The circulatory system Flashcards
What is the circulatory system made out of?
The heart, all the body’s vessels and the blood.
What does the movement of blood throughout the body depend on?
The heart
What is the heart?
What does it act as?
How does it push blood?
A muscle
A double pump
by contracting over 60 times a minute
How big is the heart?
About the size of a fist
Where is the heart?
Between the two lungs and protected by the rib cage
What are arteries?
Blood vessels with thick muscular walls that can endure a lot of pressure from the blood
What is the largest artery of the body?
The aorta
What does the aorta divide into?
smaller and smaller arteries, arterioles, capillaries
What are capillaries?
Very small blood vessels whose walls are made up of only one row of cells
What happens in the capillaries? Why?
Exchanges by diffusion between the blood and the cells
Since blood circulation is very slow
What do the cells receive?
What do they get rid of?
Nutritional substances and oxygen
Carbon dioxide and water
What do capillaries allow other than diffusion?
They allow white blood cells to leave the blood to destroy pathogens before returning to the circulatory system
Why are veins less elastic than arteries?
Blood pressure is a lot lower when blood returns to the heart
What do veins have?
Small valves that prevent blood from flowing backwards
Why are valves necessary in veins?
Since veins need help from muscle contractions that help blood return to the heart
