Cardiac output

Question 1

What does Systolic and diastolic mean

Answer 1

• Systolic : Contraction of the heart and the pressure exerted (when you feel ur pulse this is what you are feeling)
• Diastolic : Relaxation of the heart and the pressure in the artiers between contractions

Question 2

What is the Diastolic phase

Answer 2

• this is the relaxation phase which typically last ( .52s)
• During this phase the atrium passively fills with blood via Venous pressure and then the blood flows through the atrioventricular valves
• 80% of ventrical filling occurs here

Question 3

Describe the Systolic Phase for both atrim and ventricles

Answer 3

Atrium: Atrium contracts filling the rest of the ventricle (atrial kick)
* Ventricular contraction: (0.28s)
* pressure surpasses that of the atria causing the atrioventricular valve to close
* The contraction increases ventricular pressure
* when the pressure surpasses the presssure of the aorta and pulmonary artery the semilunar valves open
* this allows the blood to flow out of the heart through the arortic and pulmonic valve

Question 4

What is Cardiac output

Answer 4

The amount of blood that is pumped out by either ventricle
* Normal output is 5-6L/min

Question 5

What is Stroke Volume (SV)

Answer 5

The amount of blood that is pumped out by the Left ventricle during a single contraction
* Typically 60-100ml
* A healthy heart can increase SV by 50%

Question 6

What is Heart Rate

Answer 6

(#) of cardiac contractions per min
* Normal adult is 60-10 beats/min

Question 7

What is the Cardiac output equations

Answer 7

Cardiac Output= SV x HR

Question 8

What is preload

Answer 8

Preload is the pressure under which a ventricle fills, also the force that stretches the heart muscles prior to contraction

Question 9

What is Afterload

Answer 9

The load/pressure that the heart works against to eject blood through the systemic system

Question 10

What effects Preload

Answer 10

• Influenced by the amount of blood volume returning to the heart
• When O2 demands increase, preload increases = cardiac output increases
• atrial contraction,
• heart rate,
• resistance from valves,
• and ventricular compliance

Question 11

what affects Afterload

Answer 11

• Increase in systemic vascular pressure
• Left ventricle afterload = pressure in the aortic arch
• Right ventricle afterload= pressure in the pulmonary artery
• Sudden Hypertension can impair cardiac output and cause cardiac ischemia

Question 12

What is the Frank-starling mechanism

Answer 12

Is that the greater the stretch on the myocardial muscles the greater force of contraction
* This is not under the control of the nervous system
* Some diseases cause hearts to become enlarges this is due to the constant stretch and increased force of the contraction

Question 13

What can effect contractile force

Answer 13

• The stretch of the myocardium
• Increased Blood volume
• Increased systemic vascular resistance
• Increased levels of calcium
  *

Question 14

What is Contractility (Inotropy)

Answer 14

• The hearts ability to change degree of contraction w/out changing stretch of the muscle
• Can be induced by medications both (+) and (-) Inotropic effect

Question 15

What is Chronotropic effect

Answer 15

Change of the heart rate
* Increased beats/min is a (+) chronotropic effect

Question 16

What is Ejection Fraction

Answer 16

The portion of blood that gets ejected from the ventricle during systole
* Is expressed in a %
* normal ejection is around 50%
* 40% and lower indicated the heart is not pumping enough blood