Heart images are everywhere, especially at this time of year. The heart has been a symbol of romantic love since medieval times. But where does this representation come from, and is it anatomically accurate?
Here is a gif of beating heart.
Mesmerising, isn’t it? But it’s not much like the image on a Valentine’s day card or a box of chocolates. Some people have suggested that the heart symbol doesn’t represent a heart at all.
One theory is that it actually represents an ivy leaf, a plant associated with fidelity. Another that it represents the fruit of silphium, an extinct plant whose fruit was used as a contraceptive. Or there’s American feminist Gloria Steinem’s suggestion that it represents a vagina. Take your pick.
The human heart is also the focus of many sayings and phrases, such as “warms the cockles of my heart”, “tugged on my heartstrings” and “dying of a broken heart”. Are these sayings also as misleading as the heart symbol?
The cockles of your heart
To warm the cockles of one’s heart means to “give one a comforting feeling of contentment”. The origin of the phrase is attributed to Richard Lower, a 17th-century physician who was interested in the heart and circulatory system. (His most famous achievement was performing the first blood transfusion, from a sheep to a man.)
In his book, Tractatus de Corde, Lower described the ventricles of the heart – the two large lower chambers – as being cochlea cordis shaped (Latin for shell and heart, respectively). And from “cochlea”, we get “cockles”. In reality, the warming of the heart is unlikely, the body temperature is at, or very close to, 37℃, and the feeling in the chest in these heartwarming moments is caused by hormones such as adrenaline and its effects of increasing the heart rate.
Pulling on your heartstrings
What about the phrase: “pulling on your heartstrings”? There are most certainly strings in the heart – often multiple. They are known as the chordae tendinae, meaning tendinous cords.
These small fibre-like pieces of tissue are connected to bits of heart muscle at one end and the valves at the other. They are located in both ventricles and have the important function of ensuring that the atrioventricular valves, those that control one-way flow of blood from the atria above down into the ventricles, do not get forced the wrong way when the ventricles contract.
The phrase suggests that the heart somehow responds directly to emotions. But it isn’t true. The heart’s response is driven by the senses, such as sight, hearing, smell or taste. These senses have an impact on the brain, which in turn causes nervous impulses to the heart or release of a hormone that acts on the heart.
This was demonstrated in a recent study from Japan where a group of participants viewed fresh red roses for three minutes. The researchers found that (compared with controls), participants who viewed the roses experienced a reduced heart rate and elevated mood.
A broken heart
Unfortunately, one saying that does appear to have a basis in anatomical reality is “a broken heart”. The condition is called takotsubo cardiomyopathy. It was first reported in Japan in 1990 and takes its name from the octopus traps used by Japanese fishermen. In people with the condition, the left ventricle of the heart bulges and looks similar to these traps.
In this condition, the heart muscles are weakened or stunned. Although doctors aren’t 100% sure of the cause, there are links to suggest that those who are affected by the condition have had significant stresses recently in their lives, such as the death of a loved one. The condition typically affects women more than men, and if caught early enough, can be reversed.
A hole in your heart
When people lose a loved one, they sometimes say that absence of that person has left a hole in their heart. Although you can have a hole in your heart, it isn’t caused by grief.
Every human foetus has a hole in the heart. It is called the foramen ovale, and it connects the right atria to the left (the upper chambers of the heart) and allows blood to bypass the lungs.
The reason blood doesn’t need to go to foetus’s lungs is because it is surrounded by fluid and oxygen, supplied from the mother’s blood via the umbilical cord.
When a baby takes its first breath on being born, the pressure in the blood vessels changes and closes the opening. But in some people this process fails and they are left with a hole in the heart. This is known as an atrial septal defect.
Some people may have this hole and never know. Estimates suggest that up to a quarter of people may have this defect. Thankfully, in most people the hole isn’t big enough to cause health problems.
All of this goes to show that there’s more to sayings about the heart than meets the eye, and some of them are even anatomically correct.