FACT FILES Sports Science

A2 LEVEL FACT FILES Sports Science

Subject content link: A2 Unit 2: The Application of Science to Sports Performance • The Cardiovascular System The Application of Science to Sports Performance The Cardiovascular System Unit A22: PerformanceThe Application ofScience to Sports Structure of the heart oftheheart Structure Students should beableto: seconds andthediastole phasearound 0.5seconds. isat rest thesystoleWhen theheart phase takesaround 0.3 with bloodand Diastole stageswhichwork together incontrolled4 distinct rhythm. isaccomplished beat. in It The cardiac isonefullheart cycle • • • • • effects theyhave onexercise; compare andthe atrained anduntrained heart vasodilation; and examine andjustifyvasoconstriction at restcycle exercise; andduring explain andevaluate theprocess ofthecardiac exercise hasonthese; stroke volume andcardiac outputandtheeffect rate,explain andevaluate heart bloodpressure, ofbloodinthevascular system; transport andthe oftheheart thestructure describe is whenthechambersrelax to allow themto fill Learning Outcomes Course Content systole is thecontraction ofthechambers.

© anapgalleria/ iStock/Thinkstock.com Ve blood returning from thebodyandlungs. Atrial diastole single heart beat. single heart Above isanexample ofanelectrocardiogram (ECG) ofa valves to snapshut. the ventricles contract pushingtheblood outcausingthe and artery, andpulmonary semi-lunar valves to theaorta Ventricular systole valves. remaining bloodinto theventricles viatheatrio-ventricular Atrial systole relaxed whiletheyfillupwithbloodfrom the atria. the atrioventricular valves into theventricles whichare Ventricular diastole ntricular diastole Cardiac Cycle –thechamberscontract pushingthe - the upper chambers of the heart fillwith -theupperchambersofheart –once filledpressure overcomes the – pressure forces thebloodthrough P Ve Atr Q ntricular systole ial systole R S T contrac centricular Isovolumic tion 1 The Application of Science to Sports Performance SA node ventricles thenfullycontract. throughout fibres. theventricular walls viathepurkinje The septum between theventricles and viathebundleofHis allow fillingofthe ventricles, sendstheimpulse down the atrioventricular a0.1second nodewhichafter delay to themcontract. the atriamaking This impulsereaches the SA nodefirstsendsanimpulsewhichspreads throughout or pacemaker isresponsible for initiating thisimpulse. The impulsesoitcanbeat. electrical (SA)The node sino-atrial ismyogenicThe which meansitcreates heart itsown Control rate ofheart more exerts pressure onthewallsheart oftheaorta. increases asthegreater volume ofbloodpumpedoutthe thus increases exercise. during Systolic bloodpressure Output ventricle inonebeat.pumped outoftheleft in agreater ejected. which isactually The stronger contraction results which isthepercentage ofbloodwithintheventricle be.’ volumehigher blood thestrongercontraction will that is Thisproperties. contraction oftheventricle walls dueto theirelastic Greater fillingofthe the heart. ventricles causesastronger chambers takeinmore bloodasthere ismore returning to exercise rate During willincrease theheart andtheheart ventricular relaxation/diastole. T wave: repolarisation oftheventricles/systoles to prior ofventricular contraction/systole.QRS Complex: start ofatrialcontraction.P wave: start the heart rate to speedup,the heart while theparasympathetic faster orslower. pathwayThe sympathetic nerve stimulates to beat sinoatrial node(pacemaker) stimulating the heart (CCC) are inthemedullaoblongata. Impulses sent to the rate iscontrolledThe heart by thecardiac control centre This subsequently leadsto agreater ‘the greater thestretch ‘the oftheventricle walls dueto

is a product of heart rate andstroke ofheart volumeis aproduct and stroke volume AV Starling’s Law node , whichisthevolume ofblood Bundle ofHIS of the heart whichstates oftheheart ejection fraction ejection Cardiac , Other factors -temperature, factors Other age, gender. rate to down. slow heart nerve Acetylcholine rate. exerciseduring andbothhave theeffect ofincreasing heart Adrenaline andnoradrenaline Hormonal contraction ofmuscleswithexercise. Proprioceptors the heart. due to the greater volume ofbloodbeingpumpedout walls agreater detect stretchmajor arteries oftheartery Baroreceptors levels inacidity anddecreasedrise pH. dioxide andoxygen intheblood, aswell asaccompanying Chemoreceptors Neural signals to arrive at theCCC from thebody. rate dueto causing bothneural factors heart andhormonal pathway slows itdown. This CCC speedsuporslows down the heart. the heart. They are thickandelasticwithlayers ofsmooth andarterioles Arteries Blood Flow tostructures suittheirpurpose. muscles. The bloodhave vessels that different transport to allothertissuesofthebodyincludingworking from thelungs, whilesystemic blood circulation transports bloodto circulation and networks. Pulmonary transports pumpwhichhastwo separate is adualaction circulatory veinsof vessels andcapillaries. calledarteries, The heart throughout thebodyviaanetwork Blood istransported Transport ofblood – thisisreleased by theparasympathetic – stretch andother receptors intheaorta – detect movement –detect oflimbsand – detect changesinlevels –detect ofcarbon – transport blood away –transport from – theseare released

© blueingmedia/iStock/ Thinkstock.com 2 muscle to allow vasoconstriction and vasodilation. This Blood forced through is under vasomotor control and is responsible for the pocket valve redistribution of blood to areas of most need in the body. As the vessels get further away from the heart they branch out and become arterioles which are thinner and narrower Muscle pressure in diameter. on wall of vein

Veins and venules – transport blood back to the heart. They are similar in structure to arteries and arterioles but are less elastic and do not have as much smooth muscle. As arteries get thinner and become arterioles the further they Pocket valves closed get from the heart, venules will become thicker and wider and become veins on the return journey to the heart. Veins have structures called pocket valves which prevent back Vasoconstriction and vasodilation flow, pooling and help venous return. The vasomotor centre stimulates blood vessels to vasoconstrict or vasodilate depending on the needs of Capillaries – are responsible for the exchange of gases the body. Baroreceptors in the aorta detect rises in blood at the tissues and muscles. They are so small that only a pressure during exercise and send signals to the vasomotor single blood cell can squeeze through at a time and are thin centre constrict or allow blood flow to the areas where it is enough for gases to pass through the walls into the tissues. most needed. Pre-capillary sphincters control the flow of blood cells through the capillaries. The Vacscular Shunt CROSS SECTION OF AN ARTERY skeletal muscle Tunica Externa Tunica Media

Internal Elastic Lamina

External Elastic Lamina other organs

Tunica Intima rest exercise

BP is measured as systolic pressure over diastolic Venous Return pressure.

The blood returning to the heart is helped by various A normal resting BP is approximately 120mmHg over mechanisms as it travels further from the heart and loses 80mmHg or 120 pressure and velocity. During exercise the following factors 80 promote venous return: Blood Pressure is the pressure the blood exerts on the walls Skeletal muscle pump – the working muscles squeeze of the blood vessels. It is at its highest in the aorta when the veins pushing the blood back towards the heart. Valves the ventricles contract and decreases the further the blood in the veins allow the blood to flow one way preventing travels around the body. State of rest or exercise will have backflow and pooling. an effect on blood pressure. The resistance and friction that Respiratory pump – the changes of pressure in the blood experiences depends on the following factors: thoracic cavity during respiration helps pump the blood back towards the heart. Blood vessel length – if the blood vessel is longer the Smooth muscle – layers of smooth muscle in the veins blood experiences more resistance. squeeze the blood in the right direction. The Application of Science to Sports Performance ex during threshold resulting inimproved performance. These adaptations leadto increases in andlactate VO2Max more efficiently due of toaseries physiological adaptations. The cardiovascular system ofatrained athlete functions The ofExercise Effects onthe Cardiovascular System vasomotor centre. is calledthevascular shunt andisunderthecontrol ofthe musclesandlesstoto theotherorgans. theworking This the musclesneedmore oxygen somore bloodisshunted changes according to the bodiesneeds. exercise During Blood vessel diameter maintain cardiac output. hastobecomes work more harder viscous to andtheheart hydration. When we become dehydrated, theblood and dependsonred bloodcell count, temperature and Blood viscosity Exercise ontheCardiovascular System. andLong of Short Summary Term of effects ercise Vascular Effects Cardiac Effects ar 10. teries 00 Mean diameterof ar – this is the thickness oftheblood –thisisthethickness terioles vasoconstriction redirectvasoconstriction Cardiac outputincreases .060 blood to areas ofneed Release ofadrenalineRelease Increase in Venous Increase Increase inblood (Responses) Short TermShort Vasodilation/ capillaries increases HR pressure –thediameter ofbloodvessels return .008 ve venules ssels/m 0.04 m vein 10. Increased numberofred especially in the density especially inthedensity Arterial wall thicker and Arterial Increased enddiastolic Cardiac hypertrophy s 0 Increased maximal (Responses) vascularisation, cardiac output Long Term of capillaries blood velocity Bradycardia blood cells blood vesselCSA blood pressure Increased stronger volume • required: theinformationConsider thetablebelow andinsert Additional Work *Approximate values, exact values from willvary oneindividual to another • • • and untrained Athlete Comparison oftheCardiac ofatrained Output Function Cardiac 5 min after stopping5 minafter stopping4 minafter stopping3 minafter stopping2 minafter stopping1 minafter below applicable/suggestions RECOVERY HR(bpm)as At completion Halfway After 3min After 2min After 1min Start below applicable/suggestions EXERCISE HR(bpm)as Pre-Exercise (bpm) HR(bpm) Resting Environment Date Activity Volume (SV) Output (CO) Heart Rate Rate Heart Using a Heart Rate Monitor complete Rate apulseraising Using aHeart and discuss the changes in heart rate.and discussthechangesinheart Compare your results withotherstudents inyour group minutes finishingthemainactivity. after Complete acool down andrecord HRfor 1/2/3/4/and5 information from theHRMontablebelow. Continue to exercise for oftimeandrecord asetperiod ofawarm-up. aspart activity Cardiac Stroke (HR) 5,000ml (5l) Activities 72bpm 70ml Rest Untrained Athlete 22,000ml Maximal 190bpm 115ml (22l) 5,000ml (5l) 50bpm 100ml

Rest Trained Athlete 35,000ml Maximal 200bpm 180ml (35l) 4 The Application of Science to Sports Performance Available from: www.innerbody.com/image/cardov.html Body.Inner Cardiovascular System. Available from: www.sports-fitness-advisor.com Exercise Physiology. FitnessSports Advisor. Cardiovascular Systems andExercise: Available from: www.teachpe.com Teach P.E. Anatomy andPhysiology: The System. Circulatory Education Student Guide. Philip Allan. G.(2009)EdexcelHill, M.andRoberts, A2Unit3Physical Edexcel. Widnes, JanRoscoe Publications. Roscoe, D., Davis, B. andRoscoe, J. P.E. (2009)A2Revised for 4 Sport. Davis, B. etall(2000)Physical Education andtheStudyof Ltd. 3 Education andSport. Honeybourne, J., Hill, M.andRoscoe, J. (2009)Physical Resources th Ed. London, Harcourt.

rd Ed. Cheltenham, Nelson Thortnes