Cardiovascular and Lymphatic Systems Exam Notes

Page 1

Heart Wall Layers and Pericardial Cavity

  • Layers of the Heart Wall:
    • Epicardium (outer layer)
    • Myocardium (middle muscular layer)
    • Endocardium (inner layer)
  • Pericardial Cavity: Located between the parietal and visceral layers of the serous pericardium.

Blood Flow Circuits

  • Pulmonary Circuit: Deoxygenated blood from right ventricle to lungs, returns oxygenated blood to left atrium.
  • Systemic Circuit: Oxygenated blood from left ventricle to body, returns deoxygenated blood to right atrium.

Major Structures of the Heart

  • Blood Flow Through Heart:
    1. Right atrium via vena cavae
    2. Tricuspid valve to right ventricle
    3. Pulmonary valve to pulmonary artery to lungs
    4. Left atrium from lungs
    5. Bicuspid valve to left ventricle
    6. Aorta to body

Fetal Blood Circulation

  • Oxygenated blood from placenta via umbilical vein
  • Bypasses liver via ductus venosus to right atrium
  • Most enters left atrium via foramen ovale
  • Left ventricle to aorta; some blood to right ventricle via ductus arteriosus to bypass lungs.

Page 2

Ion Channels in Heart Cells

  • Pacemaker Cells:
    • Use If Na+ channels, T-type and L-type Ca2+, K+ channels.
  • Contractile Cells:
    • Use voltage-gated Na+ channels for depolarization, L-type Ca2+ for plateau, K+ for repolarization.

Differences in Action Potentials

  • Pacemaker Cells: Spontaneous depolarization due to Na+ influx followed by Ca2+ influx and K+ efflux.
  • Contractile Cells: Require stimulus-induced Na+ influx, Ca2+ plateau, K+ efflux for repolarization.

Cardiac Conduction System Steps

  1. Sinoatrial node
  2. Atrioventricular node
  3. AV bundle (Bundle of His)
  4. Right and left bundle branches
  5. Purkinje fibers

Regulation of Heart Rate

  • Sympathetic Nervous System: Increases heart rate via norepinephrine.
  • Parasympathetic Nervous System: Decreases heart rate via acetylcholine.

Page 3

Cardiac Output

  • Cardiac Output (CO) = Stroke Volume (SV) × Heart Rate (HR)
  • Influenced by preload, afterload, myocardial contractility.

Blood Flow Through Vascular System

  • Sequence: arteries → arterioles → capillaries → venules → veins.
  • Affected by pressure gradients and resistance.

Determinants of Blood Flow

  • Driven by pressure differences.
  • Resistance increases with smaller vessel diameter.

Maintenance of Blood Flow

  • Maintained by:
    • Heart pressure generator
    • Elastic recoil of arteries
    • Skeletal/muscular pumps in veins.

Page 4

Blood Pressure

  • Definition: Force blood exerts on vessel walls.
  • Short-term regulation: Baroreceptors and autonomic nervous system (ANS).
  • Long-term regulation: Kidney function, RAAS, blood volume.

Regulation Mechanisms

  • Short-term:
    • Baroreceptor reflex
    • Sympathetic/parasympathetic pathways.
  • Long-term:
    • RAAS system, ADH, fluid retention.

Page 5

Baroreceptors and Hormonal Role

  • Baroreceptors: Detect pressure changes, triggering nervous/hormonal responses.
  • RAAS: Increases blood volume, causes vasoconstriction.

Blood Pressure with Elasticity Loss

  • Loss of elasticity increases systolic pressure and resistance, worsening hypertension.

Chemoreceptors and Baroreceptors Interaction

  • Chemoreceptors monitor O2/CO2 and pH; baroreceptors sense pressure, influencing autonomic tone.

Page 6

Hematopoiesis

  • Process: Begins with stem cells in red bone marrow.
  • Erythropoietin: Stimulates RBC formation; Colony-stimulating factors: Influence WBC formation.

Structure and Function of Hemoglobin

  • Composed of four globin chains, each with a heme group for oxygen and CO2 transport.

Blood Clotting Steps and Proteins

  • Platelet adherence and chemical release activate clotting cascade.
  • Key Proteins: Fibrinogen, thrombin.

Page 7

Lymphatic System Function

  • Lymph Flow: From tissues through lymphatic vessels and nodes, returning to the heart via ducts.

Lymph Node Function in Immunity

  • Filter lymph and house lymphocytes/macrophages responding to pathogens.

Support of Blood Volume and Immune Defense

  • Returns excess fluid to circulation; houses immune cells defending against infections.