CTB5: Assessing performance of the cardiopulmonary system

Question 1

What specialised cells produce the hearts’ rhythm?

Answer 1

sinoatrial node

Question 2

How does the heart contract?

Answer 2

These cells spontaneously depolarise which triggers a wave of excitation through the heart’s conduction system, which resulted in coordinated contraction of the atria and, after a short delay, the ventricles.

Question 3

How does the parasympathetic nervous system affect the heart

Answer 3

via the vagus nerve it slows down the heart rate to about 72 bpm

Question 4

At rest, what is breathing controlled by?

Answer 4

By the phrenic nerves which send impulses from the medulla to the diaphragm to contract

Question 5

Most of the breaths we take are triggered from where?

Answer 5

Centrally, in the respiratory centres of the medulla oblongata

Question 6

What afferent (sensory) signal is most significant in affecting respiratory rhythm?

Answer 6

Principal driver is arterial carbon dioxide concentration (inferred via proton concentration in the cerebrospinal fluid)

Question 7

What chemoreceptors are highly sensitive and tightly regulate other inputs including the higher centres (e.g. motor control mentioned above) and peripheral sensory neurons (chemosensitive and mechanosensitive)?

Answer 7

proton concentration in the cerebrospinal fluid chemoreceptors

Question 8

Activation of inspiratory muscles has what effect on the vagus nerve? (PNS)

Answer 8

inhibitory action

Question 9

Since activation of the inspiratory muscles has an inhibitory effect on the PNS, what happens to the interbeat interval?

Answer 9

The interbeat interval is often shorter while breathing in, compared with breathing out

Question 10

Define physical activity

Answer 10

any biomechanical movement produced by the musculoskeletal system that requires metabolic energy

Question 11

Define exercise

Answer 11

Sub-set of physical activity and can be defined as any ‘purposeful increase in energy expenditure’. This can then be further subclassified into aerobic and anaerobic exercise

Question 12

How can anaerobic exercise be classified

Answer 12

High intensity and short duration. This includes activities and sports that take a matter of seconds to do and rely on the energy stored within the muscle ready to be used at a moments notice

Question 13

How can aerobic exercise be classified?

Answer 13

Low intensity and long duration. It includes activities that typically last several minutes to several hours or sometimes days. It relies on a steady supply of oxygen and nutrients to the working muscle that can meet local demand.

Question 14

What is the immediate increase in ventilation is mediated by what?

Answer 14

neurogenic afferents from active skeletal muscle

Question 15

When are neurogenic afferent nerves (attached to mechanoreceptors) activated?

Answer 15

When the muscles shorten and lengthen

Question 16

What is ventilation in plateau phase fine-tuned by?

Answer 16

Peripheral chemoreceptors

Question 17

What is this plateau is also referred to as? why?

Answer 17

‘steady state’ because the supply and demand are (just about) perfectly balanced

Question 18

Once exercise stops, what happens to the volume expired (Ve)?

Answer 18

There is an immediate sharp decrease in volume expired

Question 19

What does repaying oxygen debt do to the volume expired over time curve?

Answer 19

Causes steady decrease of Ve

Question 20

What is the respiratory rate during light and moderate intensity exercise?

Answer 20

Respiratory rate takes a small increase to 20 breaths/min (from 12-15 breaths per minute), where it stays stable

Question 21

At moderate-high intensity exercise what becomes inefficient? Why?

Answer 21

To further increase the depth of breathing.
Because getting the lungs really full or really empty takes a considerable amount of energy. Instaed Respiratory rate incraeses slightly to achieve an exponential rise in ventilation

Question 22

What is biomechanically more efficient to do during moderate to high exercise?

Answer 22

To increase the rate of ventilation (exponential)

Question 23

What is cardiac volume usually?

Answer 23

70ml

Question 24

How much can cardiac output increase during exercise in adults?

Answer 24

four-fold

Question 25

What happens to the blood from the four-fold increase in cardiac output during exercise in adults?

Answer 25

Redistribution of blood flow secondary to the sympathetic nervous system. Specifically, arterioles supplying non-essential organs (e.g. the kidneys, liver, stomach and intestines) constrict, reducing local blood flow, and vessels supplying skeletal muscle dilate, considerably increasing blood flow.

Question 26

What can the cardiac output of elite endurance athletes be?

Answer 26

35 L/min

Question 27

What is the equation for cardiac output?

Answer 27

cardiac output = HR x SV

Question 28

What is arrhythmia?

Answer 28

Abnormal heart rhythm

Question 29

What is ventricular tachycardia?

Answer 29

very high heart rate (e.g. 280 bpm) it requires rapid intervention or it could be fatal

Question 30

If the heart is beating too fast, why is this a health problem?

Answer 30

The atria are the first to contract which pushes blood into the ventricles. If the heart is beating too fast, the ventricles contract before they’re full. This has a big impact on stroke volume and results in a reduction in overall cardiac output.

Question 31

How do you calculate the age-predicted max heart rate?

Answer 31

220 - age

Question 32

How do you calculate max stroke volume?

Answer 32

Divide 22 L/min maximum cardiac output by 200 to calculate your maximum stroke volume, which is 110 mL

Question 33

By what percentage does heart rate and stroke volume increase in normal individuals during exercise?

Answer 33

stroke volume: 60% increase

heart rate: 300% increase

Question 34

What happens to the heart muscle after much training?

Answer 34

Becomes stronger and bigger

Question 35

What consequence does a stronger and bigger heart have?

Answer 35

The volume of blood pumped out per beat increases:

• maximum cardiac output can be increased as the heart can push more blood out per beat: overall a higher cardiac output can be achieved.
• a stronger heart pushing more blood out each beat needs to beat less often, so resting heart rate decreases

Question 36

Trained individuals have greater recoil and thus greater force, helping to push more blood out per beat: what does this mean for venous return and left-ventricular end-diastolic volume

Answer 36

Increase in both
venous return (blood returning back to the heart per beat)
left ventricular end-diastolic volume (the amount of blood in the ventricles prior to their contraction)

Question 37

List the 5 benefits of sustained exercise

Answer 37

1) ventricular remodelling
2) increased vascularisation of aveoli
3) increased vascularisation of myocardium
4) increased oxidation enzyme density
5) no meaningful change to lung volumes

Question 38

Explain ventricular remodelling

Answer 38

Characterised by a slight thickening of the heart muscle in the ventricles. A thicker muscle is able to contract more forcefully to eject a larger volume of blood at a faster rate than normal. This is can be achieved in two ways: hypertrophy (which is enlargement of the muscle cells) and hyperplasia (which is increased number of muscle cells)

Question 39

Explain increased vascularisation of avleoli

Answer 39

exercise requires a significant supply of oxygen to ensure that no harmful by-products (such as lactic acid) are produced. This can be achieved by increasing the density of capillaries at the gas exchange surface, to make better use of the ventilated air. Think back to Fick’s Law – this is basically increasing the surface area of the lung

Question 40

Explain increased vascularisation of myocardium

Answer 40

s mentioned above, the heart muscle needs a plentiful supply of oxygen to keep it healthy, especially during exercise. As such, the density of small blood vessels that penetrate the myocardium from the surface (where the coronary arteries lie) increases

Question 41

Explain increased vascularisation of myocardium

Answer 41

the myocardium and respiratory muscles are always active, from when you’re a tiny baby to the day you die, and they have to withstand periods of increased activity (i.e. exercise) without getting too fatigued. Exercise training helps to improve the concentration of enzymes that allow oxygen-dependent aerobic energy production to happen

Question 42

Explain no meaningful change to lung volumes

Answer 42

the existing lung volumes don’t really change with exercise training, these are usually fixed based on your genetics. There is however a small body of evidence to suggest that training in elite swimmers can make small improvements

Question 43

What are the two main ways to assess the function of the heart in a clinical environment?

Answer 43

1) electrocardiography (ECG)

2) echocardiography

Question 44

What does ECG measure?

Answer 44

The electrical activity of the heart

Question 45

What is the electrical activity of the heart that ECGs measure?

Answer 45

The frequency of the beats (the rate) the timing between beats (the rhythm) and the way the signal is propagated through the specialised conduction pathway and the myocardium

Question 46

What does the P wave show on an ECG?

Answer 46

wave of depolarisation (excitation) passes through the atria from the sino-atrial node, causing them to contract

Question 47

When does the QRS complex, which is the biggest deflection, happen?

Answer 47

When the wave of excitation moves really fast through the large amount of muscle at the apex (bottom) of the heart causing ventricular systole

Question 48

What is the T wave?

Answer 48

Repolarisation of the ventricles and happens during diastole

Question 49

What is Echocardiology?

Answer 49

a method of ultrasound imaging which allows someone to look at different cross sections of the heart

Question 50

When is echocardiology particularly useful?

Answer 50

For evaluating the heart valves, but can also be used to estimate the volume of blood in the heart before and after contraction

Question 51

What two variables are measured in spirometry?

Answer 51

Forced vital capacity (FVC) and Forced expiratory volume in 1 second (FEV1)

Question 52

What ratio is used in diagnosis of obstructive and restrictive lung diseases?

Answer 52

The ratio of FEV1 to FVC

Question 53

What is the Wright peak flow meter designed to do?

PEF (peak expiratory flow)

Answer 53

Mechanically measure the maximum flow rate during maximum expiration from total lung capacity (TLC). Highest value is used

Question 54

How can PEF be used to discriminate between COPD and asthma?

Answer 54

COPD would have stable PEF and asthma would have variable PEF

Question 55

What is a modern version of spirometry?

Answer 55

flow-volume loops

Question 56

What are the labels of the axis for flow-volume loops

Answer 56

volume (L; x-axis) and flow velocity (L·s-1; y-axis)
The left side of the loop always represents TLC, but the x-axis can either ascend (from 0 at TLC) or descend from TLC if FRC is known

Question 57

What is the flow loop drawn from?

Answer 57

changes in air flow (inspiration/expiration). Further (upwards or downwards) from the x-axis reflects higher flow rates, and steep lines represent rapid changes in flow rate.