November 20, 2023 Flashcards
Questions at beginning of lecture:
- Use words to describe in detail the consequences of degranulation
- Draw a graph of FEV1 performance after exercise at 40% and 75% of VO2max
- Explain the causes of eccentric and concentric hypertrophy, and describe cellular and heart morphology
- Why can’t cardiac muscle contract tetanically
- If HR is 100bpm and systole is 250msec long, how long is diastole (answer: 350msec)
If HR is 100bpm and systole is 250msec long, how long is diastole? 350 msec
Take 60 seconds and divide by BPM (will get milliseconds)
Then subtract systolic time to find diastolic time
which action potential is longer, Skeletal muscle AP or Ventricular muscle AP
action potential in ventricular muscle is longer because calcium channels open and calcium comes in to make the cell positive for a longer period of time (only in cardiac muscle not skeletal muscle)
page 136
why can’t your heart muscle contract tetanically like skeletal muscle
The refractory period is as long as the contraction itself so another contraction can’t occur right after
You don’t want heart muscle to contract tetanically like skeletal muscle (can’t summate force in cardiac muscle, only in twitches)
page 136
what element leaves the cell to bring Action potential back down to resting potential
Potassium leaves and cell is brought down to resting potential
page 136
what element enters the cell and cause action potential/membrane potential to become positive
Sodium comes in and causes cell to become positive
page 136
does Intraventricular pressure drop or rise as ventricles contract
Intraventricular pressure rises as ventricles contract
does Intraventricular pressure fall or rise as ventricles relax
Intraventricular pressure falls as ventricles relax
what does S1 heart sound represent?
left AV valve closure as pressure develops in ventricle
what does S2 heart sound represent?
aortic valve closure when pressure in aorta is greater than pressure in ventricle (80mmHg)
The difference between S1 and S2 is taken as the the time of ___________
systole
does diastolic filling take more or less time during exercise
In exercise, diastolic filling takes less time
An adaptation to a lower HR has 2 benefits for the heart and 1 benefit for the rest of the body:
More diastolic time = better cardiac muscle perfusion through coronary vessels (heart itself has better supply of blood flow)
Less ATP demand of cardiac muscle (higher supply:demand ratio for the heart)
More diastolic time = more time to fill the ventricle with blood for distribution to the rest of the body (more blood in there to distribute)
At very high heart rates is diastole or systole mainly reduced?
At very high heart rates, diastole is mainly reduced, however systole can also be reduced
page 138 (graph on bottom)
what is the function of action potential at the sinoatrial (SA) node
serves as the natural pacemaker of the heart, goes through several phases
Do SA node cells have a stable resting membrane potential?
SA node cells DO NOT have a stable resting membrane potential.
Instead, they exhibit a slow depolarization during diastole (resting phase) called the pacemaker potential.