Transcript 6.2_H.5 HL Opening Question

• The pumping of blood is a vital process.
Explain the roles of the atria and ventricles in
the pumping of blood.
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• Atria collect blood from veins (vena
cava/pulmonary);
• Atria collect blood while ventricles are
contracting;
• Atria pump blood into ventricles/ensure
ventricles are full;
• Ventricles pump blood into arteries/out of the
heart (pulmonary artery / aorta);
• Ventricles pump blood at high pressure because
of their thicker, muscular walls;
• Heart valves (semilunar/ AV) work with atria and
ventricles to keep blood moving;
• Left ventricle pumps blood to body systems and
right ventricle pumps blood to lungs;
(b)
Outline the control of the heartbeat. (6)
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Heart muscle cells are myogenic;
The pacemaker / SA node /is located in the right atria;
The pacemaker / SA node stimulates atria to contract;
The contraction of the atria leads to contraction of ventricles;
Autonomic nerves in the medulla oblongata can alter the pace of
the heart;
The pace of the heart can be altered by secretion of
epinephrine/adrenaline norepinephrine/noradrenaline increase the
pace;
The pace of the heart can be altered by secretion of acetylcholine
which reduces the pace;
The adrenal glands release epinephrine/adrenaline which alters the
pace of the heart ;
Epinephrine is carried by blood to heart;
Epinephrine and acetylcholine change the pace of heart rate;6 max
• Describe the relationship between the
structure and function of blood vessels. [6]
Describe the relationship between the structure and
function of blood vessels. [6]
• arteries carry blood under high pressure;
• Arteries have a thicker elastic wall and a narrower
lumen;
• Arteries have muscles that control pressure and help
move the blood;
• Veins carry blood under lower pressure;
• Veins have thinner walls with less elastic tissue, muscle
and a wider lumen;
• Veins have valves to prevent back flow;
• Capillaries have walls which are one cell thick;
• The one cell thick walls of capillaries allow easy
diffusion across their wall / ultrafiltration;
• Outline the events that occur within the heart,
which cause blood to move around the body.
[6]
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• Outline the events that occur within the heart, which cause blood to move
around the body. [6]
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• (b) blood is collected in the atria;
• blood is pumped from the atria to the ventricles;
• opened atrio-ventricular valves allow flow from the atria to the ventricles;
• closed semi-lunar valves prevent backflow from the arteries to the
ventricles;
• blood is pumped out from the ventricles to the arteries;
• open semi-lunar valves allow flow from ventricles to arteries;
• closed atrio-ventricular valves prevent backflow to the atria;
• pressure generated by the heart causes blood to move around the body;
• pacemaker (SAN) initiates each heartbeat; [6 max]
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