Flashcards in REVIEW Deck (110)
All of the muscle fibers contract as one (do not act individually)
Surrounds AV valve openings between the atria and ventricles
- helps separate contractions, so atria goes before ventricles
How does blood come back through the venous system?
Enters thru superior/inferior vena cava (carries oxygen poor blood from the body ---> right atrium --> tricuspid valve (AV valve) --> right ventricle--> pulmonary valve --> pulmonary artery (off to the lungs) --> pulmonary vein (empties oxygen rich blood) --> left atrium --> mitral valve (bicuspid, left AV) --> left ventricle --> aortic valve --> aorta --> body
Only place where deoxygenated blood is
- also occurs in the placenta for a short period of time
Carries oxygenated blood
What are the semilunar valves?
Aortic (left) and pulmonary (right) valves
- 3 cusps (resembles Mercedes logo)
What are the bicuspid valves?
Just the mitral valve!
- has 2 triangular flaps
What are the tricuspid valves?
Right AV valve
- 3 irregular flaps
Where is contraction actually happening during the action potential curve?
Ventricular muscle AP
- phase 0: fast Na channels open, then slow Ca channels
- phase 1: K channels open (tip of peak)
- phase 2: Ca channels open more (plateau)
- phase 3: K channels open more (end of peak)
- phase 4: resting membrane potential
What is the difference between conduction system and cardiomyocytes?
Conduction system has slow, leaky Ca channels that are not found in cardiac myocytes (just fast Na channels)
Muscle stimulated by action potential and contracting
Muscle reestablishing Na/K/Ca gradient and is relaxing
P: atrial wave
QRS: ventricular complex
T: ventricular repolarization
Right atrial pressure
Is generally low! (located on the low pressure side)
- diastole: blood comes in from great veins, passes thru ventricles
- contraction does not change pressure much
- when valves bulge back during peak of compression is the area of highest pressure
- diastole: raises pressure slightly
- systole: isovolumic metric pressure (volume is not changing, just pressure)
Ventricular pressure needs to be higher than ______ in order to eject blood into the aorta
Peaks with ejection peak
- systole: aorta stretches to accomodate increase in volume
- elastic muscle maintains pressure, does not go back to 0 until you reach diastole
At the start of relaxation, aortic valve closes and blood runs backward in the aorta
Sounds of the heart
- S1: AV valves close (start of systole)
- S2: aortic/pulmonic valves close
- S3: hear if you have watery blood splashing
- S4: end of diastole when atria contract (not heard unless you have hypertension)
Amount of blood that comes out
- should be around 60%
- used to calculate cardiac output
Stroke volume x heart rate
Within physiological limits, the heart pumps all the blood that comes to it without excessive damming in the veins
- extra stretch on cardiac myocytes makes actin and myosin filaments interdigitate to a more optimal degree for force generation
Does the Frank-Starling mechanism have a limit?
- if you bring back more blood than max cardiac output, you get backflow of blood
If you _____ cardiac muscle, then it performs more efficiently and you have stronger contractions
Pathway of heartbeat
Begins in SA node --> internodal pathway to AV node --> impulse delayed in AV node (allows atria to contract 1st) --> AV bundle takes impulse into ventricles --> left and right bundles of Purkinje fibers take impulses to all parts of ventricles
What is the slowest place in the conduction pathway?
AV node! It pierces fibrous insulator to get signal into ventricles
- AV bundle is second slowest
- Purkinje fibers are the fastest (have to go the farthest in the shortest amount of time)
Regular, spontaneous action potentials (depolarization)
- SA node is the fastest (leakiest) to fire
- AV node next fastest to fire
- Purkinje fibers third fastest to fire
Speed at which action potential is passed to the next cell
- Purkinje fiber is the fastest
- SA node/internodal pathways: medium speed
- AV bundles: medium slow
- AV node: slowest