Blood Composition and Functions Quiz

Veins and Varicose Veins

• Superficial veins lack muscle support and can stretch out due to excessive hydrostatic pressure, leading to valve damage and backflow of blood.
• Familial tendency, trauma, IV administration, thrombophlebitis, standing, and tight clothing can contribute to varicose veins.
• Treatment includes support hose, elevating feet, and sclerosing agents to obliterate veins.

Thrombophlebitis and Phlebothrombosis

• Thrombophlebitis refers to thrombus development in a vein with inflammation.
• Phlebothrombosis is a thrombus formation without inflammation.
• 3 factors contribute to thrombus development: stasis of blood, endothelial injury, and increased blood coagulation.
• Venous thrombosis can lead to pulmonary embolism.

Shock

• Shock results from decreased circulating blood volume, leading to decreased tissue perfusion and hypoxia.
• Types of shock include:
  • Hypovolemic shock: decreased blood volume
  • Cardiogenic shock: decreased heart contraction
  • Obstructive shock: interference with blood flow
  • Neurogenic shock: suppression of sympathetic nervous system
  • Anaphylactic shock: severe allergic reaction
  • Septic shock: systemic response to infection

Blood

• Composition of blood: 55% plasma, 45% formed elements
• Hematocrit: proportion of cells in blood, indicates viscosity
• Plasma proteins: albumin, globulins, and fibrinogen
• Blood cells originate in bone marrow

Blood Cells and Hematopoiesis

• RBCs: non-nucleated after maturation, carry oxygen using hemoglobin
• Erythropoietin: hormone produced by kidneys, stimulates erythrocyte production
• RBC count: 4.2-6.2 million per cubic mm
• Hemoglobin: 4 heme groups and globin, carries oxygen
• RBC life span: 120 days

Leukocytes

• Divided into granulocytes and agranulocytes
• Neutrophils: most common, survive 4 days, respond to danger
• Lymphocytes: comprise 40-50% of WBCs, B cells and T cells
• Monocytes: enter tissue, become macrophages
• Differential count: indicates number of WBCs in the sample

Thrombocytes

• Necessary for blood clotting (hemostasis)
• Aspirin and other pain medicines can reduce platelet stickiness
• Hemostasis: 3 steps: vascular spasm, platelet plug formation, coagulation

Antigenic Blood Types

• ABO and Rh blood grouping
• A or B antigens on RBC cell membranes
• Universal donor: O negative, universal recipient: AB positive

Diagnostic Tests

• CBC: complete blood count
• Leukocytosis: too high, often indicates inflammation or infection
• Leukopenia: too low, often indicates viral infection
• Hematocrit: percentage of blood volume
• Hemoglobin: measured as mean cellular hemoglobin (MCH)

Blood Clotting Disorders

• Excessive bleeding: thrombocytopenia, chemotherapy, defective platelet function
• Von Willebrand disease: deficiency of von Willebrand factor
• Treatment: injection or nasal spray of desmopressin

Disseminated Intravascular Coagulation (DIC)

• Often life-threatening due to excessive bleeding and clotting
• Initiated by various disorders, including obstetric complications, Gram-negative bacteria, and carcinomas

Anemias

• General information: reduce oxygen transport in blood, cause fatigue and shortness of breath
• Compensation mechanisms: tachycardia, peripheral vasoconstriction
• Signs and symptoms: pallor, fatigue, dyspnea, tachycardia
• Chronic anemia: leads to congestive heart failure

Iron Deficiency Anemia

• Reduction in iron leads to reduction in carrying capacity of oxygen
• Causes: dietary deficiency, chronic blood loss, malabsorption
• Signs and symptoms: pallor, fatigue, lethargy, cold intolerance

Pernicious Anemia (Vitamin B12 Deficiency)

• Characterized by large, immature, nucleated erythrocytes
• Deficiency of B12 or B9 (folic acid)
• Signs and symptoms: pallor, fatigue, lethargy, cold intolerance
• Treatment: supplements, increase intake of iron-rich foods

Neoplastic Blood Disorders

• Polycythemia: increased production of RBCs and other cells in bone marrow
• Leukemias: group of neoplastic disorders involving WBCs
• Acute leukemias: characterized by high number of 'blast' cells in bone marrow and peripheral circulation
• Chronic leukemias: have higher percentage of mature cells with mild signs, insidious onset, and better prognosis

Vascular Disorders

• Hypertension: high blood pressure

• Causes: familial tendency, trauma, IV administration, thrombophlebitis, standing, and tight clothing

• Treatment: phlebotomy, removal of blood to minimize risk of thromboses or hemorrhage### Hypertension

• Known as the "silent killer" due to insidious onset and mild signs

• Categories: Primary (idiopathic, blood pressure consistently over 140/90), Secondary (due to renal or endocrine disease/tumor), and Malignant (extremely high blood pressure, a true emergency)

• Signs and symptoms: Vague in early stages; fatigue, malaise, morning headache; key sign is consistently elevated blood pressure

• Treatment: Compliance is key; lifestyle changes (low salt diet, reduce body weight, less stress, increase exercise); mild diuretics (thiazide diuretics); ACE inhibitors (possible side effect: persistent dry cough)

Peripheral Vascular Disease and Atherosclerosis

• Abnormality in arteries or veins outside of the heart
• Signs and symptoms: Increasing fatigue and weakness in legs; intermittent claudication (leg pain due to exercise); sensory impairment (paresthesia); weak or absent pedal and popliteal pulses
• Diagnostic test: Doppler Studies (ultrasonography) and arteriography
• Treatment: usual diet, stop smoking, exercise, lose weight, elevate legs when sitting, compression hose, surgery (bypass grafting, angioplasty, endarterectomy)

Aortic Aneurysms

• Weakening of an artery wall (most common in thoracic and abdominal aorta)
• Shapes: Saccular (bulging wall on one side), Fusiform (circumferential dilation)
• Dissecting aneurysm: tear in the intima allowing blood to flow between layers of the arterial wall
• Signs and symptoms: Asymptomatic until very large or rupture; abdominal aneurysms may be palpated
• Diagnosis: Ultrasound, CT scan, radiography, MRI
• Treatment: Surgery, avoiding elevations of blood pressure

Venous Disorders (Varicose Veins)

• Irregular dilated and tortuous superficial or deep veins
• Most common in legs, but can be in esophagus and rectum (hemorrhoids)
• Weakness in vein walls possible due to standing for long periods
• Risk factors: Prolonged standing, obesity, family history, pregnancy