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Blood Vessels - Coggle Diagram
Blood Vessels
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Structure of blood vessels: Hollow interior called lumen. Walls consist of 3 layers: Tunica intima, Tunica media, Tunica externa
TUNICA INTIMA: INNER LAYER - Lined by endothelium, consists of simple squamous
epithelium. Smooth texture to reduce friction.
TUNICA MEDIA - Composed of smooth muscle & elastic fibres. Circular smooth muscle. Vasodilates and vasoconstricts to change the diameter of vessels.
TUNICA EXTERNA - Has and network of collagen fibres to protect & reinforce the vessel & anchor it to surrounding structures. Nerve fibres. Elastic fibres in larger vessels
BRANCHES OFF AORTIC ARCH Three arteries branch off aorta to supply head and neck, upper limbs and part of the thorax wall. 1) Brachiocephalic. 2) Left common carotid. 3) Left subclavian.
UPPER LIMBS: Supplied by arteries arising from subclavian arteries. Brachial artery. Radial arterial. Ulnar artery
CAROTID ARTERIES: External carotid supplies tissues of head Locate the carotid pulse by palpating the external carotid artery. Internal carotid supplies brain & eye. Temporal artery (sometimes used for taking temperatures).
Arteries - Elastic Arteries - Large lumen- low resistance to blood flow. Can stretch and recoil without causing damage to accommodate for high pressure. Example: Aorta. Muscular Arteries - Carry blood to furthest destinations from heart. Smaller in diameter compared to elastic. Thicker wall made from smooth muscle. Example: Brachial artery
Arterioles- Deliver blood to capillaries. Variable contraction/relaxation of smooth muscle in arteriole walls helps to change diameter, and therefore resistance of blood flow. Are the major influencer of peripheral resistance
Venules - Capillaries unite to form venules. Transport blood to veins. Walls consist of endothelial cells, a few smooth muscle cells and occasionally a fibroblast. White blood cells move out of the CVS to inflamed areas through pores in venule walls.
Veins - Act as blood reservoirs which can be drawn on when BP drops. Thin walls- but blood flowing through is at low pressure so there is a minimal risk of bursting. Contain one-way valves.
Pulmonary Circulation: Venules and veins carry oxygenated blood to the heart. Arteries and arterioles carry deoxygenated blood to the lungs.
Systemic circulation: oxygenated blood carried by arteries and arterioles. Deoxygenated blood carried by veins and venues.
MAJOR VEINS: SUPERIOR AND INFERIOR VENA CAVAE - Largest vein. Receives deoxygenated blood from all areas superior to the diaphragm (except coronary circulation).
MAJOR VEINS: LOWER LIMB VEINS - Femoral Vein may be used to take blood samples or pressure recordings from the right side of the heart. Great saphenous vein is longest vein in body. Can be used to replace blocked arteries in the heart for heart bypass operations.
Capillaries - Microscopic vessels. Carry blood from arterioles to venules. Involved in Microcirculation. Extensive branching network. Very thin walls- ideal for diffusion.
ARTERIAL PATHWAY- SYSTEMIC. 1) LV pumps blood into ascending aorta. 2) Flows to arteries then arterioles. 3) Then flows to capillaries 4) Then flows to various tissues and organs of the body.
VENOUS PATHWAY- SYSTEMIC. 1) Blood flows out of organs via venules. 2) Goes from venues to veins. 3) Drains to inferior and superior vena cava. 4) Blood is then returned to right atrium.
PERIPHERAL VASCULAR RESISTANCE (PVR): The opposition to blood flow caused by friction between blood and the vessel wall. Most resistance is encountered in arterioles & capillaries in the peripheries. Peripheral resistance in arterioles helps to determine arterial blood pressure.
ABDOMINAL AORTA→ILIAC→FEMORAL: Abdominal aorta splits to become left and right common Iliac arteries. Common iliac artery becomes Femoral artery.
LOWER LIMB ARTERIES: Popliteal artery supplies knee. Posterior tibial runs down the posterior medial
aspect of the leg supplies lower leg muscles. Dorsalis pedis supplies ankle & dorsum of foot..