SYSTEMS of the BODY

The various systems of the body are named according to the function they perform.

SKELETAL: this system consists of bones forming a movable framework for the body, and protection for some of the soft organs such as the lungs, brain, etc

ARTICULATORY: the articulatory system is concerned with the joints, or articulations of the skeleton

MUSCULAR: the muscular system consists of muscles, fascia and tendons and is responsible for bodily movement

RESPIRATORY: this system contains the various organs concerned with respiration (breathing).  When we breathe correctly with the mouth closed, the air enters the nostrils and passes to the two lungs (left and right) via the Pharynx (throat), Larynx (upper end of windpipe), the Trachea (windpipe) and finally, the Bronchi (bifurcation of the trachea to each lung). After entering the lungs, the air gives up oxygen which is carried by the red corpuscles in the blood, to the tissues of the body. Carbon dioxide, a waste product, is picked up by the blood and carried back to the lungs where it is expelled during exhalation.

DIGESTIVE: the digestive system deals with the body’s intake of food and with the preparation of that food for assimilation by the body. The digestive system consists of the Alimentary Canal and certain secretory glands. The alimentary canal extends from the mouth to the rectum and is over 9 metres in length. It consists of the following:-

The Mouth

The Pharynx

The Oesophagus (food pipe)

The Stomach

The Small Intestine

The Large Intestine (Colon)

The Rectum

As food passes along the alimentary canal, special juices from glands such as the salivary glands, gastric glands, pancreas etc, pour into the alimentary canal to mix with the food and break it down into simple substances which can be digested and absorbed by the cells of the tissues of the body. The indigestible residue enters the rectum and is excreted as faeces.

CIRCULATORY: the circulatory system is responsible for circulating the blood throughout the body. It consists mainly of the Heart positioned in the Thorax (chest) and three types of tubes – namely, Veins, Arteries and Capillaries. The heart is in fact a pump. It pumps the blood through a network of arteries, capillaries and veins. Carried by the Superior Vena Cava (vein) from the upper parts of the body and by the Inferior Vena Cava (vein) from the lower parts, impure blood enters the right Atrium of the heart, is forced through a valve into the right Ventricle and is pumped from there through the Pulmonary Artery to the lungs. The impurities int he blood are discharged in the lungs as carbon dioxide. Oxygen is picked up by the red corpuscles in the blood and the purified blood passes through four Pulmonary veins, two from each lung, into the left Atrium of the heart. It is then forced through a valve into the left Ventricle, where it is pumped through the Aorta (large artery) into a network of smaller arteries. All arteries branch off into a number of smaller arteries, the smallest being called Arterioles. These get smaller and smaller until they become Capillaries, and give off enriched blood to the tissues through their thin porous walls. Impurities from the tissues are absorbed through the capillary walls and carried into very tiny veins called Venules, eventually entering the larger veins and finally into the heart, thus completing one cycle of this repetitive function. As the blood circulates, it carries oxygen from the lungs to the tissues, and carbon dioxide from the tissue cells to the lungs. It carries digested food from the digestive system to the cells and waste products to the kidneys for excretion It conveys hormones from the glands to the cells and carries heat from the inside of the body to the surface. Also the blood protects the body against disease and germs.

EXCRETORY: this system consists of the Skin, Kidneys, Lungs and Colon

The Skin gives off sweat

The Kidneys excrete urine which is stored in the bladder and voided when the bladder is full

The Lungs eliminate Carbon Dioxide

The Colon excretes certain insoluble substances in the faeces

REPRODUCTIVE: the reproductive system is responsible for the reproduction of the species. It produces spermatozoa in the male and ova in the female.

NERVOUS: the nervous system is responsible for communication between the various parts of the body. It operates as controlling system for governing the activities of the various parts and organs of the body and it makes possible, awareness of response to environment