Higher Human Biology Unit 2: Physiology and Health Chapter 11 Structure of the cardiovascular system 1. Vessels of the cardiovascular system

What you should know The differences in structure of arteries, capillaries and veins Direction of blood flow from and to the heart What happens to blood pressure as blood moves away from the heart? What is the role of vasoconstriction and vasodilation in controlling blood flow?

Arteries Endothelium lines the inner surface of the artery Elastic fibres allow artery to stretch with each high pressure surge in blood flow from heart Smooth muscle enable vessel to stretch and recoil with each heart beat Connective tissue anchors the arteries to other tissue The lumen is the central core of the artery where the blood flows

Capillaries Endothelium very thin, one cell thick Thinness allows efficient diffusion of materials from and to cells Connect arteries to veins Blood pressure decreasing

Veins Endothelium Valve to prevent backflow of blood at low pressure Elastic tissue Smooth muscle Connective tissue Lumen

Connecting arteries to veins Arteries become smaller arterioles Arterioles become smaller capillaries Capillaries become larger venules Venules join to larger veins

Fine control of blood distribution Vasoconstriction and vasodilation occur in both arterioles and venules Enables blood flow to be regulated during different circumstances Revision – sympathetic and parasympathetic nervous systems

The cardiovascular system

What do I know? The differences in structure of arteries, capillaries and veins Direction of blood flow from and to the heart What happens to blood pressure as blood moves away from the heart? What is the role of vasoconstriction and vasodilation in controlling blood flow?