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Learn about the 12 major anatomy systems of the human body, such as skeletal, muscular, cardiovascular, digestive, endocrine, nervous, respiratory, immune/lymphatic, urinary, female reproductive, male reproductive and integumentary. Select a system to get started and see detailed diagrams and explanations of its components and functions.
- Muscular
The muscular system is responsible for the movement of the...
- Cardiovascular
The average human body contains about 4 to 5 liters of...
- Digestive
The liver weighs about 3 pounds and is the second largest...
- Endocrine System
Human chorionic gonadotropin (HCG) assists progesterone by...
- Muscular
- Overview
- Chemical composition of the body
- Organization of the body
Chemically, the human body consists mainly of water and organic compounds—i.e., lipids, proteins, carbohydrates, and nucleic acids. The human body is about 60 percent water by weight.
What are the four main types of tissue in the human body?
The four main types of tissue in the human body are epithelial, muscle, nerve, and connective.
What are the nine major organ systems in the human body?
The nine major organ systems in the human body are the integumentary system, the musculoskeletal system, the respiratory system, the circulatory system, the digestive system, the excretory system, the nervous system, the endocrine system, and the reproductive system.
human body, the physical substance of the human organism, composed of living cells and extracellular materials and organized into tissues, organs, and systems.
Chemically, the human body consists mainly of water and of organic compounds—i.e., lipids, proteins, carbohydrates, and nucleic acids. Water is found in the extracellular fluids of the body (the blood plasma, the lymph, and the interstitial fluid) and within the cells themselves. It serves as a solvent without which the chemistry of life could not take place. The human body is about 60 percent water by weight.
Lipids—chiefly fats, phospholipids, and steroids—are major structural components of the human body. Fats provide an energy reserve for the body, and fat pads also serve as insulation and shock absorbers. Phospholipids and the steroid compound cholesterol are major components of the membrane that surrounds each cell.
Proteins also serve as a major structural component of the body. Like lipids, proteins are an important constituent of the cell membrane. In addition, such extracellular materials as hair and nails are composed of protein. So also is collagen, the fibrous, elastic material that makes up much of the body’s skin, bones, tendons, and ligaments. Proteins also perform numerous functional roles in the body. Particularly important are cellular proteins called enzymes, which catalyze the chemical reactions necessary for life.
Carbohydrates are present in the human body largely as fuels, either as simple sugars circulating through the bloodstream or as glycogen, a storage compound found in the liver and the muscles. Small amounts of carbohydrates also occur in cell membranes, but, in contrast to plants and many invertebrate animals, humans have little structural carbohydrate in their bodies.
Nucleic acids make up the genetic materials of the body. Deoxyribonucleic acid (DNA) carries the body’s hereditary master code, the instructions according to which each cell operates. It is DNA, passed from parents to offspring, that dictates the inherited characteristics of each individual human. Ribonucleic acid (RNA), of which there are several types, helps carry out the instructions encoded in the DNA.
Along with water and organic compounds, the body’s constituents include various inorganic minerals. Chief among these are calcium, phosphorus, sodium, magnesium, and iron. Calcium and phosphorus, combined as calcium-phosphate crystals, form a large part of the body’s bones. Calcium is also present as ions in the blood and interstitial fluid, as is sodium. Ions of phosphorus, potassium, and magnesium, on the other hand, are abundant within the intercellular fluid. All of these ions play vital roles in the body’s metabolic processes. Iron is present mainly as part of hemoglobin, the oxygen-carrying pigment of the red blood cells. Other mineral constituents of the body, found in minute but necessary concentrations, include cobalt, copper, iodine, manganese, and zinc.
The cell is the basic living unit of the human body—indeed, of all organisms. The human body consists of trillions of cells, each capable of growth, metabolism, response to stimuli, and, with some exceptions, reproduction. Although there are some 200 different types of cells in the body, these can be grouped into four basic classes. These four basic cell types, together with their extracellular materials, form the fundamental tissues of the human body:
1.epithelial tissues, which cover the body’s surface and line the internal organs, body cavities, and passageways
2.muscle tissues, which are capable of contraction and form the body’s musculature
3.nerve tissues, which conduct electrical impulses and make up the nervous system
4.connective tissues, which are composed of widely spaced cells and large amounts of intercellular matrix and which bind together various body structures
Bone and blood are considered specialized connective tissues, in which the intercellular matrix is, respectively, hard and liquid.
- The Editors of Encyclopaedia Britannica
Jan 26, 2024 · Learn about the five vital organs (brain, heart, lungs, liver, kidneys) and the non-vital organs (gallbladder, pancreas, stomach) of the human body. See a diagram of the organs and their functions, and how they support each other in various organ systems. Find out how to maintain optimum health and what to do if you have problems with any of the organs.
People also ask
What are the parts of the human body?
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What organs and systems are included in a human body?
What is human body physiology?
- Skeletal system. The skeletal system is composed of bones and cartilages. There are two parts of the skeleton; axial and appendicular. The axial skeleton consists of the bones of the head and trunk.
- Muscular system. The muscular system consists of all the body muscles. There are three muscle types; smooth, cardiac and skeletal muscles. Smooth muscle is found within walls of blood vessels and hollow organs such as the stomach or intestines.
- Cardiovascular system. The cardiovascular system is comprised of the heart and the circulatory system of blood vessels. The heart is composed of four chambers; two atria and two ventricles.
- Respiratory system. The respiratory system consists of a series of organs; the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles and lungs (alveoli).
The human body is composed of elements including hydrogen, oxygen, carbon, calcium and phosphorus. These elements reside in trillions of cells and non-cellular components of the body. The adult male body is about 60% water for a total water content of some 42 litres (9.2 imp gal; 11 US gal).
Learn human anatomy with thousands of clearly highlighted and labeled diagrams and illustrations of human body structures. Kenhub is a free, online atlas that is easy to use, accurate and trusted by medical students and professionals.
Human Body Diagrams - Medical Art Library. Medical Art Library. Medical Art Library is a resource for teachers, students, health professionals or anyone interested in learning about the anatomy of the human body. We are medical artists who love anatomy. We believe that Illustrations can help you focus on key structures, see relationships, and ...
