Components of food necessary for the body are called Nutrients. Organisms that prepare food themselves from simple substances are called Autotrophs and animals take in ready-made food made by plants are called Heterotrophs.
Carbohydrate and fats are the energy giving food. Carbohydrate give less energy than fats. Animal fats are saturated fatty acids, which are harmful for health. We should choose unsaturated fatty acids for cooking. Trans fats are unsaturated fats that damage the heart.
Proteins are body building foods.
Proteins are polypeptides
i.e. linear chains of amino acids linked by peptide
bonds. Enzymes are
proteins which perform role of biological catalysts.
Receptors are proteins
which perform function related to communication systems in
the body.
Collagen is
the most abundant protein in animal world and
Ribulose bisphosphate
Carboxylase-Oxygenase (RuBisCO) is the most
abundant protein in the whole of the biosphere. Protein
deficiency causeskwashiorkor
and Maerasmus.
Vitamin A,E,C are anti-oxidants that absorb free radicals. The vitamins and minerals deficiency can cause the diseases mentioned in the table.
Vitamins or minirals | Disease |
Vitamin A | Night blindness / Xeropthalmia |
Vitamin B1 | Beri beri |
Vitamin C | Scurvy |
Vitamin D | Rickets |
Vitamin E | Anemia / Loss of fertility |
Vitamin K | Bleeding |
Calcium | Bone and tooth decay |
Iron | Anemia |
Iodine | Goiter |
Note: Mercury poisoning causes mina mata disease and cadmium poisoning causes itai-itai.
Roughage or dietary fibers are present in plant products like whole grains, pulses, potatoes, fresh fruits, vegetables. Don’t have nutrients but helps to get rid of undigested food.
Digestion
is a process in which complex components of food
are broken into simpler substances.
Saliva breaks down starch into sugars. Stomach
secretes mucous, hydrochloric acid and digestive juices. The
mucous protects the lining of the stomach, acid kills the
bacteria and digestive juices break proteins into simpler
substances.
Liver is the largest gland in the body.
It secretes bile stored in the gall bladder, bile is
important in digestion of fats. It produces cholesterol
[lipoprotein].
Low density cholesterol is bad and
high density cholesterol is good.
Humans can’t digest
cellulose. The temperature of a human body is 35-42°
Celsius.
Starfish feeds on animals that are covered by a calcium carbonate shell. The shell is popped open and then the starfish puts its stomach out of its mouth to eat the soft animal inside. The stomach then goes back inside and then the food is slowly digested.
Small intestine is lined with villi which help in absorption of food. Small intestine is 7.5m and large intestine is 1.5m. In herbivores, small intestine is longer to digest cellulose. In carnivores, small intestine is smaller as meat is easily digested.