THE HUMAN DIGESTION:
The food is taken into the mouth where it is chewed, mixed with saliva which is secreted by glands in the mouth. After mastication a portion of food is collected on the tongue. It is then swallowed and the opening to the larynx is closed off by a small flap of tissue called the epiglottis. This flap prevents the food from entering into the respiratory tract. Should some food stray into this tract a reflux action occurs by coughing to expel the food out.
The food passes from the esophagus into the stomach, contractions of the muscular wall of the stomach ensure further mixing and mechanical disintegration of the food, which at the same time is mixed with the gastric juice secreted by the stomach.
The stomach has a mucous membrane lining and is protected from the gastric juice which contains enzymes and hydrochloric acid. The food is broken down into smaller particles for easier absorption into the bloodstream and the rest of the food passes into the small intestine and duodenum through the pyloric sphincter valve, a muscular ring at the end of the stomach and intestine.
In the small intestine, rhythmic movements of the walls churn up the food and mix it with the digestive juices, which include pancreatic and bile juices (The bile is produced by the liver and stored by the gall bladder) further digestion then takes place as the result of the action of enzymes present in these juices.
Absorption of the digestive nutrients takes place mainly through the mucus membrane of the small intestine. The rhythmic movements of the intestine force the unabsorbed food, and waste matter excreted from the blood into the large intestine, here the water is absorbed by the walls of the intestine and partially dehydrated material passes to the rectum from which it is excreted from the body through the anus as faeces.
THE ALIMENTARY RUMINANT SYSTEM
The name ruminant means ” Chewing The Cud” and it’s a name given to those mammals of even – toed, cloven hoofed, such as Cattle, Sheep, Goats are ruminants.
Other groups of ruminant – like animals include the antelopes, deer, camels, llamas, hippopotamus, sloths and kangaroos.
The ruminant has a stomach consisting of four compartments (camels have three.)
The food is partly chewed then swallowed and it passes into the first compartment called the rumen. The large stomach has no digestive juices or excretory glands present and the food is attacked by large numbers of living protozoa, microbes and bacteria which already are present in the walls of the ruminant stomach. The breakdown of cellulose, which plants are largely composed of takes place in this section of the stomach and the food is regurgitated from time to time into the mouth in small amounts and slowly chewed to a pulp, and when food is swallowed again, it enters a second compartment called the reticulum.
This section of the stomach breaks down the cellulose further and passes it to the third compartment called the omasum.
The omasum contains large leaf – like structures that increases the surface area for effective water absorption, there the muscles stir and reduce it further until it enters the fourth compartment, called the abomasum.
“True Stomach” A stomach much like ours. In this organ gastric juice is secreted, it contains hydrochloric acid which kills most of the microbes and begins digesting them and their contents are then absorbed to provide essential vitamins, minerals and amino acids.
Ruminants have specialized metabolisms due to the presence of digestive bacteria. Protein needs are supplied by the rumen bacteria which use simple substances urea and inorganic sulphates to manufacture these proteins. This is a major difference between ruminants and other animals because they produce their own protein. Protein is a dietary requirement of all other animals.
In most ruminants (Cattle, Sheep, Goats) there is a absence of upper incisors – replaced by a hard “Dental Pad” well formed even lower incisors. Well developed molars and premolars for grinding movement is “Lateral”. The toothless gap between incisors and premolars allows the tongue to manipulate the food. Chewing movements acts as a stimuli, leads to increased salivation, particularly on the side on which the chewing is done. In cattle up to 200 litres may be produced in 24 hours. The saliva is rich in bicarbonate, which serves to neutralize the fatty acids produced by fermentation.
Specialized tongue and lip for grasping and tearing.
Well developed molars and premolars for grinding, movement is “lateral”.
In most ruminants upper teeth replaced by “Dental Pad”.
A gap between premolars and molars allows the tongue to manipulate the food into small amounts prior to swallowing.
Mouth is taken to food.
Complex digestive system (Four Stomachs).
Regurgitation of cud for chewing at rest, one set of teeth for life, teeth wear flat, with the age.
Protein needs supplied by rumen bacteria.
Herbivores – no meat.
Upper and lower teeth movement is “Vertical” Incisors and canine produce shearing action, used for cutting food, premolars and molars for grinding and crushing.
Two sets of teeth – loss through decay and improper nutrition – replaced by dentures (False Teeth).
Food is taken to mouth.
Digestive System (one stomach).
Protein is a dietary requirement and is provided by the intake of various foods.
Vomiting more common in carnivores and omnivores. Forceful ejection of gastric contents from the mouth.
Variety of foods to obtain various other nutrients.
Ill health, weather changes, irritability and stress, may have an effect on digestive processes.
Omnivores – meat and plants.
Food, water, and oxygen to sustain life, we require similar nutrients and produce waste products.