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The heart is a muscular organ found in most animals. This organ pumps blood through the blood vessels of the circulatory system. [1] . The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to the lungs. [2] .
Jul 5, 2024 · Learn about the structure, function, and diagram of the human heart, a four-chambered double pump that circulates blood through the body. Explore the evolution, electrical conduction, and diseases of the heart.
- The Editors of Encyclopaedia Britannica
- In humans, the heart is situated between the two lungs and slightly to the left of center, behind the breastbone. It rests on the diaphragm, the mu...
- The heart consists of several layers of a tough muscular wall, the myocardium. A thin layer of tissue, the pericardium, covers the outside, and ano...
- The pumping of the heart, or the heartbeat, is caused by alternating contractions and relaxations of the myocardium. These contractions are stimula...
- The rhythmic noises accompanying the heartbeat are called heart sounds. The two distinct sounds are heard, a low, slightly prolonged “lub” (first s...
40.3: Mammalian Heart and Blood Vessels. The heart is a complex muscle that pumps blood through the three divisions of the circulatory system: the coronary (vessels that serve the heart), pulmonary (heart and lungs), and systemic (systems of the body), as shown in Figure \ (\PageIndex {1}\).
Jun 8, 2024 · The Heart. Blood flows through the heart in a one way system. The right atrium receives deoxygenated blood from the body via the largest vein in the body called the vena cava. The contraction of the atrium pumps the blood into the right ventricle and then into the lungs via the pulmonary artery.
- How Many Hearts Do We have?
- Mammal and Bird Hearts
- Reptile and Dinosaur Hearts
- Amphibian Hearts
- Fish and Insect Hearts
- How Big Is Your Heart?
- Swift and Sluggish Heart Rates
- Exercise, Temperature and Hibernation All Change Heart Rate
- Mending A Broken Heart
- Conclusions
- GeneratedCaptionsTabForHeroSec
You surely know that humans and giraffes have just one heart, as most animals do—but not all. Octopuses and squids (animals called cephalopods) have three hearts. Two hearts pump blood to the gills to take up oxygen, and the other pumps blood around the body (Figure 1). Worms are also unusual, with five structures called aortic arches acting as bas...
It is not just the number of hearts that can change between species. The basic structure of this vital organ can be extremely different from one species to the next. Hearts mostly consist of muscle that contracts and relaxes, causing blood to move through blood vessels to and from the lungs and around the body (Figure 2)1. As mammals, we have four ...
Reptile hearts have three chambers, two atria and one ventricle (Figure 1). The exception is crocodilians, which have four-chambered hearts, just like mammals and birds. However, there is a hole in the crocodile chamber wall, so whether there are three or four heart chambers is up for debate. People often wonder whether dinosaurs evolved from birds...
Amphibians are an interesting group, as their hearts vary greatly. Living on land and in water, many get oxygen using their lungs, but also take it up via their skin. Most amphibians, including frogs and toads, have three-chambered hearts, with two atria and one ventricle (Figure 1). However, lungless salamanders do not have a structure called a se...
Fish hearts have just two chambers, an atrium and a ventricle (Figure 1). Insects often have just a tube that pumps hemolymph(the name for the insect equivalent of blood) freely around the entire body, with a vessel to help it move. Cockroaches, however, have 13 heart chambers!
It goes without saying that heart size varies in different animals. After all, a whale could not survive with a mouse-sized heart. An adult human heart weighs about 0.6 lbs. If you make a fist, that is roughly the size of your heart. The giraffe heart is a hefty 26 lbs, but the blue whale really tips the scales at 400 lbs. The world’s smallest hear...
The way animals’ hearts work varies between species, too. The heart rate, measured in beats per minute (bpm), varies in different species. Generally, larger animals have slower heart rates. A large slug has a heart rate of around 55 bpm, while smaller slug species are in the 90s. Many whales have heart rates of 10–30 bpm, giraffes are 40–90, and ca...
Heart rate changes in most exercising animals. Running giraffes can reach 170 bpm and humans can hit 220, but ideally it should be a little less. A crocodile heart rate at 10° C is 1–8 bpm, at 28° C it hits 24–40, and once it reaches over 40° C, the heart can become damaged. Young swifts (birds) lower their heart rates when in the nest, to avoid st...
In our previous Frontiers for Young Minds paper “Mending a Broken Heart,” we looked at fixing failing hearts [4, 5]. The zebrafish has a very important ability: it can regenerate (regrow), so if it gets injured or its heart has a problem, it can often repair itself. Human bodies are fantastic, and they continuously try to replace heart cells and re...
In this article, we looked at some of the similarities and differences between the hearts of various species. Mammals and birds have very similar hearts due to evolution, while reptiles, fish, insects, and other animals evolved hearts that are slightly differently from those of mammals. The environment both inside and outside of each animal helps c...
Learn about the fascinating world of animal hearts, from the number and structure of chambers to the speed and size of beats. Discover how hearts vary across species, from mammals and birds to reptiles and insects, and how some animals survive without hearts.
The cardiovascular system comprises the heart, veins, arteries, and capillary beds. The atrioventricular (mitral and tricuspid) and semilunar (aortic and pulmonic) valves keep blood flowing in one direction through the heart, and valves in large veins keep blood flowing back toward the heart. The rate and force of contraction of the heart and ...
Oct 4, 2019 · In most people, the heart is located on the left side of the chest, beneath the breastbone. The heart is composed of smooth muscle. It has four chambers which contract in a specific order, allowing the human heart to pump blood from the body to the lungs and back again with high efficiency.
