The Heart As a Pump

Question 1

mechanical properties of the heart

Answer 1

Heart rate
Stroke volume
Cardiac output (CO)
Ejection fraction
Preload
Afterload
Contractility
Factors on cardiac output

Question 2

Heart rate (HR)

Answer 2

*The number of heartbeats in 1 minute

• directly proportional to cardiac output
• Adult HR 80-100 beats per minute (bpm) normally
• Modified by autonomic, immune, and local factors

Question 3

Stroke volume (SV)

Answer 3

*Volume and output of blood pumped from the left ventricle per beat

• Influenced by two types of controls
  Intrinsic control
  Extrinsic control
• Both controls increase stroke volume by increasing strength of heart contraction

Question 4

what is the equation for heart as a pump?

Answer 4

SV = (EDV) - (ESV)

Question 5

EDV

Answer 5

End Diastolic Volume (volume of blood in the ventricle at the end of diastole)

Question 6

ESV

Answer 6

End Systolic Volume ( volume of blood in the ventricle at the end of systole)

Question 7

Pulse rate (PR)

Answer 7

Number of beats per minutes (beats/min)

Question 8

Cardiac output (CO)

Answer 8

• Volume of blood pumped per minute (L/min)
  SV (L/beat) * PR(beats/min) = CO (L/min)

Cardiac output = heart rate * stroke volume

Question 9

Cardiac output (CO) and reserve

Answer 9

Cardiac reserve is the difference between resting and maximal CO

Question 10

Ejection fraction

Answer 10

= stroke volume / end-diastolic ventricular volume

• Calculated by PERCENTAGE
• Increases during exercise

Question 11

Preload and afterload

Answer 11

Preload: the force that stretches the muscle before contraction
- It is related to ventricular filling

Afterload: the force that stretches muscle during contraction

Question 12

Contractility

Answer 12

The intrinsic strength of cardiac muscles

Question 13

Factors of cardiac output

Answer 13

1. Preload: increase preload = increased cardiac output
2. Afterload: increase afterload = decreased cardiac output
3. Contractility: increased contractility = cardiac output
4. Heart rate: increased heart rate * stroke volume = increased cardiac output

Question 14

what is the cardiac cycle equation?

Answer 14

Q = △P / R

Q = flow
△P = change in pressure
R = resistance to flow

Question 15

Fundamentals of the cardiac cycle

Answer 15

Contraction of myocardium generates pressure changes which result in the movement of blood

Blood flows from high pressure to low pressure area, unless flow is blocked by a closed valve

Cardiac valves open only when upstream pressure is greater than downstream pressure

Events on the right and left sides of the heart are the same, but pressure are lower on the right

Question 16

Blood pressure

Answer 16

As blood travels through the blood vessel, it exerts a force on the walls of the vessel, the force per unit area is the blood pressure

Question 17

Sphygmomanometer

Answer 17

Top number (systolic): force of blood on arteries when the heart beats

Bottom number (diastolic): force of blood on arteries between beats

Question 18

Know the blood pressure valves of dogs and cats

Answer 18

know the blood pressure valves of dogs and cats

Question 19

Blood pressures in different vessels

Answer 19

• arterioles/capillaries: drop in blood pressure due to an increased ratio of surface area to volume, meaning the blood is in contact with more blood vessel surface area
• This slows down the velocity of the blood with arterioles and thus drops the pressure

Question 20

Stroke volume times heart rate equals_______

Afterload
End-systolic volume
Cardiac output

Answer 20

cardiac output

Question 21

Ejection fraction is expressed in which unit?

mmHg
Bpm
ml/minute
Percentage

Answer 21

percentage

Question 22

If the heart rate is increased by double, which of the following decreases?

Systole
Diastole
Both

Answer 22

diastole

Question 23

Blood pressure is the force exerted by the blood against?

Venous wall
Artery wall
Both

Answer 23

artery wall

Question 24

End diastolic volume (EDV) means________.

Volume of blood in the ventricle at the end of diastole
Volume of blood in the ventricle at the end of systole

Answer 24

Volume of blood in the ventricle at the end of diastole

Question 25

During the rest which organ receives more blood?

Brain
Abdomen
Skeletal muscle
kidney

Answer 25

abdomen