Animal Husbandry
ACCESSORY ORGANS OF THE DIGESTIVE SYSTEM
So far, we have looked at the major digestive organs. We must now look at the accessory organs found along the digestive tracts of both ruminants and non-ruminants.
Salivary Glands
The function of the salivary glands is to produce fluid which pours into the mouth while the animal is eating. This fluid assists in the chewing process so that food is more easily broken down. It also makes the bolus (ball of food) more slippery so that it passes easily down the oesophagus.
There are three pairs of salivary glands:
- parotid gland : this means "ear" - the parotid gland is situated in front of the ear;
- mandibular gland : this means "jaw" - this gland is found in the lower jaw; and
- sub lingual gland : this means "of the tongue" - this gland is found under the tongue
Salivary glands produce two types of fluid. One is a thin, clear, watery fluid and the other is a thick, sticky fluid called mucous. These two fluids are mixed together to produce saliva (which is the liquid in the mouth).
The other important function of the salivary glands is to produce an enzyme called ptyalin (the p is not pronounced). This enzyme starts the process of digestion in the mouth by turning some of the starch in the food that was eaten to sugar. It is important because it starts the chemical process of digestion as opposed to the mechanical process which is carried out by the grinding action of the teeth.
Pancreas
From earlier notes you will see how the pancreas is situated below the stomach but above the part of the small intestine called the duodenum. The pancreas is made up of two types of glands - exocrine glands and endocrine glands. Exocrine glands make up the largest part of the pancreas.
An endocrine gland has no duct system - it pours its secretions directly into blood vessels which run throughout the pancreas. Exocrine glands, in contrast, pour their secretions into ducts - these join up and lead into the pancreatic duct and so into the duodenum.
The function of the pancreas is to produce two chemicals:
The enzymes produced are: trypsin, chymotrypsin, carbozypeptidase, lipase, and amylase. You do not have to remember the spelling of these complicated names. Just remember that they are enzymes and their job is to assist in the breakdown of complex nutrients such as starches, sugars, oils, and fats into the simple sugar glucose which is the end product of digestion. Glucose is the fuel for the body.
The endocrine part of the pancreas produces two hormones: insulin and glucagon. Their task is to regulate the breakdown of the complex nutrients into simpler compounds. They decide how much is broken down and how quickly.
The pancreas pours its secretions into the duodenum at a point very close to the point where the bile duct (leading from the liver) also joins the duodenum. This is important because it means that the secretions from both organs can work together in the process of digestion. Between them the two hormones, insulin and glucagon, control the levels of glucose in the blood. Glucose levels in the blood are raised by glucagon and lowered by insulin.
Although insulin performs several functions, its main task is to pass glucose across the cell membranes (or walls) into the cells where it can be further broken down and converted into energy. If there is a shortage of insulin in the body, glucose remains in the blood and builds up - it cannot be utilised by the body and some is wasted. This condition in humans is known as diabetes and if a person is a severe diabetic he has to inject himself with insulin every day and avoid eating sugary foods which are easily converted into glucose.
Glucagon controls how much and how fast sugar (that is stored in the liver) is released into the bloodstream. When the body needs more fuel, glucagon works to increase the glucose levels in the blood. Insulin and glucagon work together to maintain the ideal level of glucose in the blood.
To improve your skills and knowledge of Animal Husbandry I recommend studying the Certificate in Animal Husbandry. This comprehensive course will give you the skills and knowledge you need to master animal husbandry. It also provides you with three electives to make sure the course is relevant to you!
If you would like to discusss this with me please ask! It's free and there is no obligation - Yes, I would like some free advice!
