module 3 - 8.2 blood vessels Flashcards
what are blood vessels part of?
part of the closed circulatory systems
what are the 5 types of blood vessels?
- arteries
- arterioles
- capillaries
- venules
- veins
what do arteries and arterioles do with blood?
carry OXYGENATED blood AWAY from the heart to the body cells
what do veins and venules do with blood?
carry DEOXYGENATED blood from the body cells INTO the heart
where do capillaries go?
drain into venules, then into veins, then back to the heart
arteries and arterioles carry oxygenated blood, except which?
- pulmonary artery
- umbilical artery
both carry deoxygenated blood
which parts of the body have no blood flow?
- cornea of the eye
- lens of the eye
- epithelium
- cartilage
what are the components of a blood vessel?
- elastic fibres
- smooth muscle
- collagen
what do elastic fibres do?
- they are made of elastin
- they stretch and recoil
- provide blood vessel with flexibility
what does smooth muscle do?
contracts and relaxes changing size of the lumen
- NOT TO PUMP BLOOD
what does collagen do?
provides structural support to maintain shape and volume of vessel
what are the 3 layers to arteries, arterioles, venules and veins?
tunica externa - outer layer
tunica media - middle layer
tunica intima - inner layer
what is the endothelium a part of?
the inner layer
what is the tunica externa?
- outermost layer of artery or vein
- made of collagen fibres & elastic tissue
- has small blood vessels that supply large blood vessels
what is the tunica media?
middle layer
- made of smooth muscle cells, elastic tissue, and collagen fibres
what is the tunica intima?
- innermost layer
- has direct contact with blood flow
- made up of 1 layer of endothelial cells
what is the composition of the tunica intima within elastic arteries?
- single layer of endothelium cells
- supporting layer of elastin rich collagen
what is the composition of muscular arteries, arterioles, veins and venules?
single layer of endothelial cells
what do arteries and arterioles do?
- carry blood at high pressure
- have narrow lumen (maintains pressure)
- thick elastic & muscle layers to expand & recoil as heart beats
- arterioles have greatest influence on local AND overall blood pressure, ‘adjustable nozzles’ to greatest pressure drop occurs
what is the diameter of a capillary?
5-10µm (RBC travel in single file)
how are substances exchanged from blood cells to surrounding tissue?
gaps in endothelium
what are the 3 types of capillaries?
continuous capillaries
fenestrated capillaries
sinusoidal capillaries
what are continuous capillaries?
endothelial cells produce uninterrupted lining (joined together)
what are fenestrated capillaries?
have pores in endothelial cells (allows exchange to happen faster)
what are sinusoidal capillaries?
open-pore capillary, wider openings in endothelium
what are the adaptations of a capillary?
large SA - allows diffusion and metabolic demands to be met
cross sectional area is small - reduces rate of blood flow from artery/arteriole, allows enough time to exchange materials
endothelium is one cell thick - short diffusion pathway
what do walls of veins contain?
lots of collagen, few elastic fibres and muscle
what do venules contain?
no elastin, no elastic fibres, no smooth muscle
what are valves?
act as one way blood flow system to prevent back flow
what do large valves have?
have active muscle moving blood
what are breathing movements?
occurs in the chest, this aids the movement of blood
what happens if a vein wall becomes weakened?
valves may no longer close properly, allows backflow of blood, causes vein to become large and bumpy and VARICOSE
when does a vein become varicose?
happens in superficial veins near skin surface in lower legs
- vicarious veins can be surgically removed without affecting blood flow
what is glucose used for?
respiration in cells
what do coronary arteries do?
carries blood to heart muscle
