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CHAPTER 16 (BLOOD) OVERVIEW

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Blood Composition

• Blood: a fluid, connective tissue

1. Plasma (~55%)

2. Cells (formed elements) (~45%)

• Erythrocytes (red blood cells)

• Leukocytes (white blood cells)

• Platelets

Copyright © 2011 Pearson Education, Inc. Figure 16.1

1 Withdraw.

2 Centrifuge theblood sample.

Plasma

Buffy coat

Erythrocytes

Formedelements

Blood Composition

• Hematocrit a measure of % RBCs in blood

• 47% for males

• 42% for females

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Functions of Blood

1. Distribution

• O2

• Nutrients

• Wastes

• Hormones

2. Regulation

• Body temperature

• Buffer pH

• Blood pressure

3. Protection

• Blood loss – clot formation

• platelets

• Fight infection

• WBCs

• Antibodies

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Formed Elements

• Originate from red bone marrow

1.WBCs – involved in immunity

2.RBCs – transport oxygen

3.Platelets – form clots

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Erythrocytes (RBCs)

• Biconcave disc

• Large surface area : volume ratio

• No nucleus

• No organelles

• 120 day life span

• Filled with hemoglobin (Hb)

• transports O2

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Hematopoiesis

• Hematopoiesis: blood cell formation

• In epiphysis of long bones

• red bone marrow

• hematopoietic stem cells

• gives rise to all blood cells

• Erythropoiesis – specifically red blood cell production

Copyright © 2011 Pearson Education, Inc. Figure 16.5

Stem cell

HemocytoblastProerythro-blast

Earlyerythroblast

Lateerythroblast Normoblast

Phase 1Ribosomesynthesis

Phase 2Hemoglobinaccumulation

Phase 3Ejection ofnucleus

Reticulo-cyte

Erythro-cyte

Committedcell

Developmental pathway

Erythropoises

• Erythropoietin (EPO) is a hormone

• stimulates erythropoiesis

• produced by kidneys

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Erythropoiesis

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RBC Disorders

Anemia:

• blood has low O2-carrying capacity

• Low iron content

• Can be cause by diet, injury or genetic

• Symptoms:

• Fatigue / paleness / short breath / chills

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Causes of Anemia

• Hemorrhagic anemia

• loss of blood

• Hemolytic anemia

• RBCs rupture

• Aplastic anemia

• destruction of bone marrow

• Usually associated with cancer

• Pernicious anemia

• Low B12

• Low iron

Genetic

• Thalassemia

• RBCs are weak

• Sickle-cell anemia

• abnormal Hb

Copyright © 2011 Pearson Education, Inc. Figure 16.8

1 2 3 4 5 6 7 146

1 2 3 4 5 6 7 146

Normal RBCNormal biconcave shape

Normal a. a. sequence

Sickle Cell Anemia

Abnormal RBC“sickle” shape

Mutated a. a. sequence