1.
Definisi
The heart is a muscular organ about the size of a fist,
located just behind and slightly left of the breastbone. The
heart pumps blood through the network of arteries and
veins called the cardiovascular system.
2. The heart has four chambers:
The right atrium receives blood from the veins and
pumps it to the right ventricle.
The right ventricle receives blood from the right
atrium and pumps it to the lungs, where it is loaded
with oxygen.
The left atrium receives oxygenated blood from the
lungs and pumps it to the left ventricle.
The left ventricle (the strongest chamber) pumps
oxygen-rich blood to the rest of the body. The left
ventricle’s vigorous contractions create our blood
pressure.
3. Prevention
Some types of heart disease, such as those that are present from birth, cannot be prevented.
Other types, however, can be prevented by taking the following measures:
Eat a balanced diet. Stick to low-fat, high-fiber foods and be sure to consume five portions of
fresh fruit and vegetables each day. Increase your intake of whole grains and reduce the amount
of salt and sugar in the diet. Make sure the fats in the diet are mostly unsaturated.
Exercise regularly. This will strengthen the heart and circulatory system, reduce cholesterol, and
maintain blood pressure.
Maintain a healthy body weight for your height. Click here to calculate your current and target
body mass index (BMI).
If you smoke, quit. Smoking is a major risk factor for heart and cardiovascular conditions.
Reduce the intake of alcohol. Do not drink more than 14 units per week.
Control conditions that affect heart health as a complication, such as high blood pressure or
diabetes.
4. Looking at the outside of the heart, you can see
that the heart is made of muscle. The strong
muscular walls contract (squeeze), pumping blood
to the arteries. The major blood vessels connected
to your heart are the aorta, the superior vena cava,
the inferior vena cava, the pulmonary artery (which
takes oxygen-poor blood from the heart to the
lungs where it is oxygenated), the pulmonary veins
(which bring oxygen-rich blood from the lungs to
the heart), and the coronary arteries (which supply
blood to the heart muscle).
On the inside, the heart is a four-chambered, hollow
organ. It is divided into the left and right side by a
wall called the septum. The right and left sides of
the heart are further divided into two top chambers
called the atria, which receive blood from the veins,
and two bottom chambers called ventricles, which
pump blood into the arteries.
The atria and ventricles work together, contracting
and relaxing to pump blood out of the heart. As
blood leaves each chamber of the heart, it passes
through a valve. There are four heart valves within
the heart:
Mitral valve
Tricuspid valve
Aortic valve
Pulmonic valve (also called pulmonary valve)
The tricuspid and mitral valves lie between the atria and
ventricles. The aortic and pulmonic valves lie between the
ventricles and the major blood vessels leaving the heart.
The heart valves work the same way as one-way valves in
the plumbing of your home. They prevent blood from
flowing in the wrong direction. Each valve has a set of
flaps, called leaflets or cusps. The mitral valve has two
leaflets; the others have three. The leaflets are attached to
and supported by a ring of tough, fibrous tissue called the
annulus. The annulus helps to maintain the proper shape
of the valve.
The leaflets of the mitral and tricuspid valves are also
supported by tough, fibrous strings called chordae
tendineae. These are similar to the strings supporting a
parachute. They extend from the valve leaflets to small
muscles, called papillary muscles, which are part of the
inside walls of the ventricles.
5. The heart's electrical system
To pump blood throughout the body, the muscles of the heart must be
coordinated perfectly — squeezing the blood in the right direction, at the right
time, at the right pressure. The heart's activity is coordinated by electrical
impulses.
The electrical signal begins at the sino-atrial (or sinus, SA) node — the heart's
pacemaker, positioned at the top of the right atrium. This signal causes the
atria to contract, pushing blood down into the ventricles.
The electrical impulse travels to an area of cells at the bottom of the right
atrium called the atrioventricular (AV) node. These cells act as a gate; they
slow the signal down so that the atria and ventricles do not contract at the
same time — there needs to be a slight delay.
From here, the signal is carried along special fibers called Purkinje fibers
within the ventricle walls; they pass the impulse to the heart muscle, causing
the ventricles to contract
6. Blood vessels
There are three types of blood vessels:
Arteries: carry oxygenated blood from the heart to the rest of the body.
Arteries are strong and stretchy, which helps push blood through the
circulatory system. Their elastic walls help keep blood pressure consistent.
Arteries branch into smaller arterioles.
Veins: these carry deoxygenated blood back to the heart and increase in size
as they get closer to the heart. Veins have thinner walls than arteries.
Capillaries: they connect the smallest arteries to the smallest veins. They
have very thin walls, which allow them to exchange compounds with
surrounding tissues, such as carbon dioxide, water, oxygen, waste, and
nutrients.
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