What is beating, and why?

The National Weekender
HEALTH

In this series of articles every Friday I will explain your body to you, and how you can use this understanding to improve your health, and hopefully live a longer and more enjoyable life. You will learn how your body works, and how you can avoid damage to it. You will also learn how we doctors examine you and treat illnesses. And most importantly, you will learn how you can change your lifestyle to stay healthy.
The articles will help you to know more about your body, about health and disease. I will answer your questions in a column every Thursday. Send your questions to: [email protected]

OUR heart beats 100,000 times a day, pushing 5,000 gallons of blood through our body every 24 hours. It delivers oxygen- and nutrient-rich blood to our tissues and carries away waste. Here, we explain how this amazing organ carries out this vital work.
What is the heart? The heart is a muscular organ roughly the size of a closed fist. It sits in the chest, slightly to the left of center.
Why does the heart beat? What causes your heart to beat? Electricity! But before we can understand what electricity is doing in the body, we first need to understand the parts of the heart and how they work together.
As the heart contracts, it pumps blood around the body. It carries deoxygenated blood to the lungs where it loads up with oxygen and unloads carbon dioxide, a waste product of metabolism.
The heart, blood, and blood vessels combined are referred to as the circulatory system.

Basic anatomy of the heart
The heart consists of four chambers called by the Latin name atria: the two upper chambers (they receive blood) and the two ventricles – the two lower chambers (they discharge blood).
The four chambers are separated by four valves that help ensure that blood only flows in one direction.
On the left side of the heart: the aortic valve – between the left ventricle and the aorta and the mitral valve – between the left atrium and the left ventricle.
On the right side of the heart: the pulmonary valve – between the right ventricle and the pulmonary artery and the tricuspid valve – between the right atrium and right ventricle.
Most people are familiar with the sound of a human heartbeat. It is often described as a “lub-DUB” sound. The “lub” sound is produced by the tricuspid and mitral valves closing, and the “DUB” sound is caused by the closing of the pulmonary and aortic valves.

How the heart works
The heart contracts at different rates depending on many factors. At rest, it might beat around 60 times a minute, but it can increase to 100 beats a minute or more. Exercise, emotions, fever, diseases, and some medications can influence heart rate.

The left and right sides of the heart work in unison. The right side of the heart receives deoxygenated (venous) blood and sends it to the lungs; the left side of the heart receives oxygenated blood (arterial) from the lungs and pumps it to the rest of the body.
The atria and ventricles contract and relax in turn, producing a rhythmical heartbeat.
Each heartbeat can be split into two parts:
Diastole: the atria and ventricles relax and fill with blood.
Systole: the atria contract (atrial systole) and push blood into the ventricles; then, as the atria start to relax, the ventricles contract (ventricular systole) and pump blood out of the heart.
The muscles of the heart need to receive oxygenated blood, too. They are fed by the coronary arteries on the surface of the heart.

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 so called sinus (or sino-atrial 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.

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.

6 Simple Steps to Keep Your Heart Healthy
Keeping your heart healthy is simple when you look at the big picture: Get exercise. Eat right. Drink less. Stress less. Watch your weight. Don’t smoke.
Putting those 6 goals into action, of course, isn’t so simple. Which matter most? How can you put them into daily practice?
Here are practical hints for a way of life that makes you feel great while it strengthens your heart.

Make Time to Play
Adults need at least 30 minutes of exercise five or more days a week for heart health. Make exercise playtime and you’re more likely to get it done. Play kickball with your kids, walk the dog, or shoot hoops, or go “mall-walking” with co-workers on your lunch break.
Go for a total of at least 30 minutes of exercise daily – and break it up, if you like. Aim for a 10-minute morning walk, workout with hand weights at lunch, and walk the stairs – avoid the elevator, and you’ve met your goals.
“Folks should get their heart rate up so they’re somewhat breathless, but can still carry on a conversation”. All kinds of exercises are important, from strength training and aerobics, to flexibility and stretching exercises.

Add the ‘Food Rules’ to Your Memory
Limit Bad Fat: If you eat a typical PNG meal (meat, pork, fat), this one change can bring dramatic results: Eat less saturated fat. You can “reduce your risk of heart issues by half”. Start by switching to low-fat meat and dairy, and change to healthier fats like olive and canola oils.
Cut the Salt: Cook without salt, limit processed foods, and go easy on the salt shaker. Aim to bring down the sodium you eat to 1,500 milligrams, the daily limit.
Pump Up Produce: Eat at least 2 1/2 cups of vegetables and fruit every day. You’ll lower your risk for heart disease, stroke, and cancer. And there’s a slimming bonus: “For all the nutrients fruits and vegetables provide, you’re also getting few calories,” and “they fill you up.”
Go for Grains: Whole grains help lower cholesterol and blood pressure, and may help prevent type 2 diabetes. Think about corn tortillas, whole wheat pancakes and pasta, bulgur wheat, oatmeal, quinoa, and chewy, delicious brown rice or wild rice.

Is laughter really the best medicine?
This may be one of those old sayings that have stuck around because it’s partially true. Yes, laughter is good for your heart.
Studies show that a hearty laugh can prompt your blood vessels to expand and contract, increasing your blood flow by up to 20 per cent. That can promote healthier blood vessels – and help ward off cardiovascular disease.
Next week: The heart and breakfast – Five ideas for a healthy breakfast

  • Dr Fasol is an academic surgeon from the University of Vienna in Austria, and has worked, built and managed hospitals in Europe, Africa and China operating and treating thousands of patients.