Different Ways of Taking Food
Each species or form of organism has their own way of taking in food.
Bees and hummingbirds suck plant-nectars, infant of humans and a few animals go after mother’s milk, Snakes like python consume the animals upon which they prey.
Aquatic animals filter small food particles floating closeby and go after them.
Digestion in Humans
The alimentary tract and also the associated glands together constitute the systema alimentarium in humans.
This constitutes the entire path along which food moves through the body, ranging from the mouth and ending at the anus.
Digestive tract includes the oesophagus, stomach, bowel and huge intestine.
Salivary glands, liver and pancreas are the main digestive glands.
Buccal Cavity
The bodily cavity is more commonly called the mouth, and it's the start of the systema alimentarium for humans.
It consists of the tongue and teeth.
Teeth: Helps in chewing food and breaking down food into smaller particles.
Tongue: Fleshy muscular organ attached at the rear to the ground of the bodily cavity.
Saliva is secreted within the mouth and helps within the break down of food.
Tongue
It is a muscular organ, fleshy in nature attached to the rear of the bottom of the bodily cavity.
It helps in mixing saliva with food while chewing and aids in swallowing.
The tongue possesses tastes buds that help us recognise different tastes.
Tooth Decay
Bacteria present in mouth break down the sugars present from the leftover food and release acid.
These acids gradually damage the teeth and ends up in cavity.
Oesophagus or food pipe
The food that's swallowed, passes into the oesophagus.
It is a muscular tube, about 25 cm long, with a sphincter (valve/opening) at each end.
Its function is to move food and fluid, after being swallowed, from the mouth to the stomach.
Food is propelled down by as there in movement through the walls of the food pipe.
Stomach
It is a thick-walled bag-like structure.
It obtains food from the food pipe and opens into the tiny intestine towards the opposite opening.
The inner lining of the stomach produces mucus, hydrochloric acid(HCl)and other digestive juices.
Food is churned into semi-solid mass within the stomach.
Enzymes present within the digestive fluid disintegrate the food.
Hydrochloric acid helps in partial digestion of proteins and also kills harmful bacteria.
Small Intestine
This is a highly coiled organ of seven.5 metres length.
It receives secretion from the liver and pancreas.
Complete digestion and absorption of food happen within the bowel.
The inner walls of the intestine have finger-like outgrowth called villi.
Villi increase the extent for absorption of food.
Each villus features a small network of blood vessels.
Absorbed food by villi is transferred to the body via blood vessels.
Large Intestine
It is wider and shorter than the tiny intestine.
It is 1.5m long.
Absorption of water and salt from undigested food occurs within the bowel.
Remaining material is passed out through the rectum.
Time to time, fecal matter is removed through the anus (egestion).
Anus
The anus is that the opening at the top of the human alimentary tract.
The removal of fecal matter from the big intestine occurs through the anus and this process is termed egestion.
Saliva and Salivary glands
Three pairs of salivary glands are present round the mouth and that they pour their secretion, saliva, into the mouth by salivary ducts.
Saliva has mucous and salivary amylase.
Mucous helps in easy passage of food through the food pipe.
Salivary amylase is an enzyme answerable for breaking of starch content of food into simpler sugars.
Gall Bladder
The gallbladder may be a small pear-shaped organ present under the liver, on the proper side of the body.
It stores bile juice secreted by the liver.
Bile plays a vital role within the digestion of fats.
Ingestion
The process of taking food into the body is termed ingestion

Digestion
The breakdown of complex components of food into simpler substances is termed digestion.

Partial digestion takes place within the stomach and complete digestion takes place within the intestine.
Absorption & Assimilation in bowel
The digested food is obsessed by the blood vessels lining the tiny intestine’s walls. This phenomenon is said as absorption.
The inner walls of the tiny intestine have many finger-like outgrowths called villi.
The substances that are absorbed are transported through blood vessels to varied organs of the body where it's utilized to make complex substances like proteins essential for the body. this is often called assimilation.
Digestion in Grass Eating Animals
Digestive system in grass eating animals is different from that of humans.
These animals are chewing continuously even once they aren't eating.
They swallow the grass in no time and store it during a chamber called Rumen.
In the rumen, the bacteria partially digest the food and now it's called as cud.
Later, cud reverts to the mouth and animal chews it again slowly.
This phenomenon is said as rumination and also the animals are called as ruminants.
They even have very long bowel which helps in complete digestion of cellulose, the most component of grass.
Cud
Partially digested food, returned from rumen into the mouth, for further chewing is termed as cud.
Rumination
Rumination is that the process by which the cattle regurgitates previously consumed feed and masticates it a second time.
Feeding and Digestion in Amoeba
Amoeba
Amoeba is single-celled organism, microscopic in nature found in pond water.
Amoeba regularly changes its shape and position.
Process of Digestion in Amoeba
Amoeba captures the food particles with the assistance of pseudopodia. the method is termed as phagocytosis.
A food vacuole is thus created with the food material inside.
Digestive juices are produce
d into the food vacuole when it's moving through the cytoplasm.
They act on the food and disintegrate it down into simpler substances and also the digested food is then absorbed.
Finally, the food vacuole opens to the skin and undigested food is released into surrounding water.