Bioenergetics,cardiovascular and respiratory control

Question 1

what is the stroke volume?

Answer 1

Volume of blood ejected from the heart during each cycle, this increases during exercise therefore increasing cardiac output.
If the ventricle contains 100ml of blood at the end of filling and 40ml at the end of contraction. Volume ejected=60ml.

Question 2

what is meant by cardiac output?

Answer 2

total volume of blood pumped by the ventricle per minute

CO= SV x HR (Lmin-1)

Question 3

what is the order of the conducting system of the heart?

Answer 3

SAN–> atrial AP –> AV node (delay) –> bundle of his –> ventricular AP (apex to base)

Question 4

how do you calculate the mean arterial blood pressure?

Answer 4

2/3 diastolic basal pressure + 1/3 systolic pressure

Question 5

where is the biggest site of blood pressure drop amongst circulation seen?

Answer 5

in the arterioles

Question 6

How do you calculate vascular resistance?

Answer 6

blood viscosity x ( length of the vessel/radius^4 )

dec in diameter=inc resistance=inc pressure

Question 7

what 3 mechanisms does exercise use to increase blood flow?

Answer 7

1) inc sympathetic activity=inc bp
2) inc adrenaline release = inc bp
3) dec vascular resistance = inc blood flow

Question 8

How do baroreceptors in the aortic arch and carotid artery regulate arterial pressure?

Answer 8

INC IN PRESSURE:
baroreceptor stretch = inc vagal tone = dec HR/sympathetic activity = vasodilation
DEC IN PRESSURE :
pressure fall detected = dec vagal tone = inc HR/pressure = vasoconstriction

Question 9

What are the 3 intrinsic mechanisms of blood pressure regulation by the arteries locally are there?

Answer 9

1) DILATION BY VASOACTIVE METABOLITES - muscle will release metabolites (adenosine,K+,H+) therefore increased blood flow required to remove these away from tissue
2) ENDOTHELIAL REGULATION - endothelial layer releases NO causing vasodilation
3) MYOGENIC REGULATION - increased pressure detected by stretch activated channels in the vessels= Ca channels activated = contraction = reduced blood flow

Question 10

what happens when an organ requires extra blood flow during exercise?

Answer 10

the vessels supplying this organ will dilate = increase blood flow supply =blood flow to other areas reduced/shut down

Question 11

what 4 factors determines stroke volume change in response to exercise?

Answer 11

1) VENOUS RETURN
2) CAPACITY OF VENTRICLE TO FILL
3) VENTRICULAR CONTRACTILITY - how forcefully can ventricles contract
4) AORTIC/PULMANORY ARTERIAL PRESSURE - pressure against ventricles contract

Question 12

what are the blood pressure changes on exercise?

Answer 12

increase in systolic blood pressure but no increase in diastolic blood pressure
increase in mean arterial pressure

Question 13

what are the cardiovascular adaptations to training?

Answer 13

1) HEART SIZE HYPERTROPHY
2) STROKE VOLUME INCREASED = INC DIASTOLIC VOLUME = DECREASED VASCULAR RESISTANCE
3) RECOVERY OF HEART RATE MORE RAPID
4) CARDIAC OUTPUT STAYS THE SAME

Question 14

what does the P wave indicate?

Answer 14

atrial depolarisation

Question 15

what does the QRS complex indicate?

Answer 15

ventricular depolarisation

Question 16

what does the T wave indicate?

Answer 16

ventricular re polarisation

Question 17

what change in the ST segment indicates heart damage and what type of damage does this indicate?

Answer 17

ST segment should be flat as there should be no electrical movement in the heart during this segment
elevation/depression of this segment indicates ischaemia
exaggerated ST depression during exercise stress test indicates heart disease

Question 18

what does the QT interval indicate?

Answer 18

duration of heart beat

Question 19

what is long QT syndrome?

Answer 19

longer action potential = prolonged contractions = responses to increased HR impaired = degeneration of myocardial function

Question 20

what is IKR/IKS?

Answer 20

rapidly activating K current/slowly activating K current

Question 21

what is hypertrophic cardiomyopathy?

Answer 21

mostly caused by mutations in: B myosin heavy chain gene, myosin binding protein C, tropomyosin
force generation is impaired
fibrosis occurs
results in; inefficient pumping of blood, reduction in stroke volume, reduction in cardiac output
increases likelihood of arrhythmia and sudden death exacerbated by excessive training
extra growth of tissue = heart less elastic = reduction in stretch capacity = less efficient blood pumping = reduction in stroke volume = possible cardiac death

Question 22

what is the pleural cavity?

Answer 22

fluid filled membrane between lungs and the rib-cage, prevents the lungs from collapsing

Question 23

what is boyles law?

Answer 23

pressure of a given mass of gas is inversely proportional to the volume at a given temperature
therefore, if volume in lung increases= dec in pressure = air moves in

Question 24

Is exhalation an active or passive process?

Answer 24

exhalation is usually a passive process but during heavy exercise this becomes an active process

Question 25

what is meant by tidal volume?

Answer 25

volume moving in and out during each breath

Question 26

what is meant by vital capacity?

Answer 26

how much you can expire after a maximal inspiration

Question 27

what is meant by residual volume ?

Answer 27

amount of air remaining in the lungs after maximal expiration (calculated by height and weight)

Question 28

How is total lung capacity calculated?

Answer 28

VITAL CAPACITY + RESIDUAL VOLUME

Question 29

what may cause bronchoconstriction?

Answer 29

cold, allergens, parasympathetic activity

Question 30

what may cause bronchodilation?

Answer 30

sympathetic activity, adrenaline/noradrenaline, exercise, B2 agonissts

Question 31

how is oxygen transported in the blood?

Answer 31

2% dissolved in the blood as free oxygen

98% combined with haemoglobin

Question 32

how is carbon dioxide transported in the blood?

Answer 32

60-70% dissolved in the blood as bicarbonate ions

CO2+H20—–> H2CO3—–> H+ + HCO3-

Question 33

how is oxygen transported within the muscle?

Answer 33

1) Hb gets to cell and transfers the oxygen to myoglobin
2) myoglobin then transfers this oxygen across membrane into cell for oxidative phosphorylation
3) myoglobin has a very high affinity for oxygen even when partial pressure of oxygen very low

Question 34

How is pulmonary ventilation regulated?

Answer 34

respiratory control centres found in the medullary obloganta and pons 
central chemoreceptors (pCO2,pH) and peripheral chemoreceptors (pO2,pCO2) and signals from active muscles stimulate inspiritory centre = external intercostal muscles and diaphragm contract = volume of thorax increased drawing air into lungs 

stretching of lungs triggers expiratory centre = intercostal/abdominal muscles contract = thoracic volume decreases = air forced out of the lungs

Question 35

how does pulmanory ventilation increase on exercise to match changes on o2 demand?

Answer 35

initial change in rate due to neural inputs

later changes due to changes in chemical composition of blood gases/pH

Question 36

ventilatory threshold

Answer 36

with increased exercise you get increased ventilation, but this ventilation increase is disproportional to O2 consumption. Point in your exercise where you suddenly start to breathe heavily

Question 37

what are the respiratory limitations to performance

Answer 37

rate/depth increase in ventilation increases energy consumption of muscles involved

15% of cardiac output blood supply during exercise goes just for ventilation

limiting factor in elite athletes

Question 38

what respiratory disorders limit the ability to exercise

Answer 38

• Peripheral arterial disease (PAD) :reduced blood flow in limbs=reduced metabolites/o2=ischaemia = prolonged ischaemia = gangrene
• Exercise/allergen induced asthma
• fibrosis = stiffer lungs = less elastic = increased breathing difficulty
• COPD
• Pulmonary hypertension = reduced blood flow so right side has to work harder