Blood vessels Flashcards
Arteries
Carry blood under high pressure away from the heart to other regions of the body
Veins
Returns blood under low pressure to the heart from the lungs and body
Capillaries
Connect small arteries and veins and allows exchange of materials with tissues
Characteristics of capillaries 3
Single layer of cells (endothelium)
Small diameter lumen to slow the blood (by causing friction)
Small gaps between cells to allow solutes and ions to pass out
Three layers of arteries and veins
Tunica externa
Tunica media
Tunica intima
Characteristics of tunica externa
Made of collagen:
Strong, fibrous protein to withstand pressure
Structure and function of tunica media
Contains smooth muscle: contract to constrict lumin
Elastic tissue to allow stretch and recoil of vessel
This layer helps sustain pressure
Structure of tunica intima
Single layer of endothelial cells
Smooth and flat to minimise friction with passing blood
Lumen?
Cavity through which blood flows
Characteristics of arteries/ arterioles
Blood under high pressure
Thick walls to resist pressure
Narrow lumin to maintain high pressure
Elastic tissue to allow stretch to accommodate surge of blood and recoil for high pressure
Adjustable diameter via contraction of smooth muscle (arteroles)
Why do capillaries strive to maintain slow blood flow
Enhanced ability to exchange materials with surrounding tissues
Characteristics of veins
Blood under low pressure
Thinner walls as pressure is reduced
Wider lumen (decrease resistance and increase volume)
Outer layer of collagen
Little elastic tissue
Valves to prevent back flow of blood
What causes blood in veins to be under low pressure
No longer influenced by contractions of the heart
How does deoxygenated blood move back to the heart from organs above
Under gravity
How does deoxygenated blood move back to the heart for organs below
Venous pump produces by action of the skeletal muscle
Negative pressure in thorax produced by inspiration (lungs)
Describe how one way venous valves function (venous pump)
Skeletal muscles slither side of vein are relxed:
valves closed as blood sits either side pinching flaps closed
Skeletal muscle contracts, forces upper valve open and pushes blood upwards to heart
Sequence of main regions to which blood circulates in mammals (Health Liveing Loves Giving Kids Real Life)
Head
Lungs
Liver
Gut
Kidneys
Reproductive organs
Legs
Blood vessels from heart to head to heart
Aorta
Carotid artery
Jugular vein
Vena cava
Blood vessels from heat to lungs to heart
Pulmonary artery (De-O2)
Pulmonary vein
Blood vessels at liver
Hepatic artery and vein
Blood vessels at gut
Mesenteric artery, hepatic portal vein
Blood vessels at kidneys
Renal artery and vein
Vessels at reproductive organs
Genital vein and artery
Vessels to legs
iliac artery and vein
What type of valves are found in veins
semi lunar valves
