360 likes | 623 Vues
17 . Blood. Modified by: Olga E. Vazquez. Cardiovascular System. Cardio = heart Vascular = blood vessels Consists of three interrelated components: Blood Heart Blood vessels. Basics of Blood. Blood is Fluid Connective Tissue Blood components Plasma (matrix) - nonliving
E N D
17 Blood Modified by: Olga E. Vazquez
Cardiovascular System • Cardio = heart • Vascular = blood vessels • Consists of three interrelated components: • Blood • Heart • Blood vessels
Basics of Blood • Blood is Fluid Connective Tissue • Blood components • Plasma (matrix) - nonliving • Formed elements (cells) - living • Hematopoiesis – formation of blood cells
Blood: An Overview • Blood and the interstitial fluid (IF) are 2 fluids that provide O2 and nutrients and remove CO2 and other waste. • How do they do it? • IF bathes body cells • O2 and nutrients diffuse from blood → IF → cells • Waste and CO2 diffuse cell → IF → blood
Plasma • Makes up 55% of blood • 90% water;plasma also contains : • Proteins such as antibodies • Gases • Hormones • Waste
Formed Elements • These cells have unusual features. • Two of the three are not even true cells. Why? • Erythrocytes have no nuclei or organelles, and platelets are cell fragments. Only leukocytes are true cells • Most of the formed elements survive in the bloodstream for only a few days. • Most blood cells do not divide.
Formed Elements • RBC or erythrocytes are involved in gas transport • Carry O2 • Carry CO2
Structural Characteristics of RBCs • Major function of RBC is to transport hemoglobin. • Erythrocytes are over 97% hemoglobin.
Destruction of Erythrocytes • RBCs are anucleate • Limitations due to lack of nucleus: • Red blood cells are unable to synthesize new proteins, to grow, or to divide. • Erythrocytes become “old” & hemoglobin begins to degenerate.
Destruction of Erythrocytes • Red blood cells have a useful life span of 100 to 120 days, after which they become trapped in the spleen. • In the red pulp of the spleen, RBC rupture when they try to squeeze through because of their fragile old membrane. • For this reason, the spleen is sometimes called the “red blood cell graveyard”.
Formed Elements • WBC (white blood cells) or leukocytes have many specialized functions. • What is the purpose of WBCs ?
Formed Elements • Leukocytes: • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes
Formed Elements • Platelets • Cell fragments • Encourage clot formation
Formed Elements Formation • Hematopoiesis (hemato = blood, poiesis = to make) • Process in which formed elements of the blood develop • Erythropoiesis • Leukopoiesis • Before birth it occurs • Yolk sac • Later in the liver, spleen, thymus and lymph nodes • Last 3 months of gestation in the red bone marrow
Hematopoiesis • During childhood (up to 5 years) occurs in the epiphysis of almost all long bones. • In adults it occurs also in flat and irregular bones such as the skull, sternum, hip bone, ribs, and vertebra. • Formed element production in adults occurs in the humerus and femur.
Leukocytes • Leuko = • They are also known as white blood cells • Only formed elements that are complete cells with a nucleus and usual organelles.
Leukocytes • What do you know about these cells?
Categories of Leukocytes • Leukocytes are grouped into two major categories: • Granulocytes • Neutrophils • Eosinophils • Basophils • Agranulocytes • Lymphocytes • Monocytes
Granulocytes • All are roughly spherical in shape • Stored in bone marrow until needed • They are larger than erythrocytes
Neutrophils • Respond most quickly to tissue destruction by bacteria or fungus • Active in phagocytosis
Neutrophils • Neutrophils are our body’s bacteria slayers • First one at “war zone”. • Can phagocytize 5-20 bacteria before it dies.
Eosinophils • Parasitic worms (most important role) • Release enzymes onto the parasite’s surface, digesting it away
Basophils • Similar in function to mast cells • Bind to IgE, which causes cells to release histamine • Release of histamine intensifies inflammatory reactions
Granulocytes • All granulocytes are phagocytic but neutrophils are the most phagocytic of them all.
Agranulocytes • Include lymphocytes and monocytes • Both produced in red bone marrow but lymphocytes can also be produced in lymphatic organs such as lymph nodes and spleen. • Major soldiers with a life span of 100-300 days
B Lymphocytes • B cells • Attack bacteria, viruses and toxins • Plasma cells → antibodies (Ig = immunoglobulin) • Memory cells • Keep a “record” of pathogens
T Lymphocytes • T cells • Acting directly against virus-infected cells and tumor cells • CD 4 • T helper cells • CD 8 • T cytotoxic cells
NKC • Natural Killer Cells • Wide variety of microbes and tumor/cancer cells
Movement of Lymphocytes • Recirculate (another difference from granulocytes) • blood → interstitial space → lymphatic fluid → blood • Show ability to deformate
Monocytes • Take longer to get there but arrive in larger numbers • Migrate from blood into tissues where they enlarge and become macrophages (which are phagocytic) • Destroy more microbes • 100 bacteria because they extrude toxins
Macrophages • Most powerful phagocyte • Engulf larger and 5 times as many particles as neutrophils • They can phagocytize whole RBC, malarial parasites and dead neutrophils • They are very important in starting immune responses • They can be called different names when they stay in different tissues.
Macrophages and MHC • MHC – major histocompatibility complex (self antigen) • Glycoproteins that protrudes from plasma membrane into ECF • Cell identity markers unique for each person, what about identical twins?
Platelets • Platelets are essential for the clotting process that occurs in plasma when blood vessels are ruptured or their lining is injured. • By sticking to the damaged site, platelets form a temporary plug that helps seal the break.
Platelet Plug Formation • Platelet Aggregation • A positive feedback cycle that activates and attracts greater and greater numbers of platelets to the area begins and, within one minute, a platelet plug is built up, which further reduces blood loss