Comprehensive Study Notes: The Respiratory, Blood, Cardiovascular, and Vascular Systems

The Respiratory System

Major Function of the Respiratory System

• Primary Function: To supply the body with oxygen (O2) and remove carbon dioxide (CO2).

• Additional Functions: Involved in speech, olfaction (smell), and regulation of blood pH.

Processes of Respiration

• Pulmonary Ventilation: Movement of air into and out of the lungs (breathing).

• External Respiration: Gas exchange between air in alveoli and blood in pulmonary capillaries.

• Transport of Gases: Movement of O2 and CO2 in the blood between lungs and tissues.

• Internal Respiration: Gas exchange between systemic blood and tissues.

Upper and Lower Respiratory Organs

• Upper Respiratory Tract: Nose, pharynx, larynx.

• Lower Respiratory Tract: Trachea, bronchial tree, lungs.

• Bronchial Tree: Series of branching airways including bronchi, bronchioles (contain smooth muscle and cuboidal epithelial cells), and alveoli.

Conducting Zone vs. Respiratory Zone

• Conducting Zone: All respiratory passageways that provide conduits for air to reach gas exchange sites (nose to terminal bronchioles).

• Respiratory Zone: Site of gas exchange (respiratory bronchioles, alveolar ducts, alveoli).

• Alveoli: Thin-walled sacs specialized for gas exchange; surrounded by capillaries; contain type I and II cells (type II secrete surfactant).

The Pleurae

• Pleurae: Double-layered serous membranes (parietal and visceral) surrounding each lung, reducing friction during breathing.

Homeostatic Imbalances

• Laryngitis: Inflammation of the larynx, often causing voice loss.

• Rhinitis: Inflammation of the nasal mucosa.

• Pleurisy: Inflammation of the pleurae, causing painful breathing.

Respiratory Physiology

Pulmonary Ventilation

• Inspiration: Diaphragm contracts, thoracic volume increases, intrapulmonary pressure drops, air flows in.

• Expiration: Diaphragm relaxes, thoracic volume decreases, intrapulmonary pressure rises, air flows out.

• Gas Law: Boyle’s Law applies: $P_1V_1 = P_2V_2$ (pressure and volume are inversely related).

Gas Exchange

• Dalton’s Law: Total pressure of a gas mixture is the sum of the partial pressures of each gas.

• Henry’s Law: The amount of gas dissolved in a liquid is proportional to its partial pressure and solubility.

• External Respiration: Influenced by partial pressure gradients, gas solubility, membrane thickness, and surface area.

• Internal Respiration: Driven by partial pressure gradients between blood and tissues.

Gas Transport

Oxygen Transport

• Transport Mechanisms: 98.5% bound to hemoglobin (Hb), 1.5% dissolved in plasma.

• Partial Pressure: High in alveoli and arterial blood; low in tissues and venous blood.

• Types of Hypoxia: Anemic, ischemic, histotoxic, hypoxemic.

• Oxygen-Hemoglobin Affinity: Influenced by pH, CO2, temperature, and 2,3-BPG.

Carbon Dioxide Transport

• Transport Mechanisms: 70% as bicarbonate ion (HCO3-), 20% bound to Hb (carbaminohemoglobin), 10% dissolved in plasma.

• Partial Pressure: High in tissues and venous blood; low in alveoli and arterial blood.

• Imbalances: Excess CO2 leads to acidosis; too little leads to alkalosis.

Lung Diseases (General Descriptions)

• Obstructive Diseases: (e.g., asthma, chronic bronchitis) – increased airway resistance.

• Restrictive Diseases: (e.g., pulmonary fibrosis) – reduced lung compliance.

Blood

General Functions

• Transport: Delivers O2, nutrients, hormones; removes wastes.

• Regulation: Maintains temperature, pH, fluid volume.

• Protection: Prevents blood loss (clotting) and infection (immune cells).

Components of Blood

• Plasma: Liquid matrix (90% water, proteins, nutrients, hormones, wastes).

• Formed Elements: Erythrocytes (RBCs), leukocytes (WBCs), platelets (thrombocytes).

Erythrocytes (Red Blood Cells)

• Function: Transport O2 via hemoglobin; also carry some CO2.

• Regulation: Erythropoiesis in red bone marrow; regulated by erythropoietin (EPO) from kidneys in response to hypoxia.

Leukocytes (White Blood Cells)

• General Function: Defense against pathogens.

• Types:

  • Neutrophils: Phagocytize bacteria.

  • Lymphocytes: Immune response (B and T cells).

  • Monocytes: Become macrophages in tissues.

  • Eosinophils: Combat parasites, involved in allergies.

  • Basophils: Release histamine; inflammation.

Platelets

• Function: Essential for blood clotting (hemostasis).

Phases of Hemostasis

• Vascular Spasm: Vasoconstriction to reduce blood loss.

• Platelet Plug Formation: Platelets adhere and aggregate at injury site.

• Coagulation: Fibrin mesh forms, stabilizing the clot.

Blood Grouping (Types)

• Agglutinogens: Antigens on RBC surface (determine blood type).

• Agglutinins: Antibodies in plasma against foreign agglutinogens.

• ABO Types: A, B, AB, O (based on presence/absence of A/B antigens).

• Rh Factor: Presence (+) or absence (–) of D antigen; Rh– individuals can develop anti-Rh antibodies after exposure.

• Transfusions: Incompatible transfusions cause agglutination and hemolysis.

• Pregnancy: Rh– mother with Rh+ fetus can develop antibodies (hemolytic disease of the newborn).

The Heart

Pulmonary and Systemic Circuits

• Pulmonary Circuit: Right side pumps blood to lungs for gas exchange.

• Systemic Circuit: Left side pumps oxygenated blood to body tissues.

General Structure of the Heart

• Coverings: Pericardium (fibrous and serous layers).

• Chambers: 2 atria (receiving), 2 ventricles (pumping).

• Valves: Atrioventricular (tricuspid, mitral) and semilunar (pulmonary, aortic) valves prevent backflow.

Pathway of Blood Through the Heart

• Right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary arteries → lungs → pulmonary veins → left atrium → mitral valve → left ventricle → aortic valve → aorta → body.

Cardiac Muscle Fibers

• Characteristics: Striated, branched, interconnected by intercalated discs (gap junctions and desmosomes).

• Nutrition/Gas Supply: Coronary arteries supply O2 and nutrients.

Electrical Events of the Heart

• Sequence of Excitation: SA node → AV node → AV bundle (bundle of His) → bundle branches → Purkinje fibers.

• Electrocardiogram (ECG): Records electrical activity; main features are P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

Mechanical Events of the Heart

• Cardiac Cycle: All events in one heartbeat (atrial systole, ventricular systole, diastole).

• Heart Rate Regulation: Autonomic nervous system, hormones, ions, fitness, age.

Homeostatic Imbalances

• Myocardial Infarction: Heart attack due to blocked coronary artery.

• Fibrillation: Rapid, irregular heart contractions; can be life-threatening.

Blood Vessels

Tunics of Blood Vessels

• Tunica Intima: Endothelium (simple squamous epithelium).

• Tunica Media: Smooth muscle and elastic fibers (controls vasoconstriction/dilation).

• Tunica Externa: Connective tissue (collagen fibers).

Types of Blood Vessels

• Arteries:

  • Elastic Arteries: Large, near heart, withstand pressure fluctuations.

  • Muscular Arteries: Distribute blood to organs, more smooth muscle.

  • Arterioles: Smallest, control flow into capillary beds.

• Capillaries:

  • Continuous: Most common, uninterrupted lining.

  • Fenestrated: Pores for filtration (kidneys, intestines).

  • Sinusoidal: Large gaps, allow passage of cells (liver, spleen).

• Veins: Thin walls, large lumens, valves to prevent backflow.

Capillary Exchange and Pressures

• Exchange Mechanisms: Diffusion, filtration, osmosis, transcytosis.

• Pressures Involved: Hydrostatic pressure (pushes fluid out), osmotic pressure (pulls fluid in).

Pulse and Blood Pressure

• Pulse: Rhythmic expansion of artery due to heartbeat.

• Blood Pressure: Force of blood against vessel walls; measured as systolic/diastolic (e.g., 120/80 mmHg).

• Influencing Factors: Cardiac output, blood volume, resistance, vessel elasticity.

Blood Types Table

Blood Type	Agglutinogens (Antigens)	Agglutinins (Antibodies)	Can Receive From	Can Donate To
A	A	Anti-B	A, O	A, AB
B	B	Anti-A	B, O	B, AB
AB	A, B	None	A, B, AB, O	AB
O	None	Anti-A, Anti-B	O	A, B, AB, O

Additional info: Rh+ can receive Rh– blood once without reaction, but Rh– individuals develop anti-Rh antibodies after exposure.