How does circulation maintain homeostasis

Thus, across a gamut of pressures, perfusion in such organs remains stable. Autoregulation is achieved mainly by the arterioles in their significant vasomotor capacity. Their action protects the capillary network from pressure variations that would otherwise be harmful to the equilibrium of its tiny exchange vessels. For example, in the kidneys, the arterial resistance of the nephrons adapts automatically to prevailing blood pressure. When systemic arterial pressure rises, renal vasoconstriction occurs in order to maintain constant renal blood flux.

For example, in the case of cardiac or active skeletal muscles, the rate of perfusion can be several times greater than the value of resting blood flow.

Myogenic stretch response means that, when a vascular smooth muscle is stretched, it contracts. If arterial pressure rises, the arteriole muscle responds with increased myogenic activity. This passive stretch depends upon the volume of blood reaching the arterioles. The lessening of the stretch prompts the reduction of myogenic tone. In most tissues, a rise in temperature causes vasoconstriction. However, higher temperature at the skin produces vasorelaxation, via the central nervous system command and vascular characteristics.

Calories are conveyed towards the skin and evacuated to the external environment by the process of cutaneous vasodilation occurring when the individual must compensate for heat. Conversely, cutaneous vasoconstriction occurs with exposure to cold, reducing thermal exchange with the environment and limiting caloric loss. Generally, local hypoxia provokes vasodilation, which means that perfusion varies as a function of tissue oxygen consumption. Most products of local tissue exchange, whose levels increase as a function of metabolism, have a vasorelaxing effect.

Numerous substances belong to this group. The main ones are:. In inflammatory processes, histamines produce arteriole vasorelaxation, venular vasoconstriction, and increased capillary permeability. Allergy symptoms such as hay fever illustrate the resulting effect. These compounds have an array of significant effects. Prostaglandin F PGF is a vasoconstrictors, whereas, for example, prostaglandin E PGE and prostacyclin are vasorelaxants, very much involved in inflammatory phenomena.

They are vasoconstricting and also increase the permeability of the capillary wall. The cardiovascular system and the kidneys work together to maintain blood volume and composition. The cardiovascular system provides the blood pressure that the kidneys use to filter wastes out of the body. The cardiovascular system and the skin help maintain homeostasis by regulating body temperature.

When the body overheats, the blood vessels that serve the skin dilate. The cardiovascular system rushes warm blood to the superificial capillaries of the skin.

Heat from the blood radiates off of the skin's surface, cooling the body. When body temperature drops too low, skin capillaries constrict. This prevents warm blood from reaching the surface of the skin. Arteries divide like tree branches until they are slender.

The largest artery is the aorta, which connects to the heart and picks up oxygenated blood from the left ventricle. The only artery that picks up deoxygenated blood is the pulmonary artery, which runs between the heart and lungs.

Capillaries The arteries eventually divide down into the smallest blood vessel, the capillary. Capillaries are so small that blood cells can only move through them one at a time. Oxygen and food nutrients pass from these capillaries to the cells. Capillaries are also connected to veins, so wastes from the cells can be transferred to the blood. Veins Veins have one-way valves instead of muscles, to stop blood from running back the wrong way. Generally, veins carry deoxygenated blood from the body to the heart, where it can be sent to the lungs.

The exception is the network of pulmonary veins, which take oxygenated blood from the lungs to the heart. Blood pressure Blood pressure refers to the amount of pressure inside the circulatory system as the blood is pumped around.

Common problems Some common problems of the circulatory system include: Aneurysm — a weak spot in the wall of an artery Atherosclerosis — a narrowing of the arteries caused by plaque deposits Heart disease — lack of blood supply to the heart because of narrowed arteries High blood pressure — can be caused by obesity among other things Varicose veins — problems with the valves that stop blood from running backwards.

Where to get help Your doctor In an emergency, always call triple zero Things to remember The circulatory system delivers oxygen and nutrients to cells and takes away wastes. The heart pumps oxygenated and deoxygenated blood on different sides. The liver also removes toxins from blood.

During digestion, it cleans blood that has been enriched with vitamins before sending it back out to the rest of the body. Their primary function is to transport oxygen from the lungs to the cells of the body. Red blood cells are disc-shaped. They are flexible and bioconcave—flat and round with depressed centers. White blood cells, also called leukocytes , are the disease-fighting components of blood. There are five types of white blood cells: neutrophils, eosinophils, basophils, lymphocytes, and monocytes.

Download Blood Lab Manual. See more from our free eBook library. Blood facts and statistics from the American Red Cross.

Anatomy of the Heart.