Cardiovascular system 2: blood

Blood functions

1. Transport of Materials:

   1. Oxygen

   2. Nutrients, hormones

   3. Wastes

2. Defense

   1. Immune system:

      1. White blood cells

      2. Antibodies

3. Regulation:

   1. Temperature

   2. Osmotic pressure

   3. pH

Blood composition

Plasma: Liquid medium of the blood

• Dissolved substances: proteins, solutes

Formed elements: Cells

• Red Blood Cells

• White Blood Cells

• Platelets

Components of Blood Plasma

Water (91%) + proteins + solutes

Proteins:

• Albumins: thicken the blood

• Globulins: immunity (antibodies)

• Fibrinogen: used for blood clotting

• Prothrombin: used for blood clotting

Solutes:

• Ions (sodium, potassium), nutrients, waste products, gases, hormones

Serum: Plasma with the clotting factors removed still contains antibodies

Formed Elements of Blood

Formed in the blood marrow; skeletonal system

1. Erythrocytes (red blood cells)

   1. Transport Oxygen and CO2

2. Leukocytes (white blood cells)

   1. Cells of your immune system

3. Thrombocytes (platelets)

   1. Blood clotting

Types of WBC

1. Neutrophils:

   1. 1st responders to tissue injury

   2. Phagocytes

2. Eosinophils:

   1. Target parasite worms

   2. Clean up inflammatory proteins

3. Basophils:

   1. Allergy cells - release histamine to initiate inflammation

4. Lymphocytes:

   1. Specific immunity

   2. B cells secrete antibodies

   3. T cells kill virally-infected cells and cancer cells

5. Monocytes:

   1. Turn into macrophages

   2. Phagocytosis in the tissues

Erythrocytes (red blood cells)

Tough, flexible plasma membrane deforms easily

• Allows RBCs to pass through small diameter capillaries

• Biconcave disk shape

  • Large cellular surface for diffusion of Oxygen

• No nucleus or organelles

  • Provides more space for hemoglobin

  • ~25 trillion RBCs in your body

How do RBCS carry oxygen

RBS contain the protein Hemoglobin (Hb):

• Iron containing molecule

• 35% of total RBC content (250 million/per cell)

• binds to and holds oxygen

• binds to small amounts of CO2

• binds very well to CO

Carbon dioxide transport

23% CO2 is transported by Hemoglobin

7% CO2 is dissolved in plasma

70% is transported as a bicarbonate ion (HCO3)

Enzyme: carbonic anhydrase

RBC production

Develop and mature in the bone marrow

• Lifespan = 120 days

• Constant need to repair RBCs

• Hemoglobin from dead RBCs is recycled

Erythropoietin:

• Hormone secreted by kidneys to induce RBC production

  • Secreted when oxygen levels are too low

Blood clotting

Platelets play essential role in blood coagulation (clotting)

• Blood vessel damage causes platelets to become sticky and form a “platelet plug”

• Accumulated platelets release additional clotting factors that enter into the clotting mechanism

• Platelets ultimately become a part of the clot itself

Basic steps of blood clotting

1. Release of clotting factors from injured cells and platelets at the injury site (forms a platelet plug)

2. Series of chemical reactions result in the formation of thrombin

3. Formation of fibrin threads to trap red blood cells to form a clot

Red blood cells disorders: anemia

Nutritional anemia: dietary deficiency (iron)

Pernicious anemia: vitamin B12 deficiency - slows RBC production

Thalassemia: genetic condition, body does not produce enough hemoglobin

Hemolytic anemia: rupture of too many RBCs (sickle cell anemia)

Symptoms include fatigue, weakness, faintness, skin pallor, and headaches

Sickle cell anemia

2 mutated genes on each chromosome result in abnormal Hemoglobin proteins

• Causes oxygen to crystallize under low oxygen conditions

Causes blood stasis, clotting and “crises” that may be fatal

WBC disorders: Infectious mononucleosis

• Caused by Epstein-Barr virus in saliva

  • AKA kissing disease

  • Highest incidence is within 15-25 years of age

• Symptoms include fever, severe fatigue, sore throat, rash, and enlargement of lymph nodes and spleen

  • Generally self-limited and resolves without complications in about 4-6 weeks

Blood clotting disorders

Hemophilia:

• Most serious “bleeding disease” worldwide

  • X-linked inherited disorder

  • Comes from the inability to produce Factor VIII (a plasma protein)

  • Responsible for blood clotting, clots don’t form properly

  • Internal bleeding is common, bleeding can be life threatening

• Characterized by easy bruising, deep muscle hemorrhage, blood in urine, and repeated episdoes of bleeding into joints causing pain and deformity

• Called the “Royal Disease” due to inbreeding from royals

Blood typing

Antigen: A molecule that stimulates an immune response

Antibodies: They bind to antigens to neutralize them (toxins) or to clump cells together

RBC’s have protein “antigens” sticking out of their cellular membranes

ABO Blood typing is a classification of blood based on the presence or absence of antigens on the surface of RBC’s

Agglutination: clumping of RBCs when bound by an antibody

Blood type

Blood Type A:

• RBC surface antigen: A

• Antibodies in blood: Anti B

Blood Type B:

• RBC surface antigen: B

• Antibodies in blood: Anti A

Blood Type AB: Universal Receiver (takes both A and B blood)

• RBC Surface Antigen: AB

• Antibodies in blood: None

Blood Type O: Universal Doner (can be given to blood type A, B, AB because no surface antigen; O blood can only be given O blood because they already have both A and B antibodies)

• RBC Surface Antigen: None

• Antibodies in blood: BOTH ANTI A + ANTI B

Rh blood types

Rh-postive blood: Rh factor antigen is present on RBCs (also found on the Rhesus monkey RBCs)

Rh-negative blood: Rh factor antigen is NOT present on RBCs

• No anti-Rh antibodies are present in plasma naturally

• Anti-RH antibodies appear in the plasma of Rh-negative persons if Rh-positive RBCs have been introduced into their bodies

• Can cause erythroblastosis fetalis in second Rh-incompatible pregnancy

Rh incompatibility

1st pregnancy (Rh- mother carrying Rh+ fetus):

• Sensitization: Mother makes anti-Rh antibodies

• Usually this pregnancy is fine

2nd pregnancy:

• Mother’s antibodies attack fetus’ RBCs

Solution: RhoGAM (artifical antibody to Rh factor)

• It clears out fetal RBCs before the mother can make an antibody against them