Dani - ch 9 Flashcards
cardiac and skeletal muscle both fibers have a ___ appearance
striated
cardiac and skeletal muscle both rely on the opening of ___ ___ channels to initiate the action potential for contraction
fast sodium
cardiac and skeletal muscle contraction both are based on ____ filaments
sliding
cardiac muscle is most similar to ___ __ fibers
type I
Type I fibers are ___ twitch fibers, have more ___, and have ____ conducting neurons
slow
mitochondria
slow
cardiac muscle is ___ while skeletal is ____
involuntary
voluntary
cardiac fibers are interconnected by ___ disks
intercalated
the heart is divided into two functional ____ which allows the atria to contract before the ventricles
synctia
cardiac muscle has ___ ___ channels that must open to achieve action potentials
slow calcium
slow calcium channels of cardiac muscles cause a ____ in the action potential
plateau
duration of cardiac contraction is ~___ times longer for cardiac muscle than skeletal muscle
10
intercalated disks serve to fuse the cells together to form ___ ___ allowing for rapid diffusion of ions
gap junctions
gap junctions allow the action potential to travel rapidly from one cardiac ___ to the next
myoctye
at rest, the intracellular surface is ~___mV and if threshold is reached, it continues to ____mV at the peak of the AP
-85
20
for cardiac muscle, once the AP spikes at about ____mV, it begins to repolarize but ____ before it completely repolarizes
20
plateaus
the plateau is the reason why cardiac contraction is significantly ____ than skeletal
longer
phase 0 of AP
- opening of ___ ____ channels –> rapid _____
fast sodium
depolarization
phase 1 of AP
- at peak, repolarization begins = short ____ interval betweek peak and beginning of plateau
downward
phase 2 of AP
- opening of ___ ___ channels and continues sodium influx = ____
slow calcium
plateau
phase 2 of AP
- when slow calcium channels open, decrease outflux of sodium –> ____
plateau
phase 3 of AP
- ___ ____ channels close so increase of potassium outflow –> rapid ____
slow calcium
repolarization
___ ____ ___: the interval during the AP when a “normal” electrical impulse cannot re-excite the already excited area
absolute refractory period
___ ___ ___: a stronger than normal stimulus can re-excite the area
relative refractory period
there is no ___ ___ in cardiac muscle from premature contractions
wave summation
unlike skeletal myofibrils, cardiac myocytes rely on ___ ____ for contraction to occur
extracellular calcium
extracellular calcium enter the cardiac __ ____ and then enter the ___ via voltage gated calcium channels
t-tubules
sarcoplam
the influx of calcium activates the ____ recpetors on the SR membrane which triggers the SR to release ____
ryanodine
calcium
at the end of contraction, calcium is pumped back into the SR via the ___-____ pump
calcium-ATPase
calcium exits the sarcoplasm via the ___-___ exchanger
sodium-calcium
the sodium entering through the sodium-calcium pump is transported back out of the cell via ____-___ exchange pump
sodium-potassium
sodium-potassium pump
- __ sodium out
- __ potassium in
3
2
duration of atrial contraction
.2 sec
duration of ventricular contraction
.3sec
____ ____: series of events that occur from the onset of one heart beat to the beginning of the next heart beat
cardiac cycle
cardiac cycle is often defined as __ wave to __ wave
P
P
calculate total duration of a single cardiac cycle as a ___ of ___ ____
reciprocal
heart rate
RHR = __/___
1/HR
duration of systole at rest is about __% of total duration
40
when HR increases, the total duration of cardiac cycle decreases but the relative time spent in ventricular systole actually ___
increases
duration of systole at elevated HR is about __% of total duration
65
1st heart sound is marked by the ___ valves closing
AV
isovolumic contraction after the ___ valve close and before the ___ valve opens
AV
aortic
isovolumic relaxation is after the ___ valves close and before ___ valve opens
aortic
AV
you have to have ventricular contraction for the ___ valve to open
aortic
QRS complex happens during the ___ heart sound
1st
as ventricle contrace, the AV valves close = ___ heart sound
first
first heart sound is ___ pitched and ___ lasting
low
long
at the end of ventricular systole, the aortic and pulmonary valves snap shut = __ heart sound
2nd
2nd heart sound is ____
short
at the end of rapid filling. the AV valves opened and blood rushes from the atrium to the ventricles, the ventricle walls expand and is though it is the sound of blood against the ventricle walls = ___ heart sound
3rd
3rd heart sound = often ___ heard
isnt
p wave = depolarization of the ___
atria
p wave = atrial contraction follows which causes a slight ___ on the atrial pressure curve
increase
QRS complex = depolarization of the ___
ventricles
QRS complex = ventricular contraction follows causing the significant ____ on the ventricular pressure curve
increase
T wave = repolarization of the ____ occurs before ventricular contraction is complete
ventricles
T wave = followed by relaxation of ventricles with a significant ____ on the ventricular pressure curve
decrease
isovolumetric contraction = when ventricular ___ begins; ventricular pressure must rapidly ___ to build up pressure to push open the ___ valves against arterial pressure
contraction
increase
semilunar
isovolumetric contraction = tension has ___ without a shortening of the cardiac fibers
increased
2 periods of ejection
rapid
slow
rapid ejection = ventricular pressure reaches __mmHg which pushes open the semilunar valves
80
rapid ejection = about __% of the blood volume that is ejected during a single contraction pours out of the ventricles during the first __/__ of the ejection period
70
1/3
slow ejection = the remaining __% of the blood volume ejected takes the remaining __/__ of the ejection period
30
2/3
isovolumetric relaxation = at the end of ventricular ___, intraventricular pressure ___ rapidly and the pressure in the great arteries ___ which pushes blood back toward the ventricles and the semilunar valves ___ ___
contraction
decreases
increase
snap shut
isovolumetric relaxation = ventricular volume ___ changed, the ventricles _____. intraventricular pressures continue to ____ rapidly and the ___ valves open to begin filling ventricles again
hasn’t
relax
decrease
AV
first 1/3 of filling of the ventricles is called ____ filling
rapid
during systole, AV valves are closed so when systole ends and the pressure in the ventricles ___ and the blood accumulated in the atria ___ atrial pressure and pushes the ___ valves open so blood rapidly flows into the ventricles
decrease
increase
AV
second 1/3 of ventricular filling = blood returning to the heart continues to pass ____ through the atria into the ventricles
directly
last 1/3 of ventricular filling = ___ contract giving last push of blood into the ventricles. accounts for about __% of total filling
atria
20
a wave of atrial pressure changes = caused by ___ contraction so occurs after the ___ wave on the ECG
atrial
P
c wave of atrial pressure changes = caused by beginning of ___ contraction
ventricular
c wave of atrial pressure changes = rapid ___ in ventricular pressure causes the closed ___ valves to bulge back toward the atria
increase
AV
v wave of atrial pressure changes = occurs at the end of ___ contraction while the ___ valves are still closed as more blood is returning to the atria from the great veins
ventricular
AV
blood returning to the heart from the great veins first goes to the atria but __% passes right through the open ___ valves into the ventricles
80
AV
the atria are called ___ pumps because the ___ of these upper chambers only provides the last __% to fill the ventricles
primer
contraction
20
if the atria fail to contract properly, there __ enough blood in the ventricles to pump to the peripheral organs to meet the demands under resting conditions
is
aorta and systemic arteries work at a __ pressure compared to the pulmonary arteries
higher
pressure in the ventricles has to be more than the ___ pressure
aortic
after the peak of the ejection period, aortic pressure begins to ___ similar to the __ in ventricular pressure
decrease
decrease
when aortic valve closes there is a slight __ in pressure called the ___
incisure
incisura is caused by the cessation of ___ of blood when the valve snaps shut
backflow
___ ____ ___ = at the end of ventricular diastole, the volume of blood in each ventricle ~120mmHg
end diastolic volume
___ ___ ___ = the volume of blood remaining in the ventricles after contraction is ~50mmHg
end systolic volume
___ ___ = the volume of blood ejected from the ventricles during systole is ~70mmHg
stroke volume
___ ___ = the fraction of the EDV that is ejected during systole
ejection fraction
ways to increase SV during exercise=
- ___ EDV w/ ___ heart
- ___ ESV
increase
stronger
ESV
___ and ___: terms used to assess the contractile properties of a muscle fiber
preload
afterload
___ = tension on the muscle fibers at the onset of contraction
preload
preload is the ___ pressure resulting resulting from EDV
diastolic
___ = the pressure in the LV to overcome the pressure in the aorta the ventricle can eject blood into the aorta
afterload
cardiac muscle has a high number of ___
mitochondria
heart metabolizeds ___ ___, __ and __
FA
glucose
lactate
___ ___: the additional work required for a contraction to move toward completely emptying the LV
potential work
__-__% of chemical energy is converted into work energy and ___-__% to heat
20-25
75-80
avg person pumps __-__ liters of blood out of the heart per minute which is CO
4-6
__ ___: amount of blood flowing into the RA from the great veins
venous return
sympathetic stimulation increases ___ __ and __ __
heart rate
stroke volume
PS stimulation: serves to ___ the heart rate
slow
vagal stimulation primarily effects the ___
atria
