Chapter 9: timeline of events and structures involved

Question 1

diastolic volume (EDV)

Answer 1

total amount or volume of blood in a ventricle before it contracts

Question 2

ensystolic volume (ESV)

Answer 2

residual (what remains) after contraction

Question 3

frank startling law of heart

Answer 3

more filling= more stretching

more stretching= greater blood ejection

Question 4

cardiac output

Answer 4

volume of blood pumped per minute

Question 5

sympathetic tone

Answer 5

fight or flight

would increase heartrate and increase venous return

Question 6

parasympathetic tone

Answer 6

rest and digest
decrease in heart rate
decrease in venous return

Question 7

diastole 0s-.4s

Answer 7

atria are relaxed
ventricles relaxed
ventricular filling

Question 8

atrial systole .4 - .6s

Answer 8

atria contract
ventricles relaxed
EDV (total amount or volume of blood in a ventricle before it contracts

Question 9

ventricular systole .6-.8

Answer 9

ventricles contract
blood enters the arteries
ESV

Question 10

if stroke volume SV = EDV - ESV what would decrease SV?

Answer 10

decrease EDV

increase ESV

Question 11

Bachmans bundle

Answer 11

branch that goes from the SA node to the left atrium

• a fiber like structure that conducts electricity or depolarizing event
• main way to depolarize the left atrium

Question 12

main important part of depolarization

Answer 12

-getting the ventricles to contract forcefully, efficiently, and at the same time

Question 13

why are the right and left bundle branches insulated?

Answer 13

they are insulated so they do not come in direct contact with the work cardiomyocytes, this is way contraction of the work cardiomyocytes only happens once the purkinje fibers come in direct contatct with the work cardiomyocytes to make them contract from the BOTTOM UP!!

Question 14

conduction velocity of the SA node

Answer 14

.05 meters/ second
-kind of slow
-

Question 15

conduction velocity of the VA node

Answer 15

.05 meters /second
-really slow because it gives the atria time to fully contract while the ventricles are still relaxed, before it ever comes streaming down causing the ventricle to contract

Question 16

what happens if there is no delay of the sa and av nodces meaning what would happen if ventricular and atrial contraction happened at the same time?

Answer 16

your valve would not be able to remain closed because they would be fighting two different pressures that are similar so you could have blood go back into the atria

Question 17

conduction velocity of bundle of his

Answer 17

2 m/s

Question 18

conduction velocity of bundle branches

Answer 18

2 m/s

Question 19

why are perkinje fibers the fasted at 4 m/s

Answer 19

because by the time you get the action potential down to the bottom or apex there is no reason for delay

Question 20

why are work cardio myocytes slower to depolarize?

Answer 20

their intracellular RMP is -80 mV

the SA nodal cells depolarize quicker ttherefore preventing the work cardiomyocytes from setting up their own beat

Question 21

spontaneous depolarization

Answer 21

SA nodal cells do not need an outside factor telling them to depolarize , they just do it all on their own
-the dip down to -60 but do not stay at RMP

Question 22

how many work cardiomyocytes share gap junctions with eachother?

Answer 22

about 11!

this means you can have 11 different work cardiomyocytes sending depolarization to on cell

Question 23

stroke volume

Answer 23

amount of blood pumped per ventricle per beat

• sv= edv-esv
• refers to how much came out of the ventricle

Question 24

what would decrease stroke volume?

Answer 24

a decrease in EDV or increase in ESV
-if you decrease EDV less could eject so SV goes down
-if you increase ESV it will decrease SV because it means there is more remaining in the chamber stil
(this is bad because it could be a sign that the heart was unable to handle the amount that was put in there for whatever reason)

Question 25

How would an increase in sympathetic tone impact cardiac output

Answer 25

• cardiac output has to match the oxygen demand of its tissues that will be detected by the brain and the brain with then increase the HR
• Sympathetic tone increases the Heart Rate and Increases venous return also INCREASING EDV then increasing CO