4.2. central control of haemodynamic function

• What is the definition of vasculature?

  Network of blood vessels in the body
• What are the types of blood vessels?

  • Arteries
  • Veins
  • Capillaries
• What are the basic structures of blood vessels?

  • Tunica interna (intima): Epithelial cells
  • Tunica media: Smooth muscle & elastic tissue
  • Tunica externa (adventitia): Connective tissue
• What is the wall thickness of medium muscular arteries?

  25% of total vessel diameter
• What characterizes large elastic arteries?

  Lots of elastic fibers, less smooth muscle
• What is the wall thickness of arterioles?

  50% of total vessel diameter
• What are anastomoses in blood vessels?

  Point where two blood vessels join
• What is atherosclerosis?

  Inflammatory disease narrowing vessel lumen
• What is the end diastolic volume in ventricular filling?

  ~120ml
• What are the structural types of capillaries?

  • Continuous capillaries
  • Fenestrated capillaries
  • Sinusoidal capillaries
• What are the two types of venules?

  Post capillary and Muscular
• What characterizes post capillary venules?

  No tunica media, very porous
• What is the main characteristic of veins?

  60-70% of blood in venous system
• What causes varicose veins?

  Weakened and dilated vein walls
• What are the stages of the cardiac cycle?

  1. Ventricular filling
  2. Isovolumetric contraction
  3. Ejection
  4. Isovolumetric relaxation
• What is the average resting heart rate?

  ~70 bpm
• What is the role of the sinoatrial node?

  Pacemaker that regulates heart rate
• What neurotransmitter does the parasympathetic nervous system use?

  Acetylcholine
• What effect does sympathetic stimulation have on heart rate?

  Increases heart rate (tachycardia)
• What are the effects of the autonomic nervous system on heart rate?

  • Sympathetic: Increases heart rate
  • Parasympathetic: Decreases heart rate
• How does Starling's Law relate to cardiac output?

  Increased venous return increases stroke volume
• What is the formula for cardiac output?

  CO = Stroke Volume x Heart Rate
• If stroke volume is $70 \text{ ml}$ and heart rate is $70 \text{ bpm}$, what is the cardiac output?


  $4900 \text{ ml/min}$
• What are the hemodynamic principles in the cardiovascular system?

  • Dynamics of blood flow
  • Systemic and pulmonary circulation
  • Central pump: the heart
• What is the pressure range in systemic circulation?

  110/70 mmHg
• What happens during isovolumetric contraction?

  AV and semilunar valves are closed
• What occurs during ejection phase of the cardiac cycle?

  Semilunar valves open, blood is ejected
• What is the significance of the annulus fibrosis?

  It acts as an electrical insulator
• What are the key components of the nervous control of the cardiac cycle?

  • SA node regulates heart rate
  • ANS influences heart rate
  • Sympathetic and parasympathetic effects
• How does the structure of veins differ from arteries?

  Veins have larger lumens and thinner walls
• What is the total volume of blood in the body?

  5L / 8.8 pints
• What is the role of the vascular venous sinuses?

  They store blood in the venous system
• What happens during isovolumetric relaxation?

  Pressure in ventricles falls, valves closed
• What is the consequence of blood pooling in the heart?

  It can lead to backflow and inefficiency
• What is the average volume of blood ejected by one ventricle?

  ~70ml
• What is the effect of aging on atrial contraction during ventricular filling?

  Atria contract more, adding extra volume
• How does the autonomic nervous system regulate heart rate?

  It adjusts the rate of myocyte depolarization
• What is the primary neurotransmitter for sympathetic stimulation?

  Noradrenalin
• What is the role of the vagus nerve in heart rate control?

  It decreases the rate of SA node depolarization
• How does the structure of muscular venules differ from post capillary venules?

  Muscular venules have a tunica media