Understanding Peripheral Resistance: Key Factors and Mechanisms

Two factors that increase peripheral resistance are:

1. Vasoconstriction: When the blood vessels constrict, the resistance to blood flow increases, leading to an increase in peripheral resistance. This can occur due to various factors such as activation of the sympathetic nervous system, release of hormones like vasopressin, or local inflammation.

2. Increased blood viscosity: Blood viscosity refers to the thickness or resistance of blood to flow. Factors such as elevated red blood cell count (polycythemia), increased plasma proteins, or abnormal blood cells (sickle cell anemia) can increase blood viscosity, making it more difficult for blood to flow through the vessels and thus increasing peripheral resistance.