Blood

Questions and Answers

Albumin serves as a transport vehicle for ___ and _

Albumin serves as a transport vehicle for fatty acids and steroid hormones

What is the function of fibrinogen in the blood?

Maintaining fluid balance

Blood clotting (correct)

Regulating body temperature

Transporting hormones

Which of the following is NOT a function of blood?

Defense against pathogens

Producing insulin (correct)

Transporting metabolic wastes

Regulating pH

Which type of plasma protein is primarily responsible for maintaining fluid balance?

Albumin Signup and view all the answers

What does serum consist of?

Plasma without fibrinogen Signup and view all the answers

Which of the following is considered an electrolyte found in plasma?

Sodium Signup and view all the answers

Match to appropriate function

Erythrocytes = Aid in oxygen transportation Leukocytes (WBC) = Immune defense Platelets = Hemostasis Free bee = Free bee Signup and view all the answers

What is the primary growth factor involved in the proliferation and differentiation of erythroid precursors into rubriblasts?

Erythropoietin (EPO) Signup and view all the answers

Which nutrient is NOT required for the synthesis of heme in erythrocytes?

Vitamin K Signup and view all the answers

What feature of erythrocytes allows them to have a greater tolerance for osmotic swelling?

Lack of organelles Signup and view all the answers

What property of erythrocytes contributes to a larger surface area to volume ratio?

Discoid shape Signup and view all the answers

What is a common consequence of deficiencies in pyruvate kinase (PK) and phosphofructokinase (PFK) in erythrocytes?

Decreased glycolytic rates Signup and view all the answers

What is the main function of erythrocytes in mammals?

Carry oxygen and carbon dioxide Signup and view all the answers

What are the determinants of aged erythrocytes that lead to their removal by splenic macrophages?

Oxidative injury and surface membrane alterations Signup and view all the answers

What is the clinical significance of elevated direct bilirubin levels?

Suggests liver dysfunction or hemolysis Signup and view all the answers

Which of the following is a sign associated with erythrocytosis?

Increased risk of thrombotic events Signup and view all the answers

What is the primary difference between hematocrit and packed cell volume (PCV)?

Hematocrit is calculated; PCV is directly measured after centrifugation Signup and view all the answers

What change in plasma volume leads to relative polycythemia?

Decreased plasma volume Signup and view all the answers

Which of the following describes a common qualitative change in red blood cells?

Abnormal morphology or inclusions Signup and view all the answers

What distinguishes granulocytes from agranulocytes?

Presence of cytoplasmatic granules Signup and view all the answers

Which type of white blood cell is primarily responsible for initiating the inflammatory response?

Neutrophils Signup and view all the answers

How long do neutrophils typically survive in the bloodstream?

5-10 hours Signup and view all the answers

What characteristic of neutrophils allows them to migrate rapidly into tissues?

Shape of the nucleus Signup and view all the answers

Which type of leukocyte would show granules that do not stain with any dye?

Neutrophils Signup and view all the answers

What is the role of neutrophils in an inflammatory response?

To phagocytose infectious agents Signup and view all the answers

What is the main role of eosinophils in the immune response?

Fighting parasitic infections Signup and view all the answers

Which type of cell is considered part of the adaptive immune response?

B cells Signup and view all the answers

What distinguishes monocytes from lymphocytes?

Shape of the nucleus Signup and view all the answers

What is an important non-immune function macrophages/monocytes have?

Recycling dead cells Signup and view all the answers

Which of the following is true regarding basophils?

They are chemically similar to mast cells. Signup and view all the answers

Which statement about lymphocytes is accurate?

They include NK cells which are part of innate immunity. Signup and view all the answers

What is a significant characteristic of eosinophils in relation to allergic responses?

They release toxic substances from their granules. Signup and view all the answers

Which type of cell primarily carries out phagocytic functions in the immune system?

Monocytes Signup and view all the answers

What percentage of T lymphocytes typically survive the selection process?

1-2% Signup and view all the answers

What triggers naive T cells to stop migrating and start clonal replication?

Contact with antigen-presenting cells Signup and view all the answers

What is indicated by a left shift in neutrophils during a leukocyte evaluation?

An increase in immature neutrophils Signup and view all the answers

Which lymphocytes primarily circulate and make contact with multiple antigen-presenting cells in lymph nodes?

Naive T cells Signup and view all the answers

What is the primary role of B lymphocytes after their selection process?

To produce antibodies Signup and view all the answers

What is the physiological consequence of neutrophilia?

Increase in the number of neutrophils above normal limits Signup and view all the answers

What percentage of B lymphocytes typically survives the selection process?

Less than 20% Signup and view all the answers

What is the expected outcome of evaluating leukocytes?

Detecting hematopoietic neoplasia Signup and view all the answers

What is the primary function of platelets in hemostasis?

Form a clot by creating a platelet plug Signup and view all the answers

What regulates thrombopoiesis?

Thrombopoietin (TPO) Signup and view all the answers

Which phase in primary hemostasis involves vascular constriction?

Vascular phase Signup and view all the answers

What initiates the adhesion of platelets to the subendothelium during primary hemostasis?

Von Willebrand Factor (vWF) Signup and view all the answers

What is a direct effect of increased free thrombopoietin (TPO) on megakaryocytes?

Increased differentiation and production of platelets Signup and view all the answers

What is the lifespan of a platelet in circulation?

4-10 days Signup and view all the answers

What is the primary function of von Willebrand Factor (vWF) during platelet activation?

It binds to subendothelial collagen and aids platelet adhesion Signup and view all the answers

In which blood component does platelet activation primarily occur?

Platelets Signup and view all the answers

What structural change do platelets undergo during activation?

Form smooth discs to spheres with filopodia Signup and view all the answers

What is a characteristic sign of von Willebrand Disease in affected dogs?

Excessive bleeding from minor wounds Signup and view all the answers

What is the role of phosphatidylserine during platelet activation?

To move to the outer membrane surface and stimulate coagulation Signup and view all the answers

How does vWF affect factor VIII in the bloodstream?

It binds to and prolongs the half-life of factor VIII Signup and view all the answers

What is one of the main clinical challenges associated with von Willebrand Disease?

Affected dogs can have normal lifespans with appropriate management Signup and view all the answers

Match to their correct function

Glutathione = Protects RBC from oxidative damage Cytochrome B5 reductase = Reduces the non-functional methemoglobin 2,3 DPG = Promotes the release of oxygen to tissues Free bee = Free bee Signup and view all the answers

Aggregation to form a platelet plug is a reversible process

False Signup and view all the answers

Study Notes

Functions of Blood

Transports dissolved gases (oxygen and carbon dioxide), nutrients, hormones, and metabolic wastes throughout the body.
Plays a crucial role in maintaining fluid balance within the circulatory system.
Regulates pH levels and ion composition of interstitial fluids, ensuring stability in cellular environments.
Engages in hemostasis, which restricts fluid loss at injury sites to prevent excessive bleeding.
Provides defense mechanisms against toxins and pathogens, contributing to immune function.
Helps stabilize body temperature by redistributing heat throughout the body.

Plasma Proteins

The primary types of plasma proteins are albumin, globulins, and fibrinogen.
Albumin maintains osmotic pressure and transports various substances in the blood.
Globulins serve critical roles in immune response and transport of ions and hormones.
Fibrinogen, produced by the liver, is vital for the blood clotting process.

Serum and Plasma

Serum is defined as plasma that has had fibrinogen removed, resulting in a liquid component without clotting factors.

Solutes in Plasma

Electrolytes such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), chloride (Cl), bicarbonate (HCO3), phosphate (PO4), and sulfate (SO4) are crucial for numerous physiological functions.
Non-protein nitrogen-containing compounds found in plasma include urea and creatinine, which are waste products.
Nutrients like glucose, lipids, and amino acids are transported by the plasma to cells for nourishment and metabolism.
Gases such as oxygen, carbon dioxide, and nitrogen are dissolved in plasma, facilitating respiration and metabolic processes.
Additionally, plasma contains hormones and enzymes that regulate various body functions.

Hematopoiesis Overview

Hematopoiesis involves the proliferation and differentiation of hematopoietic stem cells into mature blood cells.
Key processes include erythropoiesis (red blood cells), leukopoiesis (white blood cells), and thrombopoiesis (platelets).

Erythrocytes (Red Blood Cells)

Main functions:
- Oxygen transport to tissues
- Carbon dioxide transport from tissues
- Buffers hydrogen ions (H+)
Structural characteristics:
- Mammalian erythrocytes are anucleate and lack organelles.
- Shape is circular, flattened, and bi-concave, enhancing surface area and minimizing diffusion distance.
- Diameter ranges from 4 to 8 µm, allowing for flexibility and plasticity.
- Possesses a cytoskeleton that supports shape changes and osmotic tolerance.

Erythropoiesis

Stimulated by various growth factors:
- Local factors in bone marrow: stem-cell factor (SCF), IL-3, GM-CSF, and thrombopoietin (TPO).
- Peripheral tissue factor: erythropoietin (EPO) and triiodothyronine (T3).
EPO is crucial for the proliferation and differentiation of erythroid precursor cells into rubriblasts, the first identifiable erythroid cells.
The regulation of red blood cell (RBC) mass is dependent on cellular oxygen levels.

Nutritional Requirements for Erythropoiesis

Essential nutrients include:
- Iron: necessary for heme synthesis.
- Vitamins B6, B9, B12: critical for various metabolic processes.
- Copper and cobalt: play roles in erythropoiesis.
Due to the absence of mitochondria, erythrocytes utilize anaerobic metabolism and do not consume the oxygen being transported.

Hemoglobin Structure and Function

Hemoglobin binds oxygen reversibly for efficient transport.
Composed of globin and heme; includes four polypeptide chains (two alpha and two beta chains).

Biochemical Components of Erythrocytes

Important enzymes and compounds include:
- Pyruvate kinase (PK): vital for glycolysis.
- Phosphofructokinase (PFK): crucial in regulating glycolytic flux.
- Phosphorus: integral for ATP generation.
Deficiencies in these components can result in decreased glycolytic rates, reduced ATP production, and premature death of red blood cells.

Removal of Aged Erythrocytes

Erythrocytes circulate for several months before removal.
Aging triggers oxidative injury and ATP depletion, leading to surface membrane changes.
Senescent erythrocytes become denser and less deformable.
Key modifications include phosphatidylserine exposure and altered Band 3 proteins.
Membrane carbohydrate residues also change with age.
Splenic macrophages are responsible for the removal of aged erythrocytes.

Bilirubin Metabolism

Indirect bilirubin is produced in the mononuclear phagocyte system (MPS) and binds to albumin in the bloodstream.
Direct bilirubin is formed through glucuronidation in the liver.

Clinical Importance of RBC Evaluation

Quantitative changes observed in conditions like anemia, which is characterized by a decrease in RBCs.
Causes of anemia include blood loss, decreased production, and increased destruction.
Clinical signs of anemia: pale mucous membranes, weakness, lethargy, rapid pulse, and rapid breathing.
Erythrocytosis results from an increase in RBCs and can be categorized into absolute and relative forms.
- Absolute polycythemia can be primary (EPO-independent) or secondary (EPO-dependent).
- Signs include increased thirst/urination (PU/PD), lethargy, and brick red mucous membranes, with an elevated risk of thrombotic events.
- Relative polycythemia occurs due to decreased plasma volume.

Hematocrit vs. PCV

Both hematocrit and Packed Cell Volume (PCV) denote the percentage of total blood volume occupied by RBCs.
PCV is manually measured via microhematocrit after centrifugation.
Hematocrit is calculated based on RBC number and size.

Qualitative Changes in RBCs

Abnormal morphology and the presence of inclusions can indicate qualitative changes in erythrocytes.

Leukocytes (WBCs)

Heterogeneous population involved in the immune response.
Classified morphologically based on nucleus shape: mononuclear or polymorphonuclear.
Presence of cytoplasmic granules distinguishes granulocytes from agranulocytes.
Critical for both innate and adaptive immunity and hold significant diagnostic value.

Granulocytes

Named according to staining properties showing affinity for different dyes.
Eosinophils: Stain with acidic dyes, involved in combating parasitic infections and allergies.
Neutrophils: Most abundant WBC, critical in the inflammatory response, with a segmented nucleus allowing quick tissue migration.
Basophils: Rare, involved in allergic responses and reacting to parasites; functionally similar to mast cells.

Neutrophils

Primary responders in inflammation, capable of phagocytosing pathogens and enhancing inflammation through pro-inflammatory substances.
Short lifespan in bloodstream (5-10 hours) and limited survival in tissues (few days).
Serve as a primary indicator for inflammatory processes.

Eosinophils

Predominantly located in the gastrointestinal mucosa.
Play a significant role in responses to parasitic infections and Type I hypersensitivity reactions.
Release toxic granules to destroy pathogens and assist in inflammation.

Basophils

Present in very low numbers and associated with allergic reactions.
Less effective than eosinophils in response to parasites.

Mononuclear/Agranulocytes

Characterized by a single large nucleus with fewer visible granules compared to granulocytes.
Monocytes: Larger than lymphocytes with variable nuclei shapes; differentiate into macrophages.
Lymphocytes: Generally possess round nuclei; key players in adaptive immunity.

Monocytes/Macrophages

Monocytes differentiate into macrophages, which are vital for phagocytosis and immune coordination.
Activated macrophages inform other immune cells of infections and present antigens to lymphocytes.
Undertake non-immune tasks, such as recycling dead cells, without triggering immune responses.

Lymphocytes

Diverse group essential for adaptive immunity.
B cells: Contribute to antibody production (10-40% of lymphocytes).
T cells: Attack foreign or cancerous cells (50-75% of lymphocytes).
NK cells: Kill tumor and infected cells, representing the innate immune response (5-10%).
Majority inhabit lymphoid organs rather than circulating in the blood (only 2-10%).

Lymphocyte Formation

Precursors of T cells migrate to the thymus, while B cell precursors either move to the Bursa of Fabricius or remain in the bone marrow in mammals.
Only 1-2% of T lymphocytes survive the selection process, indicating a strong selection mechanism.
Less than 20% of B lymphocytes manage to survive; only a few selected lymphocytes enter circulation and reach peripheral lymphoid organs.

Lymphocyte Circulation

Naive T cells circulate and are attracted to lymph nodes by chemotactic factors, making contact with numerous antigen-presenting cells daily.
Likelihood of a naive T cell being specific for a particular antigen ranges from 1 in 10,000 to 1 in 1,000,000.
If a naive T cell is not primed by an antigen, it recirculates to attempt activation in another lymph node.
Primed T cells, upon recognition of specific antigens, stop migrating, initiate cytokine release, and begin clonal replication for a few days.
Armed effector T cell clones exit the lymphoid organ and are directed to infection sites.

Leukocyte Evaluation

Assessment of white blood cells (WBCs) focuses on count and morphology.
Key objectives include detection of inflammation, identifying infections, determining prognosis, and recognizing hematopoietic neoplasia.
Diagnosis of leukemia can also be made through leukocyte evaluation.

Neutrophils and Shift Analysis

Neutrophilia refers to an increased number of neutrophils in the bloodstream, ranging from mild to severe conditions.
Neutropenia indicates a reduced number of neutrophils in the blood.
A "left shift" signifies an increase in immature neutrophils, regardless of total neutrophil count, often serving as an indicator of severe inflammatory responses.
Normally, only a small number of band forms are expected; a significant left shift with more immature neutrophils indicates a more intense inflammatory stimulus.

Platelets

Small, anucleated, round to oval thin discs.
Lifespan of 4-10 days, crucial for primary hemostasis.

Thrombopoiesis

Platelet precursor is the megakaryocyte, found in bone marrow and sometimes lungs.
Long proplatelet processes fragment into individual platelets.
Megakaryocytes are absent in nonmammalian species; these species use normal mitosis for precursors.
Regulated by thrombopoietin (TPO), produced by the liver, kidneys, and muscle.
Free TPO levels increase megakaryocyte production and differentiation; low platelet counts lead to increased free TPO.

Hemostasis

Physiological process halting bleeding at injury sites while maintaining blood flow.
Involves primary hemostasis (platelet plug formation), secondary hemostasis (clot formation), and tertiary hemostasis (fibrinolysis and clot dissolution).

Primary Hemostasis

Vascular phase involves vascular constriction.
Platelet phase includes:
- Platelet adhesion to subendothelium, reliant on von Willebrand Factor (vWF).
- Activation leading to shape changes, membrane alterations, and granule secretion.
- Aggregation into an irreversible platelet plug, aided by ADP and Thromboxane A2.

Von Willebrand Factor (vWF)

Synthesized by endothelial cells and platelets, circulates as multimeric strings.
Composed of over 100 subunits, molecular weights ranging from 500 to 20,000 kDa.
Functions as "platelet glue" by binding to subendothelial collagen, facilitating platelet interactions.
Binds and prolongs the half-life of factor VIII in blood.

Platelet Activation

Triggered by adhesion (to collagen) and ligation (to thrombin and TXA2).
Shape change transforms smooth discs into spheres with extensive filopodia, increasing surface area.
Membrane flip moves negatively charged phosphatidylserine to the outer surface, enhancing procoagulant activity.
Granule secretion includes ADP, calcium, and factors V and VIII to facilitate further platelet activation.

Secondary Hemostasis

Provides surfaces for fibrin formation and deposition necessary for clot stability.
Facilitates clot retraction through actomyosin contractions, aiding in wound closure and vessel patency.

Role in the Immune System

Platelets contribute to immune responses apart from hemostatic functions.

Clinical Correlation - Von Willebrand Disease

Most common inherited bleeding disorder in dogs, characterized by reduced, non-functional, or absent vWF.
Certain breeds, such as Doberman Pinschers and Poodles, are more susceptible.
Symptoms include skin bruising, prolonged bleeding from minor wounds, and excessive bleeding during surgery.
Diagnosis through vWF antigen assay and genetic testing.
No cure; management includes avoiding risky activities and pre-surgery plasma transfusion to prevent hemorrhage.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Understand the function and composition of blood, clinical relevances etc