Cardiovascular System Notes

Announcements

  • Review color labels of heart anatomy for the dissection on Wednesday.
  • The instructor will be in Zurich on Wednesday.
  • Phone use during activities is prohibited, especially during the dissection.

Dad Jokes

  • Surgeon holding a heart: "That one situation where the five-second rule does not apply."
  • Juggling red thing: Jugular vein.

Cardiovascular System

  • Divided into systemic and pulmonary circulation.
  • Previously covered blood components; now focusing on circulation.

Systemic Circulation

  • Delivers blood to the body and carries away waste.
  • A loop where blood returns to its starting point.
  • Umbrella term for circulation to areas other than the heart and lungs.

Pulmonary Circulation

  • Circulation to the lungs and back.
  • Eliminates carbon dioxide and oxygenates blood.
  • Also known as the lung pathway.

Double Loop

  • Circulation forms a figure-eight pattern, alternating between oxygen-poor (blue) and oxygen-rich (red) blood.
  • Blood never actually blue, it's just represented that way.
  • Blood courses through the body in a figure eight.

Structure of the Heart

  • Size: Approximately 14 by 9 centimeters, about the size of your fist.
  • Location: Mediastinum, between the second and fifth ribs in the intercostal space.
  • Heart size is proportional to body size.
  • Weight: About a pound.

Heart Muscle

  • Unique: Behaves differently from other muscles when exercised.
  • Enlargement: Unlike other muscles, a larger heart is weaker.
  • Story: A personal anecdote about a high school acquaintance whose heart enlarged due to substance abuse, leading to heart failure at age 23.

Heart Damage and Repair

  • Removal: Part of the heart can be removed (e.g., after a heart attack), and the heart can regenerate.
  • Transplants: Donor hearts are the primary option.
  • Artificial Hearts: No viable artificial hearts exist for long-term use.
  • Stem Cell Research: Research focuses on growing new hearts from stem cells to eliminate the need for donors.

Apex

  • Distal end: Pointed end of the heart.
  • Location: Points downward toward the rib cage.

Coronary Arteries

  • Blood Supply: Heart has its own blood vessels for oxygen and waste removal.
  • Heart Attack (Myocardial Infarction): Occurs when a blood clot blocks these arteries.
  • Clot Location: The closer the clot is to the top of the heart, the more damage it causes.
  • Left Main Coronary Artery Blockage: Can cause significant damage, known as a "widowmaker."
  • Golden Hour: One hour to restore circulation to prevent death and scarring.
  • Symptoms: May mimic other conditions like indigestion.

Gender Differences in Heart Attacks

  • Men: More likely to have heart attacks, but often milder.
  • Women: Less likely, but heart attacks are typically more severe.
  • Recommendation: Emphasize taking care of one's heart through diet, exercise, and awareness.

Pericardium

  • Wrapping: The heart is wrapped in a fibrous sac called the fibrous pericardium.
  • Layers: Outer (parietal) and inner (visceral).
  • Pericardial Fluid: Lubricates the heart to reduce friction (as the heart beats ~100,000 times a day).

Heart Muscle Layers

  • Three Layers: Epicardium, Myocardium, Endocardium.
    • Epi = Outer.
    • Myo = Middle.
    • Endo = In.
  • Epicardium: Outermost layer.
  • Myocardium: Middle layer, main muscle for contraction.
  • Endocardium: Innermost layer, reduces friction for smooth blood flow.

Blood Flow Through the Heart

  • Double Pump: Heart is a double pump with double-loop circulation.
  • Two Pumps: Evolutionarily, the heart is two connected pumps.
  • No Mixing: Blood on the right and left sides should not mix.
  • Simultaneous Action: Both sides enter and exit the heart simultaneously.
  • Contraction Pattern: Top to bottom contraction pattern forms a figure eight.
  • Pulmonary Circulation: Blood to the lungs and back.
  • Systemic Circulation: Blood to the body and back to the heart.
  • Circulation: Always include "and back" to emphasize the loop.

Valves

  • Heart Sounds: Valves create the "lub dub" sound of the heartbeat. Without valves, the heartbeat would be silent.
  • Function: Prevent backward blood flow.
  • Types: Atrioventricular valves and semilunar valves.

Atrioventricular Valves

  • Left Atrioventricular Valve: Also called bicuspid or mitral valve.
    • Most Problematic: Most common cause of heart problems.
    • Heart Murmur: Blood leaks backward through the valve into the atrium. Swishing sound indicates a heart murmur.
    • Grading: Murmurs are graded from one to four based on the length and volume of the swish.
    • Replacement: Grade four murmurs may require valve replacement (human donor, pig, or plastic valves).
  • Right Atrioventricular Valve: Called the tricuspid valve.

Valve Flaps

  • Bicuspid Valve: Two flaps (bi = two, cusp = flap).
  • Tricuspid Valve: Three flaps (tri = three, cusp = flap).

Semilunar Valves

  • Aortic Semilunar Valve: Prevents backflow into the ventricles from the aorta; technically tricuspid.
  • Pulmonary Semilunar Valve: Prevents backflow into the heart from the pulmonary trunk.

Heart Chambers and Blood Flow

  • Four Chambers: Right Atrium (RA), Right Ventricle (RV), Left Atrium (LA), Left Ventricle (LV)
  • Correct Labeling: Heart diagrams are shown from the patient's perspective.
  • Atria: Thin upper chambers receive blood from veins.

Atria Details

  • RA: Receives blood from Superior Vena Cava (SVC) and Inferior Vena Cava (IVC).
  • LA: Receives blood from Pulmonary Vein (PV).
    • PV carries the only oxygen rich blood of a vein

Ventricles

  • Ventricles: Thick, muscular lower chambers pump blood out through the arteries.
    • Left Ventricle (LV): Stronger, pumps blood throughout the entire body.
  • Right Ventricle (RV): Thinner, pumps blood only to the lungs.
  • Septum: Separates the two halves of the heart.

Stethoscope PSA

  • Encouragement to clean ears prior to stethoscope lab.