Marvels of unique transport systems

SCIENCE IN ACTION

By MICHAEL JOHN UGLO
THIS seventh lecture in the Science of Organisms series is on the transport systems in organisms.

When you switch on your computer or mobile phone, there is a brief moment you have to wait for assignment of values to the variables of arrays and strings of data as vectors to align appropriately in the computer programme. It presupposes that the programme was dormant somewhere at a location called a backing store in a secondary memory being the largest storage locality and has to be moved to the main memory also known as the primary memory.
After this initialisation process then, the communication path with the operating system of the computer to partner with the hardware is established. The processes that are using the resources of a central processing unit also known as the processor or micro-processor of arithmetic and logic unit for micro-programming and Complex Instruction Set Computers (CISC) communication path is now made common place.
When you are sending commands from a peripheral device as an input like your keyboard to type words, then you will realise that the built-in software has a capacity through the redundancies of the arrays to make corrections for all mistakes you make from your hands or minds.
Now when you turn your computer on, you have to give enough time and power capacity for the electronic device to power on and function to serve its purpose. Sometimes you press so many buttons at the same time which means that you are congesting its transport system.
Similarly, care must be taken with your body and care must be rendered to the other living things most integrally because all of the organisms have an inalienable right to exist as functioning systems for the benefit of all. The reason being we all live in an ecosystem that demands the presence of everyone and everything paramount for our existence.

Transport systems
In animals the transport system is also known as the circulatory system. Sometimes this transport system is most specifically known as the cardiovascular system. Cardio is to do with the heart. All living things including plants, animals and microbes have developed very efficient transport systems for effective movement of materials in and out of their systems.
The multicellular organisms develop vascular tissues such as xylem and phloem vessels in plants for their transport system. The xylem vessels transport nutrients and water up the plant.
The root hairs of plants contain glucose and so they have a sugary solution inside and thus are highly concentrated. The water diffuses from an area of less concentration (sugar/glucose solution) to an area of high concentration. This is how water enters the plant through the roots in a process called osmosis.
The water and minerals actually diffuse into the plant through the osmotic pressure developed in such a situation.
The extra water seeps out of the stomata and is termed as transpiration. This generates a force called suction that keeps the stream of water up the trunk of the tree called the transpiration stream.

The cohesive and the adhesive forces keep the water molecules together with the suspended minerals to attach themselves to each other and to the xylem vessel they are traveling in. This mechanism keeps the water together with the suspended minerals to travel up the stem or trunk and into the branches. The food that is made by the leaves through the photosynthesis process in the form of glucose is transported by the phloem vessels to every part of the plant like the roots that do not produce it.
In animals like humans the blood vascular tissues that include the arteries, the veins and the capillaries are developed for the movement of materials in and out of their transport system.
The medium in which the materials flow is the blood. Blood is composed of the liquid part called the plasma, the red blood cells (RBC) consisting of the red pigment called the hemoglobin which gives blood its characteristic red colour, the white blood cells (WBC) and the platelets.
The arteries carry the oxygen attached to hemoglobin forming a compound called oxyhemoglobin once breathed in from the nose and into the lungs. This is oxygenated blood together with the food nutrients absorbed form the small intestine carrying these vital substances that the body needs for its survival right around the body pumped by the heart.
The wastes from the body’s cells together with carbon dioxide from cellular respiration are transported through the veins in the form of the deoxygenated blood to be passed out of the body. Waste removal from the cells of the body is called excretion.
The blood circulates through the body via the three blood vascular tissues. The blood capillaries actually join the other two blood vessels together providing the medium for exchange of substances carried by the two vessels.
The thick-walled arteries and the thin-walled veins that have valves, allow the blood to maintain a one-way or unidirectional blood flow so the deoxygenated blood does not flow backward to mix with the oxygenated blood.

At the tissue levels where food nutrients and water are taken up from the small intestine and the large intestine respectively as well as oxygen from the lungs are delivered to these tissues.
Carbon dioxide and the other wastes from that tissue as received from the cells are passed to the tiny veins to be taken back to the heart to be pumped out of the body.
The thinnest of the three blood vessels is the capillary which becomes the connector and exchange site for these nutrients and wastes. Hence, the capillary’s thinness and its semi-permeability allow and provides the surface area in which all these substances carried by the veins and the arteries are exchanged for replenishment by the cells and waste removal.
The carbon dioxide is carried to the lungs to be exhaled via the gullet or windpipe through the nose while the wastes are carried to the renal and the urinary system to be filtered from the two kidneys into the two ureters, then passed to the bladder and then to the urethra to be passed out of the system through the natural openings.
There are four chambers of the heart where by the nutrients, water, oxygenated blood, the wastes and carbon dioxide enter the heart to be pumped around the body. These are the left and right atrium and the left and right ventricle chambers.
Nutrients and oxygen carried from the intestines and the lungs respectively enter both left and the right pulmonary veins which flow into the left atrium, then to left ventricle and then to the aorta (main artery) and finally to the rest of the body.
Body wastes and carbon dioxide enter the heart through the inferior vena cava to the superior vena cava, then to the right pulmonary vein of the heart and then into the right atrium, to the right ventricle and then to both the left and the right pulmonary veins.
Here they are passed to the body to enter the capillaries at the renal and urinary system to be filtered out from the two kidneys as excess water and urine. The carbon dioxide flows through the deoxygenated blood all the way to the lungs to be exhaled.

My Prayer for PNG today is: “Ten unclean men, nowhere to go. Ten men clean, as clean as snow. One returned to give God thanks, but nine ran away… Ten lepers in a Hebrew’s town, ten crying Lord won’t you please…”
Next week: Respiration and exchange of gasses.

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