Absorption
Absorption is the process through which biomolecules traverse through the GI tract into the circulatory system. Digested food gets absorbed in the small intestinal lumen through four processes, which include active transport, passive transport, endocytosis and facilitative diffusion. The efficiency of absorption of nutrients may be attributed to the large surface area lined up with hair like projections and microvilli cells .
Excretory System
Excretion is the mechanism through which waste products and eliminated from the body and osmotic pressure and homeostasis is achieved in the body . The process of excretion in the body takes place in three stages: filtration, reabsorption and tubular secretion. The filtration procedure occurs in the glomeruli of the kidneys, through which the fluid is filtered to eliminate impurities. The filtrate containing smaller particles is gathered in the renal tubules of the kidney, where reabsorption of critical ingredients like nutrients and water occurs. Tubular secretion includes the transmission of specific molecules out of the blood vessels into the renal tubules. Drugs like penicillin are released into the renal tubules, unwanted substances such as urea reabsorbed are excreted back into the urine . These excretions also preserve the pH of blood.
Transport Systems
Transport system is the mechanism through which substances are shuttled from an exchange surface to cells in the organism .
Respiratory System
Respiratory system, which involves movement of gases like oxygen inside the body of an organism, is a crucial type of transport. Mammals possess a greater ratio of surface area-volume and require specific exchange surfaces, through which oxygen is ingested and carbon dioxide is released .
Cardiovascular system
A mass transport system is a type of transport system that involves a congregation of physical structures by the means of which substances are shuttled as a fluid consisting of substances moving unidirectionally from one or more than one exchange surfaces to other cells .
Cardiovascular system is an example of a mass transport system comprising of the blood vessels and the heart. The circulatory system transfers nutrients and gases such as oxygen to the cells of the body . The arteries transport the blood away from the heart and the veins transfer it back to the heart. The human body consists of two circulation systems that are interconnected. The systemic circulation replenishes oxygen and other crucial elements through blood to the organs, tissues and cells of the body, while the fresh oxygen is received in the blood through pulmonary circulation, with release of carbon dioxide.
Systemic Circulation
In this type of circulatory system, the oxygen-containing blood is pumped by the left ventricle of the heart into the primary artery called aorta, from where the blood is transported to the bigger and smaller arteries of the capillary system . Oxygen-depleted blood is then gathered in veins and transferred to the right atrium and right ventricle of the heart.
Pulmonary Circulation
The oxygen-depleted blood is then pumped from the right ventricle into the pulmonary artery, which bifurcates into arteries and capillaries, smaller in size . The capillaries generate an intricate system of capillaries surrounding the pulmonary vesicles, wherein carbon dioxide is released from the blood into the air. Blood opulent in fresh oxygen is transported via the pulmonary vein into the left ventricle of the heart. This completes one heartbeat and initiates another round of systemic circulation.
References
DIGESTION AND ABSORPTION. (n.d.). Retrieved from diet.com: http://www.diet.com/g/digestion-and-absorption
Excretory System - Excretion In Humans. (n.d.). Retrieved from science.jrank.org: http://science.jrank.org/pages/2626/Excretory-System-Excretion-in-humans.html
PubmedHealth. (2012, June 1). Retrieved from ncbi.nlm.nih.gov: http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0072434/
Transport Systems in biology. (n.d.). Retrieved from ivoryroses.com: http://www.ivyroses.com/Biology/Transport/Transport-Systems.php
