Cardiovascular Physiology Overview
16/11/10
PY Mindmaps
Part I Notes
MUSCLE
- intercalated discs -> transmission of electrical depolarisation easy and produces a coordinated contraction.
- branching cells
- single nucleus
- visible striations
- T-tubules are located on Z-lines (not A-I function)
ELECTRICAL PROPERTIES
HAEMODYNAMICS
MAP = Q x SVR
Jeremy Fernando (2010)
Q = SV x HR
SV = Preload, Afterload, Contractility
SVR = change in P/Q
Q = DPr4/8nl
Q = rate of blood flow
DP = pressure difference
r = radius
l = length
n = viscosity of blood
Preload
- determined by:
- VR
- HR
- atrial contraction
- atrial and ventricular pressures during diastole
- compliance of ventricles
Afterload
- determined by:
- SVR
- aortic compliance
- wall thickness
- chamber radius
- ventricular size
- ventricular volume
Contractility
- determined by:
- substrate supply
- integrity of myofilaments
- co-ordinated depolarisation
- metabolic/electrolyte homeostasis
- functional muscle mass
- coronary blood flow (hypoxia)
- autonomic tone
- hormones
BLOOD SUPPLY TO HEART
Left Coronary
- arises from aortic sinus
- passes behind then to left of pulmonary trunk -> left part of the atrioventricular groove -> lateral round the left border of heart to reach the inferior interventricular groove.
- divides into:
(1) LAD -> diagonal branches
- anterolateral wall of left ventricle
- interventricular septum
- anterior wall of right ventricle
- ventricular apex
(2) Circumflex -> obtuse marginal branches
- left atrium
- posterior wall of left ventricle
- lateral wall of left ventricle
Right Coronary
- from anterior sinus and passes forwards between the pulmonary trunk and right atrium
- it descents in the right part o the atrioventricular groove to anastamose near the apex with corresponding branch of the left coronary artery
- supplies:
-> lateral wall of the right ventricle
-> posterior wall of the right ventricle
-> inferior wall of the left ventricle
-> sinoatrial node in 55% of patients
Dominance
- dominance is determined by which coronary artery supplies the posterior descending artery (PDA)
- in 85% of patients this is supplied by the RCA
Venous Drainage
- 2/3 by coronary sinus
- 1/3 drain directly into cardiac cavity
- vessels draining into the coronary sinus:
-> great cardiac vein (anterior interventricular groove)
-> middle cardiac vein (inferior interventricular groove)
-> small cardiac vein (lower border of heart)
-> oblique vein (descends obliquely on the back of LA)
- anterior cardiac vein lies in the anterior atrioventricular groove (it drains much of the anterior surface of the heart and opens directly into the RA)
Jeremy Fernando (2010)