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Cardiac function and the transport of gases in the blood

Intro
Key terms Definition
Aerobic Exercise that is sub-maximal and requires
exercise oxygen
Together the heart, blood vessels and blood form the cardiovascular system, and this works in
conjunction with the respiratory system to maintain a constant supply of oxygen…

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These together ensure an efficient flow of blood through the heart and around the body



Key terms Definition

Myocardium Cardiac muscle that makes up the heart

Myogenic The ability of the heart to produce its own
impulses




The cardiac cycle
Refers to the mechanical and electrical events during one heartbeat.…

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The control of the heart rate
During exercise, heart rate must increase and must send more impulses more rapidly in order to
meet the body's demand for oxygen. It is able to do this through two regulatory mechanisms:

neural control mechanism
hormonal control mechanism



The cardiac control centre (CCC) is…

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Adrenaline is the hormone responsible for increasing heart rate prior to a competition. It
is released by the adrenal glands into the blood stream - it prepares the body for exercise
by increasing heart rate and strength of ventricular contraction.



During exercise, adrenaline can aid the body's response:

1. increasing…

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Stroke Heart
Volume rate

Untrained 5 70ml 72bpm
litres

Trained 5 80ml 60bpm
litres

-Measured by pulse rate



Cardiac output
Volume of blood ejected by heart per minute and measured in litres per minute dm^3
(1litre=1dm^3)



Cardiac output (Q) = Stroke volume (SV) X Heart rate (HR)



Relationship shows if…

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Increased venous return- volume of blood that returns from the body to right side of
heart. Venus return increases during exercise sue to the muscle pump where skeletal
muscles squeeze blood back towards the heart.
Frank-starling mechanism (Starling's law)- mechanism suggests that when the heart
ventricles stretch more, they can…

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Vessels of circulation

There are different types of blood vessel:

Arteries and arterioles
Capillaries
Veins and venules



Arteries and arterioles

-Vessels that carry blood away from heart, supplying body tissues with oxygenated blood.

-Main artery = Aorta (large cross sectional area) - branch into smaller vessels

-Carry blood at high…

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-Contains a thin layer of involuntary muscle - when stimulated helps return blood to heart.



Venus return is aided by pocket valves within veins - ensure blood flows in only one
direction

Key Terms Definition

Vasoconstrict Reduction in diameter of artery and arteriole
walls - result in increased blood pressure…

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Gravity - Assists the flow of blood from the upper extremities of the body into the superior
vena cava right atrium



These are essential in maintaining cardiac output during exercise. A cool down after exercise can
maintain venous return - prevent 'pooling' of blood in veins.

Redistribution of blood during…

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Vasomotor control is involuntary and occurs immediately - ensuring that areas in most need
receive the necessary amount of blood and nutrients.



Blood pressure and blood velocity
-Blood pressure is the driving force that moves the blood through circulatory systems, 'the force
exerted by the blood on the inside walls…

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