blood vessels (chapter 8) Flashcards
3 main properties in blood vessels
elastic fibres : composed of elastin and can stretch and recoil, providing vessel walls with elasticity,
smooth muscle : contracts or relaxes which changes the size of the lumen,
collagen : provides structural support to maintain the shape and volume of the vessel,
arteries
- carry the blood away from the heart to the tissues of the bodies
- they carry oxygenated blood except from the pulmonary artery ( which carries deoxygenated blood to the lungs) and the umbilical artery ( which carries deoxygenated blood from the fetus to the placenta)
arterioles
- link the arteris and the capillaries
- more smooth muscle and less elastin than arteries, to control flow of blood into organs
- vasoconstriction : when smooth muscle contracts to prevent blood flowing innto the capillary bed.
- vasodilation : opposite
capillaries
- link arterioles with the venules
- they form a network through all tissues
- blood entering the capillaries from the arterioles is oxygenated (i most organs), by the time it leaves the capillaries for th venules it has less oxygen and more co2.
veins and venules
- veins carry blood away from the cells of the body towards the heart. They carry deoxygenated blood (except from pulmonary vein)
- blood flows into small veins called venules and then into the veins and back ito the heart through the superior and inferior vena cava.
- walls contain lots of collagen and little elastic fibres
- venules link capillaries with the veins, they have thin walls annd smooth muscle.
- breathing movements of the chest act as a pump, veins run through big muscles that contract and squueze the veins forcing blood up to the heart.
blood
plasma - yellow liquid that carries a wide variety of components like dissolved glucose, amino acids, minerol ions, hormones and large plasma proteins.
- plasma also contains albumin which is important for keeping oncotic pressure
-platelets are frgaments of large cells that are found in bone marrow. They help blood clot.
- a lot of plasma is water
what is oncotic pressure
- the tendency of water to move into the blood by osmosis
what is hydrostatic pressure
As the blood moves through the arterioles into the capillaries, it is still under pressure from the surge of blood that occurs every time the heart contracts.
what is tissue fluid
- at the artirial end of the capillary, the hydrostatic pressure is higher than the oncotic pressure, forcing fluid out the capillaries - this is tissure fluid.
