Nutrition In Animals - Class 7 Biology - Extra Questions

 Incisor teeth are meant for cutting or biting through food.

Nausea, vomiting, abdominal pain and loose stools are the symptoms of diarrhoea. It is caused in the stomach usually due to a virus or contaminated food.

The diagram represents the lateral section of the tooth. 

The alimentary canal is a part of the digestive system. In human beings, the alimentary canal also known as the gastrointestinal tract extends from mouth to anus. It measures about 8 to 10 meters in length. 
The gastrointestinal tract can be divided into two parts: the upper tract and the lower tract. 
     1. The upper gastrointestinal tract includes the oral cavity, pharynx, esophagus (food pipe), and stomach. 
     2. The lower tract includes the small intestine (duodenum, jejunum, and ileum) and the large intestine (colon and rectum). 
The food passes through the following organs in the sequence as given below -

($$1$$)Homodont dentition is the type of dentition in which all the teeth in the jaw look alike. It is mostly seen in the majority of vertebrates such as fish, amphibians like frogs and reptiles. In them, all the teeth are functionally and anatomically of the same type. While in mammals like human beings, there are functionally four different types of teeth namely, flat incisors for cutting, long and pointed canines for tearing flesh and large and broad premolars and molars with flat and grinding surfaces. Molars have no counterpart in milk teeth. This type of dentition is known as heterodont dentition.

$$\textbf{Nutrition:}$$

$$\bullet$$ Nutrition is the process of intake of nutrients from which the organisms derive their energy. 

$$\bullet$$ In the process of nutrition, there are five major steps which are ingestion, digestion, absorption, assimilation and egestion. 

$$\bullet$$ Ingestion is the intake of nutrients by the mouth. 

$$\bullet$$ Digestion is the process of enzyme-mediated breaking down of the larger molecules into smaller forms. 

$$\bullet$$ Absorption is the process of absorbing the digested food materials and nutrients. 

$$\bullet$$ Assimilation is the process of movement of the nutrients to the cell where it is metabolized to produce energy. 

$$\bullet$$ Egestion is the process of removal of undigested food materials. 

$$\textbf{Nutrition in Amoeba:}$$

$$\bullet$$ Amoeba is a unicellular organism that moves with the help of pseudopodia. 

$$\bullet$$ Pseudopodia are extensions of the cell membrane which direct the amoeba towards its food.

$$\bullet$$ The cytoplasm that surrounds the food molecule completely engulfs the food.

$$\bullet$$ Using the various enzymes present in Amoeba the food molecule is broken down. 

$$\bullet$$ After breaking down the food the nutrients are observed by the Amoeba. 

$$\bullet$$ The excess molecules which are necessary for Amoeba need to be removed with the help of vacuoles again.

Given above is a labelled diagram of ruminant stomach. 

$$\bullet$$Raw, green vegetables and grass are insufficient for human survival.

• The salivary gland secretes saliva, which helps in the moistening of food and helps to create food bolus. 
• In the stomach, gastric glands are present, which secretes gastric acid called hydrochloric acid. 
• The liver secretes bile juice and it is temporarily stored in the gall bladder which helps in the emulsifies of fat droplets. 
• The function of the large intestine is to absorb water from the undigested food and to prepare faeces, which is stored in the rectum.
• Digestion begins in the mouth, through chew and swallow, and is completed in the small intestine.

An animal with the carnivorous feeding habit has incisors, well-developed canines, sharply cusped premolars and reduced numbers of molars. Such an arrangement of teeth helps the animal bite through flesh efficiently and makes tearing easy.

The digestive system in the human body consists of the gastrointestinal tract, liver, pancreas, and gallbladder. All these organs function together for the digestion of food.

The teeth are composed of enamel, dentin, and pulp. Dentin is a connective tissue that holds enamel and transmits nerve impulses from enamel to pulp. It is the second hardest tissue in the body.

Ingestion	Digestion
Intake of food from the external environment into the body by swallowing or absorbing it is known as ingestion.	Breakdown of food into particles which can be absorbed by the body is known as digestion.
It helps in intake of food particles so the digestive enzymes and juices can act on it.	The action of digestive juices and enzymes on food is a part of digestion
It is a completely mechanical process.	It is a mechanical as well as a chemical process.

Basically teeth are 4 types. These are different in structure and fuction. They are 

There are total 32 teeth present in human. These are basically of 4 types, incisors, canines, premolars and molars. Each tooth is located at particular place and has a particular function. Each tooth is embedded in the maxilla (upper jaw) or the mandible (lower jaw) and is covered by gums. Humans are diphyodont. They have two sets of teeth. The first set are called milk teeth. The second set are called permanent teeth. The dental formula for primary teeth is 2.1.0.2 / 2.1.0.2. There are total 20 teeth in the set. There are 2 central incisors, 2 lateral incisors, 2 canines and 4 molars in upper and lower jaw respectively. The dental formula for permanent teeth is 2.1.2.3 / 2.1.2.3. There are total 32 teeth in the set. The arrangement of teeth is 2 central incisor, 2 lateral incisor, 2 canine, 4 premolar and 6 molar in upper and lower jaw respectively. 

Canine teeth help in tearing food.

The function of the teeth is to facilitate the mastication of food. There are following types of teeth present in the mouth along with their function:

• Humans have holozoic nutrition, that means the food is consumed as a whole and the digestion occurs internally. It can be described as:

Molar set of teeth helps in the grinding of food. it helps to grind it into small pieces which makes them easy to be gulped down and for digestion of the semi-solid food.

• Human digestive system involves gastrointestinal tract and other components such as liver, intestines, glands, mouth, stomach, gallbladder. The Human Digestive System Process has six primary tasks: ingestion, motility, secretion, digestion, absorption, excretion. 
• The food you consume not only provides the body the energy and nutrients you need, but it is also used to grow and repair cells.
• The human digestive system begins with the mouth or oral cavity, which leads to the food channel. The food channel is made up of pharynx, oesophagus, stomach, small intestine, big intestine, and anus. 
• The small intestine splits the duodenum, jejunum, and ileum into three components, while the large intestine splits into an appendix, caecum, colon, and rectum. 
• In the digestive system, liver, gallbladder, pancreas, teeth, salivary glands, tongue, etc. also play a part.

The stomach has four parts, the cardia, fundus, body and pylorus. The cardia is the point where the oesophagus enters the stomach and pylorus is the part that connects the stomach to the small intestine.

• Herbivores consume plants which is full of cellulose and the digestion of cellulose takes a long time. The small intestine in them is up to 10 times longer than their height.
• Carnivores consume meat which is easily digested in their highly acidic gut.
• Therefore, Herbivores have longer small intestine than carnivores.

Ruminants such as cows and buffaloes chew the food quickly and swallow it. This swallowed food is brought back from the stomach to mouth and chewed again. This process is to complete the digestion of food ingested.

The alimentary canal stretches from mouth to anus.

The system which converts the components of food into simple and absorbable substances is called digestive system.

According to the question:
i) Incisors (A): The cutting and biting teeth.
ii) Canines (B): The piercing and tearing teeth.
iii) Premolars (C): The grinding and chewing teeth.
iv) Molars (D): The grinding teeth present only in adults. 

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. 

The digestion of fat completed in small intestine where fat gets converted into fatty acids and glycerols.

The different parts of the digestive system are as follows: 
1. Buccal cavity opens outside through the mouth. It has  tongue, teeth and the openings of the salivary glands.
2. Buccal cavity leads to oesophagus.
3. The oesophagus opens into the stomach. The wall of the stomach contains gastric glands. 
4. The stomach opens into the duodenum. This opening is regulated by a sphincter muscle which releases small amount of food at a time.
5. The duodenum receives the secretions of the liver and the pancreas. 
6. From the duodenum the food passes into the jejunum of the small intestine. The inner wall of the jejunum has a number of finger like projections called villi. The villi increases the surface area and are richly supplied with the blood vessels. 
7. The small intestine opens into the large intestine. 
8. The terminal portion of the large intestine is called the rectum that opens out through the anus. 

The technical terms are as follows: 
(i) The three last grinders - Molars 
(ii) The pointed tooth for holding and tearing - Canines 
(iii) The broad sharp cutting teeth - Incisors 
(iv) The two temporary (deciduous) grinding teeth - Molars

In the oral cavity, food is chewed so that it can change into a semisolid paste. Saliva is mixed with food. Saliva helps in making the food particles into a bolus. Saliva makes it easier to swallow the food. It can be said that oral cavity performs the function of masticating the food and swallowing the food. Moreover, salivary amylase in saliva digests starch. Starch is converted into maltose during this process. 
$$Starch \xrightarrow[pH\ 6.8]{Salitory \ Amylase}Maltose$$

Arrangement of Teeth: In human beings, each tooth is embedded in a socket of jaw bone. This type of attachment of teeth is called the Thecodont. Human beings get two sets of teeth in their lifetime, i.e. temporary teeth and permanent teeth. Temporary teeth or milk teeth are deciduous and are replaced by permanent teeth. This type of arrangement is diphyodont. 
There are four types of teeth in human beings, viz. incisors, canines, premolars and molars. They are represented as I, C, PM and M in short. Each half of a jaw contains certain number of each type of teeth. This can be shown by following dental formula: 
$$\dfrac{2123}{2123}$$

This shows that there are 2 incisors for cutting, I canine for tearing, 2 premolars and 3 molars teeth for grinding and crushing in each half of a jaw. Thus, there are 32 teeth in a human adult. 

Mastication breaks the food into smaller particles. The tongue helps in proper mixing of saliva with the food. The mucus in saliva helps in food particles coalescing together. About $$30$$% of starch is converted into maltose in the buccal cavity due to the pressence of salivary amylase in the saliva.

(i) Part exposed above the gum - Crown 
(ii) The hard substance making the covering of the tooth - Enamel 
(iii) The soft connective tissue contained in the central space of the tooth - Pulp 
(iv) Bone-like structure fixing the root in position - Cement 
(v) Slight constriction between the root and the crown - Neck 

 Diphyodonts are organisms that  develop two sets of teeth in their lifetime, the deciduous milk teeth and the permanent teeth. Example Humans

In the given figure (W) represents - rumen, it serves as the large fermentation part of the stomach in which different microorganism resides.

$$\textbf{Digestion}$$	$$\textbf{Assimilation}$$
Digestion occurs due to the activity of specific enzymes in the alimentary canal.	Assimilation occurs due to the action of specific enzymes in the cells.
Digestion is responsible for breaking down complex food molecules into simpler forms.	Assimilation is the process in which the simpler molecules accumulate in the cells form in the complex molecules for storage.
Digestion occurs in the food passing through the alimentary tract.	Assimilation requires the movement of simpler food molecules through the blood and lymph vessels.