CH 19: Heart

1. Describe the orientation, location, and surface anatomy of the heart in the thorax.

  • Orientation: slightly to left, apex pointing downward & leftward

  • Location: mediastinum of thorax, between lungs, behind the sternum

  • Base (top) is broad at 2nd intercostal space

  • Apex (Bottom) between 5th and 6th rib

2. Describe the layers of the pericardium and the tissue layers of the heart wall.

  • Pericardium

    • Fibrious = tough outer layer & prevents overstretching

    • Serous = Parietal adheres to inner surface & Visceral aka epicardium

    • Pericardial cavity = serous fluid

  • Heart Wall

    • Epicardium = serous pericardium

    • Myocardium = cardiac muscle

    • Endocardium = connective tissue lined internal walls of the heart

3. List the important structural features of each heart chamber: right and left atria, and right and left ventricle.

  • Right atrium: receive deoxygenated blood - superior/inferior vena cava & coronary sinus

  • Right ventricle: pumps blood into lungs via pulmonary trunk - thin walls

  • Left atrium: receives oxygenated blood from pulmonary veins

  • Left ventricle: pumps oxygenated blood to body vis aorta - thickest walls

4. Name the heart valves and describe their locations and functions. Indicate where each of the valves is heard on the chest wall.

  • Atrioventricular: Tricuspid (bt right atrium & ventricle) and Bicuspid (bt left atrium & ventricle)

  • Semilunar: Pulmonary (bt right ventricle & pulmonary trunk) and Aortic (bt left ventricle & aorta)

5. Describe the path of a drop of blood through the four chambers of the heart and the systemic and pulmonary circuits.

  • Deoxygenated blood returns via right atrium - tricuspid valve - right ventricle - pulmonary valve - lungs via pulmonary artieries

  • Oxygenated blood returns via pulmonary veins - left atrium - mitral valve - left ventricle - aortic valve - body via the aorta

6. Describe the structure of cardiac muscle tissue.

  • Short, branching, one or two nuclei

  • Rich in mitochondria for endurance and constant activity

7. Describe the structure of intercalated discs and discuss their importance in the contraction of cardiac muscle.

  • Structure: complex cellular junctions 

    • Fasciae adherents: desmosomes that hold cells together during contractions

    • Gap junctions (allow ions to pass between cells & transmit faster signals

8. Name the components of the conducting system of the heart, and describe the conduction pathway.

  • Sinoatrial Node: pacemaker, initiates heart beat

  • Atrioventricular: delays signal for ventricular filling

  • Bundle of His: conducts signal to ventricles

  • Purkinje Fibers: spread impulse for ventricular contraction

9. Describe the locations of the coronary arteries and cardiac veins on the heart surface.

  • Right & Left coronary arteries -> aorta to supply oxygenated blood to the heart

  • Left coronary artery -> anterior interventricular artery & circumflex artery

  • Cardiac veins -> drain into coronary sinuses -> empties into right atrium

10. Define coronary artery disease, heart failure, and atrial and ventricular fibrillation.

  • Coronary Artery Disease = atherosclerosis (fatty plaque buildup) in coronary arteries

    • Leads to angina (chest pain) or heart attack (myocardial infarction)

  • Heart Failure = too weak to pump blood

  • Atrial Fibrillation = rapid & irregular beating, reduces blood flow efficiency

  • Ventricular Fibrillation = rapid & uncoordinated beating, stops blood pumping