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Blood Vessels

Blood Vessels. WHAT ARE BLOOD VESSELS ?. Blood vessels are intricate networks of tubes that transport blood throughout the entire body.

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Blood Vessels

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  1. Blood Vessels

  2. WHAT ARE BLOOD VESSELS ? • Blood vessels are intricate networks of tubes that transport blood throughout the entire body. • They carry blood through miles in a never ending stream. If you could take all the blood vessels of a average size child and line them up they could reach about 60,000 miles long. In an adult, the blood vessels could reach 100,000 miles long. • Part of the Circulatory System.

  3. TYPES • ARTERIES, ARTERIOLES • VEINS, VENULES • CAPILLARIES

  4. ARTERIES & ARTERIOLES • Transport Blood away from heart • Wall are thicker than veins • Walls made up of 3 layers • When they are cut, they remain opened because of their thick wall nature.

  5. VEINS & VENULES • Transport blood to the heart • Wall are thinner than arteries • Wall made up of same 3 layers • When they are cut, they remain opened because of their thick wall nature

  6. STRUCTURE… Composed Of Three Layers (Tunics) • Tunica intima –is the innermost layer, composed of epithelium • Tunica media –made up of smooth muscle cells coated with elastic tissue. • Tunica externa (adventitia) – Entirely composed of connective tissue. It also contains nerves that supply the vessel. Lumen • Central blood-filled space of a vessel

  7. Major Types Of Blood Vessels: Artery Vein Capillary

  8. WALL OF BLOOD VESSELS

  9. Structure of Blood Vessels • Composed of three layers (tunics) • Tunica intima – composed of simple squamous epithelium • Tunica media – sheets of smooth muscle • Contraction – vasoconstriction • Relaxation – vasodilation • Tunica externa – composed of connective tissue • Lumen • Central blood-filled space of a vessel

  10. % Figure 19.1a

  11. Types of Arteries • Elastic arteries – the largest arteries • Diameters range from 2.5 cm to 1 cm • Includes the aorta and its major branches • Sometimes called conducting arteries • High elastin content dampens surge of blood pressure Figure 19.2a

  12. Muscular (distributing) arteries • Lie distal to elastic arteries • Diameters range from 1 cm to 0.3 mm • Includes most named arteries • Tunica media is thick • Unique features • Internal and external elastic laminae Figure 19.2b

  13. Capillaries • Smallest blood vessels • Diameter from 8–10 µm • Red blood cells pass through single file • Site-specific functions of capillaries • Lungs – oxygen enters blood, carbon dioxide leaves • Small intestines – receive digested nutrients • Endocrine glands – pick up hormones • Kidneys – removal of nitrogenous wastes

  14. RBCs in a Capillary Figure 19.3

  15. Classification Of Vein • Superficial veins Superficial veins are those whose course is close to the surface of the body, and have no corresponding arteries. • Deep veins Deep veins are deeper in the body and have corresponding arteries. • Pulmonary veins The pulmonary veins are a set of veins that deliver oxygenated blood from the lungs to the heart. • Systemic veins Systemic veins drain the tissues of the body and deliver deoxygenated blood to the heart.

  16. Comparism Btw Arteries and Veins

  17. ROLE IN DISEASE • Main article: Vascular disease • Blood vessels play a role in virtually every medical condition. Cancer, for example, cannot progress unless the tumor causes angiogenesis,(formation of new blood vessels) to supply the malignant cells' metabolic demand. Atherosclerosis, the formation of lipid lumps (atheromas) in the blood vessel wall, is the most common cardiovascular disease, the main cause of death in the Western world.

  18. Blood vessel permeability is increased in inflammation. Damage, due to trauma or spontaneously, may lead to haemorrhage due to mechanical damage to the vessel endothelium. In contrast, occlusion of the blood vessel by atherosclerotic plaque, by an embolised blood clot or a foreign body leads to downstream ischemia (insufficient blood supply) and possibly necrosis. Vessel occlusion tends to be a positive feedback system; an occluded vessel creates eddies in the normally laminar flow or plug flow blood currents. These eddies create abnormal fluid velocity gradients which push blood elements such as cholesterol or chylomicron bodies to the endothelium. These deposit onto the arterial walls which are already partially occluded and build upon the blockage. • Vasculitis is inflammation of the vessel wall, due to autoimmune disease or infection.

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