Blood flow reduces when its flow resistance is expanded.Total peripheral resistance is characterized as total blood flow resistance in the systemic circulation. Because of their smaller size and muscle walls the arterioles are effective regulators of blood flow.
Peripheral resistance is the artery's resistance to blood flow. As the arteries restrict the resistance increases and the resistance decreases when they dilate. Three factors influencing peripheral resistance are :
Autonomous activity: a sympathetic activity which blocks peripheral arteries.
Pharmacological agents: the vasoconstrictor drugs raise resistance while it is reduced by vasodilator drugs.
Viscosity of the blood: Higher viscosity enhances resistance.
Cancer is unchecked cell growth. Mutations in genes can cause cancer by accelerating cell division rates or inhibiting normal controls on the system, such as cell cycle arrest or programmed cell death. As a mass of cancerous cells grows, it can develop into a tumor.
