Updated: 3/31/2018

Circulation through Organs

0%
Topic
Review Topic
0
0
N/A
N/A
Questions
1
0
0
0%
0%
Evidence
2
0
0
Topic
  • Snapshot
    • A 40-year-old man is training for a marathon. During a particularly steep hill, he experiences sudden chest pain. As he rests, the chest pain disappears. Later, his physician informs him that his angina is caused by increased myocardial oxygen demand.
  • Introduction
    • Distribution of cardiac output (CO)
      • liver > kidney > muscles > brain
        • liver receives the highest percentage of CO
        • because kidneys are much smaller than the liver, kidneys have the highest percentage of CO per gram of tissue
    • Heart
      • unlike other organs, the heart receives its blood supply during diastole
        • 90% of blood flow through coronary arteries is during diastole
          • during diastole, the blood vessels are open and under low pressure
          • during systole, ventricles contract and the subendocardial coronary vessels are compressed, inhibiting myocardial perfusion
        • as the heart rate increases, the amount of time spent in diastole is relatively decreased
      • myocardial oxygen demand is determined by
        • ↑ contractility
        • ↑ afterload
        • ↑ heart rate
        • ↑ diameter of the ventricle (or wall tension)
      • the heart extracts approximately 100% of oxygen in coronary circulation
        • largest arteriovenous oxygen difference
        • an increase in oxygen demand is supported by an increase in coronary blood flow not an increase in extraction of oxygen from blood like in other organs
Flashcards (0)
Cards
1 of 0
Questions (1)
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Evidence (2)
EXPERT COMMENTS (1)
Private Note