Nutrition in Animals
Science Class Seven
What is Nutrition
Nutrition requirement, mode of intake of food and its utilization in the body is known as Nutrition.
Need of Nutrition
All organisms including human require food for growth, repair and functioning of body. Getting of nutrients from food and their utilization in body is called Nutrition.
Plants synthesize food by the method of Photo Synthesis but animals cannot. Animals get their food from plants. Animals eat food obtained from plants or eat plant eating animals. Thus animals depend directly or indirectly on plants.
Mode of Nutrition
The process of getting food is called Ingestion. Different animals get their food in using different methods.
Example:
Bees and humming birds suck the nectar of plants.
Snakes like the Python swallow the animals they prey upon.
Some aquatic animals filter tiny food particles floating nearby and feed upon them.
Tiger, Lion and other flesh eating animals take food in after tearing and chewing the flesh of ther animals. Etc.
Infants of human and many other animals feed on mother's milk.
Adult human and other many animals chew their food after put in mouth and them swallow it.
Different animals have different types of organs to take and digest the food. Organs has been developed in animals according to their food habits.
Digestion in Human
Human and most of other animals take food in using their mouth. Human put food first in their mouth. After that food is chewed in the small pieces using teeth. The chewed food in small pieces then swallowed to the stomach through esophagus. Components of food such as carbohydrate, fats, etc. are complex substances, these complex substances are broken down into simpler substances in the course of digestion in stomach and in intestine. Our body absorbed the digested food and get energy from it. After that undigested food in the form of semi solid waste material come out of body through anus.
Carbohydrates, protein, fats, minerals and salt are main components of food. These are found in the complex form in the food. While digestion these components of food are broken down into simpler form so that our body can use them easily and get energy from food.
The breakdown of complex components of food into simpler substances is called Digestion
Different steps of Take food in to Digestion
In human the process of take in food to digestion is divided into five steps. These steps are Ingestion, Digestion, Absorption, Assimilation and Egestion.
(1) Ingestion
To take food in is called Ingestion. Humans take food in through their mouth and in mouth chewed it first using teeth before swallowing.
(2) Digestion
The breaking down of complex components of food into simpler substances is called Digestion. Digestion starts right from mouth as food take in and ends at intestine.
(3) Absorption
The passing of digested food into blood vessels from the wall of intestine is called Absorption. The process of Absorption is completed into intestine.
(4) Assimilation
The process in which the absorbed nutrients aer used to build complex substances, such as protein required by the body is called Assimilation.
(5) Egestion
The getting rid of undigested food from body is called Egestion.
Digestion in Humans
The digestive system in human and other four footed animals is almost similar. In human and other four footed animals digestion is taken place in a long canal called Alimetary canal. The Alimetary canal starts from mouth and ends at rectum.
Alimentary Canal is divided into following parts.
Buccal Cavity, Oesophagus, Stomach, Small Intestine, Large Intestine, Rectum and Anus.
Apart from these parts some other glands are present in the human body which help in digestion. These are Liver, Pancreas and Salivary Gland.
Buccal & Buccal Cavity
The process of digestion starts right from buccal and buccal cavity.
Human first of all put food in his mouth. The take food in is called Ingestion.
Teeth and tongue present in the buccal cavity. Teeth and tongue help to chew and swallow the food. The process of chewing of food is called Mastication. Apart from teeth and tongue some glands are present in the mouth which secrets some liquid. The glands present in the mouth are called salivary glands and the liquid secrets from the salivary gland are called Saliva. Saliva makes food soft and slippery which because of which it becomes easy to swallow the chewed food. Saliva is a type of enzyme which is called Amylaze. Amylaze converts starch present in food to sugar because of which food tastes sweet.
This means digestion of food starts right from mouth.
Teeth
Humans eat maily cereals, green leaves and vegetables, fruit, meat, fish, etc. The construction of human teeth facilitates them to chew and eat all these types of food. Our teeth cut, tear and chew the food.
There are 32 teeth in an adult human.
Types of Teeth
Teeth help us to chew the food and broken into smaller pieces, so that food can be swallowed easily. Each tooth is rooted in a separate socket in the gums.
The appearance and construction of human teeth vary form one another according to their work. Teeth are named differently according to their function.
Human has four types of teeth. These are called Incisor, Canine, Premolar and molar.
Incisor
Pair of teeth present in front of our mouth is called Incisor. Incisor makes the shape of our face proper and beautiful. There are two pairs of incisor present in our mouth. One pair in upper jaw and other pair are in lower jaw. Incisor is used to cut the food we eat.
Canines
Canines are present in both sides of incisor. There are two pari of canines present in our mouth. Canines are used to pierce the food we eat. Carnivores have long canines because they eat flesh of other animals.
Premolar
Premolars are used to chew the food. Premolars are present besides the canines in our mouth.
Molar
Molars used to chew and grind the food. Molars are the broadest teeth present in our mouth. Molars are present in the last of the series of teeth in our mouth.
Our teeth are coverd with thin layer which is called Enamel. Enamel protects our teeth. Enamel is the strongest part in our body.
Milk Teeth and Permanent Teeth
There are two sets of teeth grow in human. First set is called Milk Teeth and next set of teeth is called Permanent Teeth. Milk teeth is known as Primary Teeth also.
Milk teeth usually grow after six months of child birth in normal children. The size of milk teeth is comparatively smaller than permanent teeth. There are 20 milk teeth in normal. Out of which 10 are present in upper jaw and other ten milk teeth are present in lower jaw.
Usually all of milk teeth used to grow upto the 3 years of age and fall upto the age of 8. Usually lower incisors grow first followed by upper incisors. The order of falling of teeth is the same as they grow; this means the lower incisors fall first followed by upper one.
"Tooth" is used as singular and the word "teeth" is used as plural.
Permanent Teeth
Permanent teeth start growing after falling of milk teeth. Permanent teeth start growing from the age of 5 and finish up upto the age of 8 in normal children.
In a normal adult the number of permanent teeth are total 32. These permanent teeth lasts upto old age if cared properly.
Tooth Care
Tooth care is very important for us. We should care our teeth properly as they enable us to eat different types of food and give good and proper shape to our face. If teeth are not cared properly they they will get diseased and fall before the proper age.
Methods of Tooth Care
(a) We should brush our tooth at least twice daily. (b) We should floss our tooth on regular basis. (c) We should rinse our mouth after every meal. (d) We should visit dental surgeon at least once in a year.
Tongue
Tongue is a leaf shaped fleshy organ present in mouth. Tongue helps in mixing food with saliva and pushes food towards throat so that food can be swallowed easily. It is the tongue which enables us to speak.
There are different taste buds are present on tongue which enable us to enjoy food of different tastes.
Reference:
1. Fig:1 - By Mariana Ruiz Villarreal(LadyofHats) (Own work) [Public domain], via Wikimedia Commons
2. Fig:2 - "06-10-06smile" by dozenist - Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons.
