New CVS Flashcards
What are examples of cardiac glycosides ?
digitalis
ouxbain
What are cardiac glycosides ?
they try to increase the output force of the heart
by reducing HR
supression of the Na/K ATPase
What are cardiac glycosides used for ?
treatment in congestive heart failure
increase the amount of time spent in diastole
What is the direct mode of the Na/Ca exchanger ?
direct mode allows Na in and removes Ca
What is the indirect mode of Na/Ca exchanger ?
calcium enters and Na is removed
What happens in hyponatraemia ?
reduced Na extracellular concentration hyposmotic conditions cardiomyocytes swell extrusion of intracellular solutes- Na/Cl and K reversed mode of the Na/Ca exchanger positive iono/chrono and dromo
What happens in hyponatraemia to circualtion ?
hyposmotic conditions cardiomyocytes swell reduced blood volume polycythaemia and increased blood density hypotension leads to incrrased HR and contractility
What happens in hypernatraemia ?
increased extracellular Na
Cardiomyocytes shrink
direct mode of exchanger
negative iono.chromo and dromo
What happens in hyperkalaemia ?
increased extracellular K
Reduced driving force for K
Depolarisation
Negative iono/chromo/dromo
What happens in hypokalaemia ?
reduced extracellular K
increased driving force for K
Hyperpolarisation
positice iono/chrono and dromo effects
What happens in hypercalcaemia ?
Increased extracellular Ca
depolarisation
postive iono/dromo and chromo
What happens in hypocalcaemia ?
reduced extracellular Ca
hyperpolarisation
negative iono/chromo and dromo effects
What does the CVS system consist of ?
blood
vessels
heart
What are the channels responsible for action potentials in smooth muscle cells
L-type Ca channels
What do gap junctions in cardiomyocytes allow for ?
communication between cells without contact in the ECF
Describe the mechanism of smooth muscle contraction ?
Na enters through voltage gated sodium channels
calcium enters through L-type calcium channels
calcium induced calcium release from SERCA via RyR receptors
calcium-calmodualin complex stimulates MLCK
What are the haematocrit values for men ?
42-52%
What are the haematocrit value for women ?
37-47%
What is the rate of pulses in the SAN ?
70-100 bpm
What is the role of the SAN ?
impulse spreads from the SAN across the atria
What is bachmanns bundle ?
specialised pathway band that conducts impulse directly from right to let atrium
What is the rate of the AVN ?
40-60
What is the role of the AVN ?
delays impusle from the SAN by 100-120 ms to let blood fully eject from the atria to the ventricles
What is the instrinsic rate of the Bundle of his ?
20-40
What is the role of the bundle of His ?
transmits impulses from the AVN to the ventricles
branches into right and left
What is the intrinsic rate of purkinje fibres ?
15-30
What is the role of the purkinje fibres ?
distribute impulse to the myocardial cells in the ventricles
excitataion begins at the apex
