Blood Vessels - Circulatory System 4

Question 1

Arteries

Answer 1

• carry oxygenated blood away from the heart
• exception pulmonary artery - carried deoxygenated blood from RV to lungs.
• arterioles - smallest arteries

Question 2

Veins

Answer 2

• venules - smallest of veins
• medium and large veins have valves to stop back flow
• thinner walls than arteries as have less pressure -have the same 3 layers as arteries just less layers present
• transports blood back to heart - goes through capillaries into venules then progressively into larger and larger veins until it reaches the heart
• carry deoxygenated blood except pulmonary veins which carry oxygenated blood

Question 3

Capillaries

Answer 3

• connect arteries with veins
• blood cells and plasma proteins do not pass through
• enables exchange of oxygen and carbon dioxide

Question 4

Structure of blood vessels - 3 layers

Answer 4

Tunica intima
- inner layer - simple squamous epithelium surrounded by connective tissue basement membrane with elastic fibres

Tunica media
- middle layer - smooth and elastic tissue - usually thickest - provides support but allows changes in diameter

Tunica adventitia
- outer layer - fibrous connective tissue (elastic and collagen fibres)

Question 5

Nerve control of blood vessel diameter

Answer 5

• controlled by autonomic nervous system
• smooth muscle in tunica media controlled by sympathetic nerve function (fight or flight)

Question 6

Decreased nerve stimulation causes the smooth
muscle to relax, this is called…

Answer 6

VASODILATION and leads to increased blood flow

Question 7

Increased nerve activity and the muscle contracts,
this is called…

Answer 7

VASOCONSTRICTION and leads to decreased blood
flow