Comprehensive Study Guide: Blood, Heart, and Blood Vessels (Chapters 17, 18, 19)

Blood (Chapter 19)

Characteristics of Blood

Blood is a specialized connective tissue with unique physical and chemical properties essential for homeostasis.

• pH: Normal range is 7.35–7.45 (slightly alkaline).

• Temperature: Approximately 38°C (100.4°F), slightly higher than body temperature.

• Color: Oxygen-rich blood is bright red; oxygen-poor blood is dark red.

• Volume: Typical adult has 4–6 liters. Hypovolemic = low blood volume; Normovolemic = normal; Hypervolemic = high.

• Plasma Expander: A solution (e.g., albumin, dextran) used to increase plasma volume, often in cases of shock or blood loss.

• Relationship: Plasma volume is a major component of blood volume, which directly affects blood pressure (BP).

Components of Blood

• Formed Elements: Make up ~45% of whole blood (mainly erythrocytes, leukocytes, platelets).

• Plasma: ~55% of whole blood; 90% water, contains proteins, ions, nutrients, gases, hormones, wastes.

• Major Plasma Proteins:

  • Albumin: Maintains osmotic pressure, transports substances.

  • Globulins: Include immunoglobulins (antibodies), thyroxine-binding globulin (TBG), apolipoproteins (lipid transport), metalloproteins (metal ion transport).

  • Fibrinogen: Precursor to fibrin, essential for clotting.

• Other Components: Electrolytes (Na+, K+, Ca2+), nutrients (glucose, amino acids), gases (O2, CO2), hormones, waste products.

• Plasma Protein Synthesis: Mainly in the liver.

• Serum: Plasma without clotting factors (fibrinogen).

Formed Elements

Erythrocytes (Red Blood Cells, RBCs)

• Anucleate: Mature RBCs lack a nucleus.

• Function: Transport O2 (via hemoglobin), some CO2, and help buffer blood pH.

• Metabolism: Anaerobic (glycolysis only).

• Hemopoiesis: Formation of all blood cells; erythropoiesis is RBC production.

• Hemocytoblast: Stem cell in bone marrow giving rise to all blood cells.

• Hematocrit (Hct): % of blood volume occupied by RBCs; normal: males 42–52%, females 37–47%. Higher in males due to androgens and less body fat.

• Effects on Viscosity: Higher Hct increases viscosity; dehydration, high altitude, and exercise can increase Hct.

• Decreased Hct Causes: Blood loss, decreased RBC production, increased RBC destruction. Diagnosis via clinical history and lab tests.

• Dietary Requirements: Iron, vitamin B12, folic acid, amino acids.

• Erythropoietin (EPO): Produced by kidneys in response to hypoxia; stimulates RBC production. Renal failure can cause anemia due to low EPO.

• Hemoglobin (Hb): 4 globin chains, 4 heme groups (each binds 1 O2 via Fe2+).

• Forms: HbO2 (oxyhemoglobin), HHb (deoxyhemoglobin), HbCO2 (carbaminohemoglobin), HbCO (carboxyhemoglobin).

• O2 binds: Iron in heme; CO2 binds globin.

• Normal Hb: Males: 13–18 g/dL; Females: 12–16 g/dL.

• Fetal Hemoglobin (HbF): Higher O2 affinity; important for fetal O2 uptake.

• Vasodilation: RBCs release nitric oxide (NO).

• Reticulocyte: Immature RBC; % indicates erythropoietic activity.

• Destruction: In spleen/liver; Fe recycled, heme → bilirubin (excreted in bile), amino acids reused. Urobilin (urine), stercobilin (feces).

• Lifespan: ~120 days.

• Bruise Color: Heme breakdown products (biliverdin, bilirubin).

• Jaundice: Excess bilirubin (liver dysfunction or excessive RBC breakdown).

• Blood Transfusions: ABO and Rh compatibility required to prevent hemolytic reactions.

Leukocytes (White Blood Cells, WBCs)

• Characteristics: Nucleated, defense against pathogens.

• Abundance: Neutrophils > Lymphocytes > Monocytes > Eosinophils > Basophils.

• Largest: Monocytes.

• Production: Bone marrow.

• Lifespan: Hours to years (type-dependent).

• Normal Range: 4,800–10,800/μL.

• Diapedesis: WBCs leave capillaries to reach infection sites.

• Phagocytic WBCs: Neutrophils, monocytes/macrophages, eosinophils.

Granulocytes

• General: Cytoplasmic granules contain enzymes/chemicals.

• Neutrophils: "Polymorphonuclear leukocytes"; attack bacteria via phagocytosis, release defensins, lysozyme, oxidants.

• Eosinophils: Defend against parasites, modulate allergic responses; increased in allergies and parasitic infections.

• Basophils: Release histamine (vasodilation), heparin (anticoagulant); involved in inflammation/allergy.

Agranulocytes

• Lymphocytes: Derived from lymphoid stem cells; types:

  • B cells: Produce antibodies (humoral immunity).

  • T cells: Cell-mediated immunity; attack virus-infected/cancer cells.

  • NK cells: Destroy abnormal cells (cancer, virus-infected).

• Monocytes: Become macrophages; phagocytize pathogens/debris.

Platelets (Thrombocytes)

• Origin: Fragments of megakaryocytes in bone marrow.

• Thrombopoietin (TPO): Hormone stimulating platelet production.

• Lifespan: 5–10 days; stored in spleen.

• Function: Hemostasis (clotting).

• Normal Count: 150,000–400,000/μL.

• Thrombocytopenia: Low platelets; risk of bleeding.

• Thrombocytopoiesis: Platelet production.

• Pre-surgical Check: To prevent excessive bleeding.

Hemostasis

• Vascular Phase: Vasoconstriction; endothelial cells release endothelin, ADP, tissue factor.

• Platelet Phase: Platelet plug formation; release of ADP, serotonin, thromboxane A2 (promotes aggregation).

• Coagulation Phase: Cascade of procoagulants (clotting factors); extrinsic pathway (tissue factor), intrinsic pathway (factor XII), both converge at factor X → prothrombinase → thrombin → fibrinogen to fibrin.

• Essential Ion: Ca2+ required for clotting.

• Clot Retraction: Platelets contract, pulling wound edges together.

• Fibrinolysis: Plasmin digests fibrin; dissolves clot.

• Anticoagulants: Heparin, warfarin, antithrombin III.

Clinical Information

• Anemias: Decreased RBCs/Hb; causes: blood loss, decreased production, increased destruction. Diagnosed by CBC, reticulocyte count, iron studies.

• Polycythemia: Excess RBCs; can be due to hypoxia, EPO abuse, bone marrow disease; increases blood viscosity.

• Leukemias: Malignant WBC proliferation; acute (rapid, immature cells), chronic (slow, mature cells). Symptoms: infection, anemia, bleeding.

• Mononucleosis: Viral infection (EBV); atypical lymphocytes, fatigue.

• Platelet Disorders: Thrombosis (clot formation), embolism (traveling clot); treated with anticoagulants (heparin, warfarin), thrombolytics (tPA).

• Hemophilia: Inherited clotting factor deficiency (X-linked).

• Platelet-rich Plasma Therapy: Uses concentrated platelets to promote healing.

The Heart (Chapter 17)

General Anatomy

• Location: Mediastinum, protected by sternum, ribs, pericardium.

• Pericardial Sac: Double-walled; parietal pericardium (outer), visceral pericardium/epicardium (inner), with pericardial cavity (fluid-filled) between.

• Pericardial Fluid: Reduces friction.

• Cardiac Tamponade: Fluid accumulation compresses heart.

• Pericarditis: Inflammation of pericardium.

• GERD: Gastroesophageal reflux; can mimic heart attack symptoms.

Heart Chambers and Blood Flow

• Chambers: Right/left atria (receive), right/left ventricles (pump).

• Blood Flow: Right side: O2-poor blood to lungs; left side: O2-rich blood to body.

• Fetal Shunts: Foramen ovale (atria), ductus arteriosus (pulmonary trunk to aorta).

Heart Wall and Valves

• Layers: Epicardium (outer), myocardium (muscle), endocardium (inner; forms valves).

• Trabeculae Carneae: Muscular ridges in ventricles.

• Valves: AV (tricuspid, bicuspid/mitral) prevent backflow into atria; semilunar (pulmonary, aortic) prevent backflow into ventricles.

• Papillary Muscles/Chordae Tendineae: Prevent valve prolapse; part of AV valves.

Coronary Circulation

• Coronary Arteries: Supply heart muscle; right and left branches.

• Coronary Veins: Drain into coronary sinus (right atrium).

Heart Physiology

• Cardiac vs. Skeletal Muscle: Cardiac: branched, intercalated discs, more mitochondria, Ca2+ from SR and ECF, autorhythmicity.

• Contractile vs. Pacemaker Cells: Contractile: majority, generate force; Pacemaker: initiate/conduct impulses.

• Ca2+ in Pacemaker Cells: Triggers depolarization.

• Plateau Phase: Prolonged depolarization (Ca2+ influx); prevents tetanus.

• Conduction System: SA node → AV node → Bundle of His → bundle branches → Purkinje fibers.

Cardiac Cycle and Output

• Systole: Contraction; Diastole: Relaxation.

• Phases: Atrial systole, ventricular systole (isovolumetric contraction, ejection), ventricular diastole.

• Pressure to Open Aortic Valve: ~80 mmHg.

• Heart Sounds: "Lub" (AV valves close), "Dub" (semilunar valves close).

• EDV (End-Diastolic Volume): Volume before contraction; ESV (End-Systolic Volume): Volume after contraction.

• Cardiac Output (CO): $CO = HR \times SV$

• Stroke Volume (SV): $SV = EDV - ESV$; typical SV ~70 mL.

• Ejection Fraction: $\text{EF} = \frac{SV}{EDV} \times 100\%$; clinically significant if <55%.

• Venous Return: Blood returning to heart; affected by muscle pump, respiration, blood volume.

• Contractility: Increased by Ca2+, epinephrine; decreased by acidosis, K+.

• Afterload: Resistance ventricles must overcome; increased afterload reduces SV.

• HR Control: ANS: Sympathetic (increases HR via norepinephrine), Parasympathetic (decreases HR via acetylcholine).

• Vagal Tone: Parasympathetic dominance at rest.

• Baroreceptors/Chemoreceptors: Sense pressure/gas changes; located in carotid sinus, aortic arch; relay via glossopharyngeal/vagus nerves to medulla.

• Hormones Increasing HR: Epinephrine, norepinephrine, thyroid hormone.

• Electrolyte Effects: Hyperkalemia (decreases HR/contractility), hypokalemia (arrhythmias); hypercalcemia (increases contractility), hypocalcemia (decreases contractility).

• Other Factors: Nicotine, caffeine, pain can increase HR.

Clinical Information

• Valve Disorders: Prolapse (incomplete closure), stenosis (narrowing).

• Prophylactic Antibiotics: Prevent endocarditis in valve disease.

• MI (Myocardial Infarction): Heart attack; caused by blocked coronary artery.

• Angina Pectoris: Chest pain from ischemia.

• CHF (Congestive Heart Failure): Ineffective pumping.

• Cardiac Arrest: Sudden loss of heart function.

• CABG: Coronary artery bypass graft.

• Balloon Angioplasty: Opens blocked arteries.

• Cardiac Enzymes: Troponin, CK-MB; indicate heart muscle damage.

• Medications: Beta-blockers, ACE inhibitors, diuretics, nitrates.

Blood Vessels (Chapter 18)

Blood Vessel Anatomy

• Three Tunics:

  • Tunica intima: Endothelium; smooth lining.

  • Tunica media: Smooth muscle; controls diameter.

  • Tunica externa (adventitia): Connective tissue; support/protection.

• Types:

  • Arteries: Thick walls, high pressure.

  • Arterioles: Smallest arteries; regulate flow.

  • Capillaries: Thinnest walls; exchange.

  • Sinusoids: Leaky capillaries (liver, spleen).

  • Venules: Collect blood from capillaries.

  • Veins: Thin walls, valves, low pressure.

• Most Numerous: Capillaries.

• Thinnest Walls: Capillaries.

• Highest BP: Arteries; Lowest BP: Veins.

• Slowest Flow: Capillaries.

• Artery vs. Vein: Arteries have thicker walls, smaller lumen, no valves; veins have thinner walls, larger lumen, valves.

• Arterial Pulse: Pressure wave; pressure points used for pulse assessment.

• Vein Valves: Prevent backflow; muscular and respiratory pumps aid venous return.

• Valsalva Maneuver: Forced exhalation against closed airway; affects venous return and BP.

Blood Vessel Physiology

• Resistance (R): Determined by vessel diameter, length, blood viscosity. Diameter is most important (inversely proportional to R).

• Flow (F): $F = \frac{\Delta P}{R}$

• Pressure (P): Generated by heart contraction.

• MAP (Mean Arterial Pressure): $MAP = \text{Diastolic BP} + \frac{1}{3}(\text{Pulse Pressure})$

• Pulse Pressure (PP): $PP = \text{Systolic BP} - \text{Diastolic BP}$

• Normal BP: Systolic 120 mmHg, Diastolic 80 mmHg.

Control of Blood Pressure

• Baroreceptor/Chemoreceptor Reflexes: Adjust HR, vessel diameter, contractility.

• Vasomotor Center: Releases norepinephrine to constrict vessels.

• Hormones: Epinephrine, norepinephrine, ADH, angiotensin II (increase BP); ANP (decreases BP).

• Short-term Control: Neural/hormonal; Long-term: Renal regulation (blood volume).

• Factors Affecting BP: Blood volume, viscosity, venous return, CO, TPR, contractility, HR, ions.

Capillary Dynamics

• Types: Continuous (least permeable), fenestrated, sinusoidal (most permeable).

• Precapillary Sphincters: Smooth muscle; regulate flow into capillaries.

• Vascular Shunt: Direct connection between arteriole and venule.

• Hydrostatic Pressure (HP): Pushes fluid out; higher at arterial end.

• Osmotic Pressure (OP): Pulls fluid in; maintained by plasma proteins.

• Fluid Loss: ~1.5 mL/min lost to interstitial space; returned via lymphatics.

• Edema: Excess interstitial fluid; caused by increased HP, decreased OP, lymphatic blockage.

• Vasodilators: CO2, lactic acid, NO, histamine; vasoconstrictors: endothelin, angiotensin II.

• Blood Flow Distribution: Varies by organ and physiological state.

Clinical Information

• Aneurysm: Vessel wall dilation; risk of rupture.

• DVT (Deep Vein Thrombosis): Clot in deep vein; risk of pulmonary embolism.

• Vasovagal Syncope: Sudden drop in HR/BP; fainting.

• Atherosclerosis: Plaque buildup in arteries; risk of MI, stroke.

• Arteriosclerosis: General hardening of arteries.

• Hypertension: Primary (idiopathic), secondary (identifiable cause); treated with lifestyle, medications (diuretics, ACE inhibitors, beta-blockers).

• Circulatory Shock: Inadequate tissue perfusion; types: hypovolemic, cardiogenic, vascular, obstructive. Signs: hypotension, tachycardia, cold/clammy skin.

Example Table: Comparison of Arteries and Veins

Feature	Arteries	Veins
Wall Thickness	Thick	Thin
Lumen Size	Small	Large
Valves	Absent	Present
Pressure	High	Low
Direction	Away from heart	Toward heart

Additional info: Some explanations and normal values were inferred from standard A&P textbooks to ensure completeness and clarity.