Blood. ì The only fluid -ssue in the body. ì Components of blood. ì Classified as a connec-ve -ssue

Transcription

1 Chapter 10: Blood

2 The only fluid -ssue in the body Classified as a connec-ve -ssue Notable: collagen & elas-n absent from blood Dissolved fibrin proteins become evident during clo?ng Components of blood Living cells Formed elements RBC & WBC Non- living matrix Plasma Blood

3 When Blood is centrifuged Plasma rises to the top (55%) Erythrocytes sink to the booom (45%)5 This is known as the hematocrit Normal hematocrit: 47% +/- 5%: males 42% +/- 5%: females Buffy coat contains leukocytes & platelets (<1%) Thin, whi-sh layer that is between erythrocytes & plasma

4 Physical Characteristics of Blood S-cky, opaque fluid metallic taste More dense than water, 5x more viscous Colors: Oxygen rich blood scarlet red (bright) Oxygen poor blood dull red ph is between Blood temperature is always slightly higher than body temperature around F In a healthy man, blood volume is about 5-6 liters or about 6 quarts Women have less blood, about liters Blood makes up about 8% of body weight

5 Functions of Blood All concerned with: substance distribu-on regula-ng blood levels of par-cularly substances bodily protec-on Distribu-on: Oxygen to lungs Nutrients to diges-ve system Transpor-ng metabolic wastes from elimina-on sites (lungs, kidneys, liver) Hormones from glands to target organs

6 Functions of Blood Regula-on: Maintain appropriate body temperature by absorbing and distribu-ng heat through body, encouraging skin for heat loss Maintain normal ph, blood holds an alkaline reserve to raise ph when necessary Maintain adequate fluid volume in circula-on Salts & blood protein prevent excess fluid loss Protec-on Prevents blood loss Prevents infec-on

7 Blood Plasma Straw colored, s-cky liquid Composed of approximately 90% water Includes over 100 dissolved substances: Nutrients Salts (electrolytes) Respiratory gases (CO2 & O2) Hormones Plasma proteins Waste products Uric acid, crea-nine, lac-c acid, ammonium salts

8 Blood Plasma: Plasma Proteins Most abundant solutes in plasma Made mostly by the liver Proteins include: Albumin: regulates osmo-c pressure The pressure that keeps water in the blood Essen-ally carries all proteins around the blood High albumin almost always caused by dehydra-on Low albumin can come from liver disease, kidney disease, & malnutri-on Globulins: Alpha, beta: transport proteins that bind to lipids, metal ions, fat- soluble vitamins Gamma: an-bodies released during an immune response Clo?ng proteins: help to stop blood loss when a blood vessel is injured An-bodies: help protect the body from pathogens (disease)

9 Blood Plasma Acidosis: blood becomes too acidic Liver failure, kidney failure Alkalosis: blood becomes too basic Main cause: hyperven-la-on resul-ng in a loss of CO2 Other causes: prolonged vomi-ng, Cushing s syndrome, severe dehydra-on In each scenario, the respiratory system & kidneys help restore blood ph to normal

10 Formed Elements Erythrocytes Red blood cells (RBCs) Leukocytes Lymphocytes Both are white blood cells (WBCs) Platelets Cell fragments

11 Erythrocytes AKA Red blood cells (RBCs) 4-6 million (per mm 3 ) Developed in the bone marrow Salmon colored biconcave discs Formed Elements Anucleate CAN T reproduce produced in the bone marrow Literally, sacs of hemoglobin most organelles have been rejected Structural protein called spectrin: spectrin net is deformable allows erthyrocytes to change shape as necessary to move through blood vessels Each erythrocyte has 250 million hemoglobin sacs Normal blood contains 12-18g per 100ml of blood Func-ons: Transport oxygen to lung capillary beds Also transports small amounts of CO (about 20%)

12 Erythrocytes Formed Elements Women have lower RBC count (4.32-5, versus mm 3 ) As RBCs increase, blood viscosity increases, blood flow slows Func-on: Respiratory gas transport Hemoglobin in RBC binds to oxygen (g/100ml) infants adult males adult females Hemoglobin is inside RBCs to prevents the protein molecule from breaking apart and leaking through the bloodstream

13 Formed Elements ì Diseases of RBCs ì Anemia ì Decrease in oxygen carrying ability ì Sickle cell anemia (SCA) ì abnormally shaped hemoglobin ì Gene-cally caused ì Painful condi-on ì Polycythemia ì excessive or abnormal increase in the number of RBCs

14 Formed Elements

15 Formed Elements: Leukocytes Essen-al for body s defense against pathogens Complete cells with a nucleus & organelles Can move in/out of blood vessels on their own (diapedesis) Move with ameboid mo-on Respond to chemicals released by damaged -ssues 4,000 11,000 per mm 3 of blood

16 Formed Elements: Types of Leukocytes stem cells Granulocytes Lymphoid stem cells Possess lobed nuclei Hemocytoblast Myeloid stem cells Will show granules in cytoplasm when stained Include: neutrophils, Secondary eosinophils, stem cells & basophils Agranulocytes Lack of visible granules Erythrocytes Nuclei are spherical, oval or kidney shaped Include: lymphocytes & monocytes Basophils List of the WBCs from most to least abundant Platelets Neutrophils Never Lymphocytes Let Monocytes Monkeys Eosinophils Eat Basophils Bananas Lymphocytes Monocytes Neutrophils Eosinophils

17 Formed Elements: Types of Leukocytes Neutrophils Mul-lobed nuclei with small granules Acts as phagocyte at ac-ve site of infec-on first responder to inflammatory site (trauma) tell tale sign of acute inflamma-on Eosinophils Large brick red granules Shown in response to allergies, asthma-c reac-ons or parasi-c worms May play a role in defense against viruses

18 Formed Elements: Types of Leukocytes Basophils Least common granulocytes Contain histamine granules Ini-ate inflamma-on Contain heparin Prevent blood from clo?ng too quickly May regulate the behavior of T cells

19 Formed Elements: Types of Agranulocytes Lymphocytes Nucleus fills most of the cell Plays an important role in the immune system Types of Lymphocytes: Killer Cells (Killer T Cells) Defend against tumors and virally infected cells T Cells (Thymus Cells) Many subsets of t cells All cell mediated immunity pathogen detec-on B Cells (Bone cells) Secre-on of an-bodies Neutralize foreign objects like bacteria & viruses

20 Formed Elements: Types of Agranulocytes Monocytes Largest WBC in size ~50% found in the spleen Func-on as macrophages Specific & non- specific defense Act in response to inflammatory situa-ons to get rid of pathogen/allergic causing an-gen Important in figh-ng chronic infec-on

21 Leukocytosis WBC count above 11,000 leukocytes/mm 3 Generally indicates an infec-on But not indica-ve of any specific infec-on It s diagnos-cally similar to a fever WBC Abnormalities Leukopenia Abnormally low leukocyte level Commonly caused by certain drugs such as cor-costeroids and an-cancer agents An important indicator of infec-on risk Leukemia Bone marrow becomes cancerous, turns out excess WBC 4 types: ALL (acute lymphoblas-c), CLL, AML (acute myelogenous), & CML Can be acute or chronic Acute is more common in children, chronic in the elderly Can be lymphoid or myeloid Lymphoid is more common in children, myeloid is rare in children hop://

22 Aka thrombocytes Formed Elements: Platelets Small regular shaped cell fragments, derived from megakaryocytes (bone marrow cell) Average lifespan of a platelet is 5 to 9 days Needed for the clo?ng process If platelets are too low, excessive bleeding can occur; if too high, wanted/ unwanted clo?ng can occur.

23 Hematopoiesis Blood cell forma-on in red bone marrow All blood cells (red & white) derive from a common stem cell (hemocytoblast) Differenta-on: Lymphoid stem cells produce lymphocytes Myeloid stem cell produces all other formed elements These stem cells are self- renewing I.e. some never develop into RBCs or WBCs they stay stem cells so they can mito-cally divide into more stem cells.

24 Erthyrocyte formation Erthyrocytes are unable to divide, grow & synthesize proteins Wear out in days When they are no longer usable, they will be removed by Increased Ophagocytosis 2 - carrying by the liver or spleen ability of blood Lost cells are replaced by hemocytoblasts Stimulus: Decreased RBC count, decreased availability of O 2 to blood, or increased tissue demands for O 2 Reduced O 2 levels in blood Rate More of RBC produc-on is controlled by the hormone erthyropoie-n RBCs Kidneys produce most erythropoie-n as a response to reduced Enhanced erythropoietin oxygen levels erythropoiesis in the blood Red bone Normal blood oxygen levels Erythropoietin stimulates Kidney releases Homeostasis is maintained marrow by nega-ve feedback from blood oxygen levels

25 Formation of WBCs and platelets Controlled by hormones Colony s-mula-ng factors (CSFs) and interleukins prompt bone marrow to generate leukocytes Thrombopoie-n s-mulates produc-on of platelets

26 Hemostasis Stoppage of bleeding resul-ng from a break in a blood vessel Hemostasis involves three phases Vascular spasms Vasoconstric-on causes the blood vessel to spasm Spasms narrow the blood vessel and decreases overall blood loss

27 Hemostasis Platelets release chemicals Platelet that plug attract more forma-on platelets to the site and make nearby Collagen platelets sticky fibers that make up the blood vessel become exposed by the break PF Platelets 3 from become s-cky & cling to the collagen fibers platelets Calcium and other Those platelets + clotting release chemicals (PF 3 ) to aoract more platelets factors The platelets pile up to form a platelet plug Tissue factor in damaged in blood plasma Coagula-on tissue (blood clo?ng) Injured -ssues release TF (-ssue factor) Phases of coagulation Formation of PF 3 interacts with TF, clo?ng factors & calcium ions to ini-ate the (clotting prothrombin cascade) activator clo?ng cascade Prothrombin gets converted to thrombin by prothrombin ac;vator. Prothrombin Thrombin Thrombin joins fibrinogen proteins into hair- like molecules of insoluble fibrin Fibrinogen Fibrin (soluble) (insoluble) Fibrin forms a meshwork (the basis for a clot)

28 Hemostasis Blood usually clots within 3 to 6 minutes The clot remains as endothelium regenerates The clot is broken down ater -ssue repair

29 Thrombus Embolus Undesirable Clotting A clot in an unbroken blood vessel normal during injury but should be disposed of once the risk of excessive bleeding has past. Can be deadly in areas like the heart More likely to occur when there are problems in the heart (arrhythmia, heart valve replacement and/or recent heart aoack A thrombus that breaks away and floats freely in the bloodstream In general, an embolus is ANY detached, i-nerant intravascular mass they can be solid, liquid or gas Can later clog vessels in cri-cal areas such as the brain

30 Bleeding Disorders Thrombocytopenia Platelet deficiency = below 50,000 per microliter Normal platelet counts are between 150, ,000 per microliter of blood (that s a lot) Even normal movements can cause bleeding from small blood vessels that require platelets for clo?ng Symptoms include frequent bruising, purpura, & petechiae

31 Bleeding Disorders Haemophilia Hereditary bleeding disorder Normal clo?ng factors are missing When bleeding occurs, a scab does form, but it is temporary The clo?ng factor prevents the fibrin from reaoaching and healing the blood vessel

32 Blood Typing & Transfusions Large losses of blood have serious consequences Loss of 15 30% causes weakness Loss of over 30% causes shock, which can be fatal Transfusions are the only way to replace blood quickly Transfused blood must be of the same blood group Blood is tested for a large number of diseases before giving to the pa-ent who needs blood Tested for: All forms of HIV, All forms of hepa--s, syphillis, CMV, and West Nile virus just to name a few J Complica-ons: Hemoly-c reac-ons: you have an-bodies again the donor s RBCs symptoms include fever, chills, increased heart rate, shortness of breath, rapid drop in blood pressure. Transfusion must be stopped immediately before kidney damage occurs Allergic reac-ons: while blood banks look at the complete chemical make up of donor blood, if a pa-ent is unaware of allergies and these chemicals are in blood an allergic reac-on can occur If severe, Usually easily fixed by dosing epinephrine to stop anaphylaxis

33 Human Blood Groups Blood contains gene-cally determined proteins An-gens (a substance the body recognizes as foreign) may be aoacked by the immune system An-bodies are the recognizers Blood is typed by using an-bodies that will cause blood with certain proteins to clump (agglu-na-on) There are over 30 common red blood cell an-gens The most vigorous transfusion reac-ons are caused by ABO and Rh blood group an-gens

34 ABO Blood Groups Based on the presence or absence of two an-gens Type A: The presence of an-gen A, has an-- B an-bodies Type B: The presence of an-gen B, has an-- A an-bodies Type O: lacks the presence of any an-gens, has an-- A & an-- B an-bodies Type AB: the presence of an-gen A & an-gen B, has no an-bodies

35 ABO Blood Groups Blood type AB can receive A, B, AB, and O blood Universal recipient Blood type B can receive B and O blood Blood type A can receive A and O blood Blood type O can receive O blood Universal donor

36 Rh Blood Groups Named because of the presence or absence of one of eight Rh an-gens (agglu-nogen D) that was originally defined in Rhesus monkeys Most Americans are Rh + (Rh posi-ve) Problems can occur in mixing Rh + blood into a body with Rh (Rh nega-ve) blood

37 Dangers of an Rh mismatch Danger occurs only when the mother is Rh and the father is Rh +, and the child inherits the Rh + factor RhoGAM shot can prevent buildup of an-- Rh + an-bodies in mother s blood The mismatch of an Rh mother carrying an Rh + baby can cause problems for the unborn child The first pregnancy usually proceeds without problems The immune system is sensi-zed ater the first pregnancy In a second pregnancy, the mother s immune system produces an-bodies to aoack the Rh + blood (hemoly-c disease of the newborn)

38 Blood typing Blood samples are mixed with an-- A and an-- B serum Agglu-na-on or no agglu-na-on leads to determining blood type Typing for ABO and Rh factors is done in the same manner Cross matching tes-ng for agglu-na-on of donor RBCs by the recipient s serum, and vice versa

39 Developmental Aspects of Blood Sites of blood cell forma-on The fetal liver and spleen are early sites of blood cell forma-on Bone marrow takes over hematopoiesis by the seventh month Fetal hemoglobin differs from hemoglobin produced ater birth It can carry much more oxygen than adult hemoglobin By 12 weeks of life, fetal hemoglobin is replaced by adult hemoglobin Physiologic jaundice results in infants in which the liver cannot rid the body of hemoglobin breakdown products fast enough