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 — Higher · 4.2.2.2
Revise AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher 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 from the trachea to the alveoli?
Trachea → two bronchi → smaller airways → alveoli.
What are alveoli, and what surrounds them?
Tiny air sacs surrounded by a network of capillaries.
What does ventilation do?
It moves air into and out of the lungs.
In which direction does oxygen diffuse during gas exchange in the lungs?
From alveolar air into the blood.
In which direction does carbon dioxide diffuse during gas exchange in the lungs?
From the blood into the alveoli, from where it is breathed out.
How do the many alveoli help gas exchange?
They provide a large surface area.
What structures provide a short diffusion distance between alveolar air and blood?
The moist, thin alveolar walls and the thin capillary walls.
What maintains concentration gradients for oxygen and carbon dioxide in the lungs?
Ventilation and a continuous blood supply.
What is the heart’s natural pacemaker?
A group of cells in the right atrium.
How does the heart’s natural pacemaker set the resting heart rate?
It produces regular electrical impulses that spread through the heart and coordinate contractions.
What is an artificial pacemaker used for?
It sends electrical impulses to regulate heart contractions when the heart’s own control produces an irregular rate.
In which direction do arteries carry blood?
Away from the heart.
How are an artery’s walls and lumen adapted to relatively high blood pressure?
It has thick, strong walls and a relatively narrow lumen.
How does elastic tissue in artery walls help maintain blood pressure?
It stretches as blood is pumped in and recoils between heartbeats.
How can muscle in an artery wall affect blood flow?
By changing the artery’s diameter.
What are capillaries, and where do they connect in the circulation?
Tiny blood vessels that form networks close to body cells and connect the arterial and venous sides of the circulation.
How does the thickness of capillary walls aid exchange?
Their walls are one cell thick, giving substances a short distance to diffuse between blood and tissues.
How does the narrow lumen of a capillary aid exchange?
It brings blood close to the vessel wall.
How do extensive capillary networks aid exchange?
They provide a large surface area for exchange.
What determines the direction in which substances move between blood and tissues?
Their concentration gradients.
What is blood flow rate?
The volume of blood passing a point per unit time.
How is blood flow rate calculated from volume and time?
How is blood volume calculated from flow rate and time?
How is time calculated from blood volume and flow rate?
How should units be handled when calculating a blood flow rate?
Volume and time units must be consistent with the required rate unit. Convert them before or after the calculation.