Chapter 16

Blood

About this Chapter

• Plasma and the cellular elements of blood• Blood cell production• Red blood cells• Platelets and coagulation

Composition of Blood

Figure 16-1 (1 of 2)

BLOOD

Gases such as

such asPlasma

Ions

Trace elementsand vitamins

O2

CO2

Proteins

Glucose

Lipids

Nitrogenouswaste

Globulins

Fibrinogen

Amino acids Albumins

Organicmolecules

Water

iscomposed

of

Composition of Blood

Figure 16-1 (2 of 2)

Cellularelements

Red bloodcells

Whiteblood cells

Platelets

Lymphocytes

Monocytes

Neutrophils

Eosinophils

Basophils

include

m 0

5

10

15

BLOODis

composedof

Plasma Proteins

Table 16-1

Cellular Elements

• Three main cellular elements• Red blood cells – also called erythrocytes• Platelets – split off from megakaryocytes• White blood cells – also called leukocytes• Lymphocytes – are also called immunocytes• Monocytes – develop into macrophages• Neutrophils – neutrophils along with monocytes

and macrophages are known as phagocytes• Eosinophils – eosinophils along with neutrophils

and basophils are also called granulocytes• Basophils – tissue basophils are called mast cells

Hematopoiesis

Figure 16-2 (1 of 2)

Uncommittedstem cells

Pluripotent hematopoietic stem cell

Committedprogenitor cells

Erythroblast

Megakaryocyte

Lymphocytestem cells

BO

NE M

AR

RO

W

Hematopoiesis

Figure 16-2 (2 of 2)

Erythroblast

Megakaryocyte

Reticulocyte

Erythrocyte Platelets Basophil EosinophilNeutrophil Monocyte Lymphocyte

BO

NE M

AR

RO

WC

IRC

ULA

TIO

N

Blood Cells

Table 16-2

Clinical Tests

• Hematocrit: ratio of red blood cells to plasma

Figure 16-3

100%

�58%plasmavolume

42%packedred cellvolume

<1%whitecells

MALES FEMALES

Hematocrit 40%–54% 37%–47%

Hemoglobin (g Hb/dL* blood) 14–17 12–16

Red cell count (cells/µL) 4.5–6.5 x 106 3.9–5.6 x 106

Total white cell count (cells/µL) 4–11 x 103 4–11 x 103

Differential white cell count

Neutrophils 50%–70% 50%–70%

Eosinophils 1%–4% 1%–4%

Basophils <1% <1%

Lymphocytes 20%–40% 20%–40%

Monocytes 2%–8% 2%–8%

Platelets (per µL) 150–450 x 103 150–450 x 103

*1 deciliter (dL) = 100 mL

Focus on … Bone Marrow

Figure 16-4a

(a)

Bonemarrow

Focus on … Bone Marrow

Figure 16-4b

Bonecortex

Central sinus

Venoussinuses

Stroma ofmarrow

(b)

Nutrientartery

Radialartery

Focus on … Bone Marrow

Figure 16-4c

Platelets

Reticular cell

Stem cell

Mature blood cells squeezethrough the endothelium to

reach the circulation.

Fragments of megakaryocytebreak off to become platelets.

The stroma is composed offibroblast-like reticular cells,

collagenous fibers, andextracellular matrix.

Reticulocyteexpellingnucleus

Stem cell

Monocyte

(c)

Lymphocyte

Macrophage

Venous sinus

Matureneutrophil

Reticularfiber

Red Blood Cells

Figure 16-5

CytoskeletonfilamentAttachmentprotein

Actin(a) SEM shows biconcave disk shapeof RBCs.

(b) Cross section of RBC

(c) The cytoskeleton creates theunique shape of RBCs.

Osmotic Changes to Red Blood Cells

• The disk-like structure of red blood cells allows them to modify their shape in response to osmotic changes

Figure 16-6

Iron Homeostasis and Metabolism

Figure 16-7

1

2

3

4

5

6

7

8

88 7

4

6

532

1Intestine

Liver

Bone Marrow

Kidney

Spleen

Iron (Fe)in diet

Fe ･ transferrinFe Fe Heme Hb RBCsynthesis

Old RBCsdestroyed

Hb

Bilirubin +metabolites

Bilirubinmetabolites

in feces

Bilirubinmetabolites

in urine

Ferritin

Bilirubinmetabolism

Bile

Hb

Bilirubin

Plasma

RBC

Iron comes from the diet.

Fe absorbed by activetransport.

Transferrin proteintransports Fe in plasma.

Liver stores excess Fe asferritin.

Bone marrow uses Fe tomake hemoglobin (Hb).

Spleen converts Hb tobilirubin.

Liver metabolizes bilirubinand excretes it in bile.

Bilirubin metabolites areexcreted in urine and feces.

Red Blood Cells

• Live for about 120 days• Hemoglobin components are recycled• Amino acids are incorporated into new proteins• Some iron from heme groups reused in new

heme groups• Remnants of heme groups are converted to

bilirubin, then excreted as bile• Jaundice results from elevated levels of bilirubin

Red Blood Cells

Table 16-3

Figure 16-8

Sickled Red Blood Cells

• Morphology can provide clues to the presence of disease

Platelets Form from Megakaryocytes

Figure 16-9a

Megakaryocytes are giant cells withmultiple copies of DNA in the nucleus.

Endoplasmicreticulum

Platelets

Red blood cell

(a)

The edges of the megakaryocytebreak off to form cell fragmentscalled platelets

3

2

1

Damage towall of

blood vessel

Tissue factorexposed

Intact bloodvessel wall

Clot: reinforcedplatelet plug

Fibrin slowlydissolved by

plasmin

Clot dissolves

Collagenexposed

Platelets aggregateinto loose platelet

plug

Temporaryhemostasis

Cell growth andtissue repair

Vasoconstriction

Platelets adhere and

releaseplateletfactors

Thrombinformation

Coagulationcascade

Convertsfibrinogen

to fibrin

Overview of Hemostasis and Tissue Repair

Figure 16-10

Platelet Plug Formation

Figure 16-11

1

2

3

4

2

4

3

Preventsplatelet

adhesion

Lumen ofblood vessel

Intactendothelium

Smoothmuscle cells

Collagensubendothelial

layer

Exposed collagenin damaged blood

vessel wall

ECF

Releasesprostacyclin

and NO

Exposed collagen bindsand activates platelets.

Release of platelet factors

Factors attract more platelets.

Platelets aggregate intoplatelet plug.

1

Clotting Process

Table 16-4

The Coagulation Cascade

Figure 16-12

INTRINSIC PATHWAY

COMMON PATHWAY

EXTRINSIC PATHWAY

Cross-linked fibrin

Thrombin

Fibrin

Active IX

Active X

Active XIII

Tissue factor(III) and

active VII

Collagen or otheractivators

Damage exposestissue factor (III)

Active XII

Active XI

XII

VIII

VII

IX

XI

Ca2+

Ca2+

Ca2+

Ca2+

Fibrinogen

Prothrombin

Ca2+,V, PL

,positive feedback

positive feedback

phospholipids (PL)X

XIII

Coagulation and Fibrinolysis

Figure 16-13

Thrombin Plasminogen

Fibrinpolymer

Plasmin

tPA

Fibrinfragments

Coagulation Fibrinolysis

Fibrinogen

Clot

Coagulation

Table 16-5

Coagulation

Table 16-6

Coagulation

Figure 16-14

Summary

• Plasma and cellular elements• Plasma, red blood cells, white blood cells,

platelets, and megakaryocytes• Plasma proteins and their functions• Five types of white blood cells

• Blood cell production• Hematopoiesis and cytokines

Summary

• Red blood cell• Transferrin, ferritin, bilirubin, bile, and jaundice

• Platelets and coagulation• Hemostasis, platelet plug, platelet adhesion,

platelet aggregation, and fibrin• Coagulation cascade, fibrinogen, thrombin,

plasmin, prostacyclin, and anticoagulants