DIGESTION IN HUMAN BEINGS

LIFE PROCESSES

DIGESTION IN HUMAN BEINGS

Life Processes – The important processes carried out by the living organism to maintain and sustain life are called ‘Life Processes’.

Eg. Nutrition, Respiration, transportation, Excretion

HETEROTROPHIC NUTRITION

In this mode of nutrition organism obtain the food the outside source.

·        In amoeba food is captured at any point along the cell membrane (pseudopodia)

·        In paramecium food enter the body through one fixed point at cell membrane.

·        Saprophytes – Organisms obtain food from dead and decaying matter. Eg. fungi

·        Parasites – Organisms depends on the host for the nutrition. Eg. Leech, worms

Holozoic nutrition – In this the whole food consumed is broken down and digested with the help of enzymes. Eg. Human beings

Digestion in human beings takes place along the alimentary canal. (Mouth, oesophagus, food pipe, stomach, duodenum, small intestine, large intestine, anus)

Enzymes – These are different catalyst which helps to convert the convert the complex food molecules to the simple absorbable form.

Steps in digestion

1)    Mouth – In mouth teeth break the food in smaller particles. Saliva secreted by salivary glands mixes with the food and makes it soft. This soft ball called ‘Bolus’ is pushed towards the oesophagus.

Epiglottis, a cartilaginous flap closes the pharynx (wind pipe) while the food passes through oesophagus.

Salivary gland à amylase à starch to maltose

2)    Stomach – stomach expands when food enters into it. Gastric glands present in the inner lining of stomach secrets few digestive enzymes and helps in further digestion of food.

•           Hydrochloric acid à destroys microbes
•           Mucus à protects the inner lining of the stomach from the action of acid.
•          Pepsin à Proteins to polypeptides (chain of amino acids)
•         Rennin àMilk proteins to curd

In stomach the food is converted to semi liquid form called as ‘Chyme’.

Food is passed to the small intestine in small amounts. This is regulated by the “Sphincter Muscles”.

3)    Duodenum – This is the beginning part the small intestine. In this portion the Bile Juice from the Liver and Pancreatic Juice from the Pancreas add to the food.

Bile juice à Emulsify the fats

Pancreatic juice à         trypsin à  digests proteins

                                      Lipase à fats to simple fats

4)    Small Intestine – This is the longest part of alimentary canal. It is fitted in a compact space in coiled manner.

Walls of small intestine secrets intestinal juice, which contains different enzymes that helps in final digestion of food.

•    Proteins à Amino Acids
•    Carbohydrates à glucose
•    Fats à Fatty acids and glycerol

The walls of small intestine have numerous finger like projections called “Villi”. This increases the surface area for absorption of digested food. Villi are rich in blood vessels and absorb the digested food. This is carried to every cell of the body and utilized for obtaining energy, building new tissues and repair of old tissues.

5)    Large Intestine – The remaining food material passes to the large intestine. The Villi here absorbs the water.

6)    Anus – This is the exit of the alimentary canal. The rest of the material is thrown off the body through anus. This exit is controlled by Anal Sphincter.

·        Peristalsis – This is the contraction and relaxation movement of the muscles of the entire alimentary canal. This helps the food to move forward in the digestive track.

For the explanation of this watch the video on our youtube channel
https://youtu.be/gViM3KX6CMc