Nutrition- Nutrition is the mode of taking in food by an organism and its utilisation by the body to obtain energy to do various life processes.

Nutrients- Nutrients are the substances which provide energy, and biomolecules necessary for carrying out the various body functions. These nutrients also act as building blocks for growth and repair of the body.

Macronutrients – Carbohydrates, Proteins, Fats

• Carbohydrates- Whole grains, vegetables, fruits and beans.
• Proteins- Beans, lentils, pulses, eggs, meat.
• Fats- Olive, canola, peanut, and sesame oils, Avocados.

Micronutrients – Vitamins and Minerals

• Vitamins and minerals- Different fruits and vegetables.
• Dietary fibre- Oats, fruits, vegetables, oat bran, barley.

Balanced diet – A balanced diet is a diet which contains all the vital nutrients like carbohydrate, protein, fat, vitamins and minerals in the right amount. A healthy and balanced diet helps to reduce the risk of diseases and improves overall health.

Vitamin – Vitamin is a micronutrient that is not prepared by the body in sufficient amounts. This is the reason why it is necessary to take in from outside sources for the normal functioning of the body.

Deficiency diseases

• Deficiency diseases are diseases that are caused by the lack of certain essential nutrients in one’s diet over a prolonged period of time.
• A balanced diet is extremely important for the good health of a person. Any imbalance in the diet might lead to excess or insufficient intake of certain nutrients. Insufficient intake of a particular nutrient can lead to a deficiency disease.

Vitamin Deficiency diseases

 Vitamin A (Retinol) – Deficiency of Vitamin A causes Night blindness. Vitamin A rich food sources are carrots, spinach, milk, egg, liver and fish.

Vitamin B Complex-

This include 8 types of vitamins B-

B-1 (thiamine)

B-2 (riboflavin)

B-3 (niacin)

B-5 (pantothenic acid)

B-6 (pyridoxine)

B-7 (biotin)

B-9 (folic acid)

B-12 (cobalamin)

Deficiency of Vitamin B-1 causes Beri beri disease.

Deficiency of Vitamin B-2 causes retarded growth and skin problems.

Deficiency of Vitamin B-12 causes Pernicious Anaemia. Other diseases related to Vitamin B-12 deficiency are muscle and nerve paralysis, extreme fatigue, dementia and depression.

Vitamin C (Ascorbic acid)- Deficiency of vitamin C can cause scurvy, a disease that is characterised by bleeding gums, skin spots and swelling in joints. It also affects the immune system and can even be fatal in acute conditions.

Vitamin D (Calciferol) – Vitamin D deficiency causes rickets, which leads to weakening of bones, especially near the joints. It can also lead to tooth decay.

Vitamin K (Phylloquinone) – Vitamin K is an important blood coagulating nutrient. Its deficiency is common in infants and leads to excessive bleeding due to the inability to form blood clots.

Mineral Deficiency Diseases:

Minerals are inorganic nutrients that include copper, zinc, iodine, iron, along with the calcium, potassium, magnesium and sodium.

Following is the list of a few minerals along with the deficiency diseases-

• Deficiency of Calcium causes Brittle bones.
• Deficiency of Phosphorus causes weak teeth and weakness of bones.
• Deficiency of Iron causes anaemia which is a condition in which the blood is unable to carry the required oxygen to the tissues, that also results in death.
• Deficiency of Iodine causes Goitre, which leads to enlarged thyroid gland.
• Deficiency of Copper leads to Low appetite and retarded growth.

Disease – A disease is a condition that negatively affects the normal functioning of the cells, tissues, and organs of the body.

Malnutrition  – Malnutrition is a condition that results from eating a diet of low nutrient amount in it, which eventually results in health problems and deficiency diseases. Malnutrition is also known as malnourishment.

Examples –

1- Kwashiorkor is acute malnutrition that occurs mostly in children between the age of 6 months and 3 years of age. This condition results from severe protein deficiencies. It is also known as “edematous malnutrition” because it is associated with oedema. The children suffering from Kwashiorkor have abnormally thin and weak bodies. They have swelling in the ankles, feet and belly which is filled with water.

2- Marasmus is the type of nutrition deficiency that is mainly caused due to the deficiency of nutrients such as carbohydrates and sometimes protein. Marasmus mainly occurs due to poverty and food scarcity. It occurs mostly in children between the age of 6 months and 1 year of age. The symptoms of marasmus are more common to the symptoms of kwashiorkor, which includes: Dizziness, Weight loss, Dehydration, lack of energy, stunted growth, Chronic Diarrhoea, shrinkage of stomach.

Ingestion – Ingestion is the process of taking in food inside the mouth. The mode of food intake varies in different organisms.

Digestion – Digestion is the process of breaking down ingested complex food molecules into simpler form. The digestion process involves the alimentary canal along with various accessory glands.

Absorption – Absorption is the process which begins in the small intestine where most of the nutrients and minerals are taken up by the bloodstream from the intestinal walls.

Assimilation – Assimilation is the process of using up the nutrients by the body for growth and development.

Egestion – Egestion is the removal of undigested food wastes out of the body through the anus in the form of the faeces.

Blood vessels – Blood vessels are the tube through which the blood circulates in the body.

The primary function of blood vessels is to transport oxygen, nutrients & waste to/from all parts of the body.

Alimentary canal – The alimentary canal is a long tube through which the food we eat is passed in the digestive tract. It begins at the mouth (buccal or oral cavity), passes through the pharynx, oesophagus or food pipe, stomach, small intestines, large intestines, rectum and finally ends at the anus. The food particles gradually get digested as they travel through various parts of the alimentary canal.

The alimentary canal is about 30 feet long from the oesophagus to the anus.

Accessory organs – Accessory organs are the organs that help in the process of digestion by pouring their secretions in the form of digestive juices. These include – liver, pancreas and salivary glands.

Oesophagus – Oesophagus is also known as a food pipe. It is a long muscular tube that connects the mouth and the stomach. It passes down the food from the mouth to the stomach.

Peristalsis – Peristalsis is the wave-like movement due to contraction and relaxations of the muscles of the alimentary canal. It pushes the food from one organ to the other. This movement is involuntary and is necessary for the movement of food down the stomach and bowels down the anus.

Types of teeth

There are 4 different types of teeth in humans. They are- Incisors, Canines, Premolars and Molars.

Milk teeth – The first set of teeth a child grows- consists of canines, incisors and premolars. These are the temporary  teeth/baby teeth or deciduous teeth. These are the primary set of teeth in humans which start to erupt through the gums after the age of 6 months and generally fall off around the age of 12.

Permanent teeth – The second and final set of teeth in a human are called permanent teeth. These consist of canines, incisors, premolars and molars.

 Tooth decay – Tooth decay means the damage of enamel. It generally happens when bacteria in your mouth makes acids that attack the enamel. There can be a combination of factors which leads to tooth decay which includes  frequent snacking, sipping sugary drinks and not cleaning your teeth well. Tooth decay can lead to cavities or dental caries, which are holes in your teeth. If tooth decay is not treated, it can cause pain, infection, and even tooth loss.

 Plaque – Plaque is a mass of germs or bad bacteria that grows on the surface of the teeth. This can be seen as a soft, sticky film that builds up on your teeth. The bacteria of plaque causes tooth decay.

 Salivary gland – Salivary glands are present in the mouth that secrete saliva. There are 3 pairs of salivary glands in the mouth, three(3) on each side.

 Tongue – The tongue is a muscular organ. It helps with chewing,  swallowing and speaking. During swallowing, the tongue pushes a tiny bit of ball- shaped mass of chewed food called a bolus, towards the back of your throat and into the opening of your oesophagus.

The presence of  papillae on the tongue gives it a rough texture. It is covered with several taste buds.

Papillae – Papillae are tiny outgrowths or bumps present on the surface of the tongue that consist of the several taste buds. The presence of papillae on the tongue gives it a rough texture. They are responsible for giving the tongue its texture and are responsible for the sensation of touch.

Taste buds – Taste buds are ovoid clusters present on the surface of the tongue. These contain taste receptors which help to identify or sense the taste of the food.

Function of teeth – Teeth are used for Cutting, biting, chewing and grinding the food.

Saliva – Saliva is secreted by salivary glands. The functions of saliva are –

• It acts as digestive juice and softens the food, which further leads to the easy process of digestion.
• It moistens the food for easy swallowing.
• It helps to clean the mouth, tending to destroy germs to prevent tooth decay.  
• It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.

HCl – HCl stands for Hydrochloric acid. It is the major component of gastric juice. It helps to kill germs in the food. It also activates enzymes for breakdown of certain proteins. HCl converts pepsinogen which is not active into pepsin to break proteins in our stomach.

Mucus – Mucus is a sticky substance produced by the stomach wall. This mucus protects the stomach lining from being attacked by different acids such as HCl that are used during digestion.

Gastric juices – Gastric juice is the digestive juice which is colorless, watery, acidic fluid and is secreted by the gastric glands found on the wall of the stomach. It consists of hydrochloric acid, mucus, and different enzymes.

Bolus – Bolus  is round, ball-shaped and a mixture of chewed food formed by the combination of food and saliva in the mouth. The bolus is swallowed by the mouth which travels down the oesophagus to the stomach for digestion.

Chyme – Chyme is a thick semisolid mass of partially digested food that is formed in the stomach during digestion.

Starch – Starch is an organic compound. It is a polysaccharide made of many glucose molecules. It is a stored form of carbohydrate in plants.

Bile juice – Bile juice is secreted by the liver. Bile juice is a yellowish brown fluid. It is stored in the gallbladder. The main function of bile juice is to break down the fat molecules known as emulsification of fats.

Emulsification – Emulsification is the breakdown of bigger fat  globules into smaller fat droplets. The fat molecules are digested and broken down into fatty acids and glycerol.

Gallbladder – Gall bladder is a pouch-like organ attached to the liver. It stores the bile juice produced in the liver.

Can we live without gallbladder?

Yes, we can. If gallbladder is not there the bile juice produced will be directly sent to the small intestine without being stored and concentrated.

Insulin – Insulin is a hormone that lowers the level of glucose (a type of sugar) in the blood. Insulin is secreted by the pancreas.

Diabetes mellitus  – Diabetes mellitus commonly known as diabetes is a condition that occurs when there is excess of  glucose or sugar level in the bloodstream.

 Villi / Villus

• Villi are small, finger-like projections present on the inner wall of the small intestine.
• Villi increases the surface area of the intestinal walls for maximum absorption of digested food.

Rectum – Rectum is the last part of the large intestine where the undigested waste material  or faeces is stored temporarily until it is eliminated out of the body through anus.

Vermiform Appendix – Vermiform appendix is a finger-like, blind-ended tube connected to the cecum of the large intestine. It serves as a microbial reservoir because it stores beneficial microbes.

 Flatulence – Flatulence is a biological term for releasing gas from the digestive system through the anus.

Cellulose – Cellulose is the most abundant organic compound. Cellulose is a complex carbohydrate consisting of oxygen, carbon, and hydrogen. Cellulose is a polysaccharide made up of many glucose units. A plant’s cell wall is primarily made up of cellulose.

Anus – Anus is the last part of the alimentary canal in humans.  It is a part through which the undigested waste material or faeces are eliminated out of the body.

Herbivores – Herbivores are the organisms which only eat plants. For example- cow, buffalo, deer, etc.

Why can’t humans eat grass?

It is because the grass is rich in cellulose, which is a type of carbohydrate that humans are not able to digest due to the absence of cellulose-digesting enzymes. Animals such as cows have a specialized stomach with four chambers to aid in the digestion of grass.

Rumination – The process where cud returns to the mouth in small lumps for ruminants to chew is called rumination.

Ruminants – Grass eating animals are known as ruminants. Animals like cows, goats and buffaloes eat grass.

Four parts of stomach in ruminants-  Rumen, Reticulum, Omasum and Abomasum.

Rumen – Rumen is the first stomach of a ruminant

Reticulum – Reticulum is the second part of the stomach in ruminants, it passes the smaller digested particles from the rumen to the omasum.

Omasum – The omasum is where food particles that are small enough get transferred into the abomasum for enzymatic digestion.

Abomasum – The last part of the stomach (abomasum), called the true stomach as the protein digestion occurs in acidic conditions.

Cellulase – Cellulose is an enzyme that digests cellulose.

Cud – Cud is the partially digested food that is brought up again to the mouth from the first stomach of the ruminants for further chewing.

Amoeba – Amoeba is a type of unicellular organism which has the ability to alter its shape by extending pseudopods.

Unicellular – Unicellular organisms are those which are made of a single cell. Example- Amoeba, Bacteria

Pseudopodia – Pseudopodia are temporary cytoplasmic extensions, which helps the cell to move

Vacuole – Vacuole is one of the cell organelle which is prominent in plants and helps in storage of water and food materials. 

Nucleus – Nucleus is one of the most important cell organelles found in eukaryotic cells. It is a membrane-bound spherical organelle present at the center of the cell, that contains the entire genetic information of the cell.

Cell membrane – The cell membrane is also known as the plasma membrane.  It is a semi-permeable membrane composed of lipids and proteins. The main functions of the cell membrane includes- protecting the cell and  providing support in maintaining the shape of the cell.

Food vacuole – Food vacuole is a membrane-bound vacuole formed in amoeba and helps in the digestion of food.

Digestion in amoeba – Amoeba has a flexible membrane and finger-like projections called pseudopodia. Pseudopodia forms a vacuole around it and helps in engulfing the food. When the food particle is completely trapped inside its vacuole amoeba secretes its digestive enzymes and digests the food. The digestive enzymes are secreted into the food vacuole in amoeba to break down the food. The enzymes act on food particles in the vacuole and break down into simpler molecules by chemical reaction which are soluble in its body.

Siphoning – Siphoning is a mode of nutrition in which animals suck the food from substratum.

Sucking – Sucking is a mode of nutrition in which insects pierce the food item and then sucks the internal fluid of the food.

Defecation – Defecation is the process of discharge of faces from the body.                                                 

Photosynthesis – [Photo: light, Synthesis: to make] Photosynthesis is the process where, in the presence of chlorophyll, plants use the energy from the sunlight to synthesize food from raw materials like water, carbon dioxide.

Photosynthesis and Digestion

• Photosynthesis is the process by which plants make their own food in the presence of sunlight and chlorophyll pigment by using raw materials like water and carbon dioxide.
• Digestion is the breakdown of complex food molecules to obtain energy to do various life processes. Both these processes are the reverse of each other .

Plant nutrients and animal nutrients

Plant nutrients–

• Plants require two types of nutrients- Macronutrients and Micronutrients.
• Macronutrients are those which are required in higher quantities which include nitrogen, phosphorus, potassium, calcium, magnesium and sulphur.
• Micronutrients are those which are required in minute quantities which include boron, chlorine, copper, iron, manganese, molybdenum, and zinc.

Animal nutrients are mainly what the plants produce. These are again of two types- Macronutrients and micronutrients.

• Macronutrients – Carbohydrates, Proteins, Fats
• Micronutrients – Vitamins and Minerals.

Calories

• Food gives us energy and this energy is measured in calories. A calorie is the unit of energy.
• A calorie is the amount of energy needed to raise the temperature of one gram of water by one degree centigrade.
• Standard unit of food energy is kilocalorie 1 kilocalorie =1000 calories

Glycogen – Glycogen is a polysaccharide of glucose that serves as a form of energy storage in animals.

Fats – Fat is a stored form of energy. It produces energy in the body when required. The fat lying underneath the skin renders protection to the body against a rapid heat loss.

Proteins – Proteins are made up of amino acids that join together to form long chains. There are 20 amino acids that help form thousands of different proteins in your body.

1. Component of every cell.
2. Components of hair, nails. E.g. Keratin protein.
3. Build and repair damaged tissues.
4. Make Necessary enzymes and hormones.
5. Important building blocks of bones, cartilage, muscles, skin and blood.

Proteins can’t be stored in our body like carbohydrates and fats, no reservoir, should be replenished on a daily basis.

Protein – Proteins are a type of macronutrients required by the body for growth and repair. Hence, they are also known as “body building food”. Milk, fish, meat, cheese and eggs are the main sources of animal proteins. Plant based proteins can be obtained from pulses and beans.

Putrefaction – Slow decay of certain parts of the body.

Water

1. Helps to regulate body temperature
2. Transports nutrients and oxygen to the all parts of the body
3. Helps in the digestion and excretion of waste products
4. Prevents dry skin, reduces the intensity of fever and headache

Dog’s digestive system – The dog digestive system includes all the organs involved in eating and processing food. The digestion takes 6 hours to complete.

Cow’s digestive system – The digestion on cows takes about 80 hours as they have to process their food since their food is grass and it contains cellulose which is hard to process. The friendly bacteria in the cow’s intestine or gut help in the digestion process called rumination.

Chicken’s digestive system – Chicken’s don’t have teeth, to make up, they swallow small stones which are stored in another organ called gizzards, these small stones help to grind the cereals which they eat.

Rabbit’s digestive system

• The food which are eaten by the rabbits can’t be digested by the rabbit’s digestive system, the materials from the intestine is packaged in to small round moist pellets, microorganisms present in their intestine acts on these moist pellets to convert the undigested food in to the digestible nutrients .
• The nutrient rich pellets which are ready in the intestine must be taken into the digestive tract of the rabbit once more  by the action of the brain in which they emerge this out and eaten up immediately after that ,that is they are eating their nutrient rich pellets or it’s faeces.

Shark’s digestive system – Sharks when swallowing something which they can’t digest are able to turn their stomach inside out to expel whatever they swallowed .

Stomach -functions

1. Stomach secretes digestive enzymes and acids for digestion of food
2. Mucus protect the stomach lining by from being burnt from acids
3. Unwanted bacterias will be killed by the acidic medium
4. Food is ground and mixed by the contraction of stomach’s muscular wall
5. It takes 40 min to few hours for the stomach to break down the food
6. Average human stomach can comfortable hold about a litre of food
7. Our stomach can hold 15 ml when it is empty to 4 litres when it is full

Liver Cirrhosis  – Liver flushes out the toxic substances from our blood, if we consume alcohol, the liver needs to clean up the alcohol from our body, excess consumption of alcohol causes our liver to die and this is called cirrhosis.

Vermiform Appendix – Earlier Vermiform appendix was considered as a vestigial organ, but according to recent study the appendix acts as a safe house or reservoir for good bacteria that is needed to digest our food.

Flatulence – Humans pass through 500 – 1500 ML of gases everyday ,and this can be passed through 10-15 times in a day. This passing of gas is known as flatulence. These gases are coming from the air we breathe in, which gets into our digestive tract and  produced by the bacterias in the intestine.

Rumination – Ruminants or herbivores like cows, buffalo etc. have a 4 chambered stomach which contains rumen, reticulum, omasum and abomasum, it is an adaptation to prevent from being hunted down by predators while they are eating. In the four chamber rumen is the largest and most important chamber and some microorganisms and bacterias are present in the rumen, these microorganisms will produce enzymes required to digest the cellulose from plants. During digestion, food will form a soft chunk called cud, the cud produced is regurgitated back into the animal’s mouth where they can chew again. The saliva of the cow greatly aids in digesting the cud, after chewing the food bipasses into the two chambers of the stomach and directly enters into the third chamber, the walls of the third chamber mash and compact the food up much further and pass it on to the fourth chamber. The final digestion of the stomach is done there and passed on to the intestine.