In different parts of the body the blood vessels are of different diameters. The normal diameter of the aorta is around 2 cm and this would be the largest vessel in the human body, while the smallest, a capillary would be between 0.5 to 2.28 mm in diameter.
Blood pressure increases if the diameter of the blood vessel decreases.
Vasodilation or enlargement of the blood vessel
increase in the diameter of blood vessel. it increases the blood flow
vasoconstriction.
Tunica interna
In which of the following would the blood flow be highest? A) a vessel 0.5 cm in diameter and 4 meters long B) a vessel 1.0 cm in diameter and 10 meters long C) a vessel 0.5 cm in diameter and 2 meters long D) a vessel 1.0 cm in diameter and 2 meters long
Vasodilation: Widening of blood vessels resulting from relaxation of the muscular wall of the vessels. What widens is actually the diameter of the interior (the lumen) of the vessel. The opposite of vasoconstriction.
An important source of resistance to blood flow is not low blood viscosity, as low viscosity would actually decrease resistance. The important sources of resistance to blood flow are vessel diameter, vessel length, and blood viscosity.
Vasoconstriction would have a greater effect on increasing vascular resistance compared to vasodilation. When blood vessels constrict, their diameter decreases, leading to increased resistance to blood flow. Conversely, vasodilation results in an expansion of blood vessel diameter, reducing resistance.
Smooth muscle is mostly in the afferent branch going from the arteries to the arterioles. The body controls where blood will flow by controlling the vessel diameter. An increase in sympathetic tone constricts smooth muscle, decreases blood vessel diameter, and limits blood flow.
Total peripheral resistance is mainly influenced by the diameter of the blood vessels, vessel length, blood viscosity, and the compliance of the vessel walls. Vasoconstriction and vasodilation also play a significant role in regulating total peripheral resistance. Additionally, factors such as arterial blood pressure and neural and hormonal control can impact total peripheral resistance.
Blood Pressure can be affected by all three factors. If the vessel diameter increases (vasodilation) Blood Pressure can be lowered. Blood Viscosity can also have an affect on blood pressure, the more viscous (thicker) the blood is, the slower it will flow through the body. Finally, irregular surfaces of the blood vessel wall can cause them to catch or become stuck, which ultimately slows blood flow, reducing blood pressure!