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Circulation Continued Hepatic vein Hepatic Artery Hepatic Portal Vein Renal Vein Mesenteric artery Structure/ Function Arteries Capillaries Veins • thick strong walls so it • 1 cell think so that it can take blood / nutrients as close to the cells that need it and pick up waste from cells that the blood can take. • Oxygen diffuses from the Red Blood Cells into the tissue • Deliver blood back to the heart • have valves to stop the blood from flowing backwards • Thin walls / less elastic tissue / large lumen compared to arteries • muscle movement helps move blood along can withstand high pressure blood moves at •Stretchable walls •‘spring’ action to contract • takes blood to the body from heart More on structure Thick / Elastic fibers / small lumen (space where blood flows through Arteries Capillaries Veins Similarities -All carry blood/ plasma/ blood vessels/ have lumen - Arteries >veins>capillaries (stretchable / elastic) -(Arteries & capillaries carry oxy blood) / (Veins and capillaries carry deoxy blood) -Arteries & veins – connected to heart directly - Arteries / Veins – have elastic fibers (similar tissues) - Arteries / Veins – contract & expand (arteries>veins) Differences -Veins>Arteries>capillaries (size of lumen) -Carry blood: Arteries (high pressure) Veins (low pressure) - No elastic fibers for capillaries -No valves for arteries and capillaries / valves in veins -Size : Arteries > Veins > Capillaries -Veins have thin walls Arteries have Thicker Walls (No walls for capillaries – only 1 cell thick) Blood – material transfer: - Glucose - Amino acids - Inorganic ions - Vitamins - Water - O2/CO2 – diffuse into/ out of RBC Arterioles brings blood into capillaries Arterioles divide into smaller capillary networks Fluid (containing nutrients) leak out of capillaries especially at the beginning of the capillary bed The fluid leaked out of capillaries and now surrounding the tissue cells is now called tissue fluid Waste products like CO2 in the tissue fluid is now leaks back into the capillaries at the end of the capillary bed The venule carries the blood back to the vein Blood capillaries have tiny holes between the cells in their walls Blood Plasma (fluid that leaks out of capillary with nutrients) passes between these holes Lymphocyte (Ly) and platelet (P) located in the lumen of blood capillary. RBC – hemoglobin and oxygen transport WBC – Phagocytosis / Antibody formation Platelets – causes clotting of blood. They are tiny fragments . Role – to help blood to clot when vessels are damaged / stop pathogens Blood : Several different kinds of cells that float in liquid called - - PLASMA Red Blood Cells (RBC) Majority of cells are RBC Smallest cells Round with dent (biconcave disks with no nucleus) To transport O2/CO2 Red protein = hemoglobin (blue red) In lungs – when it picks op O2 – oxy-hemoglobin (bright red) In capillary in tissue bed – O2 is released by the oxy-hemoglobin and becomes Hemoglobin again -Large and always have nucleus Part of the body’s defense system against harmful bacteria . Viruses and other harmful organisms. Disease causing organisms = pathogens WBC destroy pathogens Neutrophils : the most plentiful leukocytes in the bloodstream ; break down bacterial cells in the body with enzymes stored in the grains in the neutrophils' cytoplasm Eosinophils : numbers of these cells in the blood increase in the presence of allergens (substances which cause allergies) or parasites Basophils are the least plentiful leukocytes in the bloodstreamin beginning the process of inflammation, one of the body's ways of responding to injury or irritation that's characterized by redness, warmth, swelling, and pain in one specific place. Monocytes : mononuclear leukocytes that typically have a horseshoe or kidney-shaped nucleus, and are the largest type of white blood cell.; help devour microorganisms by phagoytosis ;T hey also devour and digest body cells that have died or are old, and also help remove other unneeded cellular material from the body. Lympocyte: are the second most plentiful type of leukocyte in the blood, and are smaller than other types of leukocytes. Phagocytes: WBC that kill pathogens by phagocytosis. Usually first to arrive at the scene and attempt to destroy the pathogen. Phagocytosis – the process by which the phagocytic WBC puts our finger like projections and enclose a pathogen into a vacuole (enclosed space) in their cytoplasm. Then the WBC kills the pathogen. 1. Phagocytic WBC flows around the bacteria 2. The WBC traps the bacteria by closing around them (phagocytosis) 3. The bacteria is trapped I a vacuole 4. Enzymes are secreted inside this vacuole by the WBC to kill and digest the bacteria. 5. The digested substances are absorbed into the cytoplasm of the WBC. WBC (another kind) known as lymphocytes kill pathogens by making special proteins known ANTIBODIES These antibodies can kill pathogens directly or make it easier for phagocytes to kill it. There are different antibodies for different pathogens. The pathogen (invading organism) has many different antigens (the different molecules that make up the pathogen). Your WBC lymphocytes recognize your molecules but not another's When a bacteria invades your body for the first time – (your body has not seen it before) very few antibodies will be there that can actually recognize the new antigen. It takes a few days for your WBC lymphocytes to make the right one. That is when you are feeling sick. But, if it is a bacteria your body has seen before – the WBC lymphocytes will not take much time to make the right antibody. You are IMMUNE to the disease when your body can successfully kill the invading organism by itself. Tissue rejection: - Transplant – taking an organ from one person (the donor) and giving it to another who needs it (the recipient) - (eg. Kidney transplant) The cells in the transplant is not the same as the person who needs it. Tissue rejection – occurs when the recipient's immune system recognizes the donor’s as a foreign object and attacks it. To avoid tissue rejection – doctors try to find a donor who has similar antigen to the recipient . Best to have identical twins for this. If not – recipient will have to take immunosuppressant drugs (drugs to turn down the immune system). How blood clotting occurs: - Damaged blood vessel is rough not smooth (when you get a cut on your finger) - Platelets bump into the rough parts and react with them - Fribrinogen (a protein) found in blood plasma also reacts with the platelets at the same time. The reaction between the platelets and the fibrinogen causes the soluble fibrinogen to become an insoluble protein called Fibrin. The Fibrin is long and fibrous (looks like a net) and captures RBC / WBS / Platelets and forms a blood clot. A dried blood clot is called a scab Under the scab – the skin heals by forming new skin cells . It continues to do this until a new layer of skin has formed – that is when the scab falls off. Circulation of body fluids: Network of capillaries – capillary bed Capillaries have tiny holes in their walls Blood plasma can leak through the holes (in between all the cells in the tissue and fills that space) Now called Tissue Fluid WBC can move through these tiny holes but RBC can not (can’t change shape like WBC) Therefore tissue fluid does not contain RBC Tissue fluid – continuous pathway between blood plasma / cells / tissue Everything that moves between the blood and tissue diffuses through tissue fluid Tissue fluid carries oxygen and nutrients to the tissue cells Leaks back to capillary bed with waste from cells including CO2 Tissue fluid that does not return to the capillary bed returns to the blood via lymph vessels Lymphatic capillaries embedded in tissue collect the remaining tissue fluid Once the fluid is inside the lymphatic capillaries it is now called lymph The Lymph capillaries have valves like veins that prevent the back flow of tissue fluid back into the tissue Lymph capillaries join to make up the lymph vessels These take the fluid (lymph) into large veins called the subcalvian veins (just under the collarbone) The lymph flows into the blood in these veins The fluid moves due to the lymph vessels that pass alongside muscles These squeeze on lymph vessels when the muscles contract These lymph vessels pass through the lymph nodes where WBC are collected Also passes along fatty acids and glycerol to parts of body.