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Blood Vascular

System

Consists of:

1. Blood - transporting medium 2. Blood vessels a. Arteries, arterioles- carry blood away from the heart b. Veins, venules- return blood back to the heart c. Capillaries- microscopic blood vessels where exchange of substances takes place
2. Heart – pump blood to the organs and tissues Functions of blood  Transportation of gases, nutrients, hormones, heat and waste products  Regulation- circulating blood helps maintain homeostasis  Protection- blood can clot, which protect it from excessive loss; white blood cells protect against disease by carrying phagocytosis Physical properties of blood  Blood is denser and viscous than water  Temperature is 38 degrees Celsius, pH is 7.35- 7.  Color varies according to oxygen content, when it has high oxygen the color is bright red, when it has low oxygen content the color is dark red  Blood volume is 5-6 liters in an average male adult, and 4-5 liters in female Hematocrit

• the percent of total blood volume occupied by RBC’s
• normal value is 38%- 46% (female); 40%- 54% (male) Hemopoiesis
• formation of blood cells
• before birth
• first occurs in the yolk sac of the embryo, then later in the liver, spleen, thymus and lymph nodes RBC
• derived from the Pluripotent stem cells or hemocytoblast Hormones that regulate the differentiation and proliferation of Progenitor cells/ Stem cells

1. Erythropoietin (EPO)

• Produced by the kidney
• Increases RBC

2. Thrombopoietin (TPO)

• Produced by the liver
• Forms the platelets Cell type  Erythrocytes (red blood cells, or RBCs)

Occurrence in blood (per mm3)  4-6 million Cell anatomy  Salmon- colored biconcave disks; anucleate; literally, sacs of hemoglobin; most organelles have been ejected Function  Transport oxygen bound to hemoglobin molecules; also transport small amount of carbon dioxide Cell type  Leukocytes (white blood cells, or WBCs) Occurrence in blood (per mm3)  4000-11, Granulocytes Cell type  Neutrophils Occurrence in blood (per mm3)  3000-  (40- 70% of WBCs) Cell anatomy  Cytoplasm stains pale pink and contains fine granules, which are difficult to see; deep purple nucleus consists of three to seven lobes connected by thin strands of nucleoplasm Function  Active phagocytes; number increase rapidly during short- term or acute infections Cell type  Eosinophils Occurrence in blood (per mm3)  100-  (1-4% of WBCs) Cell anatomy  Red coarse cytoplasmic granules; figure- or bilobed nucleus stains blue- red Function  Kill parasitic worms; increase during allergy attacks; might phagocytize antigen- antibody complexes and inactivate some inflammation chemicals Cell type  Basophils Occurrence in blood (per mm3)  20- 50  (0-1% of WBCs) Cell anatomy  Cytoplasm has a few large blue- purple granules; U- or S- shaped nucleus with constrictions, stains dark blue Function  Granules contain histamine (vasodilator chemical), which is discharged at sites of inflammation Agranulocytes Cell type  Lymphocytes Occurrence in blood (per mm3)  1500-  (20-45% of WBCs) Cell anatomy  Cytoplasm pale blue and appears as thin rim around nucleus; spherical (or slightly indented) dark purple- blue nucleus Function  Part of immune system; one group (B lymphocytes) produces antibodies; other group (T lymphocytes) involved in graft rejection, fighting tumors and viruses, and activating B lymphocytes Cell type  Monocytes Occurrence in blood (per mm3)  100-  (4-8% of WBCs) Cell anatomy  Abundant gray-blue cytoplasm; dark blue- purple nucleus often kidney-shaped Function  Active phagocytes that become macrophages in the tissues; long- term “clean- up team”; increase in number

during chronic infections such as tuberculosis Cell type  Platelets Occurrence in blood (per mm3)  250,000- 500, Cell anatomy  Essentially irregularly shaped cell fragments; stain deep purple Function  Needed for normal blood clotting; initiate clotting cascade by clinging to broken area; help to control blood loss

Hemostasis

 Sequence of responses that stops bleeding Three mechanisms that reduce blood loss: Vascular spasm  Smooth muscles in the walls of blood vessel constrict Platelet Plug formation

1. Platelet adhesion
2. Platelet release reaction- liberate ADP and thromboxane A2 (activates platelets), serotonin and thromboxane function as vasoconstrictors
3. Platelet aggregation- gathering of platelets forms a platelet plus Blood clotting or coagulation
4. Prothrombinase converts prothrombin (Factor11) a plasma protein produced by the liver into the enzyme thrombin
5. Thrombin converts soluble fibrinogen (Factor 1) into insoluble fibrin
6. Fibrin forms the clot Vitamin K- a fat soluble vitamin required for the synthesis of clotting factors

Hemostatic control mechanisms

 Formation of blood clot involves positive feedback mechanism which tend to enlarge the clot and has a potential of blood flow impairment in undamaged blood vessel Fibrinolytic system- refers to dissolution of clot

1. Plasminogen, an inactive plasma enzyme incorporated in the clot will be activated by thrombin and activated Factor V11 to Plasmin (fibrinolysin), which dissolves clot

Blood grouping

Injury or surgery can lead to a blood transfusion  Transfusion reactions/ Aggulination: clumping of blood cells (bad)  Antigens: molecules on surface of RBC  Antibodies: proteins in plasma  Major blood group: named according to antigen (ABO)  Rh Blood Group : Rh positive means you have Rh antigens Antibodies only develop if an Rh- person is exposed to Rh+ blood by transfusion or from mother to fetus

Blood typing

Hemolytic disease of the Newborn (HDN)  Most common with Rh incompatibility during pregnancy  Occurs at birth when a small amount of Rh+ blood leaks from fetus through the placenta into the bloodstream of an Rh- mother, the mother will start to make anti- Rh antibodies. Usually the first born is not affected, however when the mother becomes pregnant again, her anti-Rh antibodies can cross the placenta and enter the bloodstream of the fetus. If the fetus is Rh- there is no problem, because there is no Rh antigen but if the fetus is Rh+, agglutination and hemolysis may occur in the fetal blood  For prevention, an injection of anti-Rh antibodies called anti-Rh gamma globulin (RhoGam) can be given to prevent HDN

Blood disorders

Anemia

 A condition in which the oxygen-carrying capacity of blood is reduced due to decreased RBC or low hemoglobin a. Iron deficiency anemia b. Megaloblastic anemia

• vitamin B12 deficiency, bone marrow produce abnormal large cells c. Pernicious anemia
• Insufficient hemopoiesis resulting from an inability of stomach to produce intrinsic factor needed to absorb vitamin B12 in the small intestine d. Hemolytic anemia
• RBC cell membranes rupture prematurely may result from inherited disease, parasites, toxins or incompatible blood transfusions e. Thalassemia
• Deficient synthesis of hemoglobin resulting to microcytic, hypochromic RBC f. Aplastic anemia
• Destruction of red bone marrow caused by toxins, gamma radiation, medications inhibiting enzymes needed for hemopoiesis Sickle- cell disease  The RBC’s contain Hb-S, the cell forms long, stiff, rod- like structures that bend Hemophilia  An inherited deficiency of clotting in which bleeding may occur spontaneously Leukemia  A group of red bone marrow cancers, in which WBC increase uncontrollably

Overview of the Cardiovascular

System

Abnormal conditions Tachycardia - elevated beating of the heart Bradycardia - slow beating of the heart Arryhythmia - irregular heart beat Congestive heart failure - loss of pumping efficiency by the heart Ischemia - reduced blood flow to the myocardium Angina pectoris - severe pain that usually accompanies ischemia Myocardial infarction - complete obstruction to blood flow in a coronary artery Rheumatic fever - acute systemic inflammatory disease after Streptococcal infection Cardiomegaly - enlargement of the heart Electrocardiogram (ECG/EKG)  A printout recording of the electrical activity of the heart Echocardiography  Using ultra high frequency sound waves (beyond human hearing), similar to “sonar,” to form an image of the inside of the heart. This procedure can demonstrate valve damage, congenital (before birth) defects and other abnormalities

Blood Vessels: Microscopic

Anatomy

Three layers (tunics)

1. Tunic intima
   • Endothelium
2. Tunic media
   • Smooth muscle
   • Controlled by sympathetic nervous system
3. Tunic externa
   • Mostly fibrous connective tissue

Structural Differences among

Blood Vessels

 Arteries have a thicker tunica media than veins  Capillaries are only one cell layer (tunica intima) to allow for exchanges between blood and tissue  Veins have a thinner tunica media than arteries  Veins also have valves to prevent backflow of blood  Lumen of veins are larger than arteries

Atherosclerosis  Build-up of fat and cholesterol deposits, called plaque, on the inside walls. This will cause the narrowing of the arteries and results in a condition called ischemia Aneurysm  Is an abnormal bulge in the wall of a blood vessel Deep vein Thrombosis  Caused by a blood clot in the leg that breaks loose and travels through the bloodstream to the lung Pulmonary embolism  Caused by a blood clot in the leg that breaks loose and travels through the bloodstream to the lung Raynaud’s disease  Is a rare disorder of the blood vessels, affecting the fingers and toes. It causes the blood vessels to narrow when you are cold or feeling stressed

Lymphatic System

 Consists of fluid called Lymph  Lymph vessels  Lymphatic tissue- contains large numbers of lymphocytes Functions:

1. Drains excess interstitial fluid from tissue spaces to blood
2. Transports dietary lipids and lipid- soluble vitamins
3. Carries out immune responses Lymphatic organs and Tissues Thymus- a bilobed organ located between the sternum and the aorta  Composed of T cells, dendritic cells (derived from Monocytes) plays a vital role in immune responses, epithelial cells and

macrophages- help clear out debris of dead and dying cells Lymph nodes- bean- shaped located along lymph vessels, functions as a type of filter Spleen- a large single mass of lymph tissue located in the left hypochondriac region between the stomach and diaphragm contains T cells and macrophages. It also stores platelets and produce blood cells during fetal life

Immunity

 Ability to resist damage from foreign substances Innate Immunity First line of Defense  Skin and mucous membranes, lysozyme from tears and saliva, urine Second line of Defense

1. Antimicrobial substances a. Interferon- antiviral protein b. Iron-binding protein- inhibit the growth of certain bacteria by reducing available iron (transferrin, lactoferrin, ferritin, and hemoglobin) c. Antimicrobial proteins- peptides with broad spectrum activity (dermicidin, defensins, cathelicidin, and thrombocidin)
2. Histamine
   • Promotes inflammation
   • Characterized by redness, pain, heat, and swelling and loss of function
3. Natural Killer cells
   • Lymphocytes
   • Phagocytes (neutrophil and macrophages)
   • Causes by cytolysis of microbes, promotes Adaptive Immunity  Specific recognition to a specific antigen Cell-mediated immunity  Helper T-cells promote production of Tcells. Cytotoxic Tcells directly attack invading antigens  Effective against intracellular pathogen like viruses, bacteria or fungi, cancer cells and foreign tissue transplants Antibody-mediated immunity or Humoral immunity  B cells transform into plasma cells, which synthesize and secrete antibodies or immunoglobulins  Effective against extracellular pathogens by neutralizing the antigen, immobilizing bacteria, agglutinating and precipitating antigen, activating complement, enhancing phagocytosis