OTHER SYSTEMS

THE RESPIRATORY SYSTEM

The lungs and airways allow for the exchange of gases in the alveoli or air sacs, by this system in the body.

THE NERVOUS SYSTEM

This is composed of the brain, the spinal cord and a network of nerves or neurons which all serve to regulate and control bodily functions.

THE LYMPHATIC SYSTEM

The lymphatic system consists of a network of capillaries known as lacteals, lymph vessels, lymph nodes and a liquid known as lymph which collectively perform the following functions:

The transport of lipids or fats from the intestine to the blood

The production of a white blood cells known as lymphocytes, which in turn produce antibodies in response to foreign proteins such as antigens

The return of excess tissue fluid to the blood.

THE IMMUNE SYSTEM

Immunity is the ability of the body to resist disease, through defence mechanisms which may be general or specific. These are designed to protect the body against disease causing organisms or pathogens. General defence mechanisms include the presence of hydrochloric acid (HCl) in the stomach, the low pH of which impedes the survival of pathogens. Specific defence mechanisms involve the production of antibodies, either actively or passively.

On the farm, the use of vaccinations is an example of active immunity whereby a small and harmless dose of a pathogen is administered to induce an immune response. The subsequent production of antibodies by lymphocytes ensures the same immune response will be activated should the animal come in contact with the pathogen again. Passive immunity on the farm can be observed in the imparting of vital antibodies in colostrums from mother to calf, or across the placentas from mother to foetus before birth.