Heterotrophic nutrition
Heterotrophic nutrition is of three types.
- Holozoic nutrition: Herbivores, carnivores and omnivores proposes the holozoic mode of nutrition. complex food molecules are taken in and then broken down into simpler and soluble molecules in this type of Nutrition.
- Saprotrophic nutrition: saprotrophs are the organisms having saprotrophic mode of nutrition. They usually feed up on dead organic matter, breaking dawn complex materials outside the body and absorption it, example fungal like that malls mushrooms yeast and bacteria.
- Parasitic nutrition:. parasites are the organisms having parasitic nutrition. This organisms live together or inside the body of other organisms obtain their nutrition without killing them example plasmodium, ticks etc .
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Nutrition in amoeba
Amoeba is a unicellular, omnivore organism that does not possess specialised organs for the process of Nutrition. the mode of nutrition in amoeba is holozoic and takes place with the help of pseudopodia. Pseudopodia is the finger like extensions. With the help of pseudopodia it engulfs the food when it comes in contact with it cell surface by ingestion.
Complex food breaks into small soluble molecules and absorbed by cytoplasm this process is called absorption.
The absorbed food is further assimilated by amoeba to derive energy for growth.
The undigested food material is removed and this process is called egestion.
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digestion is a catabolic process in which complex and large components of food on broken down into their respective similar and smaller forms with the help of various hydrolytic enzymes.
The entire system which performs this process of digestion is called digestive system.
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Alimentary canal
It is a long tube where the entire process of digestion takes place.
The absorbed food is further assimilated by amoeba to derive energy for growth.
The undigested food material is removed and this process is called egestion.
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Nutrition in human beings
Description of Human digestive system
digestion is a catabolic process in which complex and large components of food on broken down into their respective similar and smaller forms with the help of various hydrolytic enzymes.
The entire system which performs this process of digestion is called digestive system.
Alimentary canal
It is a long tube where the entire process of digestion takes place.
- Mouth. ::first part of digestive system from where the the food enter into the the alimentary canal.
- Pharynx:: small funnel shaped chamber located behind the oral cavity communicates with both oesophagus and trachea.
- Oesophagus:: thin long muscular tube that leads into stomach.
- Stomach: it is most dilated J shaped part of the alimentary canal. IT act as store house of food where partial digestion takes place through secretion of gastric glands.
- Small intestine:: the longest part of alimentary canal small intestine is fitted in a compact space as extensively coiled structure in our belly. Carnivorous have short length of small intestine but herbivores have longer length of small intestine. small intestine constitutes finger like projection called villi which increases the surface area of absorption.
- Large intestine:: Although shorter but is called large intestine because it is wider in diameter than small intestine.
- Rectum:: the last and broad chamber like structure that serves to store faecal matter temporarily.
- Anus: The endpoint of alimentary canal which helps in exit of waste material. The exit of waste material is regulated by Anal sphinster.
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Digestive glands
- Salivary glands. : Thase gland secrete saliva containing and enzyme called salivary amylase. It converts starch into sugar at an optimum pH of about 7.
- Gastric gland : these are found in the wall of stomach .the gastric glands release digestive juice containing HCL, pepsin and mucous. HCL kills the bacteria ingested with food it creates acidic medium of PH about to to help pepsin to act on food. the mucus protects the lining of stomach from the action of hydrochloric acid.
- Liver : it is known as the largest gland of the body which secretes bile juice.They act on large fat molecules to form smaller globules increasing the efficiency of enzyme action. Gallbladder stores bile juice for the further use.
- Intestinal glands : walls of small intestine contains numerous glands that secrete intestinal juice containing amylolytic, proteolytic and lipolytic enzymes.
- Pancreas : it secrets pancreatic juice which contains enzymes like amylase,trypsin and lipase. it is connected to the small intestine through its main duct called pancreatic duct which joins the bile duct to form common hepatopancreatic duct that opens into small intestine.
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