© 2014 Pearson Education, Inc. Blood. © 2014 Pearson Education, Inc. Blood Circulation Circulatory system is divided into Cardiovascular system Lymphatic.

© 2014 Pearson Education, Inc.

Blood


Blood Circulation

• Circulatory system is divided into

• Cardiovascular system

• Lymphatic system

• Blood

• Transport mechanism for

• Nutrients

• Signaling molecules

• Respiratory gases

• Waste products


Blood Circulation

• Powered by the pumping action of the heart

• Oxygen and nutrients diffuse across capillary walls to body tissues

• Regulates body temperature

Composition of Blood

• Blood has cellular and liquid components

• Is a specialized connective tissue

• Blood cells—formed elements

• Plasma—liquid portion of blood


Composition of Blood

• Hematocrit

• Is the measure of % RBC

• Males: 47% ± 5%

• Females: 42% ± 5%

• Buffy coat

• Is portion of blood composed of leukocytes and platelets

• Present at junction of plasma and RBCs


Figure 18.1 Major components of whole blood.

Withdraw bloodand place in tube.

Centrifuge theblood sample.

55% of whole bloodLeast dense component

Leukocytes and platelets1% of whole blood

45% of whole bloodMost dense component

Plasma

Buffy coat

Erythrocytes Formedelements

21


Blood Plasma

• Clear, sticky fluid portion of blood

• Approximately 90% water

• Contains over 100 kinds of molecules

• Ions—Na+ and Cl–

• Nutrients

• Sugars, amino acids, lipids

• Wastes

• Carbon dioxide, urea, ammonia

• Proteins


Blood Plasma

• Three main proteins

• Albumin

• Prevents water from diffusing out of blood vessels

• Globulins

• Include antibodies and blood proteins that transport lipids, iron, and copper

• Fibrinogen

• One of the molecules involved in chemical reactions for blood clotting


Figure 18.2b Blood cells.

Erythrocytes Platelets

Monocyte Lymphocyte Neutrophil Eosinophil

Photomicrograph of a human blood smear,Wright’s stain (610)


Erythrocytes

• Most numerous of the formed elements

• Have no organelles or nuclei

• Are packed with oxygen-carrying hemoglobin

• Hemoglobin molecule bears four oxygen molecules

• Each O2 bears an Fe

• Iron atoms give blood it’s red color


Figure 18.3 Structure of erythrocytes.

Side view (cut)

Top view

2.5 m

7.5 m


Leukocytes—White Blood Cells (WBCs)

• Protect the body from infectious microorganisms

• Function outside the bloodstream in loose connective tissue

• Originate in bone marrow


Neutrophils (50–70%)

Eosinophils (2–4%)

Basophils (0.5–1%)

Lymphocytes (25–45%)

Monocytes (3–8%)

Platelets

Leukocytes

Erythrocytes

Formedelements(not drawnto scale)

DifferentialWBC count(All total 4800–10,800 cells/l)

Mnemonic: “Never Let Monkeys Eat Bananas”


Granulocytes

• Neutrophils

• Most numerous WBC

• First line of defense in inflammatory response

• Phagocytize and destroy bacteria

Granulocytes

Neutrophil:Multilobednucleus, palered and bluecytoplasmicgranules


Granulocytes

• Eosinophils

• 1–4% of all WBCs

• Play a role in ending allergic reactions by phagocytizing allergens

• Secrete enzymes that degrade histamines

Granulocytes

Eosinophil:Bilobednucleus, redcytoplasmicgranules


Granulocytes

• Basophils-0.5% of all leukocytes

• Function in inflammation mediation

• Direct later stages of inflammation in allergies and parasitic infections

Granulocytes

Basophil:Bilobednucleus, purplish-blackcytoplasmicgranules


Agranulocytes

Lymphocytes—~35% of WBCs

• The most important cells of the immune system

• Fighting infectious organisms

• Act against a specific foreign molecule (antigen)

• 2 types of lymphocytes

• T cells—attack foreign cells directly

• B cells—multiply to become plasma cells

Agranulocytes

Lymphocyte(small): Largesphericalnucleus, thinrim of paleblue cytoplasm


Agranulocytes

• Monocytes—compose 4–8% of WBCs

• The largest leukocytes

• Transform into macrophages

• Phagocytic cells

Agranulocytes

Monocyte:Kidney-shapednucleus,abundant paleblue cytoplasm


Platelets

• Cell fragments

• Break off from megakaryocytes

• Function in clotting of blood


Table 18.1 Summary of Formed Elements of the Blood (1 of 2)


Table 18.1 Summary of Formed Elements of the Blood (2 of 2)


Blood Cell Formation

• Hematopoiesis—process by which blood cells are formed in red marrow

• 100 billion new blood cells formed each day


Bone Marrow as the Site of Hematopoiesis

• Bone marrow—located within all bones

• Red marrow—actively generates new blood cells

• Contains immature erythrocytes

• In adults, in red marrow

• Yellow marrow—dormant

• Contains many fat cells

• Located in the long bones of adults



Cell Lines in Blood Cell Formation

• All blood cells originate in bone marrow

• All originate from one cell type

• Hemopoietic blood stem cell (pluripotential hematopoeitic stem cell)

• Lymphoid stem cells

• Give rise to lymphocytes

• Myeloid stem cells

• Give rise to all other blood cells


Disorders of the Blood

• Disorders of erythrocytes

• Polycythemia

• Abnormal excess of erythrocytes

• Anemia

• Erythrocyte levels or hemoglobin concentrations are low



• Disorders of erythrocytes (continued)

• Sickle cell disease

• Inherited condition

• Results from a defective hemoglobin molecule

• Erythrocytes distort into a sickle shape



• Disorders of leukocytes

• Leukemia—a form of cancer

• Classified as lymphoblastic or myeloblastic

• Disorders of platelets

• Thrombocytopenia

• Abnormally low concentration of platelets

© 2014 Pearson Education, Inc. Blood. © 2014 Pearson Education, Inc. Blood Circulation Circulatory system is divided into Cardiovascular system Lymphatic.

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