Structure • heart, arteries, arterioles, capillaries, venules, veins Functions • transportation (oxygen, carbon dioxide, nutrients, wastes, wastes hormones) • regulation (pH, body temperature, temperature fluid & electrolytes) Principle arteries and veins
• Heart: pumps blood • Artery: vessel leaving the heart (Arteries take blood AWAY from your heart) • Vein: vessel going to the heart • Capillaries: vessels in beds for b d f exchange of h f substances between blood and the extra cellular fluid
• Systemic = heart → arteries → arterioles → capillary beds in muscles, organs etc → venules → veins → heart • Pulmonary = heart → arteries → arterioles → capillary beds in lungs → venules → veins → heart u gs e u es e s ea t
• Lumen: for blood • Innermost (tunica intima): endothelial lining for easy blood flow • Middle (tunica media): smooth muscle, innervated by ANS, for vasocontriction and vasodilation • Outermost (tunica adventita): collagen tissue for support
Arteries & arterioles • More smooth muscle to dilate or constrict the vessel Capillaries • One layer of endothelial cells to maximise exchange of gases, gases nutrients& wastes
Veins • Valves to prevent back flow • Deep veins follow arteries and are called by the same name • Superficial veins are close to the surface
• “C “Communications” i ti ” • Provide numerous pathways for blood flow in case of blockage (e.g. compression, joint position cholesterol (e g compression position, build up, surgical ligation) • Coronary anastomoses = heart → artery → arterioles → capillary beds (e.g. heart) ← arterioles ← arteries ← heart R coronary artery L coronary artery
Portal (eg. hepatic-portal system) = heart → arteries → arterioles → capillary bed (e.g. gut) → venules → veins → capillary bed (e g liver) → venules → veins...