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17 Cards in this Set

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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.
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
explain the ganlions of the sympathetic and parasympathetic nervous systemo
sympathetic- short pre ganglionic, long post ganglionic


parasympathetic- long pre ganglionic, short post ganglionic fibres
outline the autonomic input into the heart
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
outline the differences in heart rate between different people
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.
outline what effect and increas in sympathetic activity may have on the control of heart raet
outline what effect an increased parasympathetic control on the heart would have on the heart rate
opposite of previous
outline how hormones including adrenaline and other various hormones (state them) have an effect on heart rate
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.
what 3 things effect stroke volume
Stroke Volume can vary between
individual and from moment to moment.
Several Factors affect stroke volume

Ventricular Contractility
End diastolic Volume
Afterload
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.
what dose starlings law of intrinsic control state
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.
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.
outline starlings second law of the heart.
↑ 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.
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.
outline the effect of afterload on stroke volume
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
explain the danger of exercising at hot temperatures
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.