What makes a circulatory system a double circulatory system?
Blood passes through the heart twice during one complete circuit of the body.
AQA GCSE Combined Science: Trilogy (8464) — Biology — Foundation · 4.2.2.2
Revise AQA GCSE Combined Science: Trilogy (8464) — Biology — Foundation specification point 4.2.2.2, The heart and blood vessels, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What makes a circulatory system a double circulatory system?
Blood passes through the heart twice during one complete circuit of the body.
What does each of the two circuits in double circulation connect?
What route does deoxygenated blood take from the right ventricle to the lungs?
It travels through the pulmonary artery to the lungs.
How does blood change in the lungs?
It gains oxygen and loses carbon dioxide.
What route does oxygenated blood take from the lungs back to the heart?
It travels through the pulmonary vein to the left atrium.
What route does oxygenated blood take from the left ventricle to the rest of the body?
It is pumped through the aorta to the rest of the body.
What route does deoxygenated blood take from the body back to the heart?
It travels through the vena cava to the right atrium.
What route does air take to reach the alveoli in the lungs?
Trachea → bronchi → alveoli.
What surrounds each alveolus?
A network of blood capillaries.
In which direction does oxygen diffuse in the lungs?
From the air in the alveoli into the blood.
What happens to carbon dioxide during gas exchange in the lungs?
It diffuses from the blood into the alveoli and is breathed out.
How do the many alveoli increase the surface available for gas exchange?
They provide a large surface area.
How do alveolar and capillary walls provide a short diffusion distance?
Both have thin walls.
What maintains the concentration differences that support diffusion in the lungs?
Ventilation and blood flow.
What is the heart’s natural pacemaker, and where is it located?
A group of cells in the right atrium.
What do electrical impulses from the heart’s natural pacemaker do?
They coordinate heart contractions and control the natural resting heart rate.
What is an artificial pacemaker?
An electrical device that sends impulses to the heart to correct irregularities in heart rate.
What are capillaries?
Tiny blood vessels that form networks through tissues.
How does the thickness of capillary walls help substances move between blood and surrounding cells?
Their walls are one cell thick, providing a short diffusion distance.
How does a capillary’s narrow lumen help exchange?
It brings blood close to the vessel wall.
How do extensive capillary networks help exchange?
They provide a large surface area for exchange.
What does a rate relate?
A quantity to the time taken.
How is blood volume flow rate calculated?
Divide the volume of blood passing a point by the time taken. It can be expressed in .
How do you calculate the volume of blood passing a point from its volume flow rate and the time taken?
Volume = volume flow rate × time.
How do you calculate the time taken for a volume of blood to pass a point at a known volume flow rate?
Time = volume ÷ volume flow rate.
How is blood-flow speed calculated, and what kind of units does it have?
Distance travelled ÷ time; its units are distance per time.
What must be true of the units when calculating or converting a rate?
They must be consistent.