Lecture 8: THE HEART AS A PUMP

Question 1

How is the heart in the mammalian cardiovascular system?

Answer 1

Four chambered (atria and ventricle on each side)

Question 2

How does the blood flow in the mammalian cardiovascular system?

Answer 2

In one direction

Question 3

Where does arterial blood flow?

Answer 3

Away from the heart (not always oxygenated)

Question 4

Where does venous blood flow?

Answer 4

Towards the heart (not always deoxygenated)

Question 5

The heart is …

Answer 5

Two pumps that lie in series

Question 6

What is the first part of the heart series?

Answer 6

Right atrium

Question 7

What comes after the right atrium?

Answer 7

Right ventricle

Question 8

What comes after the right ventricle?

Answer 8

Lungs

Question 9

What comes after the lungs?

Answer 9

Left atrium

Question 10

What comes after the left atrium?

Answer 10

Left ventricle

Question 11

What comes after the left ventricle?

Answer 11

All organs

Question 12

What goes through the two circuits?

Answer 12

Equal flow

Question 13

What happens when the atria contract?

Answer 13

AV valves are open to allow the ventricle to fill while the semilunar valves are closed so that pressure builds up in the ventricles

Question 14

What happens when the ventricles contract?

Answer 14

AV valves close so as the ventricles contract it puts force on the blood and makes sure the blood doesn’t flow backwards.

Question 15

What happens when pressure gets great enough?

Answer 15

The semilunar valves open and ejection of the blood occurs

Question 16

What contracts simultaneously?

Answer 16

Right and left pumps

Question 17

What contracts first?

Answer 17

Atria

Question 18

What contracts second?

Answer 18

Ventricles

Question 19

What do valves do?

Answer 19

Open and close to direct blood

Question 20

What is the thin filament?

Answer 20

Actin (light coloured)

Question 21

What is the thick filament?

Answer 21

Myosin (blue coloured)

Question 22

How are calcium levels during relaxation?

Answer 22

Low

Question 23

What happens after relaxation (calcium levels)?

Answer 23

Ca2+ levels go up and more ca2+ is released form the sarcoplasmic reticulum (SR)

Question 24

What happens when calcium levels rise?

Answer 24

Myosin binds to actin to form cross bridges

Question 25

What happens after myosin binds to actin to form cross bridges?

Answer 25

Myosin pulls on actin to shorten the sarcomere and generate force (head changes position)

Question 26

What is activated during every beat?

Answer 26

Every cardiomyocyte

Question 27

How can the force of contraction be increased?

Answer 27

Increasing cytosolic calcium levels, increasing number of cross bridges formed

Question 28

What happens during relaxation (calcium levels)?

Answer 28

Decrease in cytosolic calcium levels as calcium is pumped back into the SR

Question 29

When do cross bridges release?

Answer 29

When ATP binds to myosin

Question 30

What does a reduction in force mean?

Answer 30

The heart can relax

Question 31

What do all cardiomyocytes do each beat?

Answer 31

Relax

Question 32

What is diastole?

Answer 32

Relaxing and falling pressure

Question 33

What is systole?

Answer 33

Contracting and rising pressure

Question 34

When does the cardiac cycle begin?

Answer 34

All four chambers are relaxed and partly filled with blood ready to contract

Question 35

What is the first phase of the cardiac cycle?

Answer 35

Atrial systole

Question 36

What happens in atrial systole?

Answer 36

Atria contract and fill the ventricles with blood. AV valves open and semilunar valves closed

Question 37

What is the phase after atrial systole?

Answer 37

Ventricular systole (isovolumetric contraction)

Question 38

What happens in ventricular systole (isovolumetric contraction)?

Answer 38

The volume of the bold in the ventricles remains the same as the atria relax and ventricles begin to contract. Both valves are closed

Question 39

What is the phase after ventricular systole (isovolumetric contraction)?

Answer 39

Ventricular systole (ventricular ejection)

Question 40

What happens in ventricular systole (ventricular ejection)?

Answer 40

Semilunar valves open when the pressure build up so that blood can be released into the arteries

Question 41

What phase is after ventricular systole (ventricular ejection)?

Answer 41

Isovolumetric ventricular relaxation

Question 42

What happens in isovolumetric ventricular relaxation?

Answer 42

Blood has been pushes out and semilunar valves snap shut. AV valves open, heart relaxes and falling pressure of the blood

Question 43

What phase is after isometric ventricular relaxation?

Answer 43

Ventricular diastole

Question 44

What happens in ventricular diastole?

Answer 44

All chambers relax and the atria begin to fill passively

Question 45

Which circuit has higher pressure?

Answer 45

Systemic

Question 46

What is the highest blood pressure?

Answer 46

Systolic blood pressure

Question 47

What is the lowest blood pressure?

Answer 47

Diastolic blood pressure

Question 48

What is the mean pressure?

Answer 48

The average pressure across the whole pulse and almost always closer to diastole because the heart spend more time in this phase

Question 49

What is pulse pressure?

Answer 49

The difference between the highest and lowest points

Question 50

What is hypertension?

Answer 50

High blood pressure

Question 51

What is hypotension?

Answer 51

Low blood pressure

Question 52

What is the pressure in the systemic circulation?

Answer 52

High (110mmHg)

Question 53

What is the pressure in the pulmonary circulation?

Answer 53

Low (25mmHg)

Question 54

How is the flow equal in both circuits?

Answer 54

Resistance - the pulmonary circuit has less resistance than the systemic circuit

Question 55

What is flow equal to?

Answer 55

Pressure difference/resistance