CIRCULATORY SYSTEM

HEART

• Pumps blood through the body
• The heart beats an average of 70 of Times Every minute
• The heart is a organ that pumps blood to every cell in your body

BLOOD

• Blood makes up around 7% of the weight of a human body.
• Blood contains red blood cells, white blood cells and platelets.
• These blood cells float in a yellow liquid called blood plasma. Blood plasma is made up of 90% water and also contains various nutrients, electrolytes, gases, proteins, glucose and hormones.
• Red blood cells develop in bone marrow and circulate in the body for around 120 days.

ARTERIES

• An artery is a tube-like blood vessel that carries blood away from the heart.
• An arteriole is a smaller branch off an artery. Arterioles branch into microscopic capillaries.
• Arteries run alongside most of the veins that return blood to the heart.

VEINS

• 1. Veins are elastic tubes or vessels that carry blood from your tissues or organs of the body back to the heart.
• They are usually situated closer underneath the skin.
• Each vain has three layers

CAPILLARIES

• Capillaries are the smallest blood vessels, visible only under a microscope. They link the arterioles to the venules .
• The largest capillary is just 0.2 mm wide — thinner than a hair.
• Each capillary is about 0.5 mm to 1 mm long.

WHAT I LEARNED ABOUT THE CIRCULATORY SYSTEM

• About 8 million blood cells die in a human body every second and the same number are born each second
• 1. A drop of blood contains about 5.5 million red blood cells and 12 thousand white blood cells.
• 2. Your heart beat about 30 million times in a year.