Bioenergetics,cardiovascular and respiratory control Flashcards
what is the stroke volume?
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.
what is meant by cardiac output?
total volume of blood pumped by the ventricle per minute
CO= SV x HR (Lmin-1)
what is the order of the conducting system of the heart?
SAN–> atrial AP –> AV node (delay) –> bundle of his –> ventricular AP (apex to base)
how do you calculate the mean arterial blood pressure?
2/3 diastolic basal pressure + 1/3 systolic pressure
where is the biggest site of blood pressure drop amongst circulation seen?
in the arterioles
How do you calculate vascular resistance?
blood viscosity x ( length of the vessel/radius^4 )
dec in diameter=inc resistance=inc pressure
what 3 mechanisms does exercise use to increase blood flow?
1) inc sympathetic activity=inc bp
2) inc adrenaline release = inc bp
3) dec vascular resistance = inc blood flow
How do baroreceptors in the aortic arch and carotid artery regulate arterial pressure?
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
What are the 3 intrinsic mechanisms of blood pressure regulation by the arteries locally are there?
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
what happens when an organ requires extra blood flow during exercise?
the vessels supplying this organ will dilate = increase blood flow supply =blood flow to other areas reduced/shut down
what 4 factors determines stroke volume change in response to exercise?
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
what are the blood pressure changes on exercise?
increase in systolic blood pressure but no increase in diastolic blood pressure
increase in mean arterial pressure
what are the cardiovascular adaptations to training?
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
what does the P wave indicate?
atrial depolarisation
what does the QRS complex indicate?
ventricular depolarisation
what does the T wave indicate?
ventricular re polarisation
what change in the ST segment indicates heart damage and what type of damage does this indicate?
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
what does the QT interval indicate?
duration of heart beat
what is long QT syndrome?
longer action potential = prolonged contractions = responses to increased HR impaired = degeneration of myocardial function
what is IKR/IKS?
rapidly activating K current/slowly activating K current
what is hypertrophic cardiomyopathy?
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
what is the pleural cavity?
fluid filled membrane between lungs and the rib-cage, prevents the lungs from collapsing
what is boyles law?
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
Is exhalation an active or passive process?
exhalation is usually a passive process but during heavy exercise this becomes an active process
what is meant by tidal volume?
volume moving in and out during each breath
what is meant by vital capacity?
how much you can expire after a maximal inspiration
what is meant by residual volume ?
amount of air remaining in the lungs after maximal expiration (calculated by height and weight)
How is total lung capacity calculated?
VITAL CAPACITY + RESIDUAL VOLUME
what may cause bronchoconstriction?
cold, allergens, parasympathetic activity
what may cause bronchodilation?
sympathetic activity, adrenaline/noradrenaline, exercise, B2 agonissts
how is oxygen transported in the blood?
2% dissolved in the blood as free oxygen
98% combined with haemoglobin
how is carbon dioxide transported in the blood?
60-70% dissolved in the blood as bicarbonate ions
CO2+H20—–> H2CO3—–> H+ + HCO3-
how is oxygen transported within the muscle?
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
How is pulmonary ventilation regulated?
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
how does pulmanory ventilation increase on exercise to match changes on o2 demand?
initial change in rate due to neural inputs
later changes due to changes in chemical composition of blood gases/pH
ventilatory threshold
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
what are the respiratory limitations to performance
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
what respiratory disorders limit the ability to exercise
- 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
