topic 5 pt 2

• What is blood pressure (BP) measured as?

  Systolic pressure (SBP) and diastolic pressure (DBP)
• What does systolic pressure (SBP) represent?

  The force exerted by blood upon arterial walls during ventricular contraction
• What does diastolic pressure (DBP) represent?

  The force exerted by blood upon arterial walls during ventricular relaxation
• What instrument is used to measure blood pressure?

  Sphygmomanometer
• What is the normal blood pressure range for young men?

  120-130/60-80 mmHg
• What is the normal blood pressure range for young women?

  105-115/60-70 mmHg
• What is pulse pressure (PP) and its normal value?

  PP = SBP - DBP, with a normal value of about 40 mmHg
• What is the formula for mean arterial pressure (MAP)?

  MAP = DBP + \frac{1}{3} PP
• What does cardiac output (CO) equal?

  CO = HR x SV
• What is total peripheral resistance (TPR)?

  The friction blood encounters as it passes through vessels
• What factors does TPR depend on?

  Blood viscosity, vessel length, and radius
• What is the relationship between blood pressure (BP), cardiac output (CO), and total peripheral resistance (TPR)?


  BP = CO x TPR
• How is mean arterial pressure (MAP) regulated?

  By negative feedback regulatory mechanisms
• What are the two types of control mechanisms for MAP regulation?

  1. Short term: adjustment in secs/mins by neural reflexes and hormones
  2. Long term: adjustment over hours to days by renal control of blood volume

  
• What happens to MAP with an expanded blood volume?

  It raises MAP
• What happens to MAP with a falling blood volume?

  It reduces MAP
• What are the components involved in blood pressure regulation?

  • Chemoreceptors
  • Baroreceptors
  • Higher CNS centres
  • Cardiovascular centre
  • Cardioregulatory centre
  • Vasomotor centre
• Where is the cardiovascular centre located?

  In the medulla oblongata
• What is the function of the baroreceptor reflex?

  • Changes TPR, HR, SV in response to changes in blood pressure
  • Reduces daily variation in MAP by 30-50%
• Where are baroreceptors located?

  In the aortic arch and carotid sinus
• What do baroreceptors monitor?

  The stretching of the walls of blood vessels and atria
• How do afferent sensory impulses travel in the baroreceptor reflex?

  They pass to the cardiovascular centre first and then to the heart/blood vessels
• What type of impulses do the cardioregulatory centre send to the heart?

  Parasympathetic and sympathetic impulses
• What type of impulses do the vasomotor centre send to blood vessels?

  Sympathetic vasoconstrictor impulses
• What are the steps in the baroreceptor reflex diagram?

  1. Stretch of baroreceptors
  2. Afferent impulses in buffer sensory nerves
  3. Medulla
  4. Cardiovascular centre
  5. Cardioregulatory centre
  6. Vasomotor centre
• What is the effect of sympathetic nerves on heart rate (HR) and stroke volume (SV)?

  They increase HR and SV
• What is the effect of vagus nerve stimulation on heart rate (HR)?

  It decreases HR
• How does the baroreceptor reflex affect cardiac output (CO)?

  It influences CO by changing HR and SV
• What are the hormonal influences on short term MAP control mechanisms?

  • Adrenaline and noradrenaline increase CO, TPR, and MAP
  • Atrial Natriuretic Peptide (ANP) causes vasodilation, lowering TPR and MAP
• How do chemoreceptor reflexes affect MAP?

  They may affect MAP when arterial blood CO2 rises or pH/arterial O2 falls
• What role do higher CNS centres play in MAP regulation?

  They cause MAP changes in response to pain, stress, fear, and other emotional factors
• What is the CNS ischaemic response?

  It stimulates vasoconstriction and increases MAP during emergency situations
• What are the long term MAP control mechanisms?

  1. Direct renal mechanisms
  2. Indirect hormonal control mechanisms (Renin-Angiotensin-Aldosterone System)
• How do direct renal mechanisms affect blood volume and MAP?

  Increased blood volume leads to increased renal plasma filtration and fluid excretion, reducing MAP
• What happens when blood volume decreases in terms of renal mechanisms?

  Decreased blood volume leads to decreased renal plasma filtration and fluid excretion, conserving blood volume and increasing MAP

  
• What is the Renin-Angiotensin-Aldosterone (RAA) System?

  • An important indirect hormonal renal control mechanism
  • Activated by low blood volume, low MAP, or poor renal blood flow
• What triggers renin secretion in the RAA system?

  Low blood volume, low MAP, or poor renal blood flow
• What does renin catalyse in the RAA system?

  The formation of angiotensin I from angiotensinogen
• How is angiotensin I converted to angiotensin II?

  By angiotensin-converting enzyme (ACE) as blood flows through the lungs
• What does angiotensin II stimulate in the body?

  Aldosterone and anti-diuretic hormone (ADH) secretion