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Chapter 12

The BloodThe Blood

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Circulating BloodCirculating Blood

• Important in maintaining homeostasis

• Classed as connective tissue

• Accounts for 8% of total body weight

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Functions of the BloodFunctions of the Blood

• Circulating blood serves body in three ways– Transportation– Regulation– Protection

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Transportation

• Blood– Carries oxygen to tissues– Carries carbon dioxide from tissues– Transports nutrients and other substances to

cells– Transports waste products from cells– Carries hormones to organs

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Regulation

• Blood– Buffers keep pH of body fluids between 7.35

and 7.45– Substances maintain osmotic pressure to

regulate fluid in tissues– Transports heat to aid in regulation of body

temperature

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Protection

• Blood– Carries cells and antibodies of immune system– Carries factors to protect against blood loss

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• Checkpoint 12-1: What are some of the substances transported in the blood?– Oxygen, carbon dioxide, nutrients, electrolytes,

vitamins, hormones, urea, and toxins

• Checkpoint 12-2: What is the pH range of the blood?– 7.35 – 7.45

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Blood Constituents

• Plasma– Liquid portion

• Formed elements– Erythrocytes– Leukocytes– Platelets (thrombocytes)

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Composition of whole blood

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• Checkpoint 12-3: What are the two main components of blood?– Plasma– Formed elements

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Blood Plasma• Plasma is 55% of blood

– 91% water– 8% protein

• Albumin• Clotting factors• Antibodies• Complement

• 1% other materials– Glucose– Amino acids– Lipids– Electrolytes– Vitamins– Hormones– Wastes– Drugs– Dissolved gases

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• Checkpoint 12-4: Next to water, what is the most abundant type of substance in plasma?– Protein

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The Formed ElementsThe Formed Elements

• Produced in red bone marrow

• Hematopoietic (blood-forming) stem cells can develop into any blood cell

• Mostly short-lived cells

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Blood cells as viewed under the microscope

ZOOMING IN • Which cells are the most numerous in the blood?

Erythrocytes

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• Checkpoint 12-5: Where do blood cells form?– Red bone marrow

• Checkpoint 12-6: What type of cell gives rise to all blood cells?– Hematopoietic stem cells

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Erythrocytes

• Red blood cells (RBCs) most numerous• Biconcave shape• Mature cells anuclear• Contain hemoglobin

– Binds to oxygen for transport– Carries hydrogen ions for buffering– Carries carbon dioxide for elimination

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Red blood cells as seen under a scanning electron microscope ZOOMING IN • Why are these cells described as biconcave?

They have depressions on both sides

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• Checkpoint 12-7: Red cells are modified to carry a maximum amount of hemoglobin. What is the main function of hemoglobin?– Carry oxygen

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LeukocytesLeukocytes

• White blood cells (WBCs) colorless, round– Granulocytes

• Neutrophils (polymorphs)• Eosinophils• Basophils

– Agranulocytes• Lymphocytes• Monocytes

• Prominent nuclei • Clear body of foreign material, cellular debris,

pathogens

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Granulocytes (A-C) and agranulocytes (D, E). ZOOMING IN •Which group of leukocytes has segmented nuclei? Which specific type of leukocyte is largest in size?

Smallest in size?

GranulocytesMonocytes

Lymphocytes

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Phagocytosis

ZOOMING IN • What type of epithelium makes up the capillary wall?

Simple squamous epithelium

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• Checkpoint 12-8: What are the types of granular leukocytes?– Neutrophils– Eosinophils– Basophils

• Of agranular leukocytes?– Lymphocytes– Monocytes

• Checkpoint 12-9: What is the most important function of leukocytes?– They fight infection by destroying pathogens that enter the body.

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Platelets

• Platelets (thrombocytes)

• Smallest formed element

• Not cells—no nuclei or DNA

• Fragments released from megakaryocytes

• Essential for blood coagulation (clotting)

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Platelets (thrombocytes)

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• Checkpoint 12-10: What is the function of blood platelets?– Blood clotting

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HemostasisHemostasis

• Prevents blood loss when blood vessel ruptures

• Contraction of smooth muscles in blood vessel wall (vasoconstriction)

• Formation of platelet plug

• Formation of blood clot

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Blood Clotting

• Final steps in clotting– Damaged tissues release substances that form

prothrombinase– Prothrombinase converts prothrombin to

thrombin– Thrombin converts fibrinogen to fibrin– Fibrin forms network of threads to form clot

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Final steps in blood clot formation 

ZOOMING IN • What material in the blood forms a clot?

Fibrin

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• Checkpoint 12-11: What happens when fibrinogen converts to fibrin?– A blood clot forms

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Blood TypesBlood Types

• Blood types must be compatible for blood transfusion from donor to patient

• Proteins (antigens or agglutinogens) on red cells cause incompatibility– A and B antigens– Rh factor

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The ABO Blood Type Group

• Four blood types involving A and B antigens

• A (only)

• B (only)

• AB (both antigens)

• O (neither antigen)

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Testing for Blood Type

• Blood sera (antisera) containing antibodies to A or B antigens prepared

• Sera added to blood sample

• Corresponding red cells clump (agglutination)

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• Checkpoint 12-12: What are the four ABO blood type groups?– A– B– AB– O

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Blood typing 

ZOOMING IN • Can you tell fromThese reactions whether these cells areRh positive or Rh negative?

No; you have to use the Rh antigen

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Blood Compatibility

• Safest transfusion is same blood type

• Type O blood can be given to any ABO type

• Type AB blood can receive any ABO type

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The Rh Factor

• Red cell antigen group Rh (D antigen) – Rh-positive blood has antigen– Rh-negative blood lacks antigen

• Rh incompatibility can lead to hemolytic disease of newborn (HDN)

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• Checkpoint 12-13: What are the blood antigens most often involved in incompatibility reactions?– A antigen– B antigen– Rh antigen

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Uses of Blood and BloodUses of Blood and BloodComponentsComponents

• Blood stored in blood banks up to 35 days– Anti-clotting solution added– Expiration date added

• Autologous blood- patient’s own blood donated before elective surgery

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Whole Blood Transfusions

• Used for loss of large volume of blood

• Massive hemorrhage from serious injuries

• During internal bleeding

• During or after an operation

• Blood replacement in treatment of HDN

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Use of Blood Components

• Centrifuge separates plasma from formed elements

• Hemapheresis—keep desired elements and return remainder to donor

• Plasmapheresis—keep plasma and return formed elements to donor

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Use of Plasma

• Replace blood volume

• Treat circulatory failure (shock)

• Treat plasma protein deficiency

• Replace clotting factors

• Provide needed antibodies

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• Checkpoint 12-14: How is blood commonly separated into its component parts?– By using a centrifuge

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Blood StudiesBlood Studies

• Some blood tests are standard part of routine physical examination

• Machines can perform many tests simultaneously

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The Hematocrit

• mL of red cells per 100 mL of whole blood

• Centrifuge used to pack cells

• Adult range for men 42%–54%

• Adult range for women 36%–46%

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Hematocrit

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Hemoglobin Tests

• g of hemoglobin per 100 mL of whole blood

• Adult range for men 14–17 g

• Adult range for women 12–15 g

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Blood Cell Counts

• Red cell counts– Range 4.5–5.5 million cells per microliter (μL)

• White cell counts– Range 5,000–10,000 cells per microliter (μL)

• Platelet counts– Range 150,000–450,000 per microliter (μL)

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The Blood Slide (Smear)

• Examination of stained blood slide

• Red cells examined

• Platelets examined

• Differential white count performed

• Parasites may be found

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• Checkpoint 12-15: The hematocrit is a common blood test. What is a hematocrit?– The percentage of red cell volume in whole

blood

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Blood Chemistry Tests• Batteries of blood serum tests often done by

machine– Electrolytes– Blood glucose– Nitrogenous waste products– Creatine– Enzymes– Lipids– Plasma proteins– Hormones– Vitamins– Antibodies– Drug levels

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Coagulation Studies

• Performed before surgery and during treatment of certain

• diseases• Amounts of clotting factors• Bleeding time• Clotting time• Capillary strength• Platelet function

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Bone Marrow Biopsy

• Sample of red marrow through needle from sternum, sacrum, or iliac crest

• Used in diagnosing bone marrow disorders– Leukemia– Some types of anemia