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WonderBody fact

The adult heart beats roughly 100,000 times a day at a resting rate of about 70 beats a minute. Each beat pushes out around 70 millilitres of blood, which adds up to about 7,000 litres a day at rest, and more during exercise.

Human biology

Health

The story behind the card

The heart is a muscle about the size of a fist, weighing 250 to 350 grams, with four chambers: two atria that receive blood and two ventricles that pump it out. The right side sends blood to the lungs to collect oxygen; the left side sends it round the rest of the body. Each beat is started by the sinoatrial node, a small cluster of cells that acts as the heart's natural pacemaker. It fires an electrical signal that spreads through the heart muscle and makes it contract. The rate changes all day: it falls during sleep and rises with exercise, stress, fever and illness. Over an 80-year life, 100,000 beats a day adds up to nearly three billion heartbeats.

Türkçe oku
Yetişkin kalbi dinlenirken dakikada 70 kadar atar; bu da günde yaklaşık 100.000 atış eder. Her atışta 70 mililitre kadar kan pompalanır. Dinlenme hâlinde bu, günde 7.000 litreye yakın kan demektir; egzersiz sırasında daha da fazladır.

Kalp, yumruk büyüklüğünde, 250-350 gram ağırlığında bir kastır. Dört odacığı vardır: Kanı toplayan iki kulakçık ve kanı dışarı pompalayan iki karıncık. Sağ taraf kanı oksijen alsın diye akciğerlere, sol taraf ise vücudun geri kalanına gönderir. Her atışı, sinoatriyal düğüm denen küçük bir hücre kümesi başlatır; kalbin doğal pili budur. Buradan çıkan elektrik sinyali kalp kasına yayılır ve kalbin kasılmasını sağlar. Kalp hızı gün boyu değişir: Uykuda düşer; egzersizle, stresle, ateşle ve hastalıkla yükselir. Günde 100.000 atış, 80 yıllık bir ömürde yaklaşık üç milyar kalp atışı eder.

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Background reading: Heart
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