Blood Anatomy Quiz

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Questions and Answers

What is the primary function of albumins in the plasma?

Production of red blood cells

Storage of iron

Transport of carbon dioxide

Contribution to osmotic pressure (correct)

Which of the following are major plasma electrolytes?

Na+, K+, Cl– (correct)

C6H12O6, H2O, Ca2+

O2, N2, He

H2CO3, C3H6O3, NO3–

Which component of blood is essential for the clotting process?

Regulatory proteins

Albumins

Globulins

Fibrinogen (correct)

How do red blood cells (RBCs) generate ATP for active transport?

Via glycolysis (anaerobic metabolism) Signup and view all the answers

What is the lifespan of red blood cells?

100-120 days Signup and view all the answers

Which substance is primarily involved in converting CO2 in the blood?

Carbonic Anhydrase Signup and view all the answers

What percentage of blood volume is constituted by red blood cells (RBCs)?

~45% Signup and view all the answers

Which nutrients are included in the organic nutrients found in blood?

Glucose, fatty acids, and amino acids Signup and view all the answers

What is the main effect of dehydration on hematocrit levels?

It elevates hematocrit due to decreased plasma volume. Signup and view all the answers

Which of the following statements about blood groups is correct?

Type A blood has anti-B antibodies in the plasma. Signup and view all the answers

What is the outcome when the recipient's plasma agglutinins attack the donor's RBCs during a blood transfusion?

A blood transfusion reaction occurs. Signup and view all the answers

How does an increase in plasma protein concentration affect the Erythrocyte Sedimentation Rate (ESR)?

It elevates ESR. Signup and view all the answers

What is MCHC, and how is it calculated?

Mean concentration of erythrocytes, calculated as MCH/MCV. Signup and view all the answers

What additional effects does polycythemia have on the circulatory system?

Increased blood viscosity and workload of the heart. Signup and view all the answers

Which blood type lacks both A and B surface antigens?

Type O Signup and view all the answers

Which statement is true regarding Rh factor in blood transfusions?

Most transfusion reactions result from Rh-D antigens. Signup and view all the answers

What is the primary role of platelets during hemostasis?

To form a platelet plug and aid in clotting Signup and view all the answers

What initiates the vascular phase of hemostasis?

Contraction of endothelial cells exposing the basal lamina Signup and view all the answers

What is the lifespan of platelets before they are removed by phagocytes?

10 days Signup and view all the answers

Which factor significantly enhances platelet aggregation and secretion?

Thromboxane A2 Signup and view all the answers

What is the role of actin and myosin in non-activated platelets?

To contract and release granule contents Signup and view all the answers

What substance do endothelial cells release during the vascular phase to stimulate smooth muscle contraction?

Tissue factor Signup and view all the answers

Which of the following is NOT a component found in platelets?

Nuclei Signup and view all the answers

Which process describes the cessation of bleeding and halting blood loss?

Hemostasis Signup and view all the answers

What is the primary role of Calcium in the coagulation process?

Conversion of fibrinogen to fibrin Signup and view all the answers

Which factor is crucial for the conversion of fibrin polymer to stable fibrin?

Factor XIII Signup and view all the answers

What function does von Willebrand factor serve during platelet plug formation?

Bonding collagen to platelets Signup and view all the answers

Which pathway is described as faster because it bypasses multiple steps in hemostasis?

Extrinsic pathway Signup and view all the answers

Which of the following is a critical function of Thrombin (Factor IIa) in hemostasis?

Converting fibrinogen to fibrin Signup and view all the answers

What role does Tissue Factor (TF) play in the coagulation process?

Serving as a receptor for VII/VIIa Signup and view all the answers

What does the positive feedback loop involving Thrombin accomplish in hemostasis?

Enhances thrombin generation Signup and view all the answers

What initially triggers the extrinsic pathway of coagulation?

Blood contacting tissue factor Signup and view all the answers

What is the primary function of hemoglobin in the blood?

To transport oxygen Signup and view all the answers

What is the approximate oxygen-carrying capacity of blood per liter?

~ 200 ml O2 /L blood Signup and view all the answers

During erythropoiesis, which cell type is formed directly from proerythroblasts?

Normoblasts Signup and view all the answers

Which vitamin is essential for erythropoiesis and is primarily found in animal origin foods?

Vitamin B12 Signup and view all the answers

What is the lifespan of a red blood cell (RBC)?

~100-120 days Signup and view all the answers

Which factor does NOT affect the absorption of iron in the body?

Calcium levels Signup and view all the answers

Which of the following is indicative of normal erythropoiesis?

Normal reticulocyte count within the range of 0.8-1.5% Signup and view all the answers

Which tissue is the primary site of erythropoiesis in adults?

Bone marrow Signup and view all the answers

What role do plasma proteins play in the maintenance of body fluids?

They contribute to osmotic pressure and transport substances. Signup and view all the answers

Which of the following statements about erythrocytes is correct?

Erythrocytes lack mitochondria and depend on glycolysis. Signup and view all the answers

How do bicarbonate ions influence blood pH?

They act as a buffer by binding to excess H+ ions. Signup and view all the answers

What type of protein is primarily responsible for transporting lipids in the plasma?

Albumins Signup and view all the answers

Which organic waste is primarily excreted from the body and produced during protein metabolism?

Urea Signup and view all the answers

What condition results in a greater workload on the heart due to increased red blood cell concentration?

Polycythemia Signup and view all the answers

What is the primary function of carbonic anhydrase in red blood cells?

Catalyzes the conversion of CO2 into bicarbonate. Signup and view all the answers

Which component of the blood is most involved in immune responses?

Globulins Signup and view all the answers

What is the consequence of a deficiency in both vitamin B12 and folate?

Macrocytic anemia Signup and view all the answers

Which of the following conditions primarily stimulates the release of erythropoietin (EPO) from the kidneys?

Decreased oxygen availability Signup and view all the answers

What characterizes macrocytic anemia?

Larger than normal red blood cells lacking hemoglobin Signup and view all the answers

Which factor contributes to men having a higher concentration of red blood cells compared to women?

Increased androgen levels Signup and view all the answers

What distinguishes primary polycythemia from secondary polycythemia?

Caused by a tumor or tumor-like condition Signup and view all the answers

Which nutrient deficiency is associated with microcytic anemia?

Iron Signup and view all the answers

What is the range of total body stores of folate in the human body?

5-10 mg Signup and view all the answers

Which of the following describes aplastic anemia?

Failure of bone marrow to produce adequate RBCs Signup and view all the answers

What primarily causes the increased viscosity of blood in polycythemia?

Dehydration leading to reduced plasma volume Signup and view all the answers

What factors contribute to a higher Erythrocyte Sedimentation Rate (ESR)?

Increased plasma protein concentration Signup and view all the answers

What is the main characteristic of blood type AB?

It has neither anti-A nor anti-B antibodies Signup and view all the answers

In blood transfusions, what is a primary risk associated with Rh-D factor incompatibility?

Donor’s blood being agglutinated by recipient’s antibodies Signup and view all the answers

What distinguishes Type O blood from the other blood types?

Absence of surface antigens Signup and view all the answers

Which of the following statements about plasma antibodies is accurate?

Type B blood contains antibodies against type A surface antigens Signup and view all the answers

Which condition causes red blood cells to stack and consequently sediment faster?

Higher plasma protein concentration Signup and view all the answers

Which factor is primarily responsible for most transfusion reactions?

Rh factor D antigen Signup and view all the answers

What is the primary role of plasmin in the process of blood clot resolution?

To digest fibrin and dissolve the clot Signup and view all the answers

Which of the following best describes a thrombus?

A mass formed from blood constituents that can block circulation Signup and view all the answers

What condition results from excessively low circulating platelets?

Thrombocytopenia Signup and view all the answers

What triggers the release of tissue plasminogen activator (tPA) into the vascular system?

Damage to endothelial cells and surrounding tissues Signup and view all the answers

Which statement best describes an embolus?

A freely floating thrombus in the bloodstream Signup and view all the answers

What role does von Willebrand factor play during platelet plug formation?

It forms a bridge between collagen and platelets. Signup and view all the answers

Which factor is necessary for converting fibrin polymer to stable fibrin?

Factor XIII Signup and view all the answers

Which statement best describes the role of Thrombin (Factor IIa) in hemostasis?

It enhances platelet aggregation and activates Factor XIII. Signup and view all the answers

What triggers the rapid formation of a clot in severe tissue trauma?

Activation of Tissue Factor (TF) Signup and view all the answers

Which pathway of coagulation is described as intrinsic?

Triggered by factors circulating in the blood. Signup and view all the answers

What is the primary role of Platelet-Derived Growth Factor (PDGF)?

To promote fibroblast proliferation. Signup and view all the answers

How does Calcium contribute to the coagulation process?

It acts as a catalyst for multiple clotting factors. Signup and view all the answers

What effect does the positive feedback loop involving Thrombin achieve in hemostasis?

It accelerates the activation of additional thrombin molecules. Signup and view all the answers

Study Notes

Blood Composition

Water makes up 92% of plasma, the liquid component of blood
Ions in plasma contribute to osmotic pressure
Plasma proteins include albumins, globulins, fibrinogen, and regulatory proteins
Albumins: 60% of plasma proteins, contribute to osmotic pressure, transport lipids and steroid hormones
Globulins: 35% of plasma proteins, transport ions, hormones and lipids; play a role in immune function
Fibrinogen: 4% of plasma proteins, essential for blood clotting
Organic nutrients in plasma are used for ATP production, growth and maintenance of cells; include lipids, carbohydrates, and amino acids
Organic wastes in plasma are carried to sites of breakdown or excretion; include urea, uric acid, creatinine, bilirubin

Erythrocytes (Red Blood Cells)

Constitute about 45% of blood volume
Lack nuclei, organelles, and ribosomes
Lifespan: ~100-120 days
Hemoglobin content > 97%, responsible for oxygen transport
Men: 14 - 17 Hb g/dL
Women: 12 - 16 Hb g/dL
Rely on glycolysis (anaerobic) for ATP production
Carbonic anhydrase converts CO2 into bicarbonate (HCO3-)
Hb binds to H+ ions, contributing to blood pH homeostasis

Hemoglobin

Quaternary structure, 4 folded polypeptide chains: 2 alpha and 2 beta chains
Each chain contains a single heme molecule
Heme molecule: pigment complex with an iron ion that binds to one O2 molecule
Binding is weak and reversible
Each Hb molecule can transport four molecules of O2
O2-carrying capacity of blood is approximately 200 mL O2/L blood

Erythropoiesis

Replacement rate: 2-3 x 10^6 RBCs/second
Sites of Erythropoiesis:
- Fetus: yolk sac, developing liver and spleen
- Children: most bones filled with red bone marrow
- Adults: bone marrow in ribs, sternum, vertebrae, pelvis, and upper end of long bones

Erythropoiesis Process

Hematopoietic stem cells in bone marrow give rise to proerythroblasts
Proerythroblasts develop into erythroblasts in 3 steps:
1. Ribosome synthesis in early erythroblasts
2. Hb accumulation in late erythroblasts and normoblasts
3. Ejection of the nucleus from normoblasts and formation of reticulocytes
Reticulocytes continue Hb synthesis, leave bone marrow and complete differentiation to mature RBCs in blood
Reticulocyte count (normal range 0.8-1.5%) is indicative of erythropoiesis

Erythropoiesis Requirements

Proteins, lipids, and carbohydrates
Iron, vitamin B12, and folic acid

Iron

Essential trace element, required in low concentrations
Normal diet provides 10-15 mg/day, only 10% absorbed
Amount absorbed depends on the state of iron sufficiency in the body
Daily loss for males: 0.5-1.0 mg (greater for women due to menstruation and pregnancy)

Vitamin B12 and Folate

Vitamin B12: recommended intake of 2 micrograms (µg)/day, dietary source: foods of animal origin
Folate: dietary source: leafy green vegetables, fruits, and legumes

Relative Polycythemia

Dehydration can elevate the hematocrit, RBC count remains the same, but plasma volume is reduced
Polycythemia increases blood viscosity, leading to increased peripheral resistance and workload on the heart

Erythrocyte Sedimentation Rate (ESR)

Erythrocytes sediment faster with increased plasma protein concentration
Increased ESR is a nonspecific indicator of infection, autoimmune, and inflammatory diseases

Blood Groups & Blood Transfusion Reactions

Blood types A, B, AB, and O are based on distinct antigens on RBC surfaces
Type A blood has RBCs with surface antigen A only
Type B blood has RBCs with surface antigen B only
Type AB blood has RBCs with both A and B antigens
Type O blood has RBCs lacking both A and B antigens
Plasma contains antibodies (agglutinins) that react with foreign surface antigens

Rh Factor

Discovered in rhesus monkeys
Antigens: C (c), D (d), and E (e)
Rh-D is responsible for most transfusion reactions
Rh-D positive (Rh+)
Rh-D negative (Rh-)

Blood Transfusion Reactions

Donor RBCs are attacked by recipient plasma agglutinins (antibodies)

Hemostasis

Cessation of bleeding, halting blood loss from damaged vessels
First step of tissue repair

Phases of Hemostasis

Vascular Phase:
- Endothelial cells contract, exposing the underlying basal lamina
- Lasts for 30 minutes
- Endothelial cells release chemical factors and hormones, including tissue factor, ADP, and thromboxane A2
- Stimulates vasoconstriction and tissue repair
- Endothelial cell membranes become sticky
Platelet Phase:
- Non-activated platelets do not adhere to normal endothelial cells due to repulsive glycoproteins on platelet surface
- Platelets adhere to exposed collagen, forming a platelet plug
- Actin and myosin contract, forcing out platelet granule contents
- Degranulated platelets secrete:
  - Thromboxane A2 (enhances vascular spasms)
  - ADP (enhances platelet aggregation and secretion)
  - Calcium (essential for clotting)
  - PDGF (fibroblasts)
  - VEGF (vascular endothelial cells)
  - Factor XIII (FSF)

Coagulation Phase

Series of enzymatic reactions that lead to the conversion of fibrinogen to fibrin
Fibrin forms a meshwork that traps blood cells and platelets, forming a clot

Coagulation Pathways

Intrinsic Pathway: activated by factors within the blood
Extrinsic Pathway: activated by factors outside the blood
Common Pathway: both pathways converge to activate factor X

Tissue Factor (TF) and Factor VIIa

TF is a transmembrane receptor for VII(7)/VIIa, expressed in cells below the endothelium
TF is exposed when the endothelium is damaged
TF (Factor III) activates factor VIIa, triggering the extrinsic pathway

Coagulation Factors

All factors, except TF and Factor IV (Calcium) are produced by the liver
Factors X, IX, VII and II require vitamin K
Thrombin (Factor IIa) is a key enzyme in the coagulation cascade

Thrombin (Factor IIa) Functions

Converts fibrinogen to fibrin
Activates Factor XIII (stabilizes fibrin meshwork)
Releases PF3 from platelets
Enhances platelet aggregation
Enhances its own production (positive feedback loop)

Clot Dissolution (Fibrinolysis)

Plasminogen is trapped within the clot
Tissue plasminogen activator (tPA) converts plasminogen to plasmin
Plasmin breaks down fibrin, dissolving the clot

Plasma Components

Plasma consists primarily of water (92%), accounting for the majority of blood volume.
Plasma Proteins constitute a critical component of plasma and contribute to its osmotic pressure, transport, and coagulation functions.
- Albumins (60%): Major contributors to the osmotic pressure of plasma, aiding in the transportation of lipids and steroid hormones.
- Globulins (35%): Facilitate the transportation of ions, hormones, and lipids, playing a vital role in immune functions.
- Fibrinogen (4%): A crucial element of the clotting system, it can be converted to insoluble fibrin upon activation.

Redblood Cells (RBCs)

RBCs are the most abundant cellular element of blood, constituting approximately 45% of blood volume.
Normal RBC Count:
- Males: 4.5-6.5 x 10^9/ml
- Females: 3.9-5.6 x 10^9/ml
RBC Lifespan: 100-120 days
RBC Structure:
- Lacking a nucleus and organelles, RBCs are optimized for oxygen transport.
- Their biconcave shape allows for efficient oxygen diffusion and flexible movement within capillaries.
Hemoglobin: The primary component of RBCs, responsible for oxygen transport.
- Normal Hemoglobin Levels:
  - Males: 14-17 g/dl
  - Females: 12-16 g/dl
Metabolic Activity: Rely on glycolysis for energy production as they lack mitochondria.
Carbonic Anhydrase: Catalyzes the conversion of CO2 to bicarbonate (HCO3-), the primary form of CO2 transport in the blood.
pH Homeostasis: Hemoglobin is crucial in regulating blood pH by binding to H+ ions.

Regulation of Erythropoiesis

Erythropoietin (EPO): A hormone primarily secreted by the kidneys that regulates red blood cell production.
- Stimulated by:
  - Hypoxia (decreased oxygen availability)
  - Reduced RBC number or function
  - Increased tissue demand for oxygen
  - Hemorrhage or anemia
EPO Function:
- Stimulates hematopoietic stem cells to form proerythroblasts.
- Enhances proliferation of proerythroblasts and erythroblasts.
- Promotes Hb synthesis.
- Increases RBC production significantly.

Anemia

Definition: Characterized by a below-normal oxygen-carrying capacity of the blood.
Causes:
- Decreased rate of erythropoiesis
- Excessive loss of RBCs
- Reduced hemoglobin (Hb) in RBCs
Types of Anemia:
- Microcytic anemia: Smaller than normal RBCs, often caused by Iron deficiency.
- Macrocytic anemia: Larger than normal RBCs but lacking Hb, often caused by vitamin B12 or folate deficiency.
- Aplastic anemia: Failure of the bone marrow to produce sufficient RBCs, despite adequate resources, often due to radiation damage or chemotherapy.

Polycythemia

Definition: An excess of circulating RBCs, leading to an elevated hematocrit (normal: 37-54%).
Primary Polycythemia:
- Caused by tumor-like condition of the bone marrow.
- High RBC count: 7-11 x 10^9/ml
- High hematocrit: 70-80%
Secondary Polycythemia:
- Induced by EPO, an adaptive response to improve oxygen-carrying capacity in response to environmental factors like high altitude.
- Elevated RBC count: 6-8 x 10^9/ml
Relative Polycythemia:
- Caused by dehydration, leading to a decrease in plasma volume while RBC count remains constant, artificially elevating hematocrit.