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Chapter 2 – Nutrition in Animals
NCERT Science Class 7 Chapter 2 PDF download for Nutrition in Animals Class 7 will allow students to focus on how food is consumed. Different organisms have specific ways of consuming food. When it comes to bees and hummingbirds, they prefer sucking the nectar of plants. In terms of humans and other mammals, the infants feed on mother’s milk. Snakes find their prey and swallow them entirely. Among the aquatic animals, some of them find out little food particles freely floating in the water and feed on them.
Human beings consume their food through the help of the mouth. The food particles are then digested and utilized for various bodily functions. The ingested food that remains undigested gets defecated. What exactly happens after the food is chewed and swallowed?
The food enters the stomach through a continuous canal that starts at the buccal cavity and ends at the anus. This canal is divided into several parts which include:
The buccal cavity
Food pipe or Oesophagus
Large intestine ending in the rectum
These parts together make the alimentary canal or the digestive tract. When the food travels through the different compartments of the canal, it gradually gets digested and reaches our system. The digestion process is done through secretion of digestive juices from the inner walls of the stomach, small intestine and other glands that are associated with the digestion process including salivary glands, pancreas and the liver. The digestive juice makes the digestion process easier by breaking the food particles into simpler forms. Now, let’s find out what happens to the food in the various parts of the digestive tract?
The Mouth and Buccal Cavity
Whatever food we eat, it is taken into the body through our mouth. This process of taking the food into the body is known to be ingestion. The teeth in our mouth help in chewing and further break down mechanically to form tiny particles. Each root of a tooth has a separate socket that goes right into the gums. Even teeth are categorized based on their functionalities and appearance. These functionalities are:
Cutting and biting
Piercing and tearing
Chewing and grinding
Milk Teeth and Permanent Teeth
The first set of teeth that grow during infancy are known as milk teeth. They fall off between the age of six to eight years. Each tooth comes off from the root randomly to replace it with a permanent tooth. These sets of teeth may last the entire life or fall off when an adult becomes old enough. Permanent teeth may also come off due to dental diseases.
Sweets and Tooth Decay
Usually, bacteria can be found in our mouth, but they are not always harmful. However, if we do not take care of our teeth and gums, these bacteria can start creating ill effects. They tend to find a good place and grow between the gaps and crevices of your teeth. Therefore, it is crucial to thoroughly clean and floss your mouth after every meal. The bacteria harm our teeth by releasing acids, which is used for breaking down sugar from the leftover food particles inside the mouth. This process is called tooth decay. If it’s overlooked, over time, tooth decay can cause severe toothache or loss of the tooth. Chocolates, candies, soft drinks and other sugar products are the sources of causing tooth decay. Therefore, it is pivotal to clean your teeth with a brush and also use a tongue scraper for cleaning accumulated bacteria from the pores of the tongue. Using dental floss is also a good consideration to extract trapped food particles between two teeth. Make sure not to put unwashed or dirty fingers inside your mouth.
The Food Pipe/Oesophagus
After the food is swallowed, it passes through a food pipe or oesophagus. The food pipe starts from the neck to the ends of the chest. Basically, it connects our stomach with the neck. In the food pipe, through the movement in the wall, food is pushed down to the stomach. Actually, this movement is very common in the entire alimentary canal as the system continuously tends to push the food downwards. Sometimes, based on specific situations and types of food, our stomach does not accept the ingested food particles and this causes vomiting.
The stomach is known to be a large compartment in the alimentary canal. It is a thick-walled bag that looks like a flattened U. This part is the broadest in the entire canal. Our stomach receives food from one end (food pipe) and releases it to the other. The other opening leads the food particles to the small intestine. There is the inner lining of the wall inside the stomach and secretes mucous, hydrochloric acid and digestive juices to extract the contents from the food, for example, protein, carbohydrate, minerals, water, and others. The internal lining of the stomach is protected by the mucous, and the acid released is responsible for killing different types of bacteria which enter along with the food. The digestive juice naturally digests the core contents of the food. It further helps to break proteins in a simpler version of substances.
The small intestine is known to be the tube that is extremely coiled and measures around 7.5 meters long. The secretion from the liver and pancreas reaches into the small intestine. Also, the inner wall of the intestine secretes juice to digest the remaining part of the food. The liver secretes bile, which is stored in a large sac known as the gallbladder. The bile is an important part of digestion, especially when it comes to fats. The half-digested food then reaches to the lower part of the intestine to complete the last stage of digestion.
Absorption in the Small Intestine
All digested food passes through the wall of the intestine to enter our blood vessels. This is known as absorption. The inner wall of the intestine is filled with finger-like outgrowths called villi. They are responsible for increasing the surface area to absorb the digested food.
The large instance is a bit wider and shorter when compared with the small intestine. It measures about 1.5 meters long. It is responsible for absorbing water and salts from the undigested food particles. The undigested food, in the form of waste, passes to the rectum. They are stored like semi-solid faeces. Faecal matters are then removed out of the body through the anus. The procedure is called egestion.
Sometimes when our digestive system fails, it leads to diarrhoea. This may trigger an infection, indigestion or food poisoning. This is a very common case in children, and under severe conditions, it may turn to be fatal. The excessive loss of salt and water from the body can be harmful to us.
Class 7 Science Chapter 2 solution is easily available now.
Exercise 2.4 total Solutions: 13 Questions (13 short questions).
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NCERT Solutions for Class 7 Science Chapter 2 Nutrition in Animals has been explained illustratively.
The wordings are quite simple in the file and are easy to understand for the students of Class 7.
Downloading the file from the site is completely out of hassle.
As the study materials are designed by experienced teachers, students can have complete in-depth knowledge of the chapter.
Some questions of the Class 7 Science Chapter 2 Solution comes with practical experiments that any student can perform at home for a better understanding of the topic.
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