Final

• the right side of the heart has 3 lobes, whereas the left side of the heart has 2 lobes
• The left ventricle ejects oxygenated blood into the aorta while the right ventricle ejects deoxygenated blood into the pulmonary artery.
• the upper chambers of the heart are called the atria and the lower chambers of the heart are called the ventricles
• the atria act as a receiving chamber and contract to push blood into the lower chambers
• the ventricles serve as the primary pumping chambers of the heart, propelling blood to the lungs (pulmonary circuit) and the rest of the body (systemic circuit)
• the pulmonary circuit transports blood to and from the lungs, where it picks up oxygen and delivers carbon dioxide for exhalation
• the systemic circuit transports oxygenated blood to virtually all of the tissues of the body and returns relatively deoxygenated blood and carbon dioxide to the heart to be sent back to the pulmonary circulation
• the cardiac cycle consists of two phases: diastole and systole
• diastole refers to the period when the heart relaxes and fills with blood
• during diastole, the atrioventricular valves remain open while the semilunar valves close
• the right ventricle pumps blood into the pulmonary trunk, which leads toward the lungs and bifurcates into the left and right pulmonary arteries. these vessels in turn branch many times before reaching pulmonary arteries where gas exchange occurs
• the superior and inferior vena cava return blood to the right atrium
• Blood flow


  1. Right atrium

  2. Right ventricle

  3. Pulmonary circuit
• Blood in pulmonary artery

  • Low in oxygen
  • Relatively high in carbon dioxide
• Gas exchange in pulmonary capillaries

  1. Oxygen into the blood

  2. Carbon dioxide out
• Blood returned to left atrium

  • High in oxygen
  • Low in carbon dioxide
• Blood flow


  1. Left ventricle

  2. Systemic circuit
• Exchange in systemic capillaries

  1. Oxygen and nutrients out of the capillaries

  2. Carbon dioxide and wastes in
• Blood return


  1. Right atrium

  2. Cycle repeated
• the sinoatrial node starts the electrical signal/ activation
• the atrioventricular node delays ventricular contraction, allows ventricles to fill
• the atrioventricular bundles carry signal to purkinje fibres
• the purkinje fibres trigger ventricular contraction
• 1. the SA node and the remainder of the conduction system are at rest
  2. the SA node initiates the action potential, which sweeps across the atria
  3. after reaching the atrioventricular node, there is a delay of approximately 100 ms that allows the atria to complete pumping blood before the impulse is transmitted to the atrioventricular bundle
• 4. following the delay, the impulse travels through the atrioventricular bundle and bundle branches to the purkinje fibres, and also reaches the right papillary muscle via the moderator band

  5. the impulse spreads to the contractile fibres of the ventricle

  6.ventricular contraction
• the period of contraction that the heart undergoes while it pumps blood into circulation is called systole
• the period of relaxation that occurs as the chambers fill with blood is called diastole
• cardiac output is a measurement of the amount of blood pumped by each ventricle in one minute
• CO = HR x SV
• factors effecting HR: fitness levels, age, hormones
• factors affecting SV: heart size, fitness levels, gender, contractility, preload, afterload
• nasopharynx: filters air, serves only as airway, humidify of warm air
• oropharynx: passageway for eating and drinking as well as breathing
• laryngopharynx: separates air from food and drink
• respiratory bronchioles are the smallest type of bronchioles
• an alveolar duct is a tube composed of smooth muscle and connective tissue which opens into a cluster of alveoli
• two muscle groups are used during respiration, the external intercostal muscles and the diaphragm
• the process of expiration is passive, meaning that energy is not required to push air out of the lungs
• short term adaptations of exercise are increased HR, SV, BP
• long term adaptations to exercise are lower BP and HR, peak CO