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17 Cards in this Set
- Front
- Back
AT REST each ventricle pumps>
what is cardiac output outline extrinsicn control outline intrinsic control |
At rest, each ventricle pumps 5L blood/min.
Rate at which a ventricle pumps blood is called the CARDIAC OUTPUT (CO) L/min. Number of contractions per minute is HEART RATE Cardiac output = Heart rate x Stroke Volume CO = HR x SV Extrinsic Control: regulation of the heart by neural input, circulating hormones or any other factor from outside the heart. Intrinsic Control: regulation by factors originating in the heart. |
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what does the CNS control
branches of pns branches of autonomic |
Your CNS.
It controls your muscles, and other organs by way of signals sent through the efferent branch of the peripheral nervous system. PNS 2 branches –autonomic and somatic Autonomic 2 branches- sympathetic and parasympathetic |
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explain the ganlions of the sympathetic and parasympathetic nervous systemo
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sympathetic- short pre ganglionic, long post ganglionic
parasympathetic- long pre ganglionic, short post ganglionic fibres |
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outline the autonomic input into the heart
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2 receptors used, and what division of the autonomic use them
outline the parasympathetic pathway to the heart outline the sympathetic pathway to the heart ventricular control is mainly via what |
ventricular control is mainly via the sympathetic nervou ssytem
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outline the differences in heart rate between different people
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HR is different in every individual. Can vary with age, fitness, emotional state etc.
Normal adult HR is 70 bpm. Can be range from 180 bpm to 30bpm (Michael Schumacher). Regulated by various extrinsic controls. |
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outline what effect and increas in sympathetic activity may have on the control of heart raet
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outline what effect an increased parasympathetic control on the heart would have on the heart rate
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opposite of previous
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outline how hormones including adrenaline and other various hormones (state them) have an effect on heart rate
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Adrenaline via blood stream→ AP at SA node → HR
Also, velocity of AP as sympathetic activity is usually coupled with adrenaline secretion. Thyroid hormones, glucagon and insulin, force of myocardial contraction, glucagon promotes HR. |
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what 3 things effect stroke volume
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Stroke Volume can vary between
individual and from moment to moment. Several Factors affect stroke volume Ventricular Contractility End diastolic Volume Afterload |
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what is ventricular contractility
how can it be increased why does it increase |
Force of the ventricular contraction
Sympathetic neurons project to the ventricular myocardium, influence on myocardial contractility. Sympathetic activity → ventricular contractility → cardiac output. Through an increase in [Ca2+] ion and permeability which increase contractility. Adrenaline also increases myocardial contractility. |
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what dose starlings law of intrinsic control state
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Intrinsic Control
Starling’s Law of the Heart: ‘When the rate at which blood flows into the heart from the veins (that is venous return) changes, the heart automatically adjusts its output to match the inflow’ end diastolic volume then force of ventricular contraction → SV and CO. |
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when edv increases what happens to the ventricular fibres of the myocardium
affinity for what increases what role does the cardiac muscle play in this |
increased EDV -muscle fibres of ventricular myocardium lengthen.
Stretch - increased force of contraction increased affinity of troponin in muscle fibres for calcium - ↑ number of cross-bridges activated with contraction. Cardiac muscle, optimum length of the muscle > resting length. So increase EDV brings muscle fibres closer to their optimum length for contraction therefore contract with greater force. |
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outline starlings second law of the heart.
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↑ sympathetic activity shifts Starlings curve upwards,
SV ↑ at any EDV due to ↑ in ventricular contractility ↓ in contractility shifts the curve downwards. Starlings law regulates size of heart by adjusting SV so the CO matches venous return. |
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what factors effect end diastolic volume
outline them |
End diastolic pressure (preload). Determined by the pressure of blood inside the heart before contraction-tension on the myocardium.
Preload is determined by filling time (dependant on HR) and atrial pressure determined by venous return and force of atrial contraction. |
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outline the effect of afterload on stroke volume
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When the heart ejects blood it has to work against arterial pressure.
Increases in arterial pressure tend to cause SV to decrease Arterial pressure places a load on the myocardium after contraction starts. This is called afterload. Therefore, in the left ventricle, the afterload is determined by the pressure |
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explain the danger of exercising at hot temperatures
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Cardiac Output can be increased by 7x by SV and HR
Hot conditions, more blood flow to skin-dissipate heat Exercise- lots of blood in skeletal muscles Running marathon in Athens Olympics, not enough capacity of blood to provide adequate flow to all organs and tissues due to heat, exercise and blood volume (fluid) loss. |