Basic Human Cell Structure

Basic Cell Anatomy 

In human physiology, we are concerned with the specific characteristics and mechanisms of the human body that make it a living being, to understand the function of organs and other structures of the body, it is essential to know about the basic organization of the cell and its functions. The human body, composed of living tissues can be considered as a power station generating multiple electrical signals with two internal sources, namely muscles and nerves, most of the physiological process were accompanied with electrical changes. The discovery formed the basis of explanation of the action of living tissues in terms of bioelectrical potential. Bioelectric potentials are generated at a cellular level. All living matter is composed of cells of different types. The variation of Human cells may from 1 micron to 100 microns and having diameter from 1 mm to 1m in length. The membrane thickness is 0.1 micron. Generally muscular contraction is associated with the migration of ions generating potential differences measurable with suitably placed electrodes.
The basic living unit of the body is the cell. To understand the function of organs and other structures of the body, it is necessary to study the basic organization of the cell. Each organ of our body consists of an aggregate cells. The entire body contains 100 trillion cells, 25 trillion RBC, which transports oxygen from the lungs to the tissues. The oxygen combines with carbohydrate, fat or protein to release the energy required for cell function.

Typical human Cell

Each cell consists of centrally located nucleus surrounded by cytoplasm (cell body). The nucleus is separated from the cytoplasm by a nuclear membrane and the cytoplasm is separated from the surrounding fluids by a cell membrane.


The different substances that makeup the cell collectively called protoplasm - composed of water, electrolytes, proteins, lipids and carbohydrates. Water is the principal fluid medium of the cell and its concentration is between 70 and 85 percent. The electrolytes present in the cell are potassium, magnesium, phosphate, sulphate, bicarbonate and small quantities sodium, calcium and chloride. The electrolyte provide in organic chemicals for cellular functions. (reactins proteins which constitute 10 to 20% of the cell mass are divided into structural proteins and globular proteins (enzymes). Proteins are in the form of long thin filaments composed of many proteins molecular. The globular proteins are in global form. These are mainly enzymes which catalyst the chemical reactions which provide energy for cellular function. Lipids are composed of different types of substances. They are soluble in fat solvents and insoluble in water. Phospholipids are cholester of important lipids. Carbohydrates play a major role in nutrition of the cell. They are stored in the form of glycogen. These are used to supply the cells energy.

Organelles present in the cell contain cell's chemical constituents. The cytoplasm is filled with cytosol, in which the minute and large particles and organelles are dispersed. Ribosomes are minute granular particles in the cytosol and composed of RNA (Ribonucleic Acid). Lysosomes are vericular granular and provide intracellular digestive systems that allow the cell to digest and remove bacteria. The Mitochondria organelles are called ‘Power house' of the cell. The mitochondria contain DNA (Deoxyribonucleic acid). DNA is the basic substance of the nucleus, So it is called as control centre of the cell. It controls replication. Nucleus contain large amount of DNA called genes. The gene first reproduce themselves and the cell splits by a special process called mitosis to form two daughter cells. The nucleus is surrounded by nuclear membrane. Inside the nucleus-nucleolus is present and contains large amount of RNA and Proteins. The cell size is determined by the amount of functioning DNA in the nucleus and 5-10 ┬Ám. For large amount of DNA, the cell size is larger. DNA grows due to the increased production of RNA and cell proteins.