Blood online 2

Copyright © 2011 Pearson Education, Inc.

LEUKOCYTESWhite blood cells (WBCs)


Leukocytes

• Make up <1% of total blood volume

• Buffy coat

• Increase in number (↑) b/c of infection

• Two types:

1.Granulocytes

2.Agranulocytes


Granulocytes

• Granulocytes: neutrophils, eosinophils, and basophils

• Granules in cytoplasm

• Wright’s stain

• Larger than RBCs

• Lobed nuclei

• Phagocytic


Neutrophils

• Most numerous WBCs

• aka. Polymorphonuclear leukocytes (PMNs)

• Lobed nucleus

• ↑ during acute infections

• Phagocytic

• bacteria eaters


Eosinophils

• Red-staining

• bilobed nuclei

• Digest parasitic worms

• ↑ Allergies


Basophils

• Rarest WBCs

• Large, purplish-black granules

• contain histamine

• Histamine: inflammatory, attracts other WBCs


Agranulocytes

• Agranulocytes: lymphocytes and monocytes

• Lack visible granules

• Have spherical nuclei


Lymphocytes

• Large, dark-purple, circular nuclei with thin, blue cytoplasm

• Two types of lymphocytes:

• T cells, act against viruses

• B cells, produce antibodies


Monocytes

• The largest leukocytes

• Large pale-blue cytoplasm

• Dark purple U-shaped nuclei

• ↑ chronic infections

• Phagocytes & activators


Leukopoiesis

• Production of WBCs

• All blood cells form from hemocytoblasts

• Directed by chemical messages


Leukemia

• Cancer of WBCs

• Uncontrolled growth of leukocytes

• Nonfunctional WBCs accumulate

• Death from infections

• Named by type of WBC

• Lymphocytic leukemia = lymphocytes


PLATELETS

And clot formation


Platelets

• Small fragments of megakaryocytes

• Small an irregularly shaped

• Thrombopoietin regulates formation

• Initiate clot formation


Clot Formation

Clot Formation aka. hemostasis

Fast steps to stop bleeding

1. Vascular spasm

2. Platelet plug formation

3. Coagulation (blood clotting)


Vascular Spasm

• Vasoconstriction of damaged blood vessel

• Caused by injury or pain

Platelet Plug Formation• Stick to exposed fibers

• Swell, become spiked and sticky

• release chemical messengers


Coagulation

• Blood goes from liquid to gel

• Prothrombin thrombin (protein modification)

• Causes formation of a fiber mesh

Copyright © 2011 Pearson Education, Inc. Figure 16.13

Collagenfibers

Platelets

Fibrin

Step Vascular spasm• Smooth muscle contracts, causing vasoconstriction.

Step Platelet plugformation

• Injury to lining of vessel exposes collagen fibers; platelets adhere.

• Platelets release chemicals that make nearby platelets sticky; platelet plug forms.

Step Coagulation• Fibrin forms a mesh that traps red blood cells and platelets, forming the clot.

1

2

3

Hemostasis


Clotting Disorders

1. Thromboembolytic disorders:

• Clots or “thrombus” form in unbroken vessels

• Embolisms – floating thrombus

• Help prevent with aspirin

2. Bleeding disorders:

• prevent normal clotting

• Hemophilia

• Hereditary bleeding disorders

Blood online 2

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