Blood Physiology and Hemostasis Quiz

Blood and Circulatory System Disorders

• The circulatory system comprises the cardiovascular and lymphatic systems.
• This chapter covers blood vessels, blood composition, and associated disorders.

Blood Vessels

• Arteries and arterioles carry blood away from the heart.
• Veins and venules return blood to the heart.
• Capillaries are the site of microcirculation within tissues, facilitating gas, nutrient, and waste exchange.
• Systemic circulation involves the exchange of gases, nutrients, and wastes in tissues.
• Pulmonary circulation facilitates gas exchange in the lungs.
• Arteries contain endothelium, smooth muscle, and connective tissue layers.
• Veins have endothelium, smooth muscle, and connective tissue (with elastic and collagen fibers) but include valves.
• Capillaries comprise a single layer of endothelium.

Blood

• Blood consists of plasma (and plasma proteins) and cellular components (erythrocytes, leukocytes, and thrombocytes/platelets).
• Plasma proteins include albumin, globulins, and fibrinogen.
• Cellular components include erythrocytes (red blood cells), leukocytes (white blood cells) and thrombocytes/platelets (involved in clotting).

Hematopoiesis

• Hematopoiesis is the formation of blood cells within bone marrow from a stem cell called a hemocytoblast.
• The formation of blood cells from stem cells involves multiple phases and types of cells in various stages of development.

Erythrocytes (Red Blood Cells)

• Erythrocytes have a biconcave shape.
• They lack a nucleus in the mature stage.
• They contain hemoglobin, which includes a globin portion and heme group.
• Erythrocytes have a lifespan of approximately 120 days.
• Erythropoietin, originating in the kidneys, drives red blood cell production.

Breakdown of Hemoglobin

• Senescent or damaged red blood cells are recycled in the spleen and liver.
• Hemoglobin is broken down into heme and globin.
• Globin is broken down into amino acids and reused.
• Heme is broken down into iron and bilirubin.
• Iron is recycled and bilirubin is processed by the liver into bile.

Blood Clotting (Hemostasis)

• Hemostasis involves three stages: vasoconstriction, platelet plug formation, and coagulation.
• Plasmin eventually breaks down the blood clot.

Hemostasis and Anticoagulant Drugs

• Various pathways (intrinsic and extrinsic) are involved in blood clotting.
• Different drugs, such as oral anticoagulants and thrombolytics, interfere with blood clotting, either to stop or to facilitate clotting depending on the purpose and condition.

Blood Typing

• Blood typing is based on antigens present on the surface of red blood cells.
• The ABO blood groups are based on the presence or absence of A and B antigens and corresponding antibodies.
• The Rh system is based on the presence or absence of the D antigen.

Diagnostic Tests

• Complete blood counts (CBCs) measure red blood cell count, white blood cell count, and platelet count.
• Morphology (examining a blood smear) helps to identify different types of anemia.
• Hematocrit determines the percentage of red blood cells in total blood volume.
• Hemoglobin quantifies hemoglobin per unit blood volume and measures oxygen-carrying capacity.
• Other tests, such as reticulocyte counts, chemical analyses (e.g., iron, vitamin B12, folic acid), bleeding time, prothrombin time, and partial thromboplastin time, assist in blood disorder diagnosis.

Blood Therapies

• Whole blood, packed red blood cells, and platelets are used as therapeutic interventions for severe anemia or thrombocytopenia.
• Plasma or colloid solutions maintain blood volume.
• Artificial blood products provide compatibility with different blood types.
• Epoetin alfa is an artificial form of erythropoietin that aids in red blood cell production in conditions like anemia, chronic renal failure, or before certain surgeries.
• Bone marrow or stem cell transplants treat certain cancers and immunodeficiency diseases.
• Drugs help with blood clotting.

Blood Dyscrasias

• Describes various blood disorders.
• Anemias are characterized by a decreased ability to carry oxygen, usually caused by hemoglobin deficit.
• Compensation mechanisms try to compensate for the reduced ability to carry oxygen.
• Iron deficiency anemia and pernicious anemia are examples of common anemias, differing in cause, symptoms, and treatment.
• Myelodysplastic syndromes happen when bone marrow produces inadequate/incomplete cells.
• Aplastic anemia is a bone marrow failure affecting all blood cell types.
• Hemolytic anemias involve excessive destruction of red blood cells.
• Sickle cell anemia is a genetic disorder causing abnormal hemoglobin, leading to deformed red blood cells causing various complications.
• Polycythemia (primary and secondary types) reflects an increased number of red blood cells, often caused by an underlying condition or prolonged hypoxia.

Blood Clotting Disorders

• Common clotting disorders include hemophilia A, von Willebrand's disease, and disseminated intravascular coagulation (DIC).
• Hemophilia and von Willebrand's disease involve deficiencies in specific clotting factors.
• DIC is characterized by widespread clotting and bleeding, typically resulting from an underlying condition.

The Leukemias

• Leukemias are cancers affecting white blood cells, causing uncontrolled production and release of immature and nonfunctional white blood cells.
• The different leukemias, like acute lymphocytic leukemia (ALL), acute myelogenous leukemia (AML), chronic lymphocytic leukemia (CLL), or chronic myelogenous leukemia (CML), can affect different age groups and are categorized by cell type.
• Various diagnostic tests and treatment approaches, such as chemotherapy and biological therapy (e.g., interferon), are used in leukemia management.
• Complications of leukemia include opportunistic infections (pneumonia), congestive heart failure, hemorrhage, liver failure, renal failure, and central nervous system depression.

Multiple Myeloma

• Multiple myeloma is a cancer of plasma cells (one type of white blood cell) characterized by increased plasma cell counts, bone tumors, and impaired functioning of other blood cells.
• The prognosis for multiple myeloma is generally poor, and the disorder often leads to reduced lifespan.