Copyright 2010, John Wiley & Sons, Inc. Chapter 14 The Cardiovascular System: Blood.

Copyright 2010, John Wiley & Sons, Inc.

Chapter 14

The Cardiovascular System: Blood


Functions Transportation: water, gases, nutrients,

hormones, enzymes, electrolytes, wastes, heat

Regulation: pH, temperature, water balance Protection: blood clotting, defense:

phagocytic cells, interferons, complement


Composition A connective tissue with components readily

seen when blood is centrifuged: Plasma(~55%): soluble materials (mostly

water); lighter so at top of tube Formed elements (~45%): cells (heavier so at

bottom of tube) Mostly red blood cells (RBCs)

Percent of blood occupied by RBCs = hematocrit (Hct) Normal hematocrit value: 42-47%

Females: 38 to 46%; males: 40 to 54% Buffy coat: site of white blood cells (WBCs), platelets


Composition


Plasma: Liquid Portion of Blood Water: 91.5% Plasma proteins: 7%

Albumin (54%): function in osmosis; carriers Globulins (38%): serve as antibodies Fibrinogen (7%): important in clotting

Other: 1.5% Electrolytes, nutrients, gases, hormones,

vitamins, waste products


Formed ElementsI. Red Blood Cells (RBCs)II. White blood cells (WBCs)

A. Granular leukocytes1. Neutrophils2. Eosinophils3. Basophils

B. Agranular leukocytes1. Lymphocytes and natural killer (NK) cells2. Monocytes

III Platelets


Formation of Blood Cells Called hemopoiesis or hematopoiesis Occurs throughout life

In response to specific hormones, stem cells undergo a series of changes to form blood cells

Pluripotent stem cells in red marrow Lymphoid stem cells lymphocytes (in lymphatic

tissues) Myeloid stem cells all other WBCs, all RBCs,

and platelets (in red bone marrow)


Formation of Blood Cells


Erythrocytes (RBCs) Hemoglobin (red pigment)

Carries 98.5% of O2 and 23% of CO2 RBC count: about 5 million/µl

Male: 5.4 million cells/µl; female: 4.8 million/µl Structure of mature RBC

No nucleus/DNA so RBCs live only 3 to 4 mos Lack of nucleus causes biconcave disc shape

with extensive plasma membrane Provides for maximal gas exchange Is flexible for passing through capillaries


RBC Recycling Cleared by macrophages (liver and spleen) Recycled components

Globin amino acids recycled to form proteins Heme broken down into:

Fe Carried in blood by transferrin (“protein escort” of Fe) Recycled in bone marrow for forming synthesis of new

hemoglobin; proteins and vitamin B12 required also

Non-Fe portion of heme biliverdin bilirubin Bilirubin to liver bile helps absorb fats Intestinal bacteria convert bilirubin into other chemicals

that exit in feces (stercobilin) or urine (urobilin)


Red blood celldeath andphagocytosis

Key:

in blood

in bile

Macrophage inspleen, liver, orred bone marrow

1

Globin


Key:

in blood

in bile


Heme2

1

Aminoacids

Reused forprotein synthesisGlobin


Key:

in blood

in bile


Heme

3

2

1

Aminoacids



Transferrin

Fe3+

Key:

in blood

in bile


Heme

4

3

2

1

Aminoacids



Transferrin

Fe3+

Liver

Key:

in blood

in bile


FerritinHeme

54

3

2

1

Aminoacids



Transferrin

Fe3+

Fe3+ Transferrin

Liver

Key:

in blood

in bile


FerritinHeme

654

3

2

1

Aminoacids



Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile


FerritinHeme Fe3+

7

654

3

2

1

Aminoacids


Circulation for about120 days


Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile

Erythropoiesis inred bone marrow


FerritinHeme Fe3+

8

7

654

3

2

1

Aminoacids




Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile



FerritinHeme

Biliverdin Bilirubin

Fe3+

9

8

7

654

3

2

1

Aminoacids



Bilirubin


Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile



FerritinHeme


Fe3+

10

9

8

7

654

3

2

1

Aminoacids


Stercobilin

Bilirubin

Urobilinogen

Feces

Smallintestine


Bacteria

Bilirubin


Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile



FerritinHeme


Fe3+

12

1110

9

8

7

654

3

2

1

Aminoacids


Urine

Stercobilin

Bilirubin

Urobilinogen

Feces

Smallintestine


Bacteria

Bilirubin


Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile


Kidney


Ferritin

Urobilin

Heme


Fe3+

13 12

1110

9

8

7

654

3

2

1

Aminoacids


Urine

Stercobilin

Bilirubin

Urobilinogen

Feces

Largeintestine

Smallintestine


Bacteria

Bilirubin


Transferrin

Fe3+

Fe3+ Transferrin

Liver

+Globin

+Vitamin B12

+Erythopoietin

Key:

in blood

in bile


Kidney


Ferritin

Urobilin

Heme


Fe3+

14

13 12

1110

9

8

7

654

3

2

1

Formation and Destruction of RBC’s


RBC Synthesis: Erythropoiesis Develop from myeloid stem cells in red

marrow Cells lose nucleus; are then released into

bloodstream as reticulocytes These almost-mature RBCs develop into erythrocytes

after 1-2 days in bloodstream High reticulocyte count (> normal range of 0.5% to

1.5% as more of these circulate in bloodstream) indicates high rate of RBC formation


RBC Synthesis: Erythropoiesis Production and destruction: normally

balanced Stimulus for erythropoiesis is low O2 delivery

(hypoxia) in blood passing to kidneys Kidneys release erythropoietin release (EPO) Stimulates erythropoiesis in red marrow

increased O2 delivery in blood (negative feedback mechanism)


RBC Synthesis: Erythropoiesis Signs of lower-than-normal RBC count

changes in skin, mucous membranes, and finger nail beds Cyanosis: bluish color Anemia: pale color


Regulation of Erythropoiesis


White Blood Cells (WBCs or Leukocytes) Appear white because lack hemoglobin Normal WBC count: 5,000-10,000/µl

WBC count usually increases in infection Two major classes based on presence or

absence of granules (vesicles) in them] Granular: neutrophils, eosinophils, basophils

Neutrophils usually make up 2/3 of all WBCs Agranular: lymphocytes, monocytes

Major function: defense against Infection and inflammation Antigen-antibody (allergic) reactions


White Blood Cell Functions Neutrophils: first responders to infection

Phagocytosis Release bacteria-destroying enzyme lysozyme

Monocytes macrophages (“big eaters”) Known as wandering macrophages

Eosinophils Phagocytose antibody-antigen complexes Help suppress inflammation of allergic reactions Respond to parasitic infections


White Blood Cell Functions Basophils

Intensify inflammatory responses and allergic reactions

Release chemicals that dilate blood vessels: histamine and serotonin; also heparin (anticoagulant)


White Blood Cell Functions Lymphocytes

Three types of lymphocytes T cells B cells Natural killer (NK) cells

Play major roles in immune responses B lymphocytes respond to foreign substances called

antigens and differentiate into plasma cells that produce antibodies. Antibodies attach to and inactivate the antigens.

T lymphocytes directly attack microbes.


White Blood Cell Functions Major histocompatibility (MHC) antigens

Proteins protruding from plasma membrane of WBCs (and most other body cells)

Called “self-identity markers” Unique for each person (except for identical twins) An incompatible tissue or organ transplant is rejected

due to difference in donor and recipient MHC antigens MHC antigens are used to “type tissues” to check for

compatibility and reduce risk of rejection


WBC Life Span WBCs: 5000-10,000 WBCs/µl blood RBCs outnumber WBCs about 700:1 Life span: typically a few hours to days Abnormal WBC counts

Leukocytosis: high WBC count in response to infection, exercise, surgery

Leukopenia: low WBC count Differential WBC count: measures % of

WBCs made up of each of the 5 types


Platelets Myeloid stem cells megakaryocytes

2000–3000 fragments = platelets Normal count: 150,000-400,000/µl blood Functions

Plug damaged blood vessels Promote blood clotting

Life span 5–9 days


Hemostasis: “Blood Standing Still”Sequence of events to avoid hemorrhage1.Vascular spasm

Response to damage Quick reduction of blood loss

2.Platelet plug formation Platelets become sticky when contact damaged

vessel wall3.Blood clotting (coagulation)

Series of chemical reactions involving clotting factors


Blood Clotting (Coagulation) Extrinsic pathway

Tissue factor(TF) from damaged cells 1 2 3 Intrinsic Pathway

Materials “intrinsic” to blood 1 2 3 Common pathway: 3 major steps

1. Prothrombinase 2. Prothrombin thrombin

3. Fibrinogen fibrin clot Ca++ plays important role in many steps


Clot Retraction and Vessel Repair Clot plugs ruptured area Gradually contracts (retraction)

Pulls sides of wound together Repair

Fibroblasts replace connective tissue Epithelial cells repair lining


Hemostatic Control Mechanisms Fibrinolysis: breakdown of clots by plasmin

Inactivated plasminogen Activated (by tPA) plasmin

Inappropriate (unneeded) clots Clots can be triggered by roughness on vessel

wall = thrombosis Loose (on-the-move) clot = embolism

Anticoagulants: decrease clot formation Heparin Warfarin (Coumadin)


Tissue trauma

Tissuefactor(TF)

Blood trauma

Damagedendothelial cellsexpose collagenfibers

(a) Extrinsic pathway (b) Intrinsic pathway

Activated XII

Ca2+

Damagedplatelets

Ca2+

Plateletphospholipids

Activated X

Activatedplatelets

Activated X

PROTHROMBINASECa2+

VCa2+

V

1

Tissue trauma

Tissuefactor(TF)

Blood trauma



Activated XII

Ca2+

Damagedplatelets

Ca2+


Activated X

Activatedplatelets

Activated X

PROTHROMBINASECa2+

VCa2+

Prothrombin(II)

Ca2+

THROMBIN

(c) Common pathway

V

1

2

+

+

Tissue trauma

Tissuefactor(TF)

Blood trauma



Activated XII

Ca2+

Damagedplatelets

Ca2+


Activated X

Activatedplatelets

Activated X

PROTHROMBINASECa2+

VCa2+

Prothrombin(II)

Ca2+

THROMBIN

Ca2+

Loose fibrinthreads

STRENGTHENEDFIBRIN THREADS

Activated XIIIFibrinogen(I)

XIII

(c) Common pathway

V

1

2

3

+

+

Stages of Clotting


Blood Groups and Blood Types RBCs have antigens (agglutinogens) on their

surfaces Each blood group consists of two or more

different blood types There are > 24 blood groups Two examples:

ABO group has types A, B, AB, O Rh group has type Rh positive (Rh+), Rh negative (Rh–)

Blood types in each person are determined by genetics


ABO Group Two types of antigens on RBCs: A or B

Type A has only A antigen Type B has only B antigen Type AB has both A and B antigens Type O has neither A nor B antigen

Most common types in US: type O and A Typically blood has antibodies in plasma

These can react with antigens Two types: anti-A antibody or anti-B antibody Blood lacks antibodies against own antigens

Type A blood has anti-B antibodies (not anti-A) Type AB blood has neither anti-A nor anti-B antibodies


ABO Group


Rh Blood Group Name Rh: antigen found in rhesus monkey Rh blood types

If RBCs have Rh antigen: Rh+

If RBCs lack Rh antigen: Rh–

Rh+ blood type in 85-100% of U.S. population Normally neither Rh+ nor Rh– has anti-Rh

antibodies Antibodies develop in Rh- persons after first

exposure to Rh+ blood in transfusion (or pregnancy hemolytic disease of newborn)


Transfusions If mismatched blood (“wrong blood type”)

given, antibodies bind to antigens on RBCs hemolyze RBCs

Type AB called “universal recipients” because have no anti-A or anti-B antibodies so can receive any ABO type blood

Type O called “universal donors” because have neither A nor B antigen on RBCs so can donate to any ABO type Misleading because of many other blood groups

that must be matched


End of Chapter 14

Copyright 2010 John Wiley & Sons, Inc.All rights reserved. Reproduction or translation of this work beyond that permitted in section 117 of the 1976 United States Copyright Act without express permission of the copyright owner is unlawful. Request for further information should be addressed to the Permission Department, John Wiley & Sons, Inc. The purchaser may make back-up copies for his/her own use only and not for distribution or resale. The Publishers assumes no responsibility for errors, omissions, or damages caused by the use of theses programs or from the use of the information herein.

Copyright 2010, John Wiley & Sons, Inc. Chapter 14 The Cardiovascular System: Blood.

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Transcript of Copyright 2010, John Wiley & Sons, Inc. Chapter 14 The Cardiovascular System: Blood.