– Many human activities requires a continuoussupply of materials such as oxygen, nutrients,enzymes, hormones, carbon dioxide, toxic products,and others which are transported to and fromdifferent body cells and tissues. The transport ofmaterials is a vital function of the circulatorysystem. The system is made up of three partsnamely:1. The Human2. The Blood3. The Blood Vessels
The circulatory system is made up of the vessels and themuscles that help and control the flow of the blood around thebody. This process is called circulation. The main parts of thesystem are the heart, arteries, capillaries and veins.As blood begins to circulate, it leaves the heart from the leftventricle and goes into the aorta. The aorta is the largest artery inthe body. The blood leaving the aorta is full of oxygen. This isimportant for the cells in the brain and the body to do their work.The oxygen rich blood travels throughout the body in its systemof arteries into the smallest arterioles.On its way back to the heart, the blood travels through a systemof veins. As it reaches the lungs, the carbon dioxide (a wasteproduct) is removed from the blood and replace with freshoxygen that we have inhaled through the lungs.
There are many different parts of the heart. One of these partsis the atrium. There is also the aorta. The aorta is the mainartery in the heart. It carries oxygen rich blood from the leftside of the heart to places all over the body. You also have theventricles. The ventricles are the both sides of the heart. Theventricles receive blood from the atrium, which contracts topush the blood out and into the ventricles. The ventriclessupply blood to the body by pumping it out of the heart. Thevena cava is a main vein in the body. It carries blood from thebody to the right side of the heart.
Your hearts job is to pump bloodaround your body. Its musclescontract and squeeze out blood. Theleft-hand side pumps blood from thelungs to the rest of your body. Theright-hand side pumps stale bloodfrom your body back to your lungsfor a fresh supply. They do notwork on their own, but togetheras a team. The bodys blood iscirculated through the heart morethan 1,000 times per day.Between five and six thousandquarts of blood are pumped eachday. Your heart is about the samesize as your fist.
Blood is thicker than water and has alittle bit salty taste. In an adults body there is10.6 pints of blood circulating around. Intheir blood there is billions of living bloodcells floating in a liquid called plasma. If youtook a small sample of this blood and pouredit into a test tube and then put it in a machinecalled a centrifuge, you would be able to seethe layers of this blood. The red blood cellssink to the bottom because they are theheavier, more solid parts, but the plasmaremains at the top because it is lighter. Theplasma is 95% water and the other 5% ismade up of dissolved substances includingsalts.
CELL TYPE:1. Red Blood Cells (Erythrocytes)- Transport oxygen and a small amount of carbondioxide.
2. White Blood Cells (Leukocytes): A. Neutrophil Destroy relatively small particles by phagocytosis. B. Eosinophil Inactive inflammation producing substances. It attacks parasites. C. Basophil Releases anticoagulant to prevent blood clots and histamine,which causes inflammation. D. Monocyte Give rise to macrophage, which destroys relatively large particlesby phagocytosis. E. Lymphocytes Function in the immune system.
3. Platelet (thrombocytes) – This are small, irregularly shaped clearcell fragments(i.e. cells that do not have a nucleus containing DNA),. Theaverage lifespan of a platelet is normally just 5 to 9 days.Platelets are a natural source of growth factors . They circulatein the blood of mammals and are involved in hemostasis ,leading to the formation of blood clots .
Artery/Arteriole Vein / Venules carries blood away from carries blood towardsthe heart. the heart. Artery Vein
Arteries are tough, elastic tubes that carry blood away from theheart. As the arteries move away from the heart, they divide intosmaller vessels. The largest arteries are about as thick as a thumb.The smallest arteries are thinner than hair. These thinner arteriesare called arterioles. Arteries carry bright red blood! The colorcomes from the oxygen that it carries.Veins carry the blood to the heart. The smallest veins, also calledvenules, are very thin. They join larger veins that open into theheart. The veins carry dark red blood that doesnt have muchoxygen. Veins have thin walls. They dont need to be as strong asthe arteries because as blood is returned to the heart, it is underless pressure.
Capillary The site of the exchange of materials between theblood and the body tissues.
Pulmonary circuit Systemic circuitPulmonary circulation is the Systematic is the one thathalf portion of the carries fully oxygenatedcardiovascular system which blood from the heart going tocarries oxygen -depleted the brain and body. Theblood away from the heart, to second order systemic outputthe lungs , andreturns blood is selectivelyoxygenated (oxygen-rich) deoxygenated by the needs ofblood back to the heart. the peripheral organs, returning once again to the heart .
The lymphatic system is composed of a network ofvessels, nodes, and organs. It collects intercellular fluid, cleansit, and returns it to the circulatory system. The work of thesystem prevents body tissues from becoming swollen withintercellular fluid. Components of lymphatic system: 1. Lymph Capillaries 2. Lymph Nodes
Lymph Capillaries The lymph capillaries begin blindly in the tissue spaces andform intricate networks. This are absent from the cellularstructures like brain, spinal cord, splenic pulp, and bone marrow.The superficial lymphatics accompany veins, while the deeplymphatics accompany arteries. The lymph passes through filtersor barriers of the regional lymph nodes which trap the particulatematter. The filtered lymph passes through larger lymphatics and iseventually collected into two large trunks, the thoracic duct andright lymphatic duct, which pour their lymph into thebrachiocephalic veins. Thoracic duct drains both lower limbs,abdomen, left halves of thorax, head and neck and left upper limb.Right lymphatic duct drains right halves of thorax, head and neckand right upper limb. Larger lymphatics are supplied with theirvasa vasorum and are accompanied by a plexus of fine bloodvessels which form red streaks seen in lymphangitis.
Lymph Nodes Lymph nodes are small nodules of lymphoid tissue foundin the course of smaller lymphatics. The lymph passes throughone or more lymph nodes before reaching the larger lymphtrunks. The nodes are oval or reniform in shape, 1-25 mm long,and light brown, black (pulmonary), or creamy white (intestinal)in color. Usually they occur in groups (cervical, axillary, inguinal,mesenteric, mediastinal, etc.), but at times there may be a solitarylymph node. Each lymph node has a slight depression on oneside, called hilum. The artery enters the node, and the vein withefferent lymphatic comes out of it, at the hilum. The afferentlymphatics enter the node at different parts of its periphery.
Organs or structure in the body that function as an organ ofthe lymphatic system Most of the disease-fighting function of the adult mammal iscarried out by the Lymph Nodes. These are bean shaped, and occuralong the lymph ducts. They serve as tiny filters, in which thelymphocyrtes actively attack any foreign substances that pass throughthe tiny spaces between cells. There are many clusters of lymph nodes. The three shown in theillustration are the cervical lymph nodes (in the neck), the axillary lymphnodes (in the armpit), and the inguinal lymph nodes (in the groin). Thesethree sets are called palpable lymph nodes, because they can be felt fromthe outside. Swelling of these nodes indicates infection.
Three pairs of enlarged lymph nodes called Tonsils occurin the pharynx (chamber at the back of the nose and mouth). Thepharyngeal tonsils, also called adenoids, are at the back of thesinuses, the palatine tonsils are in the palate that separates thenasal and oral cavities, and the lingual tonsils are at the base ofthe tongue. The tonsils seem to play an important role in theimmune response in children. The Thymus is a large gland that covers the top of theheart in children. Lymphocytes migrate to the thymus from thebone marrow, where they divide rapidly forming what are calledT-lymphocytes (T for thymus). The T-lymphocytes then migrateto other lymphatic organs where they mature and divide further.After puberty, the thymus degenerates slowly. Its role appears tobe more concerned with setting up the immune system, while theactual disease fighting properties are carried out elsewhere.
The Spleen is an interface between the blood and thelymphatic system. Knots of lymphatic tissue in the spleen addlymphocytes to the blood. The spleen also acts as a filter forthe blood, and helps to destroy worn out red-blood cells. Inthe event of damage to the spleen, it can be removed and itsfunctions will be carried out reasonably effectively by theliver, the bone marrow and the lymph nodes.
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