D1-D2 Flashcards
When does the SL valve open?
When pressure in ventricle is greater than in the aorta
When does left ventricular contraction start?
before right side
When does right side ejection start?
before the left side
At a HR of 75/min, what is the time of atrial systole?
0.1 sec
At a HR of 200/min, what is the time of ventricular systole and diastole?
systole-0.16 sec
diastole-0.14 sec
At how many beats/min does the ventricle have problems filling adequately?
above 180/min
What moves blood and generates a pressure wave (pulse)?
systolic contraction
When does the 1st heart sound occur?
closing of the AV valves, start of ventricular systole
When does the 2nd heart sound occur?
closing of the SL valves, end of ventricular systole
What sound does a narrowed valve make during systole and diastole?
lub-whistle-dub (systolic)
lub-dub-whistle (diastolic)
What sound does a insufficient valve make?
lub-swish-dub (systolic)
lub-dub-swish (diastolic)
How do you calculate mean arterial pressure?
Cardiac output (CO) x total peripheral resistance (TPR)
What controls the heart rate?
autonomic system (sympathetic, epinephrine, and parasympathetic)
What is the main thing stroke volume is influenced by?
contractility of the cardiac muscle is being increased
What causes increased contractility of the cardiac muscles?
more cross-bridging between actin and myosin (frank-starling law)
increase in Ca inside the cell
Which node has beta 1 receptors?
SA node
What does cAMP do in the cardiac muscle?
accelerates relaxation
What triggers L type calcium channels to be more permeable to Ca?
PKA
What makes Ca go faster and the cell to process Ca faster?
sympathetic stimulation
What inhibits Ca efflux across the sarcolemma?
PKA, to keep Ca levels high
Where are the L- type Ca channels located and what activates it?
in the T tubule membrane and are activated by action potential going down the T tubule
What do the activated L type channels do to cause a release of Ca in the cardiac muscle?
physically interact with ryanodine receptors (RyR) in the SR
What increases heart rate (chronotropy) in the SA and AV nodes?
Norepinephrine via beta-1 receptors
What increases calcium processing (inotropy) for the cardiac myocytes?
norepinephrine via beta-1 receptors
What inhances the release of calcium by troponin ?
PKA phosphorylating TN-I
What decreases chronotropy at the SA and AV nodes by opening special K channels and decreasing cAMP levels?
ACh activating the M2 receptors
What does sympathetic stimulation do to the frank starling curve?
shifts the curve to the left (higher)
What are 4 things that sympathetic activity increase during the cardiac cycle?
- stroke volume
- strength of cardiac contraction
- end-diastolic volume (EDV)
- Venous return
What does digitalis do to the contractility of the heart?
increases calcium levels
inhibits NA-K pump making Na ion levels higher in the cell (builds up)
What are some factors affecting EDV?
- increase in intrapericardial pressure (fluids) and limits ventricular expansion
- increases ventricular stiffness (from heart attack)
- not able to effectively contract the atrial muscles
What is the difference for someone with a transplanted heart?
heart rate doesn’t change because SNS and PNS isn’t hooked up
Where do the cardiac myocytes get their oxygen?
from the coronary artery system (not from the blood in the atrium or ventricles)
What does an increase in afterload increase?
O2 consumption
