Human body

The human body is the entire structure of a human being. It is made up of many different types of cells that come together to form tissues, then organs, and finally organ systems.

On the outside, the human body has a head, hair, neck, torso — which includes the thorax and abdomen — genitals, arms, hands, legs, and feet. Inside, there are important parts like teeth, bones, muscles, tendons, ligaments, blood vessels, blood, lymphatic vessels, and lymph, as well as many organs.

People who study the human body include health professionals, scientists called physiologists and anatomists, and even artists. They learn about anatomy, physiology, histology, and embryology to understand how the body works. The body keeps itself balanced, or in homeostasis, by controlling things like the levels of sugar, iron, and oxygen in the blood.

Composition

Main article: Composition of the human body

The human body is made up of different elements like hydrogen, oxygen, carbon, calcium, and phosphorus. These elements are found in trillions of cells and other parts of the body.

An adult human body contains a lot of water—about 60% of it. This water is split between fluid inside cells and fluid outside cells, which includes blood plasma and other fluids. The body carefully manages the content and composition of this water.

The body is filled with trillions of cells, which are the basic building blocks of life. These cells are organized into tissues, and tissues form organs like the heart, lungs, and liver. Each organ has a special job to keep the body working properly.

Anatomy

Main articles: Outline of human anatomy and Anatomy

Human anatomy is the study of the shape and form of the human body. The human body has four limbs (two arms and two legs), a head, and a neck that connect to the torso. The body's shape is supported by a strong skeleton made of bone and cartilage, with muscles, organs, and other structures surrounding it.

The body has special areas called body cavities that hold different organ systems. For example, the brain is protected in its own space, while the lungs and some organs like the liver are in other areas. The shape and size of the body can change with age and other factors.

Physiology

For broader coverage of this topic, see Physiology.

See also: Outline of physiology

Human physiology is the study of how the body works. It looks at how everything from cells to organs functions, including mechanical, physical, bioelectrical, and biochemical processes. The body has many systems of organs that work together to keep it healthy and balanced, a state called homeostasis.

These systems help maintain a stable environment inside the body. For example, the nervous system and the endocrine system work together as the neuroendocrine system. The nervous system sends messages to the brain through nerve impulses and neurotransmitters, while the endocrine system releases hormones to control things like blood pressure. Together, they help regulate blood flow, energy, temperature, and other important factors.

Development

Main article: Development of the human body

The development of the human body is the journey from a tiny cell to a fully grown person. It starts when an egg from a woman's ovary meets sperm, forming an embryo that grows in the uterus into a fetus. After nine months, this baby is born. From birth onward, the body continues to grow and change through childhood, adolescence, and into adulthood, eventually reaching old age. Many factors, like genes and environment, shape this growth throughout life.

Society and culture

Further information: History of anatomy, History of medicine, and History of physiology

Health professionals study the human body using illustrations, models, and hands-on learning. In medical schools, students learn about the body through subjects like human anatomy, physiology, and biochemistry.

The human body has been shown in many ways throughout history, from science and education to art. Different cultures have different ideas about what is appropriate to show, which can sometimes lead to disagreements. The study of anatomy began in Ancient Greece with writings about bones and muscles. Later, during the Renaissance, new discoveries changed how people understood the body. Today, we use advanced tools like magnetic resonance imaging and ultrasound imaging to see inside the body in amazing detail.

The study of how the body works started with early thinkers in Ancient Greece. Over time, scientists have learned more by doing experiments and careful observations. Important discoveries include how blood flows through the body and how cells are the building blocks of life. These studies continue to grow, helping us understand the human body better every day.