Cardiovascular Physiology Excitation and Conduction Part 2

Question 1

what is happening in the between beats phase of the cardiac cycle

Answer 1

-pressure in atria < pressure veins
-pressure in atria > pressure in ventricles
- pressure in ventricles < pressure in arteries
-AV valves open
- SL valves closed

Question 2

what is the period called between beats and how much blood is being loaded into ventricles at this time

Answer 2

period of passive filling
-80% of blood for contraction

Question 3

what is happening in atrial systole in the cardiac cycle

Answer 3

-pressure in atria is high so AV valves are open
- pressure in Atria > pressure in veins
- pressure atria > pressure in ventricles
- pressure in ventricles < pressure in arteries
- SL valves shut

Question 4

what is the period called in atrial systole and how much blood is being loaded into ventricles

Answer 4

-period of active filling
-20% of blood for contraction

Question 5

what is happening in atrial diastole/early ventricular systole in the cardiac cycle

Answer 5

-pressure in atria is low
- pressure in ventricles is high
- pressure in atria < pressure in veins
- pressure in atria < pressure in ventricles
- pressure in ventricles < pressure in arteries
-SL and AV valves are closed

Question 6

what is the period called in atrial diastole/early ventricular systole

Answer 6

period of isovolumetric contraction

Question 7

what is happening in late ventricular systole

Answer 7

-pressure in atria < pressure in veins
- pressure in atria < pressure in ventricles
- pressure in ventricles > pressure in arteries
- SL valves open
-AV valves shut

Question 8

what is the phase called in late ventricular systole

Answer 8

ejection phase

Question 9

what is happening in early ventricular diastole

Answer 9

• pressure in ventricles is low
• pressure atria < pressure in ventricles
• pressure in ventricles < pressure in arteries
  -SL and AV valves shut

Question 10

what period is during early ventricular diastole

Answer 10

period of isovolumetric relaxation

Question 11

what is happening in late ventricular diastole

Answer 11

-pressure in atria < pressure in veins
- pressure in atria > pressure in ventricles
-pressure in ventricles < pressure in arteries
-AV valves open
-SL valves shut

Question 12

what period begins in late ventricular diastole

Answer 12

period of passive filling

Question 13

what is the pressure/volume loop

Answer 13

change in left ventricular volume and pressure

Question 14

what is end diastolic volume

Answer 14

135 mL

Question 15

what is end systolic volume

Answer 15

65 mL

Question 16

what is stroke volume and the formula

Answer 16

-volume of blood ejected per beat
- EDV-ESV
-70 mL/beat

Question 17

what is ejection fraction and formula

Answer 17

-fraction of EDV ejected per beat
- SV/EDV
-52%

Question 18

what causes the 1st heart sound

Answer 18

AV valves close

Question 19

what causes the 2nd heart sound

Answer 19

SL valves close

Question 20

what is stenosis

Answer 20

failure of valves to open completely

Question 21

what is prolapse or insufficiency

Answer 21

failure of valves to close properly

Question 22

what is cardiac output and the formula

Answer 22

-amount of blood pumped out of each ventricle in 1 minute
- CO = HR x SV
-5 L/min

Question 23

what is cardiac output during intense exercise

Answer 23

30-35 L/min

Question 24

what is CO increased by

Answer 24

physical activity, metabolic status, drugs

Question 25

what is CO decreased by

Answer 25

blood loss, heart disease

Question 26

how do you control CO

Answer 26

by changing HR and SV

Question 27

what is HR controlled by

Answer 27

input from the nervous system

Question 28

what cells are affected by the SNS and increase HR

Answer 28

AR and Contractile cells

Question 29

what cells are affected by the PNS and decrease HR

Answer 29

AR cells only

Question 30

what meant by a positive dromotropic agent and give an example

Answer 30

increases speed of APs -ex: SNS

Question 31

what is SV controlled by

Answer 31

-change in preload (EDV) - change in afterload (blood pressure) - change in contractility (force of contraction)

Question 32

at rest, cardiac muscle sits at a length that is ____ than optimum

Answer 32

less

Question 33

how does increased EDV increase SV

Answer 33

increased EDV -> increased stretch of myocardium -> moves resting cardiocyte length toward optimum -> increases SV

Question 34

what is Starlings Law of the Heart

Answer 34

Increased EDV = increased SV

Question 35

what is the relationship between EDV and venous return

Answer 35

direct

Question 36

what do one way valves do

Answer 36

facilitate blood movement back to the heart

Question 37

what are factors that increase VR

Answer 37

-increased skeletal muscle pump - increases thoracic pump (breathing) - increases venoconstriction via SNS

Question 38

what is the relationship between SV and HR

Answer 38

inverse

Question 39

what is the relationship between CO and HR

Answer 39

direct

Question 40

does HR have a greater effect on CO or SV

Answer 40

CO unless extremely tachycardic

Question 41

what is afterload

Answer 41

the pressure that the ventricles must overcome to force open the aortic and pulmonary valves

Question 42

what can increase afterload

Answer 42

anything that increases systemic or pulmonary arterial pressure

Question 43

what does increased afterload do to SV

Answer 43

decreases it

Question 44

is afterload a major factor in healthy subjects

Answer 44

no

Question 45

what does load do to skeletal muscle and cardiac muscle contraction

Answer 45

leads to hypertrophy and decreased function or ability to contract

Question 46

how is contractility varies

Answer 46

calcium concentration that enters contractile cells via L type VG Ca2+ channels

Question 47

what are the 3 effects of B1 adrenergic receptor activation on contractility

Answer 47

-increased force and speed of contraction by: 1-L type Ca2+ channel gets phosphorylated 2- cross bridge cycling 3-increased Ca2+ ATPase activity causes quicker relaxation

Question 48

what does acetylcholine affect

Answer 48

HR

Question 49

what does NE and Epi affect

Answer 49

HR AND SV

Question 50

what part of the heart is the influence for HR

Answer 50

atria

Question 51

what part of the heart is the influence for SV

Answer 51

ventricles