Untitled Flashcards Set

1. Sympathetic vs. Parasympathetic Systems and the Heart

• Control Center: The medulla oblongata regulates autonomic input.

• Neurotransmitters:

  • Sympathetic: Norepinephrine (↑ HR, contractility).

  • Parasympathetic: Acetylcholine via the vagus nerve (↓ HR).

2. EKG Basics: What Does Each Wave Mean?

3. Path of Depolarization Through the Heart ('Wiring')

1. Sinoatrial (SA) Node – Pacemaker of the heart, initiates the signal.

2. Internodal Pathways – Carries impulses through atria.

3. Atrioventricular (AV) Node – Delays impulse for ventricles to fill.

4. AV Bundle (Bundle of His) – Conducts impulse from AV node to ventricles.

5. Right & Left Bundle Branches – Carries signal down the septum.

6. Purkinje Fibers – Distributes impulse to ventricular muscle fibers.

4. Coronary Arteries

• Function: Supply oxygenated blood to the myocardium.

• Major Coronary Arteries:

  • Right Coronary Artery (RCA) – Supplies right atrium, right ventricle.

  • Left Coronary Artery (LCA) splits into:

    • Left Anterior Descending (LAD) – Supplies anterior ventricles.

    • Circumflex Artery – Supplies left atrium and lateral left ventricle.

5. Valves and Associated Structures (What Makes Valves Open/Close?)

• Heart Valves:

  • Atrioventricular (AV) Valves):

    • Tricuspid (RA → RV).

    • Bicuspid (Mitral) (LA → LV).

  • Semilunar Valves:

    • Pulmonary Valve (RV → Pulmonary Artery).

    • Aortic Valve (LV → Aorta).

• What Controls Valve Opening/Closing?

  • Pressure differences! Valves open when pressure behind them is greater and close when pressure in front is greater.

  • Chordae Tendineae & Papillary Muscles prevent AV valves from inverting.

6. Layers of the Heart

7. How the Cardiovascular System Regulates BP Irregularities

• Short-Term Regulation:

  • Baroreceptors (Carotid & Aortic): Detect BP changes → Adjust HR.

  • Sympathetic activation → Vasoconstriction (↑ BP).

  • Parasympathetic activation → Vasodilation (↓ BP).

• Long-Term Regulation:

  • Renin-Angiotensin-Aldosterone System (RAAS):

    • Renin → Angiotensin II (vasoconstriction) → Aldosterone (↑ Na⁺, H₂O retention → ↑ BP).

  • Antidiuretic Hormone (ADH): Increases water retention → ↑ BP.

8. Cardiac Output Formula

CO=HR×SVCO=HR×SV

• Cardiac Output (CO) = Volume of blood pumped per minute.

• Heart Rate (HR) = Beats per minute.

• Stroke Volume (SV) = Blood pumped per beat.

9. Capillary Density and Importance

• Capillary Density = Number of capillaries per unit tissue.

• Higher density:

  • More oxygen and nutrient exchange.

  • Found in muscles, brain, heart.

• Lower density:

  • Found in cartilage, tendons (less metabolic demand).

10. Movement of Blood Through the Venous System

• Mechanisms Helping Blood Return to Heart:

  1. Skeletal Muscle Pump – Muscle contractions push blood upward.

  2. Respiratory Pump – Breathing creates pressure changes in the chest.

  3. Venous Valves – Prevent backflow.

  4. Sympathetic Stimulation – Vasoconstriction increases venous return.

11. Overall Control of the Heart’s Electrical Activity

• Intrinsic Control (SA Node):

  • Heart generates its own rhythm (pacemaker potential).

• Extrinsic Control:

  • Sympathetic: Increases HR & force.

  • Parasympathetic: Decreases HR via vagus nerve.

12. Ions Involved with Cardiac Action Potentials

13. Movement of Molecules in a Capillary Bed (Pressures)

• Arterial End: Hydrostatic pressure > Oncotic pressure → Filtration (fluid leaves).

• Venous End: Oncotic pressure > Hydrostatic pressure → Reabsorption (fluid enters).

14. How Frank-Starling Law Affects Cardiac Function

• Definition: The more the heart stretches (venous return), the stronger the contraction.

• Mechanism:

  • Increased preload (venous return) → Increased stretch.

  • Stronger contraction → Increased stroke volume (SV).

• Why It Matters:

  • Maintains equal output between left and right sides of the heart.

  • Ensures that the heart pumps all the blood it receives.