Cardiovascular 2

Question 1

Definition:

Systole

Answer 1

Contraction; pumps blood into circulation

Question 2

Definition:

period of relaxation that occurs as teh chambers fill with blood

Answer 2

diastole

Question 3

What does the P wave represent?

Answer 3

Depolarization of the atria

Question 4

When does the atria start contracting in relation to the P wave?

Answer 4

25ms after the start of the p wave

Question 5

What part of the ECG represents the depolariation of the ventricles?

Answer 5

QRS complex

Question 6

T/F: ventricles begin to contract at the point Q of the QRS complex

Answer 6

fales! they begin to contract as the QRS reaches the peak of the r wave

Question 7

What does the T wave represents?

Answer 7

Repolarization of the ventricles

Question 8

Why is there no wave representing the repolarization of the atria?

Answer 8

It occurs during the QRS wave so it is masked

Question 9

Definition:

Measures the duration from the beginning of the atrial depolarization (p wave) to the initiation of the QRS complex

Segments

Answer 9

PR interval

Question 10

What may cause the QT interval to change? How?

Answer 10

myocardial damage, ischemia, or conduction impairments

this interval measures the depolarization and repolarization of the ventricles so can indicate if there is tissue damage if this segment is prolonged

Question 11

Definition:

TP Interval

Answer 11

time between start of ventricular repolarization and teh next atria depolarization

Question 12

What interval changes in a healthy person with exercise?

Answer 12

TP interval

Question 13

T/F

Atrial contraction pumps all the blood into the ventricles

Answer 13

false! due to pressure gradients 70-80% of the blood flows into the ventricle during diastole, atrial systole contributes the the remaining 20-30% of ventricular filling

Question 14

How long does atrial systole last?

Answer 14

100ms

Question 15

What causes the tricuspid and mitral valves to close?

Answer 15

Blood pressure rising above that of the atria during ventricular systole

Question 16

Definition

Isovolumetric contraction

Answer 16

Period of ventricular systole when ventricle is contracting, but blood is not being ejected

Question 17

definition

End diastolic volume (EDV)

Answer 17

Blood remaining in ventricles at the end of atrial systole just prior to ventricular contraction
~130mL

Question 18

Definition:

Remaining blood at the end of venrticular systole (~50-60 mL)

Answer 18

End systolic volume (ESV)

Question 19

Definition

Difference between EDV and ESV

Answer 19

Stroke volume

Question 20

What is the normal range for stroke volume?

Answer 20

70-80mL

Question 21

Definition

‘lub’

Answer 21

sound created by the closing of the atrioventricular valve during ventricular contraction

May hear a swishing sound instead (not good)

Question 22

Definition

Sound of the closing of the semilunar valves during ventricular diastole

Answer 22

‘dub’

Question 23

BP sounds

systolic pressure

Answer 23

onset of tapping (swish)

Question 24

BP sounds

Diastolic Pressure

Answer 24

disappearance of sound (end of swish)

Question 25

# Definition: Volume of Blood ejected from the ventricles each minute

Answer 25

cardiac output

Question 26

# Definition: Stroke volume

Answer 26

amount of blood pumped out of ventricle in one beat

Question 27

Equation fo CO:

Answer 27

SV x HR

Question 28

What are the 3 main factors affecting SV?

Answer 28

1. Preload 2. Contractility 3. Afterload

Question 29

What is preload?

Answer 29

degree of stretch the heart performs befoe it contracts (EDV) | Frank-Starling law

Question 30

What is afterload?

Answer 30

pressure which needs to be exceeded before blood can be ejected from the heart - 20mmHg for pulmonary trunk - 80mmHg for aorta

Question 31

How does HR affect filling time?

Answer 31

If heart rate is increased, filling time decreases

Question 32

What 2 things affect preload?

Answer 32

Venous return and filling time

Question 33

What is the frank-starling mechanism/law?

Answer 33

Force of heart contraction is directly proportional to the initial length of the muscle fibre greater the stretch, the more powerful the contraction which increase SV

Question 34

How does the autonomic nervous system regulate HR?

Answer 34

- down regulation via parasympathetic input (Ach lengthens repolarization period by hyperpolarizing it-- funny channel) - up regulation via sympathetic input (norepinepherine shortens the reploarization period)

Question 35

How does the endocrine system regulate HR?

Answer 35

- adrenal medulla releases epinepherine and thyroid realease thyroid hormones which both act to increase HR - increased levels of K+ decrease HR

Question 36

How does SV change with exercise?

Answer 36

- SV will intially increase despite less filling time - as HR increases further, SV plateaus and can eventually decrease if filling time is too short (filling time balances with venous return)

Question 37

How does cardiac output change with exercise?

Answer 37

Increases with exercise, intially due to both HR and SV - at higher intensities, mainly driven by HR

Question 38

How does volume of oxygen consumption change with exercise?

Answer 38

Increases in a linear fashion until it plateaus with maximal exercise