cardiovascular Flashcards
whats sa node for
is where depolarisation occurs heart’s natural pacemaker because it generates electrical impulses that initiate and regulate the heart’s rhythm.
whats av node for
causes delay 100m/s
elastic artery
large and near heart and havwe elastic walls that expand during systole and push blood out during diastole. Helps maintain bp
muscular artery
transports blood from elastic arteries to organs at high pressure. Rate of blood flow is adjusted by using smooth muscle to vary the radius. flow is proportional to fourth power of radius
arterioles
controls blood flow to capillaries. greatest pressure drop occurs. degree of contriction determines total peripheral resistance
capillaries
allows exchange of gases, nutrients, wastes. no connective tissue or smooth muscle.
venules
collect deoxygenated blood from the capillaries and transport it to larger veins. during inflammation this is site where wbc leave to attack bacteria
coronary arteries
arteries that supply blood to the heart muscle (myocardium)
Where do inputs to CV centre come from
Higher brain centres (cerebral cortex), proprioceptors, baroreceptors, chemoreceptors
whats p wave
atrial depolarisation
whats qrs complex
ventricular depolarisation
whats t wave
ventricular depolarisation leading to contraction (ventricular systole)
What’s preload
EDV or degree of stretch of cardiac muscle fibres at end of relaxation (diastole)
Increase in contractility (sympathetic) does what
Reduces ESV therefore increasing SV = EDV-ESV
What’s intropy
Another way of saying contractility
What happens to depolarisation at SA node for both systems
Sym- increase rate of depolarisation
para- decreases rate of depolarisation
What’s angiotensin II
Hormone that causes blood vessels to constrict to increase bp
What’s frank starlings law
More in more out
What is increase of preload
Increase in forcefullness of contraction which increases stroke volume. This increases CO
Increase in bp results in
Increase firing rate of baroreceptor nerve
What does high bp do to heart rate
Decreases it
Relationship between bp and sympathetic nervous system
Sympathetic system brings bp down
What neurotransmitter is realeased to slow down heart rate
Ach by vagus nerve
What’s afterload
Resistance that heart must overcome to eject blood during contraction
What’s cardiac accelerator nerves
Part of sym nervous system and inc HR by innervating SA and AV nodes
What do cardiac accelerator nerves do
Release NE to act on SA node by increasing rate of spontaneous depolarisation (inc heart beat) and on beta receptors of ventricles that inc contractility
What’s diff between persons max and resting CO called
Cardiac reserve
What’s stroke volume
Amount of blood pumped out per cardiac cycle
What’s Angina pectoris
pain accompanying myocardial ischemia
What’s vasomotor region
Regulated peripheral resistance by changing diameter of blood vessels
What does blood viscosity directly affect
Systematic vascular resistance
What’s starlings law
Movement of fluid between capillaries and interstitial space based on balance of hydrostatic and oncotic pressure
BHP+IFOP - BCOP+IFHP
Blood hydrostatic pressure, + interstitial fluid osmotic pressure
Blood colloid, osmotic pressure + interstitial fluid, hydrostatic pressure
What’s brachiocephalic
artery that branches out from aorta arch and supplies blood to right arm head and neck
Result of standing still too long
Venous return decrease due to lack of skeletal muscle pumping of veins so SV drops = decrease in CO
What’s hypertension
bp in arteries is elevated
Does sym or para have vagus as primary nerve
Para
What can increase calcium in cell
Sympathetic system
