Structure of the Heart

• What are the two unique features of cardiac muscle?

  1. Myogenic- can contract and relax without nervous or hormonal stimulation.
  2. Never fatigues, as long as it has a supply of oxygen.
• What is the role of coronary arteries?

  • Supply cardiac muscle with oxygenated blood.
  • Branch off aorta.
  • Blockage = no oxygen to cardiac muscle = no respiration = cell death = myocardial infarction (heart attack)
• What are the four chambers of the heart?

  1. Right atrium
  2. Left atrium
  3. Right ventricle
  4. Left ventricle
• Why do the atria have thinner muscular walls than the ventricles?

  They do not need to contract as hard as they do not pump blood far- only to the ventricles, which is helped by gravity.
• What is a feature of atria walls?

  They are elastic so can stretch as blood enters.
• Why do ventricles have much thicker muscular walls than atria?

  They need to contract harder in order to generate a higher blood pressure, which enables blood to flow longer distances (even against gravity).
• What is the role of the right ventricle as how is it adapted to it?

  • The right ventricle pumps blood to the lungs.
  • It has a thinner muscular wall so does not contract as hard. This means the blood is at a lower pressure so:

  1. It does not damage capillaries.
  2. The blood is slowed down for more gas exchange.
• What is the role of the left ventricle and how is it adapted to it?

  • Pumps blood to the body.
  • Has a thicker muscular wall, allowing for larger contractions. This means the blood is at a higher pressure, enabling it to reach all respiring cells.
• What are the two majors veins attached to the heart?

  1. Vena Cava- carries deoxygenated blood from the body into the right atrium.
  2. Pulmonary vein- carries oxygenated blood from the lungs to the left atrium.
• What are the two major arteries attached to the heart?

  1. Pulmonary artery- carries deoxygenated blood from the right ventricle to the lungs.
  2. Aorta- carries oxygenated blood from the left ventricle to the rest of the body.
• What are the two types of valves found in the heart?

  1. Semi-lunar valves
  2. Atrioventricular valves
• Where are semi-lunar valves found?

  In the aorta and the pulmonary artery.
• Where are atrioventricular valves found?

  Between the atria and ventricles.
• What is the left vs right atrioventricular valve called?

  Left= bicuspid

  Right= tricuspid
• Mechanism of valves

  A) valve closed

  B) valve open

  
• What is the role of the septum?

  Separates deoxygenated and oxygenated blood.
• Why is the separation of oxygenated and deoxygenated blood in the heart so important?

  • Maintains a high concentration of oxygen in the oxygenated blood
  • Maintains concentration gradient at respiring tissues
  • To enable diffusion of oxygen at respiring cells