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EXAMPLE - Pacemaker cells have a depolarising pre-potential due to - PowerPoint PPT Presentation

Key points EXAMPLE - Pacemaker cells have a depolarising pre-potential due to high sodium permeability - End-diastolic volume ( pre-load ) determines force of contraction by controlling myocyte length - Sympathetics increase SAN rate , reduce AVN


  1. Key points EXAMPLE - Pacemaker cells have a depolarising pre-potential due to high sodium permeability - End-diastolic volume ( pre-load ) determines force of contraction by controlling myocyte length - Sympathetics increase SAN rate , reduce AVN delay and increase ventricular contractility - Heart failure causes right - & down -wards shift on Frank-Starling curve One 2 One Medicine: Pre-clinical science revision course 2013

  2. Module outline EXAMPLE Anatomy Capillaries Myocytes Temperature Cardiac cycle Exercise Baroreflex Vasovagal syncope Coronary circulation One-2-One Medicine: Pre-clinical science revision course 2014

  3. haemodynamics Vessel EXAMPLE Blood pressure Total cross-sectional (mmHg) area (cm 2 ) Velocity (cm/s) Elastic Muscular Arterioles Capillaries Venules Veins arteries arteries One-2-One Medicine: Pre-clinical science revision course 2014

  4. Vessel haemodynamics Flow = Arterial BP - Venous BP EXAMPLE Resistance Low resistance Flow High resistance Perfusion pressure (ABP - VBP) One-2-One Medicine: Pre-clinical science revision course 2014

  5. Vessel haemodynamics Flow = Arterial BP - Venous BP EXAMPLE Resistance Flow Vasoconstriction ↓ pressure ! ↑ pressure ↑ resistance ∴ ↓ flow One-2-One Medicine: Pre-clinical science revision course 2014

  6. of blood pressure Determinants EXAMPLE *SBP Blood pressure *DBP Systolic blood pressure - stroke volume Diastolic blood pressure - heart rate & total peripheral resistance One-2-One Medicine: Pre-clinical science revision course 2014

  7. of blood pressure Determinants EXAMPLE *SBP Blood pressure *DBP Systolic blood pressure - stroke volume Diastolic blood pressure - heart rate & total peripheral resistance One-2-One Medicine: Pre-clinical science revision course 2014

  8. of blood pressure Determinants EXAMPLE *SBP Blood pressure *DBP Systolic blood pressure - stroke volume Diastolic blood pressure - heart rate & total peripheral resistance One-2-One Medicine: Pre-clinical science revision course 2014

  9. of blood pressure Determinants EXAMPLE *SBP Blood pressure *DBP Systolic blood pressure - stroke volume Diastolic blood pressure - heart rate & total peripheral resistance One-2-One Medicine: Pre-clinical science revision course 2014

  10. of blood pressure Determinants EXAMPLE *SBP *SBP *SBP *SBP Blood pressure *DBP Systolic blood pressure - stroke volume Diastolic blood pressure - heart rate & total peripheral resistance One-2-One Medicine: Pre-clinical science revision course 2014

  11. Factors influencing arteriolar tone EXAMPLE 1. ENDOTHELIAL SUBSTANCES 2. MYOGENIC TONE 3. AUTONOMIC EFFECTS 4. METABOLIC HYPERAEMIA 5. HORMONES 6. PLATELETS: serotonin → vasoconstriction One-2-One Medicine: Pre-clinical science revision course 2014

  12. Arteriolar tone endothelial substances EXAMPLE ↑ shear stress ↑ Shear stress ↑ NO + ↑ PG Endothelial cell → NO ↑ sGC ↑ AC → Relaxation ↑ cGMP ↑ cAMP ↓ [Ca2+] Relaxation Vascular smooth muscle cell One-2-One Medicine: Pre-clinical science revision course 2014

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