Cardiovascular system

• How does the cardiac conduction system work?

  SA node - atrial systole - AV node - Bundle of His - Purkinje fibres - Ventricular systole
• What is the heart described as for its self beating properties?

  Myogenic
• What system stimulates the heart to beat faster?

  Sympathetic nervous system
• What system returns the heart to its resting level?

  Parasympathetic nervous system
• What is the main cardiac control centre?

  The medulla oblongata
• What is the cardiac control centre stimulated by?

  Baroreceptors, Chemoreceptors and Proprioceptors
• What do chemoreceptors detect?

  An increase in blood carbon dioxide levels
• What do baroreceptors detect?

  An increase in blood pressure
• What do proprioceptors detect?

  An increase in muscle movement
• What is the main hormone which stimulates the heart?

  Adrenaline
• What is stroke volume?

  The volume of blood pumped out of the left ventricle in each contraction
• What is venous return?

  The volume of the blood returning to the right atrium
• What is starlings law?

  increased venous return -> increased diastolic filling of the heart -> increased cardiac muscle stretch -> increased force of contraction -> increased ejection fraction
• What is cardiac output?

  The amount of blood pumped by the heart per minute.
• What's the difference between Low density and high density cholesterol?

  LDL is considered bad cholesterol as they transport it to the tissues

  HDC is considered good cholesterol as they transport excess cholesterol to the liver to be broken down
• What is cardiovascular drift?

  Occurs after 10 mins of exercise in warm environment,

  $\uparrow$sweating -> $\downarrow$blood plasma volume -> $\downarrow$venous return -> $\uparrow$heart rate and $\downarrow$stroke volume

  This maintains cardiac output
• What are some characteristics of arteries?

  Arteries :

  • Transport oxygenated blood
  • High pressure
  • Thick walls
  • Thin lumen
  • Smooth inner layer
• What are some characteristics of veins?

  Veins :

  • Transport unoxygenated blood
  • Low pressure
  • Thin walls
  • wide lumen
  • Have valves to prevent backflow
• What are the 4 venous return mechanisms?

  • Skeletal muscle pump
  • Respiratory pump
  • Pocket valves
  • Right atrium acting as suction pump
• How is oxygen transported in the blood?

  97% combines with haemoglobin to form oxyhaemoglobin

  3% dissolves in the plasma
• How is oxygen transported and stored at the muscle?

  It is stored in the Myoglobin due to it having a higher affinity for oxygen causing oxygen to disassociate from the haemoglobin.

  Oxygen is stored for the mitochondria until it is used by the muscles
• What is the Bohr shift?

  Where the oxyhaemoglobin dissociation curve shifts to the right
• What causes the Bohr Shift?

  • Increase in blood temperature
  • Partial Pressure of Carbon Dioxide increases
  • Blood pH increases
• What mechanism causes the redistribution of blood?

  Vascular Shunt Mechanism
• The vascular shunt mechanism is important as it ensures ...

  • More oxygenated blood goes to the heart
  • More blood goes to the muscles to supply oxygen and remove waste products
  • More blood goes to the skin to cool the body
  • Maintaining blood flow to the brain
• During exercise what are blood flow and pressure controlled by?

  Vasomotor centre
• What two processes redistribute blood flow?

  Vasodilation and vasoconstriction
• What is the Arterio-venous difference?

  The difference between the oxygen content of the arterial blood arriving at the muscles and the venous blood leaving the muscles