Lesson 12: Blood

Introduction to Blood Blood is a specialized, fluid connective tissue—and a purveyor of our emotions? • Cold when we do evil? • Curdled when we’re afraid? • Hot when we’re excited? • Boiling when we’re angry?

What does blood do? • Transports • Regulates • Defends

Courtesy of Cliaprt.com

What’s in the Blood? • Red blood cells (RBC): carry oxygen

to the body. • White blood cells (WBC): the body’s

freedom fighters. • Platelets: help with blood clotting • Plasma: made mostly of water,

proteins, nutrients, and hormones. • Nutrients and regulators: carried

throughout the body in the blood stream.

• Wastes: carried to the lungs, digestive tract, and kidneys for disposal.

Photo by JHeuser

Where Does It All Come From? • All the RBC, WBC, and platelets originate in

the bone marrow (that doesn’t necessarily mean they mature there).

• Blood picks up nutrients from the digestive system and from recycling by the cells of the body.

• The liver makes the majority of proteins in the plasma, except for antibodies, which lymphocytes make.

• Hormones come from the various endocrine glands in the body.

Courtesy of the Department of Histology, Jagiellonian University Medical College

Plasma • Water: 90%-92% • Plasma proteins: major

ones are albumin, globulins, and fibrinogen

• Salts • Nutrients: lipids, glucose,

amino acids • Hormones: testosterone,

hCG • Waste products: urea, uric

acid

Graph by Schmin

RBCs (Erythrocytes) • RBCs carry oxygen to tissues throughout

body and bring carbon dioxide from tissues throughout body to the lungs.

• RBCs have hemoglobin. • Hemoglobin has heme groups. • The heme groups have iron. • Iron binds to the oxygen in the lungs

and lets it go in the tissues. • Iron also binds CO2 in the tissues &

brings it back to the lungs. • Anemic folk and pregnant women need

lots of iron. • Online movie clip: What it may be like for

RBCs as they journey in blood vessels. • Interesting article: Blood May Help Us

Think By Actively Modulating How Neurons Process Information.

From EM Unit, Royal Free Hospital School of Medicine

Anemia • Lack of oxygen-carrying capacity

in the blood. • Caused by number of factors,

including low levels of iron, inadequate B12 or folic acid, blood loss, and sickled cells.

• Patients feel run down, as if they don’t have enough energy. Can you explain why?

• Sickle cell anemia: Genetic disorder in which abnormal hemoglobin molecules in RBCs stick together, creating long rods of protein that disfigure the shape of the cell and make it quite rigid.

From EM Unit, Royal Free Hospital School of Medicine

WBCs (Leukocytes) Different types of WBC include:

• Granulocytes • Eosinophils • Basophils • Neutrophils

• Agranulocytes • Lymphocytes • Monocytes

Electron Microscopy Facility at The National Cancer Institute

Neutrophils • Grains don’t take on any dye for

microscopy. • Most abundant (50-70%) of WBC. • Phagocytic cells; they like to envelop

pathogens. • Weird-lobed nucleus. • First cells to respond to an infection

(chemotaxis). • Short life span (about a day). • Pus is mostly made up of dead neutrophils.

Basophils • Grains dye blue for miscroscopy. • Weird-lobed nucleus. • Release histamines in allergic reaction that

help to dilate the capillary walls.

Diagram by A. Rad

Eosinophils • Grains dye red for microscopy. • Divided, lobed nucleus. • Eosinophil count goes up when a

person is infected with a worm or other parasite.

• They also increase in the event of an allergic reaction.

Photo by Dr Glenn Littel

Monocytes • Agranular and very large. • Phagocytic. • Move out of the blood and into

tissue to become macrophages. • Macrophages are quite loyal to the

tissue they reside in.

Courtesy: Department of Histology, Jagiellonian University Medical College

Lymphocytes (B and T) • B-lymphocytes make antibodies

(we will talk more about them when we get to the immune system).

• B-lymphocytes tag pathogens for recognition by other immune cells.

• Killer T cells are T-lymphocytes. • T-cells directly attack and kill

any cell the recognize as “foreign.”

Photo by Dr. Triche, National Cancer Institute

Platelets (Thrombocytes) • Platelets help stop blood loss by

sticking together to make a platelet plug.

• They also release chemicals that promote blood clotting.

From Centers for Disease Control and Prevention

Erythropoiesis • Red blood cell production. • Life span of an RBC is ~ 4

months. • 2.5 million new red cells enter

the blood every second. • 10 Million Red Cells entered

your blood in the last 4 seconds.

Electron Microscopy Facility at The National Cancer Institute

Hemostasis Sequence of body responses that stops blood loss. Must be quick, localized, and carefully controlled. Three mechanisms reduce loss of blood: • Vascular spasm:

• Blood vessel insult results immediately in vascular spasm. • Smooth muscle surrounding the vessel contracts. • Reaction to muscle cell damage? Reflex stimulated by pain receptors? • Platelet accumulation and release of vasoconstrictors maintain spasm.

• Platelet plug formation: • Adhesion: platelets contact and stick to damaged parts of vessel. • Release reaction: alteration in shape with release of chemicals. • Aggregation: platelets stick to one another and eventually form plug.

• Blood clotting: • Extremely complex pathway, involves at least 12 clotting factors and

calcium. • Activation of prothrombinase is the common step. • Stimulates conversion of prothrombin to thrombin. • Stimulates conversion of fibrinogen to fibrin.

Hemophilia Disease that causes a lack of some type of clotting factor, resulting in profuse bleeding. • Called the “bleeder’s” disease. • Even a bruise can be fatal. • Affected most of Queen Victoria of

England's family; the disease traveled to Russia, Spain and Germany through royal-family intermarriage.

Photo by Alexander Bassano

Blood Typing Based on two molecules, antigen and antibody. • Antigen (antibody generator): Substance that provokes an immune

response and reacts with the antibodies or cells that result from the immune response. In the case of blood typing, the antigen is located on the cell membrane.

• Antibody: Protein that the body produces in response to an antigen; each antibody combines with a specific antigen.

• The type of blood is based on what antigen is present on RBC. • Functionally, the type of antibodies present in plasma is important.

Blood Type (%)

Population Group O A B AB

European-American 45 40 11 4

African-American 49 27 20 4

Korean 32 28 30 10

Japanese 31 38 21 10

Chinese 42 27 25 6

Native American 79 16 4 1

Blood Types in United States

Agglutination Clumping due to reaction between antigens and antibodies. In ABO blood typing, antibodies A and B combine with their respective antigens.

Rh Factor Rh+: the Rh antigen present on RBCs. • Rh antigens on red cells. • No Rh antibodies in plasma initially.

• Plasma has Rh antibodies only if the person has been previously exposed to Rh antigens.

• A slow increase in plasma Rh antibodies occurs after first exposure. It is more rapid after second exposure.

Rh-: no Rh antigen on RBCs. (Note: There are normally no Rh antibodies in blood of any individual.)

Hemolytic Disease of the Newborn Occurs only when mother is Rh- and baby is Rh+. • During delivery, the blood of baby and mother mixes. • The Rh+ antigens on RBCs of the baby are identified as foreign to the

mother, and her body makes antibodies to fight against the “attack.” • When the mother gets pregnant again, if the baby has Rh+ blood, the

antibodies from the mother will cross the placenta and coagulate the blood of the baby.

Results: • Baby becomes jaundiced from excess bilirubin in blood (looks yellow). • Spleen and liver swell. • Brain damage can occur. Treatment: RhoGAM is the answer! • What is it? Rh+ antibodies, injected within 72 hours of delivery. • RhoGAM binds with Rh+ antigens before mother’s immune system can

mount immune reaction to fetal Rh+ cells. • Injected Rh+ antibodies recognize and bind with fetal Rh+ cells and prevent

maternal immune response from occurring.