Cardiovascular Phys Flashcards
What are the two endocrine hormones in the heart and what do they respond to
ANP- In response to increased atrial pressure
BNP- in response to overstreached ventricles
what is the unique feature of cardiac musculature and how does contraction spread
-individual fibres are connected by intercalated discs with gap junctions
-the gap junctions allow for passage of ions between the myocytes
-the intercalated discs allow the heart to contraction in synchrony as one unit
What are the 5 phases of cardiac mm contraction
Phase 0- NA influx- rapid depolarization
Phase 1- inactivation of fast NA with K efflux (small lil repolarization)
Phase 2- Ca influx they L type (plateu phase)
Phase 3- inactivation of Ca channels with K efflux (full repolarization)
Phase 4- remove of excess Na and Ca
What is the absolute and relative refractory periods of the cardiac cycle
absolute- no action potential can be initiated regardless of stim strength because NA channels closed (phase 1/2)
Relative- stronger contraction needed (half way thru phase 3-4)
what does digoxin do
increases influx of calcium thus increasing force of contraction
what is the frank starling law
cardiac output is directly proportional to the venous return
-force of contraction of a myocardial fibre is proportional to the length
–the greater amount of blood entering=the greater stretch
what is the 1st and 2nd heart sounds
1st- closure of tricuspid and mitral valves
2nd- closure of pulmonary and aortic
What is the 3rd and 4th heart sounds
3rd- congestive heart failure
4th- just before 1st heart sound- hypertrophic ventricles
what is the normal pace for the SA node and AV node and then when they superimposed normally
SA- 80-100
AV- 40-60
Together- 70
where is conduction velocity the fastest and slowest in the heart
slowest- AV node
Fastest- purkinje fibres
what does the P, QRS and T wave represent
P- atrial depolarization
QRS- ventricular depolarization
T- ventricular repolarization
(atrial not seen as its under QRS complex)
What would the U wave be
repolarization of the purkinje fibres
Sympathetic inn of the heart is from what
T1-5 (the middle and inf cerv ganglia)
How is the heart rate, conduction velocity and force of contraction increased in heart
HR (chronotropism) increas rate of Phase 4
Conduction (dromotropism)- decrease PR interval (from p to q)
Force (inotopism)- increasing Ca influx in phase 2
What is parasympathetic inn of heart
vagus vis its cardiac branches
What is blood pressure calculated by
CO x Peripheral resistance
What are the 2 main mechanisms of controlling BP
Baroreceptors (fast due to NT)
Renin-angiotensin- aldosterone mechanism (slow due to hormones)
How does the baroreceptor system work
located on carotid sinus and in aortic arch (afferent carried by CNIX, X)
what is poiseuilles law
Peripheral resistance is directly proportional to the viscosity of blood and length of the vessel and inversely proportional to radius to 4th power
what % of blood is found in each part of the body (venous system, arteries, pulmonary, capillary systems)
Venous- 60%
arterial- 20
pulmonary 15
cap- 5
