Blood

Accept no substitute

Artificial Blood?

• Yes it has been developed.• Unfortunately, the oxygen-

carrying function, the primary function of blood is very difficult to replicate.– Can you think of any advantages?• Demand generally outweighs donations of blood.• Blood supply is not safe everywhere (HIV, etc.)• Trauma situations (battlefield, etc.)

Creatures of the Night?

• From Nosferatu (1922) to Daybreakers (2010), vampire just can’t seem to get their fix.

Blood

• Blood is a type of connective tissue whose cells are suspended in a liquid matrix.

• Its cells, formed mostly in bone marrow, include red blood cells, white blood cells, and platelets. These are the formed elements.

• The liquid portion of blood is called plasma.

Blood functions

• Transports nutrients and oxygen = primary function.

• Cellular metabolism• Homeostasis of fluid

volume• Homeostasis of pH• Homeostasis of T• Defense

Blood Volume

• Blood is heavier and 3 x more viscous than water.

• Average adult has blood volume of about 5 liters.

• Men have more blood than women. Men have 1.5 gallons / women have 0.875 gallons.

• Effect of body fat – inversely proportional.

Blood Composition

• Blood is about 45% formed elements. This is called the hematocrit (HCT).

• Blood plasma = 55%– Water 92%– Proteins 7%– Other solutes 1%

Red Blood Cells - Erythrocytes

• RBCs make up 99.9% of formed elements.

• 5.5 million per cubic mm in men; 4.8 in women

• Blood loss in women reduces their number.

Red Blood Cells - Erythrocytes

• Shape is concave disc.• Lack nucleus, therefore

live only 120 days.• Shape is function which

allows for increased surface area through which gases can diffuse.

• Also allows better transport of Hemoglobin.

Hemoglobin

• Hemoglobin is an oxygen-carrying protein.

• It has four parts.• Each part contains an iron

carrying portion = heme and protein portion = globin.

• Fe will carry an oxygen molecule to form iron oxide (rust) and give blood a red color

• Oxygen taken to cells while carbon dioxide removed

Formation of RBC -Erythropoiesis

Erythropoiesis

• All blood cells start as stems cells in bone marrow - hemocytoblast.

• Controlled through negative feedback by hormone released from kidney: erythropoietin.

• Released in response to oxygen deficiency.– Why would this be released when O2 is low?

Anemia

• When red blood cells can’t carry enough oxygen it is termed anemia

• Normocytic – too few• Macrocytic – large / less• Microcytic – too small• Sickle cell – cell folds on

itself (sickles); gets stuck and can’t carry oxygen• Related to malaria-

resistance.

RBC Death

• Macrophages are sent in to destroy damaged and old RBCs.

• Hemoglobin is broken down into its heme and globin portions.

• Heme decomposes into iron and biliverdin – a green pigment.

• Often the iron and globin are recycled.• If not, the biliverdin is converted into bilirubin – an

orange pigment. – Jaundiced patients have ineffective bilirubin excretion.

Jaundice

• Occurs fairly often in newborns.– Too many RBCs so too much

bilirubin production.• Result of malfunctioning liver

or gallbladder with ineffective excretion of bilirubin.

• Here a Russian man has been the victim of bootleg alcohol containing medical disinfectant.

The White Blood Cells

The Armed Forces of the Human Body!

White Blood Cells - Leukocytes

• WBCs protect against disease.

• Develop from stem cells in response to hormones.

• Contain a nucleus.• No hemoglobin –

cannot carry oxygen.• 5,000 – 9,000 / mm3.

Neutrophils – The Marines

• Account for over 50% of the leukocytes in adult humans.

• First to arrive on the scene of infection.• Phagocytic - engulfs small particles.• Contains lysosomes, organelles that break

down organic matter in captured bacteria.• Release chemicals to kill bacteria (H2O2,

defensins, leukotrienes)

Eosinophils – the Air Force

• Make up only 1-3 % of leukocytes.

• Kill certain parasites.• Help control

inflammation and allergic reactions by removing biochemicals associated with these reactions.

Examples of Human parasites

Basophils – the Navy

• Account for less than 1% of leukocytes.

• Help relieve inflammation.• Releases histamine

(increases blood flow to injured tissue) and heparin (blood-clot-inhibiting substance) therefore keeping things fluid.

Monocytes – the Army

• Largest blood cells – 3 x larger than RBCs.• Make up less than 10% of leukocytes.• Live for several weeks or months.• Phagocytic – devour large bacterial cells• Go directly to site and release chemicals to

attract other WBC• Attract fibroblasts which begin rebuilding

process (scar tissue)

Lymphocytes – the Reserves

• Account for 25-33% of leukocytes.• Live for many years (in the reserves).• Most are in lymphatic system.• Important in immunity – produce antibodies

that attack specific foreign substances.– T Cells – Coordinate immune response– B Cells – Humoral immunity (antibodies) – NK Cells (Natural killer cells)– Respond to tumors

and viruses.

Check your Understanding

• 1. The most common type of blood cell is the– A. Leukocyte.– B. Erythrocyte.– C. Monocyte.

• 2. The primary function of red blood cells is– A. Immunity.– B. Blood transport.– C. Transport of oxygen.

• 3. The eosinophils are a type of white blood cell whose function it is to– Help with allergic reactions.– Attack tumors.– Engulf large particles.

Platelets - Thrombocytes

• Incomplete cells from fragmented cells in bone marrow called megakaryocytes.

• Lacks nucleus – lives only about 10 days.• Platelet count varies from 130,000 – 360,000 /

mm3.• Platelets help close breaks in damaged blood

vessels and initiate formation of blood clots.

Blood Plasma

• Plasma – clear, straw-colored liquid portion of blood in which cells and platelets are suspended.

• Plasma proteins:– Albumins – osmotic pressure– Globulins – transport lipids– Fibrinogens – help coagulation

Hemostasis

• Hemostasis – stoppage of bleeding.

• Coagulation – causes formation of a blood clot.

• Complex with many steps, utilizes many biochemicals called clotting factors.

• Results in scab.

FACTOR “X” – The Clotting Process

• Used to prevent bleeding to death

• Involves calcium ions and 11 plasma proteins

• Cascade of changes occur to make a clot

1. One protein converted to an enzyme that activates the next protein

2. Extrinsic pathway – begins outside bloodstream

3. Intrinsic pathway – inside bloodstream

4. Pathways converge with Factor “X”

The Extrinsic Pathway

• Starts when a blood vessel is damaged, usually within 15 seconds

• Begins with the release of a lipoprotein, called tissue factor, by damaged cells

• Tissue factor combines with calcium ions and clotting protein called Factor VII

• Factor VII forms and enzyme able to activate Factor X

The Intrinsic Pathway

• Begins with the activation of a clotting protein exposed to collagen fibers at site of injury

• Pathway assisted with platelet factor• Along with Calcium and other clotting factors

we get series of reactions that lead to Factor X

The Common Pathway

• Begins when intrinsic or extrinsic pathways make factor X

• Factor X changes to enzyme prothrombinase• Prothrombinase changes prothrombin to

thrombin• Thrombin converts fibrinogen to fibrin• Fibrin is stringy and catches platelets and cells

for “scab”

When Good Clotting Goes Bad

Excessive Coagulation• Embolus – drifting clot• Thrombus – blood clot

attached to vessel wall * also known as plaque

Inadequate Coagulation• Hemophilia – inherited

disorder of missing factor VIII

• Transfusion of plasma can restore clotting factors

• Increases risk of infection from AIDS and HepB

Blood weapons

Timber Rattlesnake (Crotalus horridus) • Most rattlesnakes have hemotoxic venom.

• Cause hemolysis (destroy RBCs)

• Cause organ degeneration and destroy tissue

• Cause coagulopathy (disrupted blood clotting)

• Why would disrupted blood clotting be an effective blood weapon?

Blood weapons

Hirudinea (Leeches)

• Leeches in Medicine Video

• Many leeches are hematophagous but not all can bite. Some survive off decaying matter and already open wounds.

• Leeches secrete an anticoagulant, hirudin, which impairs blood clotting and allows the leech to acquire more blood from the wound.

• Derivatives of hirudin are used in some pharmaceuticals.

Blood weapons

Vampire Bats (Desmodontinae)

• Vampire Bats Feeding Video

• Vampire bats are hematophagous and feed on the blood of mammals.

• A piece of skin is first removed, painlessly, with razor-sharp front incisors.

• Vampire bat saliva has an anticoagulant, allowing the blood to flow freely, which it then sucks up with its tongue and lower lip.

Blood weapons

Culcidae (Mosquitoes)

• Mosquito Video

• Many female mosquitoes are hematophagous. They drink blood to supplement protein and iron for their developing eggs.

• Mosquito saliva inhibits vascular constriction, blood clotting, platelet aggregation, angiogenesis (growth of new blood vessels), and immunity.

• They are also vectors of many diseases.

Blood weapons

Assassin Bug (Triatominae) a.k.a. The Kissing Bug• Most of the bugs in this

family are hematophagous.• Widespread in South

America, these insects are vectors for Chagas disease.

• This disease can cause cardiac, nervous, and digestive system damage.

Assassin Bug VS Bat Video

Blood weapons

VS

Blood Groups and Transfusions.

• Early blood transfusions sometimes resulted in blood clumping.

• Agglutination is the clumping of red blood cells following a transfusion reaction.

• Antigens are red blood cell surface molecules. Known as agglutinogens during clumping.

• Antibodies are proteins carried in the plasma. They are called agglutinins when they react during clumping.

ABO Blood Group

• Blood groups are based on presence or absence of two major protein antigens on RBC membranes – antigen A and antigen B.

• Every person has four possible combinations of antigens on the surface of their RBCs:– Only A = Type A Blood (41% of USA)– Only B = Type B Blood (9% of USA)– Both A and B = Type AB Blood (3% of USA)– Neither A or B = Type O Blood (47% of USA)

ABO Blood Group

• 2 to 8 months after birth certain antibodies are produced. This is an inherited trait.

• If antigen A is absent, an antibody called anti-A is produced.

• If antigen B is absent, antibody anti-B is made.– What antibodies do people with Type A, B, AB, and O

blood have?• An antibody of one type will react with an antigen

of another type and clump RBCs.– Which could be donated to which?

Rh Blood Group

• Named after rhesus monkey. Inherited trait.• Includes several Rh antigens, main = antigen D• If antigen D or any other RH antigens are

present in the blood, blood is Rh-positive.• If blood lacks antigens = Rh-negative• Only 15% of the US has Rh-negataive blood.• O- = Universal Donor• AB+ = Universal Acceptor.– Why?

Rh Blood Group

• If an Rh-negative person receives an Rh-positive transfusion, the Rh antigens began to produce anti-Rh antibodies.

• No effect first time, but now body is sensitized to Rh-positive blood and thus another transfusion of Rh-positive blood could cause the blood to agglutinate.

Rh Blood Group

• This can be a problem with pregnancy.• If a woman who is Rh-negative conceives a

child with an Rh-positive father, their child will be Rh-positive then this blood will enter the woman’s bloodstream.

• The woman’s body will now have antibodies that will attack a second child’s fetal red blood cells.

• Modern medicine can help the child.

Check Your Understanding

• 1. What antibodies does a person with type A blood produce?– A. anti-A– B. anti-B– C. anti-A and anti-B– D. none

• 2. A person with O- blood can safely receive blood from people with– A. O- blood– B. O+ blood– C. AB+ blood