Cardiac function

Question 1

What does LVEDD stand for in cardiac measurements?

Answer 1

Distance between walls

Question 2

What does WT mean in cardiac measurements?

Answer 2

Wall thickness

Question 3

Do we want a more compliant/stretchy heart muscle or one with lots of resistance?

Answer 3

More compliant/stretchy muscle

Question 4

How much we fill the heart up with blood is positively OR negatively related to strength of contraction?

Answer 4

Positively

Question 5

What 3 things is the parasympathetic nervous system wired into in the heart to have an effect on the heart rate?

Answer 5

SA node, AV node and atrial muscle.

Question 6

What two factors does the sympathetic nervous system have?

Answer 6

Chronotropic and inotropic

Question 7

What muscles of the heart does the sympathetic nervous system initiate?

Answer 7

The muscles of the ventricles and atria.

Question 8

Which one (PNS and SNS) decrease and increase HR?

Answer 8

PNS decreases HR

SNS increases HR

Question 9

How much could the SNS increase HR by?

Answer 9

300%

Question 10

Is the normal HR (72bpm) dominated by the PNS or the SNS??

Answer 10

The PNS

Question 11

HR increases by how many bpm per 1 MET

Answer 11

10 bpm

Question 12

What impact does SNS have on contractility?

Answer 12

Increases it compared to control.

Question 13

What effect does a bigger Left Ventricle have on SV?

Answer 13

bigger SV

Question 14

Why do we see an increase in SV from an athletes bigger left ventricle?

Answer 14

Because the ejection fraction increases.

Question 15

True or False…a healthy myocardium does not stretch as blood fills ventricles?

Answer 15

False

Question 16

What mechanism does the stretchy myocardium help with?

Answer 16

The Frank-Starling Mechanism

Question 17

what does a Pericardiectomy do to the SV and Q?

Answer 17

increase both

Question 18

what is a pericardium?

Answer 18

wrapper around heart

Question 19

What intrinsic control does the Frank-Starling mechanism have through increase stretching of walls?

Answer 19

increase strength of contraction

Question 20

How does the frank starling mechanism increase strength of contraction?

Answer 20

Stores energy so re-coils and double the force

Question 21

True or false? Cardiac muscle has a similar length-tension properties to skeletal muscles?

Answer 21

True

Question 22

Does the cardiac muscle normal operate well below or above the optimum length?

Answer 22

Below

Question 23

What does increasing the ventricular volume do to the ventricular muscle length?

Answer 23

It stretches the ventricular muscle towards optimum length

Question 24

What happens if you overstretch the muscle?

Answer 24

contractile force decreases

Question 25

Why does the contractile force decrease with being overstretched?

Answer 25

lose ability for actin and myosin to overlap and work

Question 26

Why is venous return important?

Answer 26

Because if no blood is returned to the heart there's nothing to pump

Question 27

What is the typical blood volume in adults?

Answer 27

5 litres

Question 28

Why might blood volume decrease?

Answer 28

Due to haemorrhage or dehydration.

Question 29

How much blood resides in the veins at rest due to having excess blood?

Answer 29

Two thirds

Question 30

True or false? the body has insufficient blood needed for maximal exercise.

Answer 30

True

Question 31

What 6 things that increase which are causes of vasodilation?

Answer 31

Nitric oxide, bradykinin, prostagladins, K+, CO2, lactate

Question 32

What decreases to cause vasodilation?

Answer 32

Local decrease in PO2

Question 33

What releases nitric oxide?

Answer 33

the endothelium

Question 34

What is Bradykinin and prostagladins?

Answer 34

An inflammation marker

Question 35

What causes vasoconstriction?

Answer 35

Increase in SNS activity releases NE - and this acts on a-receptors to cause contriction

Question 36

What causes leakage of K?

Answer 36

Muscles de-polarise and re-polarise

Question 37

What is a trigger for increase in blood flow?

Answer 37

Hypoxia which is related to exercise

Question 38

What percent of blood resides in the venous system at rest?

Answer 38

70%

Question 39

What happens to the venous smooth muscle during exercise?

Answer 39

Constriction

Question 40

What percent of blood shunting occurs through venoconstriction?

Answer 40

20%

Question 41

What do the valves in the veins do?

Answer 41

Prevent back flow of blood

Question 42

What 2 ways does blood move through the veins?

Answer 42

By the action of nearby active muscles and/or by the contraction of smooth muscle bands within the veins themselves

Question 43

What does the ventricular return pumps do to actively suck blood back in towards heart?

Answer 43

High pressure during contraction then low pressure during relaxation which creates a vacuum sucking blood towards the heart.

Question 44

What does ventricular rotation do to the heart in systole?

Answer 44

Wrings blood out

Question 45

What does ventricular rotation do to the heart in diastole?

Answer 45

Twist, recoils to such blood in.

Question 46

Does pressure increase or decrease in thorax during expiration?

Answer 46

Increases

Question 47

What happens to blood during expiration?

Answer 47

Back to heart

Question 48

What happens to the blood during inspiration?

Answer 48

Vacuum created to suck blood towards heart.

Question 49

What is squeezed during breathing which facilitates blood back to the heart?

Answer 49

The vena Cava

Question 50

What is Afterload?

Answer 50

How much blood is left in the heart at the end of contraction (end systolic volume)

Question 51

What 6 things does the heart have to pump against?

Answer 51

- Volume of blood - Pressure in aorta - Compliance of aorta - Size of pulmonary/aorta lumen - Inertial component of the ejecting blood column - Systemic vascular resistance

Question 52

As increase arterial pressure more than 150mmHg what happens?

Answer 52

Start to decrease cardiac output

Question 53

What are effects of increased afterload in the acute phase?

Answer 53

SV will be reduced and reduction in velocity of contraction and ejection

Question 54

What happens to myocardial O2 consumption from an increased afterload?

Answer 54

Marked increase

Question 55

What is a compensation mechanism to restore SV?

Answer 55

Preload increasing

Question 56

What do Mechanoreceptors detect?

Answer 56

Stretch and muscle contraction

Question 57

What do mechanoreceptors do in order to increase SNS activity?

Answer 57

Send afferent signal to the brain

Question 58

what type of receptors are mechanoreceptors?

Answer 58

Type III afferent receptors

Question 59

What four things are metaboreceptors sensitive to?

Answer 59

Increased lactate, phosphate and prostagladins, and decreased pH

Question 60

What are metaboreceptors?

Answer 60

Chemical sensing sites that are activated

Question 61

What happens when the metaboreceptors sense the things and how does this facilitate?

Answer 61

Increase HR and this increase in HR facilitates returning of these back to normal level

Question 62

Where are the baroreceptors?

Answer 62

In the walls of carotid sinus and aortic arch

Question 63

What do baroreceptors sense and what is activated from this?

Answer 63

Arterial pressure which activates stretch and increased signals to brain

Question 64

What do the afferent nerves IX(carotid) and X(aortic arch) trigger in the brain?

Answer 64

to decreased SNS and increase PNS

Question 65

Blocking signals from baroreceptors allows what and how does this effect HR and Q?

Answer 65

Vasodilation and decreases HR and Q which decreases BP

Question 66

True or false? Baroreceptors inhibited when BP falls below normal range

Answer 66

True (note: Baroreceptors decrease BP)

Question 67

What happens to baroreflex during exercise?

Answer 67

reset to a higher operating pressure

Question 68

Why does the baroreflex reset to higher with exercise?

Answer 68

So that Q and HR can still increase with exercise which is healthy

Question 69

Where are chemoreceptors found?

Answer 69

In carotid sinus and aortic arch

Question 70

What do chemoreceptor sense?

Answer 70

High levels of CO2 in blood

Question 71

What does high levels of CO2 in the blood trigger?

Answer 71

Brain to increase SNS and decrease PNS = increase HR

Question 72

What elicits tachycardia?

Answer 72

Increased cardiac filling

Question 73

What does the bainbridge reflex do to HR and SV and why?

Answer 73

Increase HR and SV due to increased venous return and stretch receptors detecting increase blood volume

Question 74

What does the bainbridge relex do to the firing rate to the brain?

Answer 74

Increase