Source : British Heart Foundation
Your heart is a pump that keeps blood moving around your body. It delivers oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products.
The structure of the human heart
The heart is made up of three layers:
● Pericardium – thin outer protective sack.
● Myocardium – specialised cells making up the thick muscular wall.
● Endocardium – thin inner lining of the heart.
Inside the heart there
are four chambers – two on the left side and two on the right.
● The two small upper chambers are called the atria.
● The two larger lower chambers are called the ventricles.
The left and right sides
of the heart are divided by a muscular wall called the septum.
There are four valves
in your heart. They act like ‘gates’ that open and close, making sure that your
blood travels in one direction through your heart – a bit like a one-way
traffic system. They are called the tricuspid valve and the pulmonary valve on the right side of the heart, and the and the aortic valve on the left.
Like every other
living tissue, the heart itself needs a continuous supply of fresh blood. This
blood supply comes from the coronary arteries which branch off from the main
artery (the aorta) as it leaves the left ventricle. The coronary arteries spread
across the outside of the myocardium, supplying it with blood.
How a healthy heart
works
Your heart is a pump that keeps blood moving around your body.
It delivers oxygen and nutrients to all parts of your body, and carries away
unwanted carbon dioxide and waste products.
How blood travels around your body
As your heart muscle
contracts, it pushes blood through your heart. With each contraction, or
heartbeat:
● Your heart pumps blood
forward from its left side, through the aorta
(the main artery leaving the heart) and into the arteries. Blood
from the
right side is pumped to your lungs.
● The blood continues through the arteries, which divide off into smaller and
● The blood continues through the arteries, which divide off into smaller and
smaller branches of microscopic capillaries.Travelling
through this network
of capillaries, blood reaches every part of your body.
● The blood then travels back to the heart from the capillaries into the veins.
● The blood then travels back to the heart from the capillaries into the veins.
The branches of the veins join to form larger veins,
which deliver the blood
back to the right side of your heart.
As the heart relaxes
in between each heartbeat or contraction, blood from your veins fills the right
side of your heart and blood from the lungs fills the left side of your heart.
The two sides of the
heart are separate, but they work together. The right side of the heart
receives dark, de-oxygenated blood which has circulated around your body. It
pumps this to your lungs, where it picks up a fresh supply of oxygen and
becomes bright red again.
The cardiovascular system
The cardiovascular system
This movement of blood
around the body, pumped by the heart, is called circulation. This system is called the cardiovascular
system (or heart and circulatory system).
● It contains about five
litres (eight pints) of blood, which your heart is
continuously circulating.
● Each day, your heart beats about 100,000 times.
● It pumps about 23,000 litres (5,000 gallons) of blood around your body.
● Each day, your heart beats about 100,000 times.
● It pumps about 23,000 litres (5,000 gallons) of blood around your body.
For your heart to keep
pumping regularly, it needs an electrical supply. This is provided by a special group of
heart cells called the sinus node, which is also known as your heart’s natural
pacemaker.
What if something goes wrong?
What if something goes wrong?
Some people are born
with hearts that have not developed properly before birth - this is
calledcongenital heart disease. Some heart conditions may develop
later in life, including coronary heart disease and atrial fibrillation. Sometimes you can inherit a heart
condition from your family.
People who have
coronary heart disease are at risk of having a heart attack. Damage to the heart muscle because of a heart
attack can lead to heart failure which will affect you
for the rest of your life. Your donations are helping our scientists to mend broken hearts like these. You can also watch ourstem cell video to find out more.
Heart failure can also
be caused by other conditions. How heart failure affects you will depend on the
cause of the heart failure and how much of your heart muscle it affects.
http://www.bhf.org.uk/heart-health/how-your-heart-works.aspx