Digestion

is broken down of big molecules (Carbohydrates, proteins and lipids) into their monomers to be used by organisms in production of energy and building new organic molecules. Digestion takes place in cell (Intracellular) or out of cell (Extracellular).

Intracellular digestion refers to broken down of big molecules (Carbohydrates, proteins and lipids) into their monomers takes place inside the cell. Occurs inside food vacuoles within the cell. Ingestion occurs through phagocytic vacuoles by lysosomes. Wastes are removed from the cytoplasm by exocytosis. Intracellular digestion. It can be observed in unicellular organisms like paramecium and sponges.

Extracellular digestion refers to a form of digestion where the breakdown of materials into smaller components takes place outside the cell. Occurs outside the cell in the lumen of the digestive system, in a gastric cavity or other digestive organ, or completely outside the body. A process by secreting enzymes through the cell membrane into the food. The enzymes catalyze the digestion of the food into molecules small enough to be taken up by diffusion phagocytosis. The indigestible materials are excreted through the anus in extracellular digestion Extracellular digestion is a form of digestion found in annelids, crustaceans, arthropods, lichens and chordates, including vertebrates.

A. Swallowing the food. B. Breaking down the food into monomers. C. Absorption of digested food. D. Excretion of wastes.

incomplete digestive tract., complete digestive tract

This system starts by mouth and end by anus. Earthworms have this system and feed on organic materials in soil. These animals absorb nutrients by muscular pharynx and wastes are removed through anus. Nutrients pass from pharynx to the crop where food is stored. Then food pass to the gizzard where food broken down by help of small stones in it. Extracellular digestion happens in digestive tract digested food absorbed

This kind of digestive system has only one opening called as mouth Planaria has this kind of digestive system. Planaria are tiny aquatic organisms and they feed on organic remains. Mouth is used for ingestion of food and excretion of wastes. Digestive system starts by mouth and muscular digestive tract and extend as branched gastrointestinal cavity. During ingestion digestive tract extends out of body to take food and extracellular digestion is performed in digestive tract.

The gizzard is where food broken down by help of small stones in it, and it's found in earthworm and some birds.

Mosquito is carrier of these parasites. It secretes a kind of substance on human body to prevent blood coagulation and absorb blood. Only female mosquito absorbs the blood. And parasites pass the human body in this way.

It is a finger like small extension at the beginning of large intestine. It is site of cellulose digestion in herbivores. It causes dangerous medical problems in human when it is inflamed and can be removed by surgery.

 Food transport by movement of muscles in wall of digestive tract and fimbrea (Villi).  Movement of food by fimbrea performs in animals which have pseudo-coelom.  In other animals food transport by contraction and relaxation of muscles in wall of digestive tract.

These waves like movement (contraction and relaxation) of muscles in wall of digestive tract and it's contributed to transporting food.

A. Food reception zone (mouth, mouth components and muscular pharynx). B. Transport and storage zone (Pharynx, esophagus). C. Digestion zone (stomach). D. Last digestion zone and absorption (intestinal zone). E. Water absorption zone (large intestinal).

 Food reception zone it is front part of digestive tract.  Digestion starts in this zone by secretion of Ptyalin enzyme which involved in digestion of complex carbohydrates like starch. This enzyme found in snail, some insects, mammals and human.  Ptyalin enzyme loses its function when reach the stomach with semi digested food.  Digestion of starch complete in small intestine.  The tongue is a distinctive feature of vertebrates that help chewing and swallowing of food.  Epiglottis closes the trachea during swallowing and food pass into esophagus then by peristaltic movement transports to the stomach.

This enzyme found in mouth of snail, some insects, mammals and human, which involved in digestion of complex carbohydrates like starch, and its function lose when reach the stomach with semi digested food.

is a distinctive feature of vertebrates that help chewing and swallowing of food.

a small piece of cartilage closes the trachea during swallowing and food pass into esophagus and it prevent entering of food into trachea

has differentiated parts (Teeth, salivary glands and tongue) and its function chewing food and digestion of starch

1) Secretion of digestive enzymes. 2) They sometimes involved in calmness of prey. 3) Prevent pain during biting prey or prevent blood coagulation in some insects.

 Pharynx involved in transmission of nutrients to the digestive tract of invertebrates and some vertebrates.  Pharynx is followed by esophagus. It`s front part enlarged to form crop in some animals.  Crop stores the food, moistens it before digestion in birds. This stored food became semi digested before coming back for offspring's.

It`s front part enlarged of esophagus crop in some animals (birds), crop stores the food, moistens it before digestion and became semi digested before coming back for offspring's.