Hello everyone, welcome to Magnet Brains. Today we will study about nutrition in animals which is a chapter of class 7 science. So we had studied that plants are autotrophs because they make their own food and do not depend on any other organism.
But animals are heterotrophs because they are not autotrophs. They cannot make their own food, they depend on other organisms for their food and survival. So their mode of nutrition is called holozoic nutrition.
In this type of nutrition, one organism feeds upon the other organism. So one organism feeds on another organism, like we humans feed on plants. Or we humans, who are non-vegetarians, some animals also eat it so let's see what are the 5 steps of this type of nutrition first is ingestion that is taking enough food second is digestion that is breaking the food into small and simpler substances then after ingestion and digestion comes absorption now what is the meaning of absorption whatever food you have eaten, what blood has absorbed it Then comes assimilation, which means that the food is being taken with the blood to different parts so that different body organs can get energy. And last is ingestion, which means that the waste material is being excreted or thrown out from the body.
So now let's see the definitions. Ingestion is the taking in of food. Yes, we have understood that what is ingestion? Taking in of food.
Or if we talk about next comes digestion. Digestion is the process of breaking down food into simple soluble molecules. Absorption is the process by which digested food enters the blood and assimilation is the process by which the food is carried by the blood and is utilized by the body. Fast digestion is the process by which undigested food is thrown into the blood and is utilized out of the body. So the food that is undigested gets thrown out of our body.
But this whole process is done by some system and we know that the main digestion is done by digestive system. So first we will study about human beings and human digestive system. So let's see.
The human digestive system. The path taken by food as it travels down the elementary canal which is a long tube starting from the mouth and ending in the anus. So this digestive system has an elementary canal and in that elementary canal from where we ingest food and from where it is being ingested, this whole path is connected to a long tube which we call elementary canal. So, now let's see where does the starting take place? The starting takes place in the mouth of food digestion.
As soon as we eat, what happens? Teeth are present in our mouth. So, teeth, milk teeth are present in children.
And now our teeth are permanent teeth. Because they don't break now. So, what do these permanent teeth do?
helps us to bite food and then saliva secretes salivary amylase and this acts on our food first of all saliva easily mixes our food with itself and then salivary amylase which is an enzyme comes and what it does it breaks carbohydrates in our food in sugar so Digestion process starts from mouth because carbohydrates are broken down into sugars. So, let's read. In the mouth, the teeth help us to chew the food.
The process of chewing is called mastication. What do we use for chewing? Young children have 20 teeth which are known as milk teeth. Milk teeth get replaced by permanent teeth. At what age?
I am sure you would know when your teeth were broken and you would remember. It is very painful at that time. So, at the age of 7, all our teeth were broken.
then milk teeth goes away and then what comes is permanent teeth so next if I talk about now we come to next organ that is tongue so tongue is also present in mouth so we talked about teeth now we will talk about tongue so tongue is muscular organ which is attached to the floor of the mouth we all know It helps in the process of chewing by pushing the food towards the teeth. It helps to mix the food with saliva. We have also read that saliva secretes in our mouth by salivary glands.
What happens is that it mixes with our food. And the food we eat, our tongue helps us to get it in contact with our teeth. So that the chewing process becomes faster and easier. So the chewed food...
food mixes with saliva which is secreted by salivary glands and an enzyme called salivary amylase is present in the saliva what it does is it converts carbohydrates or starch into sugar now you will say carbohydrates which are there in food? we all know carbohydrates carbohydrate rich foods like roti rice pulses etc so here we are seeing This enzyme, myelase, what is it doing? It is breaking carbohydrates into simple sugars. So, what is the digestion process started here in the mouth? So, who helped?
Teeth, tongue. Here we can see a tongue diagram. If you keep something on the front part of your mouth, if you keep it in front of your tongue, you will find it sweet.
taste buds are there and if you keep it at the back, then at the end, that area is bitter, there you have bitter taste buds. So this is the diagram of tongue, salty, sour, bitter, sweet, I am showing you all this. So I hope the tongue is absolutely clear to you and its functions also. Next we will talk about pharynx and esophagus.
Pharynx is nothing else but the food that comes out of our mouth goes into a long tube. You all must be able to imagine. And we call that long tube pharynx.
pharynx. The tongue rolls chewed food into a ball and pushes into short muscular tube known as pharynx. So now what is the food in pharynx?
And after pharynx, food goes into another tube which is known as So, we know that our food goes through windpipe and food pipe. So, why our food goes through food pipe and not windpipe? You know that food goes through food pipe and it causes cough and choking. But, Most of the time food goes into food pipe because of a flap like structure called epiglottis Epiglottis closes the windpipe when we eat food So from there food goes into food pipe and not windpipe From the pharynx the food goes into a long tube known as esophagus. Food is prevented from going into the windpipe by a small flap like structure known as epiglottis.
Every time we swallow food the epiglottis closes the windpipe. So it puts a flap on the food pipe. That is why it is a flap like structure. When it forgets to time its movement, food or water enters in the windpipe and we choke. So if the epiglottis forgets to close the windpipe, then what will happen?
Our food will go into the windpipe instead of the food pipe. Or water can also go and we will get choked. So I hope you are clear about pharynx and oesophagus.
Now pharynx and esophagus are long tubes Where will food go after these? Of course you can tell where it will go, in the stomach Now we all know that in the stomach, HCL is present HCL helps in digestion And there is one more enzyme, pepsin That also releases in the stomach and helps in digestion But If we eat some junk food which already contains acid, then the content of acid in our stomach will increase. And this is called acidity. And we take eno or some type of substance which gives us relief from acidity.
So let's see what happens in the stomach. Food travels down the esophagus to the stomach which is a J-shaped tube. So stomach is a J-shaped tube. Glands in the walls of stomach secrete digestive juice which consists of hydrochloric acid and pepsin.
The food is churned gently in the stomach and it mixes thoroughly with the digestive juice. So digestive juices and enzymes like hydrochloric acid or pepsin help in digestion. But where is main digestion? The main digestion of food is done in small intestine.
So now let's talk about small intestine. The semi liquid food enters a long coiled tube known as small intestine. Now we will see the diagram of small intestine, large intestine, stomach.
But you have to remember that stomach is a J-shaped tube and small intestine has a lot of coiled Coiled like structure, so it's a coiled tube. It is here that most of the digestion takes place. So, here mainly digestion takes place. Complex food molecules are broken down into simpler molecules so that the body can absorb. For example, carbohydrates are broken down into glucose and proteins are broken down into simpler amino acids etc.
What is the meaning of digestion? Breaking down big complex food materials into simpler food materials Like carbohydrates are broken down into simple sugars So I hope if I ask you where digestion is mainly done Your answer will be small intestine Now what will happen after small intestine? Where will the remaining undigested food go? it will go to the large intestine for completion of the digestion process. Some of the enzymes are produced by an organ called pancreas.
So, in our large intestine there are pancreas and it secretes pancreatic juice which helps in digestion. Like proteins, carbohydrates, fats, helps in digestion. So, pancreas lie behind the stomach and liver lies in front of the stomach.
So now we will study about pancreas and liver. So pancreas are behind the stomach and liver lies in the front of the stomach. What secrete pancreas?
Pancreatic juice and liver secrete bile. Bile is most important in digestion of fats. Bile is stored in a structure called gallbladder. Gallbladder is a structure in which bile which is secreted by large intestine is stored and now bile helps to break down fats into small droplets.
So who digests fats? Bile. And this way digestion of fats becomes easy. The inner wall of small intestine has millions of finger like structures known as villi.
So what are the functions of villi? They are finger like millions of structure which They are in small intestine walls So what happens is that they absorb food particles So for absorption surface area increases Because they are finger like structures The villi increase the surface available for absorption So villi increases the surface available for absorption And how do they happen? Finger like structures or finger like projections So I hope If you have understood this digestive system We started with buccal cavity Buccal cavity means teeth, saliva and tongue These are collectively called buccal cavity After that pharynx, esophagus, stomach Then comes small intestine and lastly large intestine So the waste materials produced, digestion large intestine which is completed is excreted out using anus.
So let's see the picture of human digestive system. So in the large intestine the undigested food that remains in the small intestine passes to the large intestine some water is absorbed in the large intestine the remaining Waist is adjusted through anus. So now we will see diagram of human digestive system. So, we have a hypothetical human being and we are showing the internal structures. We are focusing on the human digestive system.
So, This mouth part is called buccal cavity. It has teeth, tongue and saliva. Saliva is secreted by salivary gland. Then food travels in a tube.
This part is called pharynx and the long tube is called esophagus. After that, there is a J shape. This J shaped structure is called stomach.
It is a J shaped structure. The front part of the stomach is the liver and the liver secretes bile. The bile is stored in the gall bladder.
round shaped this is nothing but gall bladder after that here is pancreas which is created by pancreatic juice which helps in digestion after pancreas this whole stomach is complete and now our food goes in a long coiled tube which is called small intestine In small intestine finally digestion of food happens that is breaking of complex food substances into simpler substances and after that the undigested and here you know that there are also herbs present which helps in absorption surface area, after that the undigested food goes to large intestine and there it secretes out of our body. So I hope human digestive system you will be absolutely clear. So this large intestine, the food the undigested food from the large intestine enters rectum and from rectum it moves to anus and from anus it is excreted out of your body. So I hope this human digestive system is clear to you. So our next In the next video, we will study about nutrition in animals In which we will study about nutrition in amoeba and cow Thank you so much Hello everyone Welcome to Magnet Brains Today we will study about nutrition in animals In our previous video, we studied about human digestive system And in today's video, we will study about nutrition in grass eating animals and amoeba So, grass eating animals are very important In the nutrition of grass eating animals, our first step will be to visualize the cows.
I am sure you all must have seen the cows. Cows eat grass first and after some time they sit and chew the grass. I am sure you must have noticed.
So basically, what does a cow do? A cow has four chambers in its stomach. First of all, as soon as it eats, it doesn't chew properly and all of its food goes into the first chamber. Then he goes to the second chamber and the food is sent to the mouth again.
Again the cow chews the food. Then the food goes to the third chamber. digestion and then goes to the fourth chamber.
So, these four chambers in grass eating animals, which are also called ruminants, we will see why these four chambers help them in their nutrition and then digestion. So, let's see the example of cow. Cows, buffaloes and other grass eating animals are chewing continuously even when they are not eating. We have seen that cows are chewing even while sitting.
If they are not near the tree, they are not eating, then how they chew? Because first they ingest the food and after that what they do is, they come back to eat again and again the chewing process goes on. So, Then they quickly swallow the grass and store it in a part of stomach called rumen.
That's why we call these animals as ruminating animals. So what they do is initially they just swallow it and store it in rumen which is present in their stomach. Here the food gets helps in digestion of cellulose.
Digestion of cellulose happens in the human. Animals like horses, rabbits have a large sac-like structure called caecum between the esophagus and the small intestine. The cellulose of the food is digested here by the action of certain bacteria which are not present in humans.
So apart from cows, if I talk about horses and rabbits, So, in the stomach where the leg structure is present, the digestion of cellulose is done. Whereas in cows, the digestion of cellulose is done in the human body. So, I hope you are clear that in the human digestive system, neither rumen nor kekum was present. So, it is not present in human beings.
We have already studied our digestive system in our previous video. So, here you can see that we have taken cow's milk. diagram is made here, it is a grass eating animal grass directly goes to the rumen from the esophagus and comes back to its mouth from the rumen and then goes to the small intestine then goes to the large intestine and finally excretion will happen because the waste materials will be excreted out so I hope these grass eating animals have been cleared to you and why they are called ruminants and why they are called ruminants Now we will read about amoeba. We all know that amoeba has no shape. It can take any shape.
So, the first thing I would like to tell you about amoeba is that it is a unicellular organism. That is, it has only one cell. We know that there are millions of cells in the human body. Cells make tissue together and so on.
But there is only one cell in amoeba. It is a unicellular organism. Now, how does amoeba also obtain nutrition? We have to see this.
So, here you can see how amoeba is obtaining nutrition. So, I will tell you about this in a little detail. First of all, there is a dense structure inside the amoeba known as its nucleus. There is only one cell in the amoeba and there is definitely a nucleus in every cell. So, what is present in the center?
It is the nucleus. And there is cytoplasm nearby. That means, apart from the nucleus, whatever part is there is called cytoplasm. And in cytoplasm, food vacuoles are present. So, these food vacuoles help in nutrition in amoeba.
Let's see how. So, as soon as a food particle comes near the amoeba, then what does the amoeba do? It extends its false leg, which is called a false leg, called pseudopodia.
It extends its false leg and captures the food. As you can see here, these are extensions, which are called false legs. And through this, it captures the food particle and now it will take it inside, that is, it will engulf it.
So can I call it ingestion of food in amoeba? So, amoeba ingested food using pseudopodia which is false feed. After that, the food particle that amoeba ingested will be stored in a food vacuole form. It will enter into the food vacuole and there it will be digested as you can see.
After digestion, the food particle that amoeba ingested will be digested. The energy that it will get will use that energy further to perform multiplication and other processes After that, the waste will be excreted out of amoeba and that will be called ejection So, let us now read Amoeba is a microscopic single-celled organism So, we can see it only through the microscope, we cannot see it with naked eye And single-celled means unicellular organism It is found in pond water. Amoeba has a cell membrane, a rounded dense nucleus and many small bubble like vacuoles in its cytoplasm. So this is amoeba, in the center there is a nucleus, around it is cytoplasm and in cytoplasm there are many food vacuoles.
After that, the outer most covering of amoeba is called its cell membrane. It pushes out one or more of its finger like projections called pseudopodia or false feet for movement and capture of food. So how does it capture food?
Using its false feet which is known as pseudopodia. When it senses food, it pushes out pseudopodia around the food particle and engulfs it. The food becomes trapped in the food vacuole. So as soon as it sees the food particle, it captures it and then engulfs it. And what is this food particle used for?
It's called food. In vacuole, where it will have digestion. So, let's see the next part, Digestion. Digestive juices are secreted into the food vacuole. They act on the food and break it down into simpler substances.
So, where is this digestion process happening? In the food vacuole. Generally, the digested food is absorbed.
So, now, ingestion is done, digestion is done, absorption is done. Now we will discuss about assimilation. The absorbed substances are used for growth, maintenance and multiplication.
Multiplication means reproducing one amoeba and making another amoeba. So all this will be possible due to assimilation. After that what will come?
Ejection. The undigested residue of the food is expelled outside by the vacuole. So, vacuole will do the digestion of undigested food. So, here you can see that as soon as this food particle came around amoeba, it extended the pseudopodia and captured it quickly. So, this is how all the five processes take place in amoeba.
So, I hope you have clear nutrition of amoeba and those five stages are also clear to you. In our next video, we will discuss the frequently asked questions of this chapter. Thank you.
Hello everyone, welcome to Magnet Brains. Today we will study about Nutrition and Animals. This is the chapter of Class 7 Science about the frequently asked questions of this chapter.
So friends, I will discuss the frequently asked questions with you. I am sure you will get the answers to these questions if you will... chapter ki videos ko dekha hoga. Aur agar nahi dekha hai toh aap humari official website magnetbrains.com par jaa kar unhe dekh sakte hai and then you can study from there.
Toh friends ye questions let's discuss. The first question fill in the blanks. The main steps of nutrition in humans are hume pata hai five steps hota hai. Kya hota hai wo ingestion.
digestion, absorption, assimilation and ingestion So these 5 steps are in the nutrition of human beings and it is called as holozoic nutrition. Next, the stomach releases hydrochloric acid and dash juices which act upon the food. So we know that digestion happens in the stomach. So which juices will be secreted?
Digestive juices. Next, the inner wall of small intestine has many finger-like outgrowths known as we know these are called villi and they increase the surface area for absorption and these are present in small intestine. Amoeba digests its food in the, where does it digest its food?
In food vacuole. So I hope friends you have understood all these fill in the blanks. Let's move to the next question. Take the correct option.
Fat is completely digested in the... We know where digestion is complete. We all know it is majorly done in the small intestine.
Next, water from the undigested food is absorbed mainly in the... So the maximum amount of water that is absorbed is absorbed by the large intestine. So your answer is large.
I hope these two questions are clear to you. Next we will move on. What are villi?
What is their location and function? So villi are finger like outgrowths or projections which are present in small intestine and help in the absorption of food. So villi are present in small intestine walls and they are finger like projections and they make absorption of food easy because their surface area is very wide.
So I hope you understood where will I present small intestine and its main function is absorption of food. So next question 4, where is the bile produced? What component of food does it help to digest?
So, we all know that bile is produced by the liver. And it mainly helps in the digestion of fats. So, your answer is that bile is produced in the liver and it mainly helps in the digestion of fats.
Fats can also be called lipids. Which part of digestive canal is involved in absorption of food? We all know that absorption of food is done by the stomach.
And where do we study the stomach? Small intestine. Chewing of food. Chewing of food is done in mouth with the help of teeth, saliva and tongue. So, we can also call it buccal cavity.
Or, mouth bhi bol sakte hai yaa phir mouth bhi bol sakte hai chewing of food ke liye killing of bacteria agar main baat kero killing of bacteria kahan hoti hai toh woh hoti hai stomach me next complete digestion of food humne abhi abhi pada completely kahan digest hota hai food small intestine me And where does the formation of facis occur? Where it gets excreted through anus. That happens at the last step.
Therefore it happens in large intestine. So I hope the digestive canal parts and functions were clear to you. So now let's proceed to the next. So this is the last question.
Question number 6. Match the following. So I am sure you will be able to do this easily. Let's proceed. You have to see what function of salivary gland is. Because if I see the options here, I will understand that if I want to match, then on what basis do I have to match?
Like if there is a stomach, then I know acid will be released. If there is a salivary gland, then saliva secretion will happen. So the main function of the salivary gland is saliva secretion.
So I hope you understood this. Stomach. Stomach's main function is acid release. please I hope this is clear liver liver kya karta hai humne abhi abhi para bile juice ka secretion korn karta hai liver so liver is responsible for bile juice secretion rectum humko pata hai anus ke upar hi rectum hota hai aur wahan se jo hai kya hota hai ejection hota hai excretion hota hai food and digested food ka ya waste material So, can I say that there is storage of undigested food in rectum?
No. Can I say that digestion is completed? No. Can I say that absorption of water?
No. So, the answer is release of faces. Next, small intestine. In small intestine, we know that digestion is complete. So, we will match small intestine here.
Digestion is completed. Large intestine, storage of undigested food is in large intestine. Yes, because from there it is excreted through the rectum and anus.
And absorption of water is also mainly in large intestine. the answer is yes. So, do we have two functions of large intestine?
Absorption of water as well as storage of undigested food. So, I hope you have understood the whole match the following. Many of these questions are in the NCERT class 7th textbook.
I am sure these FAQs will be very helpful for you for this chapter. Thank you.