Circulatory System Flashcards
What is the circulatory system made up of?
your heart and blood vessels
Is the circulatory system open or closed?
closed
What does blood do?
transports substances around the body to the cells that need them, including oxygen and glucose needed for respiration and carrying away waste products such as carbon dioxide
Why is it called a double circulatory system?
blood flows twice through the heart during each circuit of the body
What are the 3 main blood vessels?
arteries, veins and capillaries
What is the definition of blood vessel?
tubelike structures that transport blood around the body
Describe an artery.
thick outer wall, thick layer of muscle and elastic fibres, small lumen, smooth lining
Describe a vein.
fairly thin outer wall, thin layer of muscle and elastic fibres, large lumen, smooth lining
Describe a capillary.
very small lumen with a wall made of a single layer of cells
What do arteries do?
carry blood away from the heart under high pressure
What do veins do?
return blood to the heart and have valves to stop blood flowing the wrong way
What do capillaries do?
link arteries and veins in tissues and organs by forming networks so that every cell is close to a capillary
Why do arteries have thick walls?
To withstand high pressure of blood caused by strong contractions of the heart
Why might organisms need a double circulatory system?
