Week 2

why is blood considered a connective tissue?

- It is a fluid connective tissue composed of formed elements (RBCs, WBCS, platelets) and plasma - Has a clotting effect where collagen fibers of blood vessel wall become exposed for platelets to stick onto

How does the structure of red blood cells contribute to their function?

- Lack nucleus & organelles to carry O2 and CO2 gases more efficiently between tissues and lungs - Packed with hemoglobin for oxygen transport - Biconcave disc shape - allow them to maximize SA/line up in single file as they pass through capillaries, increases flexibility

Describe the roles of the liver and vitamin K in clotting.?

- Vitamin K used by liver to produce clotting factors/plasma proteins. - Used for synthesis of clotting factors - Vit K defiencies can lead to bleeding/blood clotting disorders

clot elimination

-Requires clot retraction and fibrinolysis clot retraction = *actinomyosin protein* contracts and squeezes serum out of developing clot to make it smaller fibrinolysis = degradation of fibrin strands by *plasmin* - starts within 2 days of clot formation - occurs over number of days

temp of blood

1 Celsius higher than body temperature

Briefly describe the process of RBC recycling.

1. Erythrocytes form in red bone marrow 2. Erythrocytes enter blood and circulate for 120 days 3. Aged erythrocytes are phagocytized by macrophages in liver and spleen. Hemoglobin components separated into globin, iron ion, and heme. 4. Each separated component has different fate : Heme - converted to bilirubin. Bilirubin transported to liver by albumin and released as bile in small intestine. Converted to urobilinogen, transported to large intestine and expelled in feces - Iron ion - small amounts lost in sweat, urine, feces, injury, menstruation. - Other iron amount is stored in liver and transported by transferrin to red bone marrow for erythrocyte production. - Globin proteins - broken into amino acids and enter blood, some used to make new erythrocytes

Describe the sequence of events leading to platelet activation and aggregation, and the formation of a platelet plug. What helps keep this process localized?

1. Hemostasis occurs. Vascular spasm is the first response to in response to blood vessel injury (limits blood leakage, platelets and endothelial cells release chemicals to stimulate further constriction) 2. Platelet plug formation occurs next. Collagen fibers in wall are exposed. Platelets stick to collagen with von Willebrand Factor. Platelet's cytosol degranulates and releases chemicals (*serotonin and thromboxane A cause prolonged vascular spasms*, *ADP and thromboxane* attract other platelets and facilitate their degranulation/positive feedback) - Coagulation cascade initiated by intrinsic and extrinsic pathways - Intrinsic = initiated by platelets upon damage to blood vessel wall - Extrinsic = initiated by damage outside vessel - Platelet plug is localized by *prostacyclin* secretion by nearby healthy cells, which prevents platelet plug from getting too large. Von Willebrand Factor helps platelet stick to collagen wall.

Briefly describe the three phases of hemostasis (VERY brief).

1. Vascular spasm (blood vessel constricts to limit blood escape) 2. Platelet plug forms (platelets arrive at injury site and stick to exposed collagen fibers) 3. Coagulation phase (coagulation cascade converts inactive proteins to active forms, to form fibrin strands of blood clot)

What is the lifespan of a typical red blood cell?

120 days

what composes blood plasma?

92% water, 7% plasma proteins 1% dissolved molecules/ions it is extracellular fluid higher protein concentration than intercellular fluid

ABO blood typing

ABO group Consists of 2 surface antigens, A & B. Presence of A or B determines blood type Type A blood has erythrocytes with antigen A only Type B blood has erythrocytes with antigen B only Type AB has both antigens A and B Type O has neither antigens A nor B ABO accompanied by specific antigens/agglutinins within blood plasma. Antibody = Y-shaped protein that binds to specific antigen perceived as foreign to body. Type A = has anti-B antibodies in its plasma Type B = has anti-A Type AB = has neither Type O = has both

What are the 3 primary classes of plasma proteins and what are their roles?

Albumins =most abundant plasma protein (58%), exerts greatest colloid osmotic pressure to maintain blood volume & pressure, transports & carries ions, hormones and lipids in blood Globulins = second largest plasma protein in blood (37%), alpha & beta-globulins bind & transport water insoluble molecules & hormones. Gamma-globulins/antibodies part of immune system Fibrinogen = 4%; blood clot formation, converted into fibrin to form a blood clot

Briefly describe the main function of the neutrophils, eosinophils, basophils, monocytes and lymphocytes.

All contain a nucleus and cytosol Neutrophils = most numerous in blood (50-70%), 1.5x larger than erythrocyte, phagocytizes infectious pathogens/bacteria, destroys bacteria Eosinophils = phagocytizes antigen-antibody complexes/allergens, releases chemicals to attack parasitic worms Basophils = contains granules with histamine and heparin. When histamine is released from its granules, causes increase in blood vessel diameter (vasodilation) and increased capillary permeability Release of heparin from basophils inhibits blood clotting (anticoagulant) Increases in response to myeloproliferative disorders (overproduction in red bone marrow) Monocytes = phagocytizes pathogens (bacteria, viruses), cell fragments, debris, dead cells, becomes macrophages Increases in response to chronic inflammatory disorders or TB Decreases in response to prolonged prednisone therapy Lymphocytes = produces antibodies, attacks pathogens and abnormal infected cells,

Define the following terms: anemia, athlete's anemia, sickle cell anemia, pernicious anemia, and polycythemia.

Anemia = percentage of erythrocytes lower than normal/oxygen-carrying capacity of blood decreased Reduced oxygen delivery to tissues, heart works harder to supply oxygen to body athlete's anemia: induced polycythemia by athletes to increase endurance. extra RBCs are saved and introduced a few days before the event. Polycythemia: increased level of RBC's that increases blood viscosity making the blood move slowly. sickle cell anemia: a genetic disease where RBCs are deformed (sickle cell shape) and have a diminished ability to carry oxygen. often too much clotting is also a problem accompanied by severe pain.

What is the normal value of leukocytes in blood?

Between 4500 and 11,000 per cubic mm of blood

Hemophilia

Bleeding disorders caused by a lack of clotting factors in the blood. Protein is abnormal and cannot function. Most common is A and B. Hemophilia A: deficiency in factor VIII. Hemophilia B: deficiency of factor IX Hemophilia C: deficiency of factor XI

RH factor

Determines presence/absence of Rh surface antigen Rh present = Rh positive/Rh+ Rh absent = Rh negative Rh-

Define diapedesis and positive chemotaxis.

Diapedesis = process where leukocytes enter the tissues from vessels by squeezing between endothelial cells of blood vessel walls Chemotaxis = process where leukocytes are attracted to site of infection by presence of molecules released by damaged cells/dead cells/invading pathogens; part of inflammatory response

Describe the process of erythropoiesis. Describe the steps starting from hemocytoblasts and the formation of RBC.

Erythrocytes makeup 99% of all formed elements Begins with myeloid stem cell (under influence of multi-CSF cell) --> forms progenitor cell --> becomes proerythroblast --> erythroblast (cell forming hemoglobin in cytosol) --> normoblast (more hemoglobin in cytosol, ejected nucleus) --> reticulocyte (lost all organelles except ribosomes to continue producing hemoglobin)

What are the two classes of WBCs, and how are they grouped?

Granulocytes = have specific granules in cytosol visible under microscope, refers to neutrophils, eosinophils and basophils Agranulocytes = small specific granules in cytosol not visible under microscope, lymphocytes and monocytes

Define the following terms: leukemia, leukopenia, leukocytosis.

Leukemia = cancer in leukocyte-forming cells, abnormal leukocytes increase in number as RBCs and megakaryocytes decrease in number b/c abnormal leukocytes overtake red bone marrow and leave no room for normal formed elements (e.g. erythrocytes, platelets). Decrease in erythrocyte and platelet production causes anemia and bleeding Leukopenia = deficiency in number of leukocytes in blood --> increase risk of infection/ability to fight infections Leukocytosis = slightly increased leukocyte count caused by infection or stress

What are the main functions of platelets?

Membrane-enclosed cell fragments/aka thrombocytes No nucleus, produced in red bone marrow by megakaryocytes Important in hemostasis to form platelet plug by sticking to fibrin network/collagen fibers of a blood clot

What is the function of plasmin and heparin in blood?

Plasmin destroys the fibrin framework of clot by degrading fibrin through fibrinolysis (starts within 2 days of clot formation Heparin = anticoagulant (prevents blood clot formation) enhances inflammatory response when released by basophils and mast cells

Hematopoiesis

RBC production that occurs in red bone marrow 1) Starts with hemocytoblast (multipotent cells that can differentiate into any type of cell) 2) 2 lines for RBC development: myeloid line forms erythrocytes & leukocytes. Lymphoid line forms only lymphocytes. 3) Maturation & division influenced by CSFs (growth factors)

Briefly explain the structure and function of hemoglobin. How is it differ from myoglobin?

Red protein that transports oxygen and CO2 Contains globin (protein molecules). 2 of them are alpha and beta chains. All globin chains contain a heme group (iron at center to bind to oxygen for blood transport) 4 heme groups = capable of binding 4 oxygen molecules Myoglobin = globular protein that binds oxygen when muscle is at rest

What is the difference between sickle cell disease and sickle cell trait?

Sickle cell disease = anemia occurs when person inherits 2 copies of sickle-cell gene, erythrocytes become sickle-shaped at lower blood oxygen concentrations --> unable to flow through blood vessels and tissues --> hemolysis Sickle cell trait = person inhibits one sickle cell gene and one normal gene. Person does not get the disease, but can pass the defective gene to offspring

What is hemostasis?

Stops bleeding Stimulus is trauma to a blood vessel occurring, causing blood to coagulate

3 types of lymphocytes

T cells, B cells, NK cells

What is the relationship between testosterone and red cell production?

Testosterone stimulates erythropoietin production in kidneys (males have more RBCs than women)

What are the functions of blood?

Transportation - transports oxygen from blood vessels and CO2 to the lungs for gas exchange Transports nutrients absorbed from GI tract, hormones released by endocrine glands, and heat and waste products from systemic cells Regulation - regulates body temp (blood absorbs heat from body cells as it passes through blood vessels, heat is then released from blood at body surface), body pH (blood contains buffers, protein and bicarbonate, that bind and release H+ ions to maintain blood pH, and fluid balance (water added to blood from GI tract and is lost through urination, sweat, breathing; contains proteins and ions that exert osmotic pressure to pull fluid back into capillaries to maintain normal fluid balance Physical characteristics Blood color depends on oxygen concentration Average volume in adult = 5 L Blood is 4-5x more viscous than water (thicker) depending on amount of dissolved substances relative to amount of fluid Plasma concentration = relative concentration of solutes (protein, ions) in plasma Temperature = 2 Celsius higher than measured body temp b/c blood warms areas through it travels Blood pH = slightly alkaline, pH 7.35-7.45 Plasma proteins depend on H+ concentration If pH is off normal range, plasma proteins denature/unable to function

agglutinins

Y-shaped protein antibodies that bind to specific ABO antigens/agglutinogens in blood plasma that are perceived as foreign to the body

Leukemia

abnormal development & proliferation of leukocytes - increase in abnormal leukocyte number - decrease in erythrocyte and megakaryocyte lines causes anemia and bleeding

acute & chronic leukemia

acute is rapid progression, death occurs in months in children and young adults chronic is slow, in middle aged and older adults

Agglutinogens

antigens on the surface of the RBC that is the basis for blood typing (ABO group)

NK cells

attrack abnormal and infected tissue cells

B-lymphocytes

become plasma cells and produce antibodies

clotting requires ___

calcium, clotting factors, platelets + vitamin K

agglutination

clumped erythrocytes e.g. When a person is transfused with blood of *incompatible type* --> antibodies in plasma bind to surface antigens of transfused erythrocytes --> clumps of erythrocytes bind together --> clumped erythrocytes block blood vessels, prevent blood circulation --> can lead to hemolysis (ruptured clumped erythrocytes)

antigens

foreign substances that trigger the attack of antibodies in the immune response. or Molecules on surface of erythrocyte plasma membrane, antibodies bind to antigens

lymphoid stem cells

give rise to lymphocytes

myeloid stem cell

gives rise to RBC, most WBC and platelets

megakaryocytes

gives rise to platelets

leykocytosis

increased leukocyte count caused by recent infection or stress

hypercoagulation

increased tendency to clot blood - can lead to thrombus (blood vessel clot) - embolus is when clot is dislodged in blood - if the clot lodges in lungs, pulmonary embolism occurs (causing bleeding and death) - drug-related, environmental, and genetic causes (e.g. birth control pills)

basophil count changes when

increases in response to myoproliferative disorders (overproduction in bone marrow)

if blood osmolarity decreases, ADH ___

increases to retain water ADH = increases water retention

what happens to iron when RBCs are broken down?

iron from hemoglobin is transported by *transferrin protein* to liver storage proteins are *ferritin and hemosiderin*

T-lymphocytes

manage immune response

differential count

measures amount of each type of leukocyte & whether they are immature

Hematocrit

percentage of blood volume occupied by red blood cells

serum

plasma with clotting proteins removed

thrombocytopenia

platelet deficiency may occur in bone marrow infections or cancer

thrombopoiesis

platelet production, megakaryoblast produced from myeloid stem cell

hemopoiesis

production of all formed elements

plasma proteins

protect against blood loss

leukopenia

reduced number of leukocytes, increasing risk of infection

what happens if you lose proteins and have kidney disease?

swelling in ankle occurs b/c fluid becomes hypotonic, as fluid moves out of the cell

platelets

thrombocytes -membrane-enclosed cell fragments -no nucleus -important for blodo clotting -30% stored in spleen -circulates for 8-10 days then is broken down + recycled

monocytes

transforms into phagocytic cells, macrophages, phagocytizes bacteria, viruses, debris increases in response to chronic inflammatory disorders or TB decreases in response to prednisone therapy

reticulocyte

young RBC, not fully mature, gives rise to erythrocytes if # of reticulocytes decrease, # of RBCs will decrease too