ArteryArteries in RedMedValetWhat Is an Artery?An artery is an elastic blood vessel that transports blood away from the heart. There are two main types of arteries: pulmonary arteries and systemic arteries.Pulmonary arteries carry blood from the heart to the lungs where the blood picks up oxygen. The oxygen rich blood is then returned to the heart via the pulmonary veins. Systemic arteries deliver blood to the rest of the body. The aorta is the main systemic artery and the largest artery of the body. It originates from the heart and branches out into smaller arteries which supply blood to the head region (brachiocephalic artery), the heart itself (coronary arteries), and the lower regions of the body.The smallest arteries are called arterioles and they play a vital role in microcirculation. Microcirculation deals with the circulation of blood from arterioles to capillaries to venules (the smallest veins). The liver, spleen and bone marrow contain vessel structures called sinusoids instead of capillaries. In these structures blood flows from arterioles to sinusoids to venules.
Capillary SizeCapillaries are so small that red blood cells can only travel through them in single file. Capillaries measure in size from about 5-10 microns in diameter. Capillary walls are thin and are composed of endothelium (a type of simple squamous epithelial tissue). Oxygen, carbon dioxide, nutrients and wastes are exchanged through the thin walls of the capillaries. Capillary MicrocirculationCapillaries play an important role in microcirculation. Microcirculation deals with the circulation of blood from the heart to arteries, to smaller arterioles, to capillaries, to venules, to veins and back to the heart.The flow of blood in the capillaries is controlled by structures called precapillary sphincters. These structures are located between arterioles and capillaries and contain muscle fibers that allow them to contract. When the sphincters are open, blood flows freely to the capillary beds of body tissue. When the sphincters are closed, blood is not allowed to flow through the capillary beds. Fluid exchange between the capillaries and the body tissues takes place at the capillary bed.
Pulmonary veins carry oxygenated blood from the lungs to the left atrium of the heart. Systemic veins return deoxygenated blood from the rest of the body to the right atrium of the heart. Superficial veins are located close to the surface of the skin and are not located near a corresponding artery. Deep veins are located deep within muscle tissue and are typically located near a corresponding artery with the same name (for example coronary arteries and veins).A vein can range in size from 1 millimeter to 1-1.5 centimeters in diameter. The smallest veins in the body are called venules. They receive blood from the arteries via the arterioles and capillaries. The venules branch into larger veins which eventually carry the blood to the largest veins in the body, the vena cava. The blood is then transported from the superior vena cava and inferior vena cava to the right atrium of the heart.
Circulatory system - Blood Vessels and Lymph fluid
Blood Vessels and Lymph fluid Jorge Melo
Recap- blood lets play taboo Groups of two One facing the whiteboard Other facing the Audience
Aim: Explore the structures and functionsof blood vessels Objectives List different types of blood vessels Describe the different structures of blood vessels List properties of the lymph and tissue fluid
Introduction Cardiovascular system The heart The blood vessels Double circulation
Double circulatory system For each circuit- blood passes through the hear twice Blood Heart ( Pressure) Lungs (capillaries)( Pressure) Heart ( Pressure) Body
Where do we find them? Near the heart Large Carotids Subclavian Far away from the heart More smooth muscle Similar structure
Arterioles From the arteries Blood enters in arterioles Only endothelium wrapped round by a few muscles fibres
Sphincters Circular muscle fibres Prevent blood from flowing into the capillaries Regulation
Capillaries Extremely small Blood vessel located within the tissues of the body, that transports blood from arteries to veins Most abundant in tissues and organs that are metabolically active. Muscle tissues and the kidneys have a greater amount of capillary networks than do connective tissues.
Structure of Capillaries No muscle No elastic No valves Thin layer of cells only 4- 10 um diameter Blood flow 1 mm/sec
Venules Blood from capillaries drains into the venules Walls: thin layer of collagen fibres Tough Inelastic
Veins A vein is an elastic blood vessel that transports blood from various regions of the body to the heart. Thin muscle layer Valves 4 main types: pulmonary, systemic, superficial, and deep veins.
Lymph Not all of the tissue fluid returns to the blood capillary. About one-tenth of it enters a separate system of capillaries called the lymph capillaries. These are part of the lymph system. Lymph capillaries have tiny valves that allow the tissue fluid to enter but will not let it out again. Once inside the lymph system, the tissue fluid is called lymph.
Lymph What is the difference between tissue fluid and lymph? They both consist of plasma minus the large plasma proteins. But it is largely a matter of where they are found. Tissue fluid surrounds the tissue.
Lymph Lymph is found only in the lymph system. Is a milky looking fluid. The tiny lymph capillaries join up to form lymph vessels. These have a structure very similar to veins. They have thin walls and semi-lunar valves. The flow of lymph is very slow.
Lymph It relies upon pressure from nearby muscles, the action of valves and the negative pressure in the chest when we breathe in. Unlike blood, lymph is transported in one direction only. From tissues towards the heart.
Lymph The smaller lymph vessels join up to form two large lymph vessels. These empty the lymph into the subclavian veins, under the collar bone. Here the lymph mixes with the blood before joining the vena cava just before it enters the heart.
Lymph It contains fats absorbed by the lymph capillaries in the villi of the small intestine. These lymph capillaries are called lacteals. The wall of lymph vessels are more permeable than the walls of blood capillaries, so large molecules such as fats can pass through them. At intervals along the length of the lymph vessels are structures called lymph nodes, these have an important part to play in the bodies defence system.
Lymph This is where lymphocytes are produced. They have an important role to play in producingantibodies. Lymphocytes are released from the lymph nodes and find their way into the blood. The lymph nodes often swell up of you have an infection.
Quiz1. What are the different types of blood vessels?2. Which ones come away from the heart?3. Which ones go to the heart?4. Which type of vessel can you feel the pulse in?5. What is the name of the vessel that you feel the pulse in in your wrist?
Answers1. What are the different types of blood vessels? Arteries, veins, capillaries2. Which ones come away from the heart? Arteries3. Which ones go to the heart? Veins4. Which type of vessel can you feel the pulse in? Arteries5. What is the name of the vessel that you feel the pulse in in your wrist? Radial (Artery)
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