Anatomy And Physiology

All activities taking place in living organisms are aimed at growth and reproduction. In order to grow the animal needs energy. The source of energy is food, which must be searched for the animal may supply itself or fed to the animal by its caretaker or parent. To be able to search for food the animal needs a locomotor system and also senses in order to smell, see and hear. To make the food available to the body it must first be broken down into more elementary substances (e.g. proteins to amino acids, carbohydrates to glucose and fats to fatty acids). The digestive system, which includes all the structures and organs from the mouth to the anus, is necessary for this.

The digestive system removes the useful parts from food and discards the rest. For the absorbed nutrients (amino acids, glucose and fatty acids) to be changed into energy and thus made available to the body they must first undergo a process, which is called metabolism. The liver plays the biggest role in this process. Before energy can be released from nutrients it must first be “burnt” by the body and oxygen is necessary for this. The respiratory system supplies this oxygen to the body. To transport oxygen from the respiratory organs (lungs) to the rest of the body and also for the distribution of nutrients through the body, the circulatory system is necessary. The circulatory system also transports the waste products of metabolism to organs where it is excreted e.g. the kidneys which are part of the urinary system. To reproduce the animal needs a reproductive system. This complicated system is controlled by the endocrine system, consisting of ductless glands, which secrete their chemicals/fluids called hormones into the bloodstream for distribution to the whole body. When a hormone reaches its target organ, it will have the desired effect on that organ. This is called negative feedback. The production of hormones may be triggered by environmental factors or physiological changes in the animal’s body. The endocrine glands control various involuntary processes in the body e.g. metabolism, growth, digestion, etc. To synchronise and control all the systems a nervous system is necessary. The nervous system can be divided into two functional parts, namely, that which controls voluntary processes like walking, vision, hearing, smelling, etc. and that which controls the involuntary processes like heart rate, movement of the intestines etc. A short preview of the anatomy of the different systems of the body will be given in order to know the anatomy of a normal healthy animal. For practical reasons the different systems will be dealt with separately, but it should always be borne in mind that the function of each system is dependent on that of others and that it is really impossible to study one without having a thorough knowledge of the rest.