
basically for killing a prey. Premolars and molars help in chewing and grinding
the food.
Q 6.
Sketch and label a diagram of the digestive system and describe it in your own
words.
Ans.
The digestion of food starts from mouth cavity. (1) Mouth: The food that is
ingested is broken down into
small bits by teeth. The tongue helps to understand the taste. The food is
mixed with saliva by tongue. After the morsel
is gulped it enters the pharynx.
(2)
Pharynx : In the pharynx the oesophagus
and trachea open. When food is gulped the small flap called epiglottis covers the opening
of trachea. This makes the food to enter into oesophagus.
(3)
Oesophagus : This is the first part of the alimentary canal. It starts from
pharynx and ends in stomach.
(4) Stomach
: The stomach is a large J
shaped bag. There are gastric glands in the wall of stomach. They secrete
gastric juice. It has mild hydrochloric acid, pepsin and mucus. The food is churned
into semi solid slurry and mixed with gastric juice in the stomach.
The food
becomes acidic in the stomach. The preliminary digestion of proteins is done by
the enzyme pepsin present in the gastric juice. The mucus protects the inner
lining of the stomach. The slurry of semi digested food is passed into small
intestine from the stomach.
(5) Small intestine : Small intestine is a
very long, narrow tube like part of alimentary canal.
It is
about 6 metre long. Here two main functions take place, viz, completion of
digestion and absorption of nutrients.
The
intestinal juice from wall of small intestine, the bile juice, secreted by the
liver and the pancreatic juice secreted by the pancreas are mixed with the food
here. The digestive enzymes from these secretions act on the food and complete
the process of digestion here. The soluble nutrients which are not ready are
absorbed in the blood vessels.
(6)
Large intestine : Large intestine is about 1.5 metres and is wider in diameter.
It has two parts, colon and rectum. There is small functionless appendix near
the beginning of large intestine. The water is reabsorbed here in the large
intestine and the faeces is formed. The undigested and unwanted matter from the
food is thrown out through the anus.
(7)
Associated digestive glands : The digestive glands are as follow :
(i)
Salivary glands: Three pairs of salivary glands open in the mouth. They are
located near ear, under the tongue and in the pharynx. These glands secret
saliva which contains salivary amylase or ptyalin. The food is mixed with this
enzyme in the mouth. Starch is converted into maltose by this enzyme.
(ii)
Liver : Liver is the largest gland in the human body. It stores the glucose.
There is gall bladder near the liver. The bile juice secreted by the liver is
stored in the gall bladder. The bile juice helps in the emulsification of fats.
Bile juice contains bile slats and bile pigments.
