Blood Vessels Flashcards
What are the types of blood vessel?
Arteries - Arterioles - Capillaries - Venules - Veins
What are the two blood vessel circuits and what do they do?
Pulmonary Circulation
Larger Systemic Circulation
Describe the structure of capillaries.
Single layer of epithelium cells with basement membrane
Describe the structure of veins and arteries.
Three layers
Innermost layer of epithelial - Tunica Interna
Smooth muscle - Tunica Media
Connective Tissue - Tunica Externa
What is main difference between the structure of arteries and veins?
Artery walls are a lot thicker.
Veins have valves to prevent back flow
Some arteries, particularly those close to the heart have elastic tissue, why?
The elasticity helps to maintain the forward flow of blood during the relaxation phase of the cardiac cycle (diastole). Arteries spring back when relaxing and this propels blood forward.
Discuss the structure and function of arterioles.
Arterioles have a well defined layer of smooth muscle. This allows for contraction resulting in vasoconstriction and relaxation resulting in vasodilation. This allows for the control of blood to the organs and capillaries and has a major impact on blood pressure.
Discuss the skeletal muscle pump.
The movement of leg muscles assists in there return of blood to the heart.
Contraction of leg compresses veins and closes valves stopping back flow while blood moves upwards. Muscles relax and more blood flows in.
Why are artery walls thicken than vein walls?
To cope with the higher blood pressure in arteries and the blood is travelling faster
Why do veins have valves?
To assist return of blood to heart as it is flowing slowly and at low pressure.
What is the difference between arteries close to the heart and arteries far away?
Arteries close to heart are elastic arteries.
Arteries far away are muscular arteries and have more smooth muscle tissue.
What are the two main functions of arterioles?
Control blood flow to capillaries and hence to tissues via contraction and dilation
Major influence on blood pressure via contraction and dilation
What controls blood flow between arterioles and capillaries
The pre-capillary sphincter
What do capillaries drain into?
Venuels - the smallest type of vain
What occurs in capillaries?
Site of exchange of O2 and nutrients between blood and tissues.
Blood flow is slow and at low pressure
