This document is a revision booklet for BTEC Applied Science Level 3 Unit 5 Biology, which is an examined unit in applied science.
This booklet covers ALL topics in unit 5, biology, in an organised way with diagrams, mind maps etc.
• The average beat per minute is 60-85 beats per minute
• Stress, alcohol, and drugs can affect the hearts performance
The right side of the heart
1. Blood enters the heart through two large veins, the inferior and superior vena
cava, emptying oxygen-poor blood from the body into the right atrium of the
heart.
2. As the atrium contracts, blood flow from the right atrium into the right ventricle
through the open tricuspid valve.
3. When the ventricle is full, the tricuspid valve shuts. This prevents blood from
flowing backwards into the atria while the ventricle contracts.
4. As the ventricle’s contracts, blood leaves the heart through the pulmonic
valve, into the pulmonary artery and to the lungs where it is oxygenated.
The left side of the heart
1. The pulmonary vein empties oxygen-rich blood from the lungs into the left
atrium of the heart.
2. As the atrium contracts, blood flow from the left atrium into the left ventricle
through the open mitral valve.
3. When the ventricle is full, the mitral valve shuts. This prevents backflow of blood
into the atria while the ventricles contract.
4. As the ventricle’s contracts, blood leaves the heart through the aortic valve, into
the aorta and to the body.
, Cardiac muscle
• Cardiac muscle is myogenic, meaning It can initiate its own contraction
without being stimulated by neurons.
• Tendinous cords make sure the valves are not turned inside out by the
pressure exerted.
Controlling the Heart Rate
1) All the electrical impulses start in the pace-maker cell in the Sino-atrial node - atria
contracts
2) These impulses travel to the atrioventricular node and then after a slight delay* to
the bundle of His
3) The electrical impulse travels to the Purkinje fibres at the apex of the heart, and the
heart controls the apex upwards.
*Between the ventricle and the atria, there is an insulating layer which doesn't allow message
to pass through
Cardiac output
Formula
Cardiac output = Stroke Volume X Heart Rate
CO = SV x HR
Symbol Meaning
CO The amount of blood ejected by each ventricle in one minute
SV The volume of liquid pumped by ventricle with each heartbeat
(contraction)
HR The number of contractions per minute (How many beats per minute)
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