Chapter 6 Cardiovascular System: Blood

Points to Ponder What type of tissue is blood and what are its components? What is found in plasma? Name the 3 formed elements in blood and their functions. How does the structure of red blood cells relate to their function? Describe the structure and function of each white blood cell. What are disorders of red blood cells, white blood cells and platelets? What do you need to know before donating blood? What are antigens, antibodies and blood transfusions? How are ABO blood types determined? What blood types are compatible for blood transfusions? What is the Rh factor and how is this important to pregnancy? How does the cardiovascular system interact with other systems to maintain homeostasis?

Functions of Blood 1.Transportation: -Oxygen (from lungs), nutrients (from digestion), wastes (from tissue fluid), carbon dioxide (from tissue fluid) and hormones (influence cellular metabolism) 2.Defense: -against invasion by pathogens -Some cells phagocytize and destroy pathogens -Others secrete antibodies into the blood -Antibodies incapacitate pathogens so they can be destroyed 3.Regulatory functions: -body temperature  pick up heat from active muscle and transport around or out of the body -water-salt balance and body pH (blood contains buffers) 6.1 Blood: An overview

Composition of Blood Remember: blood is a fluid connective tissue Formed elements: Cells and cell fragments –produced in red bone marrow via stem cell differentiation –Cells and cell fragments: Red blood cells/erythrocytes (RBC) White blood cells/leukocytes (WBC) Platelets Plasma: liquid medium –suspends the formed elements, carries substances, distributes the heat generated by metabolism and muscle contractions –91% water and 9% salts and organic molecules Salts act as buffer to help maintain the pH of the blood Organic molecules = glucose and amino acids for the cells –Plasma proteins are the most abundant molecules 6.1 Blood: An overview

3 major types of plasma proteins Produced by the Liver Functions 1. Maintain homeostasis take up and release hydrogen ions 2. Establish osmotic pressure between blood and tissue fluid Force that prevents excessive loss of plasma from the capillaries into tissue fluid Albumins – most abundant Function: plasma’s osmotic pressure and transportation Globulins – Function: transportation of hormones, cholesterol, and iron Fibrinogen – Function: formation of blood clots 6.1 Blood: An overview

Formed Elements 6.1 Blood: An overview

Structure and Function of Red Blood Cells Lack a nucleus  Biconcave shape increases surface area Lack most organelles  including mitochondria –ATP produced anaerobically so they don’t consume any oxygen that they transport Contain about 280 million hemoglobin molecules that bind 4 molecules of O 2 each –Globin: 4 tertiary polypeptides –Heme: iron-containing group  Iron combines reversible with oxygen 6.2 Blood: Red blood cells and transport of oxygen

How is carbon dioxide transported? 68% as bicarbonate ions in the plasma –this conversion of CO 2 takes place in RBC’s by carbonic anhydrase –H + binds to amino acids of the globin to assist in keeping the pH of the blood constant –At lungs carbonic anhydrase in RBCs reverse this reaction to expel CO 2 from the blood 25% bound to hemoglobin in red blood cells 7% as carbon dioxide dissolved in the plasma 6.2 Blood: Red blood cells and transport of oxygen

Production of red blood cells Produced in red bone marrow Lifespan = 120 days Erythropoietin (EPO) –Excreted by kidney cells –Moves to red marrow when oxygen levels are low –Stimulates the stem cells to produce more RBCs Old cells are destroyed by the liver and spleen –Hemoglobin Globin: broken down into amino acids and recycled Iron is recovered and reused Heme undergoes chemical degradation and is excreted

What is blood doping? Any method of increasing the number of RBC’s to increase athletic performance It allows more efficient delivery of oxygen and reducing fatigue EPO is injected into a person months prior to an athletic event Is thought to be able to cause death due to thickening of blood that leads to a heart attack 6.2 Blood: Red blood cells and transport of oxygen

What disorders involve RBC’s? Anemia – –a condition resulting from too few RBC’s or hemoglobin that causes a run-down feeling –Maybe due to decrease levels of iron, vitamins B12 and B vitamin folic acid Sickle-cell anemia – –genetic disease that causes RBC’s to be sickle shaped –tend to rupture as they pass through the narrow capillaries Hemolytic disease of the newborn – –condition with incompatible blood types –leads to rupturing of blood cells in a baby before and continuing after birth 6.2 Blood: Red blood cells and transport of oxygen

White blood cells (leukocytes) Derived from red bone marrow Large blood cells that have a nucleus Production is regulated by colony-stimulating factor (CSF) Can be found in the blood and tissues Fight infection and part of immune system –Phagocytosis: engulf pathogen and fuses with lysosome where enzymes digest the pathogen to debris that leaves the cell –Antibodies: proteins that combine with antigens and mark them for destruction Some live days and others live months or years 6.3 White blood cells and defense against disease

Movement of WBC’s out of circulation 6.3 White blood cells and defense against disease

How are white blood cells categorized? Granular – contain noticeable granules, lobed nuclei –Eosinophil –Basophil –Neutrophil Agranular – no granules, nonlobed nuclei –Lymphocyte –Monocyte 6.3 White blood cells and defense against disease

Neutrophils About 50-70% of all WBC’s Contain a multi-lobed nucleus Upon infection they move out of circulation into tissues to use phagocytosis to engulf pathogens Large numbers result in pus 6.3 White blood cells and defense against disease

Eosinophils Small percentage of WBC’s Contain a bilobed nucleus Many large granules function in parasitic infections and play a role in allergies 6.3 White blood cells and defense against disease

Basophil Small percentage of WBC’s Contain a U-shaped or lobed nucleus Release histamine related to allergic reactions –Dilate blood vessels and constricts the air tubes that lead to lungs 6.3 White blood cells and defense against disease

Lymphocyte About 25-35% of all WBC’s Large nucleus that takes up most of the cytoplasm Develop into B and T cells that are important in the immune system –B-cells protect us by producing antibodies that mark pathogens for destruction –T-cells directly destroy pathogens 6.3 White blood cells and defense against disease

Monocyte Relatively uncommon WBC’s Largest WBC with horseshoe-shaped nucleus Take residence in tissues and develop into macrophages Macrophages use phagocytosis to engulf pathogens 6.3 White blood cells and defense against disease

How do blood cell leave circulation? 6.3 White blood cells and defense against disease

What disorders involve WBC’s? Severe combined immunodeficiency disease (SCID) –an inherited disease in which stem cells of WBC’s lack an enzyme that allows them to fight any infection Leukemia –a groups of cancers that affect white blood cells in which cells proliferate without control Infectious mononucleosis –also known as the “kissing disease” occurs when the Epstein-Barr virus (EBV) infects lymphocytes resulting in fatigue, sore throat and swollen lymph nodes 6.3 White blood cells and defense against disease

Platelets (thrombocytes) Made of fragments of large cells called megakaryocytes made in the red bone marrow About 200 billion are made per day Function in blood clotting –Blood proteins thrombin and fibrinogen (produced in the liver) are important for blood clotting by leading to fibrin threads that catch RBC’s Thrombin: acts as an enzyme that severs two short amino acid chains from each fibrinogen molecule Activated fragments join end to end, forming long threads of fibrin Fibrin threads wind around the platelets plug and provide framework for the clot Plasmin enzyme: destroy fibrin network and restores the fluidity of plasma after repair is complete 6.4 Platelets and blood clotting

What disorders involve platelets? Thrombocytopenia – –a disorder in which the number of platelets is too low due to not enough being made in the bone marrow or the increased breakdown outside the marrow Thromboembolism – –when a clot forms and breaks off from its site of origin and plugs another vessel Hemophilia – –a genetic disorder that results in a deficiency of a clotting factor so that when a person damages a blood vessel they are unable to properly clot their blood both internally and externally 6.4 Platelets and blood clotting

Health Focus: What do you need to know about donating blood? Donating blood is a safe and sterile procedure You will donate about a pint of blood You will replace the plasma in a few hours and the cells in a few weeks A few people may feel dizzy afterwards so sit down, eat a snack and drink some water Your blood will at least be tested for syphilis, HIV antibodies and hepatitis and if any of them come back positive you will be notified Your blood can help save many lives You should not give blood if: –You have ever had hepatitis, malaria or been treated for syphilis or gonorrhea within 12 months –If you risk for having HIV or have AIDS 6.4 Platelets and blood clotting

Terminology for ABO blood typing Antigen - a foreign substance, often a polysaccharide or a protein, that stimulates an immune response Antibody – proteins made in response to an antigen in the body and bind to that antigen Blood transfusion – transfer of blood from one individual into another individual Involves determining the –ABO blood group –Rh- or Rh+ 6.5 Blood typing and transfusions

The A, B, AB or O blood type Presence and/or absence of 2 blood antigens, A and B Type of antibodies present Antibodies are only present for those antigen lacking on the cells because these proteins recognize and bind the protein they are named after 6.5 Blood typing and transfusions

How can you remember what each blood type means? Blood types are named after the protein antigens that are present on the surface of their cell, except type O that entirely lacks A and B proteins Blood types only have antibodies to antigens they do not have on the surface of their cells For example: Type A blood –Have A proteins on its surface –Has B antibodies What can you say about someone with type AB blood? 6.5 Blood typing and transfusions

How can you determine if blood types are compatible for a blood transfusion? 1.Consider the antigens found on the blood transfusion recipient 2. Consider the antibodies found in the donor blood If the antibodies in the donor blood can recognize the antigen on the recipient’s blood then the blood will agglutinate (clump) and cause rejection 6.5 Blood typing and transfusions

Testing your understanding Can a person with blood type O accept blood type A without agglutination occurring? Why or why not? Why can people with AB blood type accept more blood types than people with type O, A or B? Which blood type is able to be used most often as a donor blood type? Why? 6.5 Blood typing and transfusions

What about Rh blood groups? The Rh factor is often included when expressing a blood type by naming it positive or negative People with the Rh factor are positive and those without it are negative Rh antibodies only develop in a person when they are exposed to the Rh factor from another’s blood (usually a fetus) 6.5 Blood typing and transfusions

When is the Rh factor important? During pregnancy under these conditions: –Mom: Rh - –Dad: Rh + –Fetus: Rh + (possible with the parents above) In this case above some Rh + blood can leak from the fetus to the mother during birth causing the mother to make Rh antibodies This can be a problem if the mother has a second fetus that is Rh + because she now has antibodies that can leak across the placenta and attack the fetus This condition is known as hemolytic disease of the newborn that can lead to retardation and even death 6.5 Blood typing and transfusions

Visualizing how hemolytic disease of the newborn happens? 6.5 Blood typing and transfusions

How can hemolytic disease of the newborn be prevented? Rh - women are given an injection of anti-Rh antibodies no later than 72 hours after birth to an Rh + baby These antibodies attack fetal red blood cells in the mother before the mother’s immune system can make antibodies This will have to be repeated if an Rh - mother has another Rh + baby in case she has later pregnancies 6.5 Blood typing and transfusions

Heart, blood vessels and blood work with other systems to maintain homeostasis