T1 L2: Blood Pressure Physiology and Pathologies

• Units of blood pressure?

  mm Hg
• Range of normal blood pressure?

  90/60 to 120/80
• Series circuit?


  flow same in both parts

  pressure higher in first part than second
• Parallel circuit?


  flow split between 2 paths

  pressure same in start or identical if same resistance
• 'Blood vessel - capillary bed - blood vessel - capillary bed' system?

  portal system
• Importance of a portal system?

  allows transport from one tissue to another without being diluted/mixed with blood at heart
• Example of a portal system?

  hepatic portal system
• Factors that increase blood pressure if increased?

  1. Cardiac output
  2. Peripheral resistance
  3. Blood volume
• Volume of blood pumped out of a ventricle during one beat of the heart?

  stroke volume
• Reciprocal of heart rate?

  RR interval
• How to find RR interval?

  60/HR
• Volume of blood pumped out of a ventricle per minute?

  cardiac output
• Volume of blood in a ventricle at the end of diastole?

  end diastolic volume
• Volume of blood remaining in a ventricle at the end of systole?

  end systolic volume
• Percentage of filled ventricular volume pumped out during a heart beat is called?

  ejection fraction
• If radius of a blood vessel increases, what happens to flow?

  increases to the power of 4
• What does exercise cause in blood vessels?

  1. peripheral vasodilatation (muscle/skin)
  2. vasoconstriction in splanchnic circulation (viscera)
• How does standing affect blood pressure?

  1. initial drop in BP
  2. compensatory recovery by peripheral vasoconstriction and increased heart rate
  3. BP final: systolic no change, diastolic increase, heart rate increase
• Receptors in blood vessels that detect pressure?

  baroreceptors
• Baroreceptor locations?

  • transverse aortic arch
  • carotid sinuses of internal carotid arteries
• Baroreceptor activity causes?

  decreased blood pressure
• Chemoreceptor locations?

  • carotid bodies
  • aortic bodies
• "Stroke volume of heart increases in response to end diastolic pressure (an increase in the stretching of blood filling the heart)."?

  Frank-Starling mechanism
• Stretching of heart muscle as it fills with blood?

  preload
• The resistance that the chambers of the heart must overcome to eject blood out of the heart?

  afterload
• How is afterload increased?

  1. back pressure from aorta and pulmonary arteries
  2. if exit valve fails to open completely
• Result of elevated afterload?

  pressure overload
• Result of elevated preload?

  volume overload
• How does thoracic pump work?

  pressure gradient

  inspiration: high bp in gut, low bp in thorax, blood pulled from gut to thorax
• How does muscle pump work?

  rhytmical contraction of limb muscles during normal locomotor activity
• Effect of O2, CO2 and pH changes in pulmonary circulation is opposite to that of systemic circulation.
• What happens in pulmonary circulation if O2 is low in blood in pulmonary circulation?

  vasoconstriction, which direct blood to better oxygenated segments, minimising the amount of blood that is poorly oxygenated
• When does most flow occur through coronary circulation?

  diastole
• Hypertension is secondary to what disease?

  kidney disease
• Low BP on standing, low venous return, syncope, caused by hypovolaemia?

  orthostatic hypotension
• Too little extracellular fluid and hence blood volume?

  hypovolaemia
• Cardiogenic shock compensatory mechanisms?

  tachycardia, tachypnoea
• Low urine output, hypotension, confusion, syncope, acidosis are signs of?

  cardiogenic shock failure to compensate
• When infection spreads to blood?

  sepsis
• Distributive shock via sepsis mechanism?

  vasodilation by cytokines to fight infection,

  causes drop in blood pressure,

  low perfusion