Thermoregulation Process in Human Body

Thermoregulation – including both vasodilation and vasoconstriction: the increase in the internal diameter of blood vessels that is caused by relaxation of smooth muscles within the wall of the vessels, thus causing an increase in blood flow is process of vasodilation. In vasodilation, when blood vessels dilate, the blood flow is increased due to a decrease in vascular resistance. However, for practical purposes, dilation of arterioles has the most significant therapeutic value since these blood vessels are the main contributors to systemic- vascular resistance and because of that dilation of arteries and arterioles leads to an immediate decrease in blood pressure and heart rate.

Chemical-arterial dilation of venous-blood vessels decreases venous-blood pressure. Pacific agents can be used to reduce cardiac output, venous-and-arterial pressure, tissue edema, and myocardial oxygen demands. The process of vasoconstriction is the opposite of vasodilation. In vasoconstriction the narrowing blood vessels result from contraction of the muscular wall of the vessels, the large arteries and small arterioles. The process is particularly important in staunching haemorrhage and acute blood loss. When blood vessels constrict, the flow of blood is decreased or restricted, all though retaining body heat or increasing vascular resistance, which makes the skin look paler because less blood is reaching the surface, reducing the radiation of heat. On a higher level, vasoconstriction is one mechanism by which the body regulates and maintains arterial pressure. Thermoregulation is the process of your body maintaining its core internal temperature. All thermoregulation mechanisms are designed to return your body to homeostasis which is of state of equilibrium. The healthy internal body temperature falls within a narrow window. The average person has a baseline temperature between 37 degrees Celsius and 37.8 degrees Celsius. The body has flexibility with temperature. However, if you get to the extremes of body temperature, it can affect the body’s ability to function like if you have for example, a temperature that falls to 35 degrees Celsius or lower, you have ‘hypothermia’. In this condition you can potentially lead to cardiac arrest, brain damage or even death.

Another example is if your body temperature reaches as high as 42 degrees, there will be a high possibility of death or brain damage. Factors that affect your body temperature is spending time in cold or hot weather conditions. Factors that can raise your internal body temperature is fever, exercise, digestion. Factors that can degrees body temperature includes alcohol and drug use. The hypothalamus is a section of your brain that controls thermoregulation. When it senses your internal temperature becoming too low or high, it will send signals to your muscles, organs, glands, and nervous system. They respond in many ways to help return your normal body temperature. The thermoregulation works in the central nervous system when your internal temperature changes, sensors in the central nervous system send messages to the hypothalamus. In response, it sends signals to loads of organs and systems in your body. They respond with a variety of mechanisms. Such as sweating for your body to cool down, your sweat glands releases sweat. or vasodilation the blood vessels under your skin get wider. This increases blood flow to your skin where it is cooler. And if your body needs warming up due to a decrease in temperature, vasoconstriction is in use of the blood vessels under your skin become narrower, which decreases blood flow to your skin, retaining heat near the warm inner body. Thermogenesis is the process of your body’s muscles, organs, and brain producing heat in a variety of ways, an example is muscles can produce heat by shivering.

Hormonal thermogenesis is the thyroid gland releases hormones to increase metabolism. This is what increases energy your body creates and the amount of heat produced.

Removal of waste products: the excretory system is a system combined of organs that removes waste products from the body. When cells break down proteins (large molecules that are essential to the structure and functioning of all living cells), they produce wastes like urea which is a chemical compound of hydrogen, oxygen, carbon, and nitrogen. When cells break down carbohydrates, they produce water and carbon dioxide as waste products. If these waste products can accumulate in the body, they would become dangerous to the health’s body. The kidneys, are considered the main excretory organs in humans, eliminate water, urea, and other waste products from the body by urine. other systems and organs in the body also play a part in excretion.

The respiratory system eliminates water vapor and carbon dioxide through exhalation.

The digestive system removes the solid undigested wastes of digestion, by a process called defecation or elimination.

The skin acts as an organ of excretion by removing water and small amounts of urea and salt with in sweats. Kidneys are bean- shaped organs that are located at the small of the back near the spinal column. The left kidney is slightly higher than the right one.

To maintain a human life, you need at least one kidney to function properly. Waste products are carried by blood to the kidneys via renal artery. Blood is transported to inside each kidney 1.2 million filtering units called nephrons. The cells in nephrons take in the liquid portion of the blood and filter out waste products. Substances such as certain salts, water, sugars and other nutrients are returned to the blood stream via renal vein.

Delivery of oxygen and nutrients: the cardiovascular system acts as an internal road network, linking all parts of the body via a system of highways such as arteries and veins, main roads arterioles and venules and streets, avenues and lanes (capillaries). The network allows a non-stop courier system which is the blood to deliver and expel nutrients, gases, and waste products throughout the body. Nutrients such as glucose from the digested carbohydrate are delivered from the digestive tract to the muscles and organs that require them for energy.

Chemical messengers which are also known as hormones are from endocrine glands that are transported by the cardiovascular system to their main organs. The cardiovascular system works in conjunction with the respiratory system to deliver oxygen to the tissues of the body and remove carbon dioxide. The cardiovascular system is divided into two circuits, known as the pulmonary circuit and systemic circuit this is in order to make things effectively. The pulmonary circuit is formed of the heart, lungs, pulmonary veins and pulmonary arteries. The circuit pumps deoxygenated blood from the heart to the lungs where it becomes oxygenated and returns to the heart. The systemic circuit is formed of the heart and all the remaining arteries, arterioles, capillaries, venules, and veins in the body. The circuit pumps oxygenated blood from the heart to all the tissues, muscles and organs in the body, to provide them with nutrients and gases they need to function. After oxygen has been delivered the systemic circuit picks up carbon dioxide and returns deoxygenated blood to the lungs where then it enters the pulmonary circuit to become oxygenated again.

Function of the cardiovascular system

Capillaires: is the smallest of all blood vessels and form the connection between veins and arteries. When arteries branch and divide into arterioles and continue to reduce in size as they reach the muscle they become capillaries. Capillaries form a capillary to form a network throughout the muscle from a vast expanse of very small vessels. Unlike veins and arteries, the main function is not transporting blood but is specially designed to allow the movement of substances, like types of gases which are oxygen and carbon dioxide into and out of the capillary. Their process of gaseous exchanges is oxygen within the red blood cells as oxyhaemoglobin, and at this point dissociates from haemoglobin and passes through the capillary wall into the muscle cells where it is handled by myoglobin, the muscle cells are equivalent to haemoglobin. The oxygen can now be used in aerobic metabolism to provide the muscle with energy. The wasted product produced during aerobic metabolism is only carbon dioxide. Because of the lower concentration of carbon dioxide in the capillaries than the muscle tissue and especially during high levels of metabolism there is a surge through the capillary wall. Which from there the blood continues into venules and then veins which return the deoxygenated and CO2 rich blood back to the heart and then into the lungs where the CO2 is exhaled, and more oxygen is taken up.

Capillaries have a very thin wall comprised only of endothelial cells, which allows substances to move through the wall with difficulty. They are very small and have a measuring of 5 to 10 micrometres in width. But, the cross-sectional area of capillaries within an average size muscle would be even larger than the Aorta. This allows a fast and efficient transfer of oxygen that is carrying red blood cells to the site where they belong and are needed.

Venules: they are small blood vessels in the microcirculation that connect capillary beds to veins, in the microcirculation that allows deoxygenated blood to return from capillary beds to larger blood vessels which are veins. Venule walls contain three layers: an inner endothelium composed of squamous endothelial cells that act as a membrane, a middle layer of muscle and elastic tissue, and an outer layer of fibrous connective tissue. Venules are very porous so that fluid and blood cells can move easily from the bloodstream through the walls. High endothelial venules are specialized post- capillary venous swellings characterized by plump endothelial cells, in contrast with the thinner endothelial cells found in regular venules. HEVs allow lymphocytes that are white blood cells to circulate it to the blood and directly into a lymph node by crossing through the HEV. Venules range from 8 to 100 in diameter and are made when capillaries come together. Many venules come together to form a vein.

Veins: even though all 3 tunics are in the veins, the tunica interna and tunica media are quite thin, and both internal & external elastic laminae are absent or very thin. These features render the veins capable of great expansion to hold the variable volume of blood passing through them. At any given time, there is three times as much blood volume in the venous system than there is there is in the arterial system. veins are not designed to handle high blood pressure found in arteries. Because of relatively large lumen and thin walls, veins will appear flattened in a micrograph since the vessels collapses when it is not filled with blood. One feature in veins is that augments venous returns the presence of venous valves within the vessels, most commonly in the limbs. These valves close when the blood in the vein tries to move backwards, away from the heart. the closed valve forms a barrier to the backward flow of blood. Venous sinuses are large in diameter with extremely thin walls that do not have a smooth muscle. Support is then provided by dense connective tissue surrounding the vessel. Between the veins are connected channels called anastomoses. They are commonly found in the limbs, and the veins that form them, they are not always associated with arteries. Portal veins drain one capillary network, travels to another organ or tissue, and empties into another capillary network. The hepatic portal vein carries nutrient rich blood from the gastrointestinal tract and spleen to the live

Arterioles: are smallest vessels that carry blood away from the heart, the arterioles, direct blood into the capillary networks. Both the tunica interna and externa of arterioles are thin, and the tunica media is made of only one or two layers of muscle cells that encircle the vessel. However, these arterioles are particularly important in regulating the amount of flow delivered to the tissues that they feed. These arterioles have a rich supply of sympathetic nerve fibres. When they receive a high number of signals from the sympathetic nervous system, the arterioles constrict, increasing resistance to blood flow. When the signals from the sympathetic nervous system decreases, the arterioles adjust their diameters in response to hormonal signals and local signalling molecules. Fine adjustment to the diameter of the arteriole lumen has a direct effect on the flow of blood into the capillary network supplied by that exact arteriole. Arterioles are multiples and don’t have individual names as the elastic arteries do.

Arteries: they are blood vessels which carry blood away from the heart. Except for the pulmonary artery, carry oxygenated blood. The most known artery within the human body is the aorta, which is the largest of all blood vessels and transports blood away from the left ventricle to the right of the heart and then branches into smaller arteries. As the arteries divide further they become smaller and smaller vessels and decrease in size below 10 micrometres in diameter are known as capillaries. The structure of artery wall is made of 3 layers which are tunica adventitia: the strong outer covering of arteries and veins which consists of connective tissues, collagen and elastic fibres. Tunica intima: the inner layer which is in direct contact with the blood flowing through the artery. It is made of an elastic membrane and smooth endothelial cells. The hollow centre through which blood flows is called the lumen. Tunica media: the middle layer and is made of smooth muscle and elastic fibres. This layer is thicker in arteries than in veins.