Cardiovascular System and Blood Physiology Essentials

Chapter 14: Heart Mechanics and Blood Flow

Blood Flow Path: Superior/Inferior Vena Cava (SVC/IVC) → Right Atrium (RA) → Tricuspid Valve (TV) → Right Ventricle (RV) → Pulmonary Valve (PV) → Pulmonary Artery (PA) → Lungs → Pulmonary Veins (PV) → Left Atrium (LA) → Aortic Valve (AV) → Aorta (AO) → Body.

Heart Valves and Sounds

• Right AV Valve: Tricuspid
• Left AV Valve: Bicuspid (Mitral)
• Right Semilunar Valve: Pulmonary
• Left Semilunar Valve: Aortic

Heart Sounds: Lub (AV valves close, start of systole) and Dup (Semilunar valves close, start of diastole).

The Pressure-Volume Loop

• Ventricular Filling: AV valves open, Semilunar valves closed.
• Atrial Contraction: Pushes the last blood into the ventricle; ends at End-Diastolic Volume (EDV).
• Isovolumetric Contraction: Both valves closed, pressure increases, volume stays the same; starts with the Lub sound.
• Ventricular Ejection: Semilunar valves open, blood leaves the heart.
• Isovolumetric Relaxation: Both valves closed, pressure decreases, volume stays the same; starts with the Dup sound.

Key Terms:

• EDV: End-Diastolic Volume (before contraction).
• ESV: End-Systolic Volume (blood remaining after contraction).
• Frank-Starling Law: More venous return → more EDV → more stretch → stronger contraction → higher stroke volume.
• Preload: Stretch before contraction, dependent on EDV.
• Afterload: Pressure the heart must pump against; high blood pressure leads to higher afterload.
• Contractility: Strength of contraction, influenced by sympathetic nerves.

Chapter 15: Hemodynamics and Blood Pressure

Blood flows from high pressure to low pressure (highest in the aorta, lowest in the vena cava). Resistance increases when the radius decreases, or when vessel length and viscosity increase. Vasodilation increases the radius, which decreases resistance and blood pressure.

Essential Cardiovascular Equations

• Pulse Pressure (PP): Systolic - Diastolic (e.g., 120/80 = 40).
• Mean Arterial Pressure (MAP): Diastolic + 1/3 Pulse Pressure.
• Stroke Volume (SV): EDV - ESV.
• Cardiac Output (CO): Heart Rate (HR) × Stroke Volume (SV).
• Ejection Fraction (EF): (SV / EDV) × 100 (Normal: 55-70%).

Autonomic Regulation: The Sympathetic Nervous System increases heart rate, contractility, and blood pressure. The Parasympathetic Nervous System decreases heart rate.

Chapter 16: Blood Composition and Hemostasis

Blood consists of Plasma (60%) and Cells (40%).

Plasma Proteins

• Albumin: Keeps water in the bloodstream.
• Globulins: Immune defense.
• Fibrinogen: Blood clotting.
• Transferrin: Iron transport.

Formed Elements

• Red Blood Cells (RBCs): No nucleus, no mitochondria; contain hemoglobin to carry oxygen; 120-day lifespan.
• White Blood Cells (WBCs): Neutrophils are the most common (fight bacterial infections); Basophils are the least common (release histamine during allergies).
• Platelets: Made from megakaryocytes; no nucleus; function in blood clotting and platelet plug formation.

Hemostasis and Gas Laws

Hemostasis Process: Vasoconstriction → Platelet plug → Coagulation → Fibrin clot. Vitamin K is needed to make clotting factors; low Vitamin K leads to decreased clotting and increased bleeding.

Dalton's Law: The total pressure of a gas mixture equals the sum of the partial pressures of each gas. For example, oxygen makes up 21% of the atmosphere; so at 760 mmHg, the partial pressure of oxygen is 760 × 0.21 = 160 mmHg.

Physiological Relationships and Summaries

• Venous return ↑ → EDV ↑ → Preload ↑ → Stretch ↑ → Stroke volume ↑ → Cardiac output ↑
• Venous return ↓ → EDV ↓ → Preload ↓ → Stroke volume ↓ → Cardiac output ↓
• EDV ↑ → Stroke volume ↑
• ESV ↑ → Stroke volume ↓ → Ejection fraction ↓
• Heart rate ↑ → Cardiac output ↑ (very high HR → Stroke volume ↓)
• Sympathetic ↑ → Heart rate ↑ → Contractility ↑ → Stroke volume ↑ → Cardiac output ↑ → Blood pressure ↑
• Parasympathetic ↑ → Heart rate ↓ → Cardiac output ↓
• Contractility ↑ → ESV ↓ → Stroke volume ↑ → Ejection fraction ↑
• Afterload ↑ → ESV ↑ → Stroke volume ↓
• Preload ↑ → Stretch ↑ → Stroke volume ↑
• Radius ↓ (vasoconstriction) → Resistance ↑ → Blood pressure ↑ → Blood flow ↓
• Radius ↑ (vasodilation) → Resistance ↓ → Blood pressure ↓ → Blood flow ↑
• Viscosity ↑ → Resistance ↑ → Blood pressure ↑
• Vessel length ↑ → Resistance ↑
• Cardiac output ↑ → Blood pressure ↑
• Total peripheral resistance ↑ → Blood pressure ↑
• Blood pressure ↓ → Heart rate ↑ → Vasoconstriction ↑ → Blood pressure ↑
• Albumin ↓ → Edema ↑ → Blood volume ↓
• Hematocrit ↑ → Resistance ↑ → Blood pressure ↑
• RBC ↓ → Oxygen carrying ↓ → Anemia
• Neutrophils ↑ → Bacterial infection
• Eosinophils ↑ → Parasites/Allergies
• Platelets ↓ → Bleeding ↑
• Vitamin K ↓ → Clotting ↓ → Bleeding ↑
• Fibrinogen ↓ → No stable fibrin clot