The Cardiovascular System: The Blood, Heart, & Blood Vessels

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1 The Cardiovascular System: The Blood, Heart, & Blood Vessels

2 Fluids of the Body Cells of the body are serviced by 2 fluids 1. Blood a liquid connective tissue that consists of cells surrounded by a liquid extracellular matrix. 2. Interstitial fluid the fluid that bathes body cells and is constantly renewed by the blood Nutrients and oxygen diffuse from the blood into the interstitial fluid & then into the cells Wastes move in the reverse direction Hematology is study of blood and blood disorders

3 Functions of Blood 1.Transportation O 2, CO 2, metabolic wastes, nutrients, hormones 2. Regulation helps regulate ph through buffers helps regulate body temperature coolant properties of water vasodilatation of surface vessels removes heat from interior helps regulate water content of cells by interactions with dissolved ions and proteins - osmosis 3.Protection from disease & loss of blood

4 Physical Characteristics of Blood Thicker (more viscous) than water and flows more slowly than water - 8% of body weight Temperature of o F ph 7.4 ( ) - metabolic acidosis vs. metaoblic alkalosis Color is bright red when saturated with O 2 and dark red when unsaturated Blood volume 5 to 6 liters in average male 4 to 5 liters in average female

5 Venipuncture Techniques of Blood Sampling sample taken from vein with hypodermic needle & syringe Finger or heel stick common technique for diabetics to monitor daily blood sugar method used for infants

6 Components of Blood After centrifuging 55 % plasma 45 % cells 99 % RBCs < 1 % WBCs and platelets

7 Blood Plasma 0ver 90% water 7% plasma proteins made in the liver normally confined to bloodstream Albumin maintains blood osmotic pressure Globulins (immunoglobulins) antibodies bind to foreign substances called antigens form antigen-antibody complexes Fibrinogen - produced by liver for blood clotting 2% other substances electrolytes, nutrients, hormones, gases, waste products

8 Formed Elements of Blood 1. Red blood cells (erythrocytes) 2. White blood cells (leukocytes) Granular leukocytes Neutrophils / Eosinophils / Basophils Agranular leukocytes Lymphocytes - multiple cell types Helper T cells, B cells, and natural killer T cells Monocytes becomes a macrophage when leaving the blood stream 3. Platelets - special cell fragments that help form clots

9 Hematocrit The percentage of total blood volume occupied by RBC s. Normal females = 38-46% Females loose RBC s during menstruation and have lower levels of testosterone. Normal males 40-54% Testosterone stimulates the synthesis of erythropoietin (EPO) by the kidneys that stimulated RBC production in the red bone marrow.

10 Anemia is a drop in hematocrit. There are many different types of anemia caused by many different conditions. Polycythemia is a high hematocrit 65% or higher. Increases blood viscosity from abnormal production of RBC s, tissue hypoxia, dehydration and blood doping or the use of EPO by athletes.

11 Formation of Blood Cells Most blood cells types need to be continually replaced die within hours, days or weeks RBCs number is regulated by negative feedback WBCs numbers are in response to pathogens or foreign antigens Process of blood cells formation is Hematopoiesis or Hemopoiesis In the embryo Hematopoiesis occurs in yolk sac, liver, spleen, thymus, lymph nodes & red bone marrow In adult occurs only in red marrow of flat bones like sternum, ribs, skull & pelvis and ends of long bones (femur etc.)

12 Disappears by about 12 weeks

13 Red Bone Marrow in Adults

14 Hematopoiesis Resides in bone marrow 99% of Formed elements 0.1% of Formed elements

15 Granular leukocytes eosinophils neutrophils basophils STEM CELLS (in bone marrow In adults) Immature macrophagas (monocytes) Agranular leukocytes mature macrophagas B lymphocytes T lymphocytes megakaryocytes Monocytes leave the blood Stream to become Macrophages platelets

16 Hemopoietic Growth Factors Regulate differentiation & proliferation Erythropoietin (EPO) - Oxygen dependent produced by the kidneys (90%) & liver (10%) / It increases RBC precursors (cells that will become RBC s) Thrombopoietin (TPO) hormone from liver stimulates platelet formation Cytokines are local hormones of bone marrow Broad category of small proteins that are important cell signals for the cells around them produced by some marrow cells to stimulate proliferation in other marrow cells colony-stimulating factor (CSF) & interleukin stimulate WBC production

17 Red Blood Cells or Erythrocytes Contain oxygen-carrying protein Hemoglobin that gives blood its red color 1/3 of cell s weight is hemoglobin Biconcave disk increased surface area tovolume ratio flexible shape for narrow passages no nucleus or other organelles no cell division or aerobic respiration Normal RBC count male 5.4 million / mm female 4.8 million / mm 3 new RBCs enter circulation at 2 million / second

18 RBC Life Cycle RBCs live only about 120 days (4 months) wear out from bending to fit through capillaries no repair possible due to lack of organelles Worn out cells removed by fixed macrophages in spleen & liver Breakdown products are recycled

19 Erythropoiesis: Production of RBCs Begins in the red bone marrow with a proerythroblast. These divide until they produce cells that start to produce hemoglobin Many steps later the nucleus is ejected & a reticulocyte is formed Nucleus ejection gives RBC its concave shape Retain some mitochondria, ribosomes and ER Reticulocytes escape from bone marrow into the blood through sinusoid capillaries & mature in 1-2 days. (Lose ER) Every hour, about 180 million newly formed red blood cells enter the bloodstream

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21 Normal Reticulocyte Count Should be.5 to 1.5% of the circulating RBC s Low count in an anemic person might indicate bone marrow problem leukemia, nutritional deficiency or failure of red bone marrow to respond to erythropoietin stimulation High count might indicate recent blood loss or successful iron therapy

22 Recycling of Hemoglobin Components In macrophages of liver (Kupffer cells) or spleen globin portion broken down into amino acids & recycled heme portion split into iron (Fe +3 ) and biliverdin (green pigment)

23 Hemoglobin ( Hgb ) million Hgb molecules per RBC 4 heme groups per Hgb molecule o Each heme contais Fe 2+ combines reversibly with 1 oxygen molecule Therefore each RBC carries 2 Billion atoms of oxygen Hgb level and the total number of RBC s indicate the O 2 carrying capacity of the blood

24 Transport of Oxygen and Carbon Dioxide Each gas is carried at a different site on the Hgb molecule so there is no competition The Hgb carries both CO 2 and O 2. The O 2 is attached to Fe 2+ of the heme and the CO 2 attaches to amino acids within the globin part of Hgb Hgb transports 23% of total CO 2 waste and 99% of O 2

25 Feedback Control of RBC Production Tissue hypoxia (cells not getting enough O 2 ) high altitude (lower O 2 pressure) anemia- RBC production falls below RBC destruction circulatory problems, emphysema, lung disease Kidney & liver response to hypoxia release erythropoietin speeds up development of proerythroblasts into reticulocytes

26 Anemia Not enough functional RBC s or a reduction in their Hgb content oxygen-carrying capacity of blood is reduced fatigue, cold intolerance & paleness lack of O 2 for ATP & heat production Types of anemia 1. iron-deficiency =lack of absorption or loss of iron 2. pernicious = lack of intrinsic factor for B12 absorption. B12 needed for RBC production. 3. hemorrhagic = loss of RBCs due to bleeding (ulcer) 4. hemolytic = RBC burst open 5. thalassemia = hereditary deficiency of hemoglobin 6. aplastic = destruction of bone marrow (radiation / toxins / antibiotics)

27 Blood Groups Antigen - something that can cause an immune response Self-antigens present on cells and are normally not attacked by the immune system. Red blood cell antigens can be sugars or proteins and are determined by DNA

28 HUMAN ANTIGENS ON RED BLOOD CELLS

29 ABO Blood Groups Based on 2 glycolipid antigens called A and B found on the surface of RBCs display only antigen A -- blood type A display only antigen B -- blood type B display both antigens A & B -- blood type AB display neither antigen -- blood type O Plasma contains antibodies to the A or B antigens on the RBC s Anti - A antibody reacts with antigen A Anti - B antibody reacts with antigen B Remember-the antibody is in the serum/ pack cell vs whole blood

30 Antibodies are In the Plasma Blood Groups and Blood Types

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32 RH Blood Groups The antigen discovered in blood of Rhesus monkey People with Rh antigen on RBC surface are Rh+. Normal plasma contains no anti-rh antibodies Different from ABO blood groups - Antibodies are already in plasma Antibodies develop to Rh+ blood only by a Rh- person & only after exposure to the Rh antigen (blood) - this is different from ABO antibodies Anti-Rh antibodies only produced after 1 st exposure of a Rh- person to Rh+ blood during transfusion

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34 Universal Donors and Recipients People with type AB blood called Universal Recipients since have no antibodies in plasma can only receive pack cells / Type O whole blood has antibodies against Type A & B & Type AB & Type A & type B whole blood have antibodies against the other type in their serum also People with type O blood cells called Universal Donors since have no antigens on their cells can only donate pack cells / their serum still has antibodies to Type A or Type B or Type AB

35 Transfusion and Transfusion Reactions Transfer of whole blood, cells or plasma into the bloodstream of recipient used to treat anemia or severe blood loss Incompatible blood transfusions antigen-antibody complexes form between plasma antibodies & foreign proteins on donated RBC's causes agglutination clumping donated RBCs become leaky & burst (hemolysis) loose hemoglobin / causes kidney damage / jaundice

36 Hemolytic Disease of the Newborn (HDN) (Erythroblastosis Fetalis) 1. Rh neg. mom with Rh + baby 2. Cells from Rh+ baby enter mother s blood stream at birth 3. Mother sensitized / antibodies form to fight Rh+ blood of 2nd Rh+ pregnancy causing hemolysis (HDN) of RBC RhoGam binds to fetal blood cells preventing mother from making antibodies against the baby s blood

37 Platelet (Thrombocyte) Anatomy Disc-shaped, 2-4 micron cell fragment with no nucleus / limited life span Normal platelet count is 150, ,000mm 3

38 Hematopoiesis of Platelets Resides in bone marrow 99% of Formed elements 0.1% of Formed elements

39 Platelets Life History Platelets form in bone marrow Myeloid stem cell form Megakaryocyte whose fragments form Platelets Short life span (5 to 9 days in bloodstream) formed in bone marrow few days in circulating blood aged ones removed by fixed macrophages in liver and spleen trauma can deplete platelets leading to bleeding problems several days late

40 Hemostasis Stoppage of bleeding in a quick & localized fashion when blood vessels are damaged Prevents hemorrhage (loss of a large amount of blood) 3 ways to stop bleeding 1. Vascular spasm 2. Platelet plug formation 3. Blood clotting (coagulation = formation of fibrin threads)

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42 1. Vascular Spasm Damage to blood vessel stimulates pain receptors Reflex contraction of smooth muscle of small blood vessels in the area of wound Can reduce blood loss for several hours until other mechanisms can take over Only for small blood vessel or arteriole

43 2. Platelet Plug Formation Circulating platelets become sticky when exposed to collagen on the outside of the vessel. Called platelet adhesion leading to platelet aggregation. Platelets release thromboxane A 2 which calls other platelets to the scene. Platelet plug formation along with vascular spasm may stop bleeding if the hole is small enough.

44 Platelet Adhesion Platelets stick to exposed collagen underlying damaged endothelial cells in vessel wall

45 Platelet Aggregation Activated platelets stick together and activate new platelets to form a mass called a platelet plug Plug may be reinforced by fibrin threads formed during clotting process if necessary

46 3. Blood Clotting Blood Clot stops bleeding Clotting is a cascade of reactions in which each clotting factor activates the next in a fixed sequence resulting in the formation of fibrin threads (clot) Intrinsic Pathway damage to blood vessel surface & important for the amplification of the cascade Extrinsic Pathway damage to surrounding tissue releases tissue factor. Important for initiating the clotting cascade.

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48 Thrombosis vs. Embolism Thrombosis clot (thrombus) forming in an unbroken blood vessel forms on rough inner lining of BV or valve of heart forms if blood flows too slowly (stasis) allowing clotting factors to build up locally causing coagulation may dissolve spontaneously or dislodge & move Embolus - a moving obstruction /a moving thrombus clot, air bubble or fat from broken bone in the blood ex. pulmonary embolus is a clot found in lungs that usually originates in leg primary cause of strokes (blockage of brain blood vessels) and myocardial infarctions (blockage of the coronary arteries)

49 Anticoagulants and Thrombolytic Agents Anticoagulants suppress or prevent blood clotting; heparin administered during hemodialysis and surgery warfarin (Coumadin) antagonist to vitamin K so blocks synthesis of clotting factors slower than heparin stored blood in blood banks treated with citrate phosphate dextrose (CPD) that removes Ca 2+

50 Hemophilia Inherited deficiency of clotting factors bleeding spontaneously or after minor trauma subcutaneous & intramuscular hemorrhaging nosebleeds, blood in urine, articular bleeding & pain Treatment is transfusions of fresh plasma or concentrates of the missing clotting factor