Science of the human body


OUR fifth lecture today is on the sciences of our body as an organism. Our body is very important and therefore understanding how it functions and to help maintaining it will help us to live a healthy life.
In public offices in PNG people do not care about other peoples’ concerns. People meeting at those places who are the officers and the concerned citizen who goes there for help is most of the time not accorded the respect, attention and service the citizen deserves. They may get that after a few struggles. This is not the right thing to do. People just don’t care.
I am sick and tired to see people talking like they are the bosses, and that is pride at its best. Always remember that you are not the best because your character shows you are not a humble person and know that pride is the source of all evil.
The best way to solve this matter is, everyone in this country must earn respect from doing a simple job or a service. Every Papua New Guinean must be a servant leader. To lead you must be a servant. Show some simplicity and humility for heaven’s sake because humility commands respect. It is a fantasy for someone to buy his way through the use of money. You will soon be forgotten and the public will curse your grave if the respect you commanded was not from the heart but was bought superficially and chiefly with the use of cash and favours.

Organisms grow through the cell cycles. – Picture from

Our body
For the human body to exist on its own as a self-sustaining entity, it is made of eleven elements in total as macro and micro constituents or nutrients. The first six major elements are carbon, hydrogen, oxygen, nitrogen, calcium and phosphorus.
The next five elements in minute requirements are potassium, magnesium, sulfur, sodium and chlorine. A deficiency in any of these nutrients will result in acute health problems. Rickets is caused by lack of calcium and phosphorus. Goiter as the enlargement of the thyroid gland is caused by a lack of the element iodine. Sickle cell anemia is caused by shortage of red blood cells as a result of a shortage in the element magnesium. Poor growth results due to lack of protein intake which is composed in animal meat together with vitamins and minerals.
The major component of protein, apart from the elements carbon, hydrogen and oxygen, is the element nitrogen. Nitrogen makes plants and animals grow and it also repairs the damaged or worn cells and tissues.
The four major parts which the body is composed of firstly are the many different kinds of cells such as muscle cells, brain cells, nerve cells and so on. Cells are very important because all the macronutrients as well as the micronutrients are interactively involved through and by them.
Many cells make up a tissue. For instance, many different cells like the white blood cells, red blood cells, fibrin and platelets are some major components that make up the blood tissues. Some more tissues are the muscles. There are others still, like cardiovascular tissues. The tissues combined make up an organ. The heart is an organ and the lungs are organs as well. Also, the liver, the eyes and the ears are organs.
All the organs put together make up an organism like us as human beings. To function as a self-sustaining human being all our organs coordinate and function together as different systems to bring about the independent nature of a human being.

The endocrine system. – Picture from biological

There are about 11 systems which operate together to sustain a human being.
The first is the digestive system and the excretory system. All organisms including humans have to take in ready-made plant food such as carbohydrates for energy as well as dietary fiber, water, greens, proteins from either plants or animals together with vitamins and minerals.
These foods go through the gastrointestinal tract from the mouth known also as the buccal cavity to the esophagus or the food pipe, then to the stomach where churning takes place and the intestines, both the small intestines where most digestion takes place, and the large intestines where absorption of water takes place.
The respiratory system is the second system whereby the nose known as the nasal cavity allows air passage and oxygen intake into the body and carbon dioxide out of the body. The oxygen is breathed in through the wind pipe also known as the gullet to the two bronchi leading into left and the right lungs. At the lungs the small air sacs filled with the much smaller alveoli consisting of the tiny blood vessels composed of arteries and veins are joined by the very thin capillaries.
At that site, the exchanges of food nutrients, oxygen, nitrogenous wastes and carbon dioxide take place. The wastes are passed through the renal system of the filtering organ of the left and the right kidneys. The carbon dioxide diffuses out of the thin semipermeable membrane of the capillaries into the lungs to be exhaled.
The third system is the renal system and the urinary system. This system uses the left and the right kidneys to filter out the wastes from the blood. The nitrogenous wastes are filtered into the bladder to be urinated out from the urinary tract and the external opening.
The reproductive system is the fourth system. The male sex gamete called the sperm cell and the female sex gamete, the egg cell both meet to form a zygote which is a fertilized egg. The zygote is implanted as a fetus on the thick uterus lining filled with the blood vessels for the fetus to be nourished when a placenta is developed around it.
The placenta develops with the zygote to nourish the baby with nutrients and oxygen through an umbilical cord which becomes its lifeline because it connects the baby to the placenta for the passage of food nutrients and oxygen to the fetus and it removes wastes and carbon dioxide from it to the mother’s blood system. Placenta is also an endocrine organ that produces hormones to regulate the health status of the fetus such as the temperature level, oxygen and carbon dioxide levels.
The integumentary system or the exocrine system is the fifth system. These include the hairs, the skin, the nails and the sweat with the other exocrine glands. Such exocrine glands are extended by a duct to the outside surface for corrective actions such as salivary glands, sweat glands, digestive glands found in the stomach, pancreas and intestines.
The other glands are such as lacrimal glands that produce the secretions that cleanses the eye and even moistens it are called the tears. Those that produce milk are the mammary glands.
The sixth is the immune system and the lymphatic system. The body is defended by the immune system by the white blood cell that engulfs the pathogens. An antibody is created by an antigen introduced into the body. Such similar events happen in humans such as a disease called mumps whereby a child’s cheeks are swollen when the child catches it.
When it is healed, the body develops antibodies to it already and with a next swathe of mumps break out the child will not catch it because it already has antibodies that protect it. The body also has a network of lymphatic vessels that has a clear liquid called the lymph. The lymph is an intercellular fluid that collects into the lymphatic vessels to return to the blood stream. It contains all fluids like the blood cells except the red blood cells.
The muscular system is the seventh system and it is the elastic fiber that allows for the body’s movement when it contracts and relaxes. Muscles are attached to the bones by a very strong network of non-elastic connective tissues called the tendons.

Cell’s semi-permeable membrane. – Picture from

There are always two muscles that work in pairs. These work in antagonism. As one muscle contracts, the other relaxes to produce the movement in the direction of the contraction by pulling on the bone. For instance, the biceps and triceps work in pairs. As the biceps contract to pull the hand towards the chest, the triceps relax. As the bicep is relaxed the triceps contract to pull the hand away from the body.
Nervous system is the eighth system. It comprises nerve cells called the neurons that allow for receiving and sending information throughout the body. Is collects all information from the body’s senses such as the eye for sight, ear for hearing, skin for touch, tongue for tastes and the nose for smelling. After such information is collected, it is sent to the brain as electric nervous impulses via sensory neurons to the central nervous system.
The information is then sent to the brain to be processed there and appropriate actions are necessitated as relayed via the motor neurons carried away from the central nervous system to the effectors such as the appropriate muscles for movement or the appropriate glands for secretions of the relevant hormones for corrective actions.
The ninth system supports the body and keeps the organs safe and it is the skeletal system. It maintains the shape of the body. The skeleton is attached to each other or connected by a very strong fiber of collagen and connective tissues called the ligaments.
The body’s biochemical functions and communication network for growth, repair, sight response and many varied functions is carried out by the tenth system which is the endocrine system. It involves the hormones which are a chemical substances that are secreted into the blood stream. A hormone then flows to the site where it is needed most, to effect the action.
Such hormones include growth hormones for growth and repair, adrenaline hormone for burning of fats and insulin hormone with glucagon hormones for blood sugar and glycogen level regulation in its correct level. When there is a higher level of blood sugar, the extra sugar is converted into glycogen for storage by the hormone glycogen. When the blood sugar level is low, the hormone insulin converts the stored sugar into glycogen to maintain the balanced blood sugar state.
Finally, the circulatory system is the 11th system also known as the cardiovascular system and is the one that maintains a steady flow of blood flow around the body carrying with it all necessary nutrients from digestion and oxygen inhaled from the nose into the lungs for nourishment and respiration as well as the wastes and carbon dioxide to be expelled by the body.
It is the heart that pumps all these substances around the body through the blood via the vascular tissues known as the arteries, the veins and the capillaries. The oxygen and nutrients are carried in the arteries the oxygenated blood while the carbon dioxide and wastes are carried in the veins which is the deoxygenated blood.
The veins have a valve that allows the blood to only flow forward and not backward or in the reverse direction.
The exchanges of the materials that flow in the body happen at the capillaries which is the thinnest of the three vessels that connects the arteries and the veins. The capillary has semipermeable that allows the nutrients to be diffused and absorbed by the body and oxygen to be delivered to sites hard at work or respired much and need oxygen for replenishment.
The wastes are delivered to the renal system for filtering by the kidneys for the urinary tract to expel it through the natural openings to the outside environment.
The carbon dioxide is carried to the lungs and exchanged through the semi-permeable membrane of the alveoli of the air sac of the lungs which diffuses out and collects at the lungs to be breathed out through the nose to the external environment.
My Prayer for PNG today is: “If when you give the best of your service, Telling the world that the Savior is come; Be not dismayed when men don’t believe you; He’ll understand; and say well done.”

Next week: Signals and responses to stimuli

  • Michael Uglo is a science textbook author and a lecturer in Avionics, Auto- Piloting and Aircraft Engineering. Please send comments to: [email protected]