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Leaving certificate biology
Ecology theory5 Topics|1 Quiz
Unit 1Nutrient recycling4 Topics|1 Quiz
Ecological relationships and population dynamics2 Topics
Human impact on the ecosystem2 Topics
Study of a grassland ecosystem3 Topics
Responses in the Flowering Plant4 Topics|1 Quiz
Unit 3Sexual reproduction in the flowering plant1 Topic
The human reproductive system3 Topics
The menstrual cycle2 Topics
The circulatory system4 Topics
The heart5 Topics
Lesson 11, Topic 2
Arteries carry blood away from the heart.
They carry blood under high pressure causing them to expand as the heart beats (pulse)
Veins carry blood towards the heart.
They carry blood under low pressure so they require valves to prevent back flow of blood
When muscles contract they squeeze the veins and help to push blood back to the heart
Arteries vs veins
Capillaries are tiny tubes that link arterioles to venules.
Their function is to allow exchange between blood and tissues via tissue fluid.
Capillaries have thin walls just one cell thick and are porous