Connective tissue Consists of Formed elements and Plasma 45% - Formed elements 55% - Plasma Average total blood volume in adult male – 5-6 L Average total blood volume in adult female – 4-5 L Makes up about 8% of total body wt. Oxygen-rich blood is scarlet red Oxygen-poor blood is dull red Heart pumps blood through blood vessels, which extend throughout the body

• If blood is centrifuged– Erythrocytes sink to the

bottom (45% of blood, a percentage known as the hematocrit)

– Buffy coat contains leukocytes and platelets (less than 1% of blood)

• Buffy coat is a thin, whitish layer between the erythrocytes and plasma

– Plasma rises to the top (55% of blood)

Transport of gases, nutrients and waste products: eg. O2

Transport of regulatory molecules: Transport hormones from endocrine organs to target organs

Regulation of pH : Buffers maintain the normal pH of most body tissues between 7.35 and 7.45

Maintenance of body temperature: By absorbing and distributing heat throughout the body

Protection against foreign substances: e.g., antibodies, white blood cells

Clot formation: Protects excessive blood loss

Liquid part of blood Colloid – liquid suspension Pale yellow fluid Consists of 91% water, 7% protein,

2% other solutes, such as ions, gases, nutrients, waste products

Proteins Albumins: 58%, viscous Maintain osmotic pressure

Globulins: 38%, transports lipids, carbohydrates, hormones, ions, involve in immunity (protection against microorganisms)

Fibrinogen: function in blood clotting

Serum: plasma without clotting factors

Consists of red blood cell (95%), white blood cells and platelets (5%)

Red blood cells (erythrocytes): Contains hemoglobin, which colors the cell red, no nuclei

White blood cells (leukocytes): – Granulocytes: cytoplasm contains

large granules; have multi-lobed nuclei. Three types: neutrophils, eosinophils, basophils

– Agranulocytes: cytoplasm lack granules and nuclei that are not lobed.

– Two types : lymphocytes and monocytes

Platelets (thrombocytes): Function in blood clotting

Biconcave disk Increase surface area Movement of gases faster No nucleus 5 million RBCs per cubic

millimeter of blood

Components– 1/3 Hemoglobin – accounts

for red color– 2/3 Lipids, ATP, enzyme

carbonic anhydrase

Transport oxygen from lungs to tissues 98.5% of O2 attached to hemoglobin 1.5% dissolved in plasma

Transport CO2 from tissues to lungs 7% dissolved in plasma 23% in combination with hemoglobin 70% transported as bicarbonate ions

CO2 + H2O carbonic anhydrase H2CO3 H+ + HCO3

-

– Iron-containing protein– Binds strongly to oxygen– Each hemoglobin molecule

has four oxygen binding sites– Each erythrocyte has 250

million hemoglobin molecules– Hemoglobin in one red blood

cell transports 1 billion O2

molecules– Normal blood contains 12–18

g of hemoglobin per 100 mL blood

Process of blood cell production – Hematopoiesis

Occurs in red bone marrow of: Ribs, sternum, vertebrae,

pelvis, proximal femur and humerus

All formed elements derived from single population of stem cells – Hemocytoblasts

Hemocytoblasts divide into:– Lymphoid stem cell:

Produces lymphocytes– Myeloid stem cell:

Produce other classes of formed elements

Hemocytoblaststem cells

Secondary stem cells

Basophils

Eosinophils

Neutrophils

MonocytesLymphocytes

Erythrocytes

Platelets

Lymphoidstem cells

Myeloidstem cells

• Erythrocyte does not contain nuclei, cannot divide, grow, or synthesize proteins

• Wear out in 100 to 120 days

• When worn out, RBCs are eliminated by phagocytes in the spleen or liver

• Lost cells are replaced by division of hemocytoblasts to new RBCs in the red bone marrow

Formation of Erythrocytes

Control of Erythrocyte Production

• Rate of erythrocyte productions is controlled by a hormone (erythropoietin)

• Kidneys produce most erythropoietin as a response to reduced oxygen levels in the blood

• Homeostasis is maintained by negative feedback from blood oxygen levels

Anemia – Deficiency of hemoglobin in blood

– Reduces blood`s ability to transport oxygen– Unable to support normal metabolism– Symptoms: fatigue, paleness, shortness of breath, and chills

Polycythemia - Is an excessive or abnormal increase in the number of

erythrocytes

Sickle-cell anemia – RBCs become sickle shape

– single mutation changes amino acid in globin of Hb

– causes RBCs to become sickle-shaped

Make up 1% of the total blood volume 4,000 to 11,000 WBC per cubic millimeter of blood No hemoglobin Contains nuclei Protect body against microorganisms Remove dead cells and debris Motile Movements:

– Ameboid– Diapedesis: Enter tissue by diapedesis, cells

become thin, elongate and move between blood capillaries

– Chemotaxis: move toward foreign materials or damaged cells

– Phagocytize bacteria and dead cells

Two major categories of Leukocytes:

Granulocytes: Contains cytoplasmic granules Lobed nuclei Neutrophils Eosinophils Basophils

Agranulocytes: Lack granules Spherical or kidney shaped nuclei Lymphocytes Monocytes

Neutrophils: Comprise 60-70% of white blood cells

Contains small cytoplasmic granules

multilobed nucleus

Phagocytize bacteria, foreign matter

Eosinophils: Comprise 2-4% of white blood cells

Their no. increases during allergies and infections by parasitic worms

Destroy parasitic worms: tapeworms, flukes, pinworms, hookworms

Basophils: Comprise 0.5-1% of white blood cells

Increases no. in both inflammation & allergies

Release heparin, which inhibits blood clotting

Lymphocytes: Comprise 20-25% of white blood cells, smallest WBCs Nucleus fills most of the cellProduced in red bone marrow, migrate to lymphatic tissues Play role in immunity, produce antibodies destroy tumor cells

Monocytes: Comprise 3-8% of white blood cells, largest WBCs

leave circulation and become macrophages

Phagocytize bacteria, dead cells, debris

• Controlled by hormones– Colony stimulating factors (CSFs) and

interleukins prompt bone marrow to generate leukocytes

– Thrombopoietin stimulates production of platelets

Formation of White Blood Cells and Platelets

• Abnormal numbers of leukocytes– Leukocytosis

• WBC count above 11,000 leukocytes/mm3• Generally indicates an infection• Including viral, bacterial, fungal, or parasitic infection,

cancer, hemorrhage

– Leukopenia• Abnormally low leukocyte level• Commonly caused by certain drugs such as corticosteroids

and anticancer agents• Other causes are: malaria, HIV, tuberculosis

• Cancer of red bone marrow• Abnormal production of WBCs• WBCs are immature • Lack normal immunologic function• Interferes with RBCs and platelet production• Lead to anemia, bleeding• Death is caused by internal hemorrhage and infections• Treatments include radiation, antileukemic drugs, and

bone marrow transplants

Small fragments of cells Produce within red marrow Derive from megakaryocytes Cell fragments pinched off from megakaryocytes in red

bone marrow Essential for blood clotting Prevent blood loss Normal platelet count = 300,000/mm3

Series of reactions for stoppage of bleeding Three phases occur in rapid sequence

– Vascular spasms – Platelet plug formation– Coagulation (blood clotting)

Vascular spasms: Immediate constriction of blood

vessel - injury Close small vessels Stop blood flow

Hemostasis• Platelet plug formation

– Collagen fibers are exposed by a break in a blood vessel

– Platelets become “sticky” and cling to fibers

– Anchored platelets release chemicals to attract more platelets

– Platelets pile up to form a platelet plug

Hemostasis• Coagulation

– Injured tissues release tissue factor (TF)

– PF3 (phospholipid that coats the surface of platelets) interacts with TF, blood protein clotting factors, and calcium ions to trigger a clotting cascade

– Prothrombin activator converts prothrombin to thrombin (an enzyme)

– Thrombin joins fibrinogen proteins into hair-like molecules of insoluble fibrin

– Fibrin forms a meshwork (the basis for a clot)

• Blood usually clots within 3 to 6 minutes

• Endothelium regenerates

• And the clot is broken down after tissue repair

Hemostasis

Disorders of Hemostasis

• Thrombus– A clot in an unbroken blood vessel– Can be deadly in areas like the heart

• Embolus– A thrombus that breaks away and floats freely

in the bloodstream– Can later clog vessels in critical areas such as

the brain

• Thrombocytopenia– Platelet deficiency– Even normal movements can cause bleeding

from small blood vessels that require platelets for clotting

• Hemophilia– Hereditary bleeding disorder– Normal clotting factors are missing

Disorders of Hemostasis

• Large losses of blood have serious consequences– Loss of 15–30% causes weakness– Loss of over 30% causes shock, which can be

fatal

• Transfusions are the only way to replace blood quickly

• Transfused blood must be of the same blood group

Blood Groups and Transfusions

• Surface of RBC have specific glycoprotein - antigens

• These antigens are:– Unique to the individual

• Antibodies (present in plasma) can bind to specific RBC antigens

• If different blood cell type is transfused, antigen combines with antibody – agglutination (clumping) takes place

• Antigens – agglutinogens• Antibodies - agglutinins

• Based on the presence or absence of two antigens– Type A– Type B

• The lack of these antigens is called type O

ABO Blood Groups

• The presence of both antigens A and B is called type AB

• The presence of antigen A is called type A

• The presence of antigen B is called type B

• The lack of both antigens A and B is called type O

ABO Blood Groups

• Blood type AB can receive A, B, AB, and O blood– Universal recipient

• Blood type B can receive B and O blood

• Blood type A can receive A and O blood

• Blood type O can receive O blood– Universal donor

ABO Blood Groups

ABO Blood Groups

• First studied in rhesus monkeys

• Types– Rh positive: Have D antigen present on surface of RBCs– Rh negative: Do not have D antigen

• Most Americans are Rh+ (Rh positive)

• Problems can occur in mixing Rh+ blood into a body with Rh– (Rh negative) blood

Rh Blood Groups

• Danger occurs only when the mother is Rh– and the father is Rh+, and the child inherits the Rh+ factor

• RhoGAM shot can prevent buildup of anti-Rh+ antibodies in mother’s blood

Rh Dangers During Pregnancy

• The mismatch of an Rh– mother carrying an Rh+ baby can cause problems for the unborn child

– The first pregnancy usually proceeds without problems

– The immune system is sensitized after the first pregnancy

– In a second pregnancy, the mother’s immune system produces antibodies to attack the Rh+ blood (hemolytic disease of the newborn)

Rh Dangers During Pregnancy

ERYTHROBLASTOSIS FETALISERYTHROBLASTOSIS FETALIS• RhRh++ fetus / Rh fetus / Rh-- mother mother • Fetal organ damageFetal organ damage

maternal circulation maternal circulation (Rh(Rh--))

fetal circulation fetal circulation (Rh(Rh++))

FIRST PREGNANCYFIRST PREGNANCY SECOND PREGNANCY SECOND PREGNANCY

(RH(RH--) antibodies develop in ) antibodies develop in the mother after deliverythe mother after delivery

Agglutination of fetal Agglutination of fetal (RH(RH++) fetus) fetus