Heart Function and Circulation

Heart Function

• Generates blood pressure to move blood through vessels.
• Routes blood, separating pulmonary and systemic circulations to ensure adequate O2 levels in tissues.
• Ensures one-way blood flow via heart valves.
• Regulates blood supply by adjusting heart contraction rate and force based on metabolic needs.

Systemic vs. Pulmonary Circulation

• Pulmonary circulation starts on the right side of the heart, carries blood to the lungs for CO2 removal and O2 intake, then returns to the left side.
• Systemic circulation starts on the left side, delivers O2 and nutrients to body tissues, collects CO2 and returns to the right side.

Vessels Connecting to the Heart

• Arteries:
  • Aorta: Carries oxygen-rich blood from the left ventricle to the body.
  • Pulmonary arteries: Carry oxygen-poor blood from the right ventricle to the lungs.
• Veins:
  • Superior vena cava: Brings deoxygenated blood from the upper body to the right atrium.
  • Inferior vena cava: Brings deoxygenated blood from the lower body to the right atrium.
  • Pulmonary veins: Carry oxygen-rich blood from the lungs to the left atrium.

Blood Flow Through the Heart

• Left side:
  • Mitral valve: Between left atrium and left ventricle.
  • Aortic valve: Between left ventricle and aorta.
• Right side:
  • Tricuspid valve: Between right atrium and right ventricle.
  • Pulmonary valve: Between right ventricle and pulmonary arteries.

Coronary Circulation

• Provides blood flow to the heart muscle itself.
• Sequence: Aorta → Coronary arteries → Heart tissue → Coronary sinus (cardiac veins) → Right atrium.

Action Potentials in Cardiac Muscle

• SA node: Primary pacemaker, initiates heartbeats, and controls heart rate; autorhythmic.
• Contractile cells: Non-autorhythmic, depolarized only when stimulated.

Electrocardiogram Waves and Intervals

• SA node spreads electrical impulses through the atria, causing them to contract.
• AV node delays impulses to ventricles, ensuring atria have fully ejected blood before ventricular contraction.

Commotio Cordis

• Sudden blunt impact to the chest leading to cardiac arrest.
• Occurs during the repolarization phase (ascending phase of the T wave).
• Causes ventricular fibrillation due to disruption of the heart's electrical cycle.
• Defibrillation (AED shock) can restore normal heart rhythm if administered quickly.

Intrinsic vs. Extrinsic Regulation of the Heart

• Intrinsic regulation:
  • Occurs within the cardiovascular system without neural or hormonal input.
  • Cardiac muscle cells stretch, generating more force upon contraction.
  • Starling’s law: Stroke volume increases with increased blood volume in the ventricle before contraction.
  • Increased blood pressure → Increased ventricle volume → Ventricle stretch → Stronger contraction → Stronger stroke volume → Decreased blood pressure.
• Extrinsic regulation:
  • Heart rate and blood vessel size regulated by neurons and hormones.
  • Parasympathetic: Decreases blood pressure.
  • Sympathetic: Increases blood pressure.

ECG Abnormalities

• Fast heart rate: Tachycardia.
• Slow heart rate: Bradycardia.
• Irregular heart rate: Arrhythmia.

Blood's Role in Homeostasis

• Transports gases, nutrients, waste products, and signaling molecules.
• Regulates pH and osmosis using buffers and ion exchange.
• Maintains body temperature through blood movement.
• Protects against pathogens via immune cells.
• Facilitates clot formation to prevent blood loss.

Components of Blood

• Plasma:
  • 91% liquid matrix transporting nutrients, hormones, waste, and proteins.
  • 55% of total blood volume (Females: 4-5L, Males: 5-6L).
  • Albumin (60%): Major contributor to osmotic pressure.
  • Globulins (35%): Antibodies and transport proteins.
  • Fibrinogens (4%): Blood clotting.
• Red blood cells (Erythrocytes) (95%):
  • Transport O2 and CO2.
  • Lack nuclei.
• White blood cells (Leukocytes) (5%):
  • Nucleated.
  • Granulocytes:
    • Neutrophil: Phagocytizes microorganisms.
    • Eosinophil: Attacks parasites, modulates inflammation.
    • Basophil: Releases histamine (inflammation) and heparin (prevents clotting).
  • Agranulocytes:
    • Lymphocyte: Produces antibodies and regulates immune system.
    • Monocyte: Becomes a macrophage, phagocytizes bacteria and debris.
• Platelets:
  • Form platelet plugs and release chemicals for clotting.

Origin of Red vs. White Blood Cells

• Hematopoiesis:
  • Blood cell production from stem cells.
  • In embryos, occurs in yolk sac, thymus, spleen, liver, lymph nodes, and red bone marrow.
  • After birth, confined to red bone marrow; WBCs complete development in lymphatic tissue.
  • All formed elements derived from hemocytoblasts (stem cells).

Oxygen Transport by Red Blood Cells

• 98.5% of O2 transported by hemoglobin.
• Hemoglobin: Protein with four subunits.
  • Each subunit: Globin (polypeptide chain) bound to heme group.
  • Heme: Red pigment containing iron atom.
• RBC production:
  • Reduced blood oxygen → Kidney → Increased erythropoietin → Red bone marrow (increased RBC) → Increased blood oxygen.

Structure and Function of Platelets

• Small cytoplasm surrounded by a plasma membrane.
• Glycoproteins and proteins on surface attach to other molecules, controlling blood loss.
• 5-9 day lifespan.

Hemostasis (3 Steps)

• Hemostasis: Sealing ruptured blood vessels to prevent blood loss.
• Vascular spasm: Smooth muscle contraction in vessel walls prevent excessive bleeding, triggered by endothelins.
• Platelet plug formation: Platelets seal small vessel breaks.
  • Platelets adhere to collagen, become activated, and release ADP and thromboxane.
  • Platelet aggregation, shape change, fibrinogen receptors, fibrinogen bridges create a plug.
• Coagulation (blood clotting):
  • Fibrin fibers trap blood cells and platelets.
  • Clotting factors activate more coagulation factors.
    • Extrinsic pathway: Begins with tissue damage releasing factor 3.
    • Intrinsic pathway: Begins in bloodstream, triggered by internal vessel wall damage.
  • Common pathway:
  • Clot removal: Fibrinolysis by plasmin enzyme.
  • Bradykinin release: Vasodilation, restoring local circulation.

Diagnostic Blood Tests

• Complete blood count (CBC):
  • RBC count.
  • WBC count.
  • Differential WBC.
  • Hemoglobin levels.
  • Hematocrit (RBC percentage).
• Abnormal counts:
  • Erythrocytosis: Excess RBC, thickened blood.
  • Anemia: Hemoglobin deficiency.
  • Leukemia: Cancer of bone marrow, elevated WBC.
  • AIDS: HIV progresses when CD4 count falls below 200.

Functions of Arteries, Veins, and Capillaries

• Arteries: Carry blood away from the heart.
  • 3 layers: tunica intima, tunica media (smooth muscle), tunica externa.
  • Blood pressure highest in aorta, lowest in veins.
• Capillaries: Smallest vessels for nutrient exchange.
  • Only tunica intima for diffusion.
  • Slow blood flow.
• Veins: Carry blood toward the heart.
  • Same 3 layers as arteries but less elasticity.
  • Valves prevent backflow.

Cross-Sectional Area of Blood Vessels

• Blood flow velocity changes with cross-sectional area.
• Capillaries have a greater total cross-sectional area than the aorta.
• Blood travels slower through capillaries.

Laminar vs. Turbulent Blood Flow

• Laminar blood flow: Streamlined flow in smooth vessels (diastolic).
• Turbulent blood flow: Interrupted flow exceeding vessel capacity (systolic), creating noise.

Factors Determining Blood Flow

• Blood pressure: Force exerted by blood on vessel walls.
• Cardiac output: Blood pumped per minute (5L).
• Vascular resistance: Friction between blood and vessel walls.
• Factors increasing cardiac output or resistance increase blood pressure.
• BP = CO x TPR (total peripheral resistance).
  • Vasoconstriction: High TPR.
  • Vasodilation: Low TPR.

Capillary Types

• Continuous:
  • No gaps, less permeable to large molecules.
  • Found in nervous and muscle tissue.
• Fenestrated:
  • Many fenestrae (windows), increased permeability.
  • Found in small intestine and kidneys.
• Sinusoidal:
  • Discontinuous, large gaps.
  • "Leaky" and rare.
  • Found in liver, spleen, and bone marrow.

Vascular Diseases

• Hypertension
• Peripheral Arterial Disease (PAD):
  • Fatty deposits narrow arteries, reducing blood flow to limbs.
  • Symptoms: Leg pain, skin color changes, cold feet, sores.
  • Treatment: Diet, exercise, reducing tobacco products, weight loss, drugs.
• Deep Vein Thrombosis (DVT):
  • Blood clot in deep veins.
  • Causes: Conditions affecting blood clotting, prolonged immobility.
  • Symptoms: Leg pain, redness, swelling, warmth.
  • Treatment: Blood thinners, compression stockings, surgery.

Respiratory System Functions

• Breathing (pulmonary ventilation): Air movement into/out of lungs.
• Gas exchange: Diffusion of gases across membranes (pulmonary and tissue).
• Regulation of blood pH: Altering blood CO2 levels.
• Production of chemical signals: Angiotensin-converting enzyme (ACE) for blood pressure.
• Voice production: Air past vocal folds in larynx.
• Olfaction: Sensation of smell in nasal cavity.
• Protection: Ciliated epithelium traps microorganisms.

Anatomy of Respiratory Passages

• Upper respiratory (Conducting zone):
  • Nose to smallest air tubes, pulmonary ventilation only.
  • Includes:
    • External nose: Cartilage and nasal bones.
    • Nasal cavity.
    • Pharynx: Connected to respiratory system at the larynx, and to the digestive system at the esophagus.
      • Nasopharynx
      • Oropharynx
      • Laryngopharynx
• Lower respiratory (Gas exchange zone):
  • Alveoli involved in gas exchange.
  • Includes:
    • Trachea (Windpipe): Attached to larynx, reinforced with tracheal rings.
    • Carina: Cartilage ridge (cough reflex).
    • Bronchi:
      • Lobar bronchi
      • Segmental bronchi
      • Bronchioles: Less cartilage, more smooth muscle.
      • Terminal bronchioles: Smooth muscle only.
      • Respiratory bronchioles: Few alveoli.
      • Alveolar ducts and sacs: Site of pulmonary gas exchange.

Cough Reflex

• Protective mechanism clearing airways of irritants.
• Trachealis muscle narrows trachea diameter, aiding cough.

Lungs Comparison

• (Content on comparing right and left lungs was not provided)*

Larynx and Speech

• Larynx: Voice box containing ligaments for speech.
  • Located in anterior laryngopharynx, attached to hyoid bone.
  • 9 cartilages, thyroid cartilage largest (Adam's apple).
  • Vestibular folds: False vocal cords, protect vocal folds.
  • Vocal folds: True vocal cords, vocal ligaments change shape for speech (wide = low pitch, thin = high pitch).

Respiratory Membrane

• Alveolar walls and pulmonary capillaries.
• Alveolar cell layer:
  • Type 2 pneumocytes secrete surfactant (preventing collapse).
• Capillary endothelial layer

Muscles of Inspiration and Expiration

• Muscles of inspiration:
  • Increase thoracic cavity volume.
  • Diaphragm contracts inferiorly, accessory muscles pull superiorly.
• Muscles of expiration:
  • Decrease thoracic volume.
  • Passive during quiet breathing.

Pressure, Volume, and Airflow (Boyle's Law)

• Inverse relationship between pressure and volume.
• Boyle's Law: P = 1/V
• Airflow: F = (P1 - P2)/R
  • F = Airflow (ml/min).
  • P1 = Atmospheric pressure.
  • P2 = Intrapulmonary pressure.
  • R = Resistance.

Respiratory Volumes and Capacities

• Quiet breathing (Eupnea).
• Forced breathing (Hyperpnea).
• Tidal volume: Air entering lungs during quiet breathing (500 mL).
• Expiratory reserve volume: Air forcefully exhaled past normal tidal expiration (1200 mL).
• Inspiratory reserve volume: Extra air inhaled past tidal inspiration.
• Residual volume: Air left in lungs after exhaling.
• Total lung capacity: Sum of all lung volumes.
• Vital capacity: Air moved in/out, sum of all volumes except residual volume.
• Inspiratory capacity: Maximum air inhaled past tidal expiration, tidal volume + inspiratory reserve volume.
• Functional residual capacity: Air remaining after tidal expiration, expiratory reserve volume + residual volume.

Surfactants, Pleural Pressure, and Chest Tubes

• Lungs located in pleural cavity at negative pressure.
• Negative pressure allows lungs to expand.
• Loss of negative pressure: Collapsed lung (pneumothorax).
• Chest tube: Returns negative pressure post-pneumothorax.

Partial Pressure and Gas Exchange

• Partial pressure: Pressure of a gas in a mixture.
• Gases diffuse from high to low partial pressure, like concentration.
• Partial pressure gradients drive gas exchange.

Allergies, Asthma, and Air Passage

• Allergies/asthma: inflammation, swelling, narrowing airways.
• Asthma: Long-term inflammatory disease.
  • Causes: Genetics and environment.
  • Symptoms: Wheezing, shortness of breath, chest tightness, reduced expiratory volume.
  • Treatments: Bronchodilators (albuterol), anti-inflammatories (corticosteroids).

Alimentary Canal

• Tube from mouth to anus.
• 4 layers:
  • Mucosa: Innermost, produces mucus and absorbs nutrients
  • Submucosa: Holds blood capillaries for nutrient absorption.
  • Muscularis: Muscle layer for peristalsis.
  • Serosa/Adventitia: Outermost layer for protection and lubrication.

Organs of Digestive System

• Digestive tract:
  • Oral cavity.
  • Esophagus.
  • Stomach.
  • Small intestine.
  • Large intestine.
  • Rectum.
  • Anus.
• Accessory organs:
  • Liver.
  • Pancreas.
  • Gallbladder.
  • Salivary glands.

Functions of Digestive System

• Oral cavity: Mechanical processing, moistening.
• Pharynx: Propulsion to esophagus.
• Esophagus: Transport to stomach.
• Stomach: Chemical breakdown, mechanical processing.
• Small intestine: Digestion and absorption.
• Large intestine: Dehydration, compaction, elimination.
• Accessory organs:
  • Salivary glands: Lubricating fluid with enzymes.
  • Liver: Bile secretion, nutrient storage.
  • Gallbladder: Bile storage.
  • Pancreas: Enzymes and hormones.

Processes of Digestion

• Ingestion and Mastication: Taking in and chewing food in mouth
• Propulsion and Mixing: Pushing food from one end to the other
• Secretion: Secretions such as mucus, water, digestive enzymes serve to break down food molecules
• Digestion: Breaking food down through mechanical or chemical mediators
• Absorption: Movement of molecules from digestive tract into blood
• Elimination: Removing waste products of digestion via defecation

Chemical Digestion

• Carbohydrates (Sugars):
  • Broken down to monosaccharides.
  • Salivary amylase begins breakdown in mouth.
  • Pancreatic amylase in duodenum breaks down polysaccharides.
  • Small intestine converts disaccharides to monosaccharides.
• Lipids (Fats):
  • Broken down to fatty acids and monoglycerides.
  • Bile salts from liver and lipase from pancreas break down lipids in duodenum .
  • Absorbed by epithelium of small intestines.
• Proteins:
  • Broken down to amino acids.
  • Pepsin in stomach: Break proteins into polypeptides
  • Epithelium of small intestines can convert these small peptides into single amino acids

Hepatic Portal System

• Veins transport blood from digestive tract to liver.
• Liver processes raw nutrients before blood returns to the heart.

Insulin and Glucagon

• Pancreas: Exocrine (enzymes), endocrine (hormones).
• Insulin:
  • Secreted in response to high glucose.
  • Liver stores glucose as glycogen.
• Glucagon:
  • Secreted in response to low glucose.
  • Liver breaks down glycogen and releases glucose.