Cardiovascular System Notes

Heart and Blood Vessels

The cardiovascular system consists of two major components that work in tandem to circulate blood throughout the body:

  • Heart: A muscular organ responsible for pumping blood.
  • Blood Vessels: A network of tubes that transport blood.

This system delivers oxygen and nutrients to cells while removing waste products.

Heart Anatomy

The heart's anatomical features include:

  • Location: Situated slightly left of the sternum (breastplate).
  • Size: Approximately the size of a closed fist.
  • Nature: A powerful muscle that functions involuntarily.
  • Exercise: Light cardio three times a week for thirty minutes each time is sufficient, avoid overexertion.
  • Function: To move blood throughout the entire body.

Heart Layers

The heart is composed of three layers:

  • Endocardium:
    • The innermost layer of the heart.
    • Lines the atria and ventricles.
  • Myocardium:
    • The muscular layer of the heart.
    • Damage or overgrowth to the heart typically occurs here.
    • Myo means muscle.
  • Pericardium:
    • The outermost layer of the heart.
    • Protects the heart and secretes pericardial fluid.
    • Peri mean surrounding or around.
    • Pericardial Fluid: Aids smooth contraction and relaxation.

Heart Chambers and Valves

The heart features four chambers:

  • Two at the top: Atria (or Atriums).
  • Two at the bottom: Ventricles.
  • Valves: Act as doorways to control blood flow between the chambers. Function to keep blood flowing in the correct direction.

Heart Valves

Specific heart valves include:

  • Tricuspid Valve:
    • Located between the right atrium and right ventricle.
  • Mitral Valve:
    • Located between the left atrium and left ventricle.
  • Pulmonary Valve:
  • Aortic Valve:
    • Located at the base next to the pulmonary valve.
    • Also referred to as semilunar valves.

Valve Function and Issues

  • Valves open and close to regulate blood flow. If a valve does not close completely, it can lead to:
    • Regurgitation:
      • Backflow of blood due to incomplete valve closure.
    • Heart Murmur:
      • The sound produced by the backflow of blood, audible upon listening to the heart.

Blood Vessels

The main types of blood vessels are:

  • Arteries
  • Veins
  • Capillaries

Arteries

  • Carry blood away from the heart.
  • Carry oxygenated blood.
  • Mnemonic: Artery, Away, both start with "A".

Veins

  • Carry blood to the heart.
  • Carry deoxygenated blood (blood that has already been used by the body).
  • Superior Vena Cava:
    • Brings blood from the head and arms to the heart.
    • Superior: Head is superior.
  • Inferior Vena Cava:
    • Brings blood from the abdomen and legs to the heart.
    • Inferior: Lower portion of the body.

Gas Exchange

  • Occurs in the pulmonary arteries to the lungs and pulmonary veins from the lungs.

Capillaries

  • The smallest blood vessels.
  • Connect arteries to veins.
  • Facilitate the exchange of oxygen and nutrients between the blood and cells.

All components of the cardiovascular system work involuntarily to maintain adequate oxygenated blood levels throughout the body.