Control of the heart

Question 1

What is systole?

Answer 1

Maximum pressure when heart pumps, occurs after contraction of ventricle

Question 2

What is diastole?

Answer 2

The bottom level of pressure, occurs after contraction of atria

Question 3

How do you measure heart rate (beats/time seconds)?

Answer 3

Systolic Pressure- Diastolic Pressure

Question 4

How do you measure flow in terms of Darcy’s Law?

Answer 4

Flow (volume/time)= Pressure 1- Pressure 2/ Resistance
Pressure- mmHg
Resistance- mmHg time/volume

Question 5

What is another term for flow?

Answer 5

Cardiac Output (CO)

Question 6

What is the equation to calculate Cardiac Output?

Answer 6

CO (volume/time)= (Arterial Pressure- Venous Pressure)/ Resistance

Question 7

How do you calculate Arterial blood pressure?

Answer 7

Arterial blood pressure= CO x TPR (total peripheral resistance)
Arterial blood pressure= heart rate x stroke volume x TPR

Question 8

What are the pacemakers in the parasympathetic nerve system?

Answer 8

Sino atrial (SA) node- iniates contraction 
Atrioventricular (AV) node- drives system is SA node fails

Question 9

What is Bradycardia?

Answer 9

Slowing down of heart rate

Question 10

What is tachycardia?

Answer 10

Speeding up of heart rate

Question 11

Where does each electrical signal in the heart begin?

Answer 11

SA node

Question 12

What does an Electrocardiogram record?

Answer 12

Strength and timing of electrical signals as they pass through the heart

Question 13

From the SA node where does the electrical signal move to?

Answer 13

Through the left and right atria

Causes atria to contract, helps move blood into lower chambers of the heart

Question 14

What is the electrical signals recorded as that pass through the atria?

Answer 14

P wave

Question 15

What does the electrical signal between the atria and ventricle pass through?

Answer 15

Atrioventricular node (AV)

Question 16

What is the pathway of a electrical signal in the heart?

Answer 16

SA node-> Atria-> AV node (P wave)-> Ventricle-> Bundle of His->Contraction of heart (QRS wave)

Question 17

What are the phases of action potential in heart cells?

Answer 17

1. Early repolarization- brings the potential down to a plateau level over 2 to 3 milliseconds
2. Plateau- accounts for most of the action potential duration
3. Repolarization- brings the potential back to resting level
4. Period between action potential- stable except in cells that have the property of autorhythmicity

Question 18

What do baroreceptors do?

Answer 18

Pressure-sensitive neurones that monitor stretch in the aorta (prevent build up of pressure)

Question 19

Where does blood flow from and to?

Answer 19

Areas of high pressure to areas of low pressure

The greater the gradient the greater the flow