Blood Flashcards by James Dietrick

How does blood act as a transportation fluid (general)?

Blood BRINGS: nutrients, oxygen, water, etc.; blood REMOVES: CO2, waste/toxins, heat, water, etc.

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How is erythropoesis in bone marrow controlled?

The hormone erythropoietin from the kidneys

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In order to do functional work, blood must do what?

Be kept ceaselessly moving

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What is the normal appearance of blood?

Darker when deoxygenated, lighter when oxygenated

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What type of secondary polycythemia conditional to living in high elevation?

Physiologic (high altitude) polycythemia

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What is the normal pH of blood?

~ pH 7.4

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What are some of the adverse effects of polycythemia?

Increased RBC’s increases the viscosity of blood, putting increased work load on heart

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At what temperature is blood normally maintained?

37 C or 98.6 F

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How might anemia put strain on the heart?

Decreased RBC’s decreases

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How much more viscous is blood than water?

3-5X more viscous

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What are some of the non-regulatory factors required for RBC synthesis?

Iron and amino acids (hemoglobin synth.), Vit B12 and folic acid (DNA synthesis in erythropoiesis)

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How much blood is normally found in the circulatory system?

~ 5 liters

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What is a malabsorption of Vit B12 that would slow erythropoiesis, producing fragile macrocytes (large RBCs)

Pernicious anemia

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What percent of blood is plasma, WBC’s/platelets, and RBC’s?

Plasma ~ 55%, WBC’s ~ tiny %, RBC’s ~ 45%

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What is the normal lifespan of an RBC?

120 days

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What is another name for the WBC/platelet layer of centrifuged blood?

The “Buffy Coat”

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What is the erythrocyte sedimentation rate (ESR)?

Taking a sample of blood and letting the RBC’s settle out on their own (no centrifuging)

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What might an altered WBC count indicate?

The presence of infectious agents (usually elevates the WBC count)

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What might an elevated erythrocyte sedimentation rate indicate?

During infection, arthritis, and other inflammatory diseases, the ESR would be elevated. Reacting blood tends to clump and fall out of solution.

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What is the name of the inferior layer of centrifuged blood and what is it called?

This layer is composed of erythrocytes (RBC’s) and is known as the HEMATOCRIT

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What fraction of blood does plasma represent?

~55%

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What is a low hematocrit indicate?

Anemia

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What are some common functions of plasma proteins?

Plasma colloidal osmotic pressure (greatest), carriers, defense, clotting/coagulation, blood viscosoty (small).

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What are the two general causes of anemia?

Loss of blood or inadequate production

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What are the three classifications of plasma proteins?

Albumin (smallest, greatest %), globulin (larger, less common), fibrinogen (largest, smallest %)

An RBC count \< 4 million/mm^3 is known as \_\_\_\_\_\_.

Anemia

What condition is marked by a lack of plasma proteins (particularly albumin)?

Hypoproteinemia

An RBC count \> 6 million/mm^3 is known as \_\_\_\_\_\_\_\_.

Polycythemia

What are some of the complications of hypoproteinemia; when might they be seen?

Seen during starvation, liver disease, nephrosis, intestinal malabsorption; lack of plasma proteins decreases osmotic pressure, leading to adema.

What are three typical causes for polycythemia?

disease, dehydration, or living in high altitudes

Which plasma protein is the most common and greatest contributer to plasma colloidal oncotic pressure?

Albumin.

RBC's contain hemoglobin, which carry lots of O2; about how much Hb is there in normal blood?

~ 15 grams per 100 ml (1 dl)

Why is maintaining plasma colloidal oncotic pressure necessary?

To prevent excessive fluid filtration (out of blood vessels)

How is total RBC# (hematocrit) a FUNCTION of O2 content of blood?

O2 availability is critical and is a function of RBC number and Hb content per RBC.The greater the demand for O2, the greater the O2 content in blood.

What are the three classifications of globulin proteins?

alpha globulin, beta globulin, gamma globulin

What type of globulin functions as carrier protein for lipids (LDLs) and iron (transferrin)?

beta globulin

What type of globulin functions as clotting factors and carrier proteins, such as HDLs, clotting factors, and complement system?

alpha globulin

What type of globulin functions as antibodies?

gamma globulin

As the main precursor to a clot, what zymogen is a precursor to fibrin?

fibrinogen

What protein polymerizes when activated into an insoluble mesh to minimize blood loss (aka coagulation)?

Fibrin

Define hemostasis.

Ability of blood to maintain its volume.

How does hemostasis react to a tear in a blood vessel?

By vascular constriction and formation of platelet plugs

Vascular constriction in blood vessels is initiated by trauma, which then initiates:

Nervous stimulation from area, vasoconstrictors such as endothelin-1 (vessels), and thromboxane A2 and serotonin (platelets).

Platelet plug formation in blood vessels is initiated by trauma, which then initiates:

Thromboxane (tissues) and thrombin (from clot), which promote platelet aggregation.

Platelets are small cell fragments from which cell located in bone marrow?

Megakaryocytes

What is the three phase reaction of platelets that is initiated by contact with a damaged vessel wall?

Adherence (mostly to exposed collagen), aggregation (forming platelet plug), and secretion (mostly seretonin for vasoconstriction).

What is clot formation?

The initiation of the conversion of fibrinogen to fibrin via a clotting cascade.

What key initiating enzyme activates prothromin to thrombin?

Prothrombin activator

What is prothrombin activator?

Complex substance of several molecules, mostly Factor X (and Factor Va, Ca, membrane phospholipids)

Describe the clotting cascade from Prothrombin Activator to a dense mat of fibrin

Prothrombin activator -\> prothrombin -\> thrombin -\> fibrinogen -\> fibrin -\> fibrin threads -\> loose mesh -\> dense mat

What are the two pathways that can initiate the formation of a clot?

Intrinsic pathway and extrinsic pathway

Describe the intrinsic pathway of clot formation.

Starting with factor IX (with co-factor Factor VIIa) -\> Factor X -\> Factor Xa -\> prothrombin -\> thrombin -\> fibrinogen -\> fibrin

Describe the extrinsic pathway of clot formation.

Starting with factor VIIa (with co-factor Factor III) -\> Factor X -\> Factor Xa -\> prothrombin -\> thrombin -\> fibrinogen -\> fibrin

Which clotting pathway is fastest and which is strongest between extrinsic and intrinsic?

The Intrinsic pathway is more powerful, but is slower; extrinsic is faster, but weaker

What outside element is required for the extrinsic pathway to function, thus naming it so.

Tissue Factor (TF); required along with Factor VIIa to convert Factor X to Factor Xa

What role does Ca2+ have in the clotting pathways?

A common cofactor that is required in several reactions in both the extrinsic and intrinsic pathways.

During normal hemostasis, which pathway is preferred, extrinsic or intrinsic?

Neither; both are activated.

How does thrombin help to facilitate clot formation?

Thrombin positively feeds back onto both extrinsic (on VII, X) and intrinsic (on X, XI, VIII, V) pathways.

How long does clotting normally take?

~1-6 min

What is partial thromboplastin time?

A measurement of clotting time that gives an indication of the total amount of prothrombin in blood.

The last stage of a clot is retraction, which produces plasma free of clotting factors, also known as:

serum

How are the endothelial linings of BVs designed to be anti-clotting in nature?

Smooth, simple squamous epithelium, and a glycocalyx coating that repels clotting factors

How does consumption of clotting factors work as an anticlotting mechanism?

Clots minimize blood flow and cover collagen

What protein functions to reduce clotting factors by binding and inactivating thrombin?

Thrombin activates ? globulin Antitrombin III, which binds and deactivates it.

What is heparin and what does it do?

Anticoagulant produced by mast cells and basophils; binds to Antithrombin III and enhances its ability to destroy thrombin

What is fibrinolysis, or the fibrinolytic system?

System that breaks down fibrin.

When does the destruction of fibrin take place?

Almost immediately

What protease, activated simultaneously as fibrin forms, destroys clotting factors?

Plasminogen is activated to plasmin, which destroys fibrin

What cofactor helps activate plasminogen to plasmin?

Tissue plasminogen activator (tPA), released from injured tissues a day or so later

Where is Vit. K utilized and where is it made?

Required for synthesis of several clotting factors, produced by intestinal bacteria

What substance (drug) acts as a competative inhibitor for vitamin K sites in hepatocytes?

Coumarin (dicourmarol), used to minimize dangerous clotting

What bleeding disease results from a lack of Factor VIII?

Hemophilia A

What is a thrombus?

An abnormal clot that forms in a vessel

What is an embolism?

A thrombus that breaks away and freely floats, it can plug any vessel it cannot fit through.