lesson 16 control of heart 2013-14

8/13/2019 Lesson 16 Control of Heart 2013-14

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Student videos

STARTER


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AIMS: CONTROL & REGULATIONOF THE HEART

Objectives:ALL learners will be able to control & regulation ofthe heart:Autonomous Nervous System (ANS)

Regulation during exercise

MOST learners will be ableSOME learners will be able to

HAND IN HOMEWORK


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In pairs you will be given a role to describe to the rest of group:

Pair 1: neural factors (incl ude proprioceptors,mechanoreceptors, chemoreceptors, baroreceptors)

Pair 2: hormonal factors (include adrenaline, noradrenaline,vasoconstriction, vasodilation)

Pair 3: intrinsic factors (include body temperature)

Start your description: I am neural factors and I

ACTIVITY 2: CONTROL FACTORS


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CONTROL & REGULATION OF HEART

1. Neural factors:Once exercise begins proprioceptors & mechanoreceptors in muscles, tendons & jointssend messages to CCC

CCC informed amount of movement increased &more blood neededChemoreceptors in aorta & carotid arteries tell CCCof changes in blood composition especiallyincreased CO2CCC increases HR to speed up CO2 removalBaroreceptors respond to changes in blood pressurecaused by increased activity


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2. Hormonal factors:When stimulated, sympathetic nervescause release of adrenaline &

noradrenalineIncreases strength of ventricularcontractions of heart & increases HR &cardiac output

Also help control BPAssist in redistribution of blood to workingmuscles through vasoconstriction & Vasodilation of arterioles


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3. Intrinsic Factors:Body temperature increases when we exerciseHelps increase in blood flow round body (blood becomesless viscous)

Helps increase HR by increasing speed of ner ve impulsetransmission

ACTIVITY 3:Describe what happens to cardiac regulation during exercise

(how sympathetic parasympathetic systems workantagonistically processes involved)


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Regulation during exercise:At rest PARASYMPATHETIC SYSTEM overrides SYMPATHETIC

SYSTEM & keeps HR down

Once exercise begins SYMPATHETIC SYSTEM more active so HRcan rise

Increased metabolic activity causes increased concentration ofCO2 & lactic acid in blood

Increases acidity & decreases blood pHChemoreceptors (in aortic arch/carotid arteries) detect these

changes


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then inform sympathetic centre in upperthoracic area of spinal cord

Increases HR to transport CO2 to lungs to beexpelled

Messages from sympathetic centre sent to SAnode via accelerator nerves releasing

adrenaline & noradrenaline on stimulation


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Adrenaline & noradrenaline (released fromadrenal medulla at top of kidneys) havesame effect:

Increases HRIncreases strength of contractions

Increases metabolic activity

Converts glycogen into glucose & makes itavailable to muscles

Redistributes blood to working muscles


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Other factors increasing HR during exercise:

Increased body temperature & blood viscosity

Increased venous return (more pumping)

Both result in greater cardiac output


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When exercise stops SYMPATHETIC stimulation decreases& PARASYMPATHETICsystem takes over

Responds to info from baroreceptors (BP recorders)

If BP too high, cardiac inhibitory centre sends message toSA node via vagus nerve

Parasympathetic nerve releases acetylcholine decreases HR

Continuous interaction of sympathetic & parasympatheticsystems ensures heart works efficiently as possible

Also enables sufficient nutrients to reach tissue cells toensure effective muscle action


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Cardiac dynamics:

Stroke volume

Heart rate

Cardiac output

During exercise

The pulse

The trained heart

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lesson 16 control of heart 2013-14

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