The Cellular Level of Organization

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The Cellular Level 
of Organization

Cells and homeostasis





Cells carry out a multitude of functions that help each system contribute to the homeostasis of the entire body. At the same time, all cells share key structures and functions that support 

their intense activity.

The human body these are combined into about 200 different types of words called cells—living structural and functional units enclosed by a membrane. All cells arise from existing cells by the process of cell division, in which one cell divides into two identical cells. Different types of cells fulfill unique roles that support homeostasis and contribute to the many functional capabilities of the human organism. Cell biology or cytology is the study of cellular structure and function. As you study the various parts of a cell and their relationships to one another, you will learn that cell structure and function are intimately related. In this Blog you will learn that cells carry out a dazzling array of chemical reactions to create and maintain life processes—in part, by isolating specific types of chemical reactions within specialized cellular structures.

PARTS OF CELL 

1. The plasma membrane forms the cell’s flexible outer surface, separating the cell’s internal environment (everything inside  the cell) from the external environment (everything outside the  cell). It is a selective barrier that regulates the flow of materials  into and out of a cell. This selectivity helps establish and main- tain the appropriate environment for normal cellular activities.  The plasma membrane also plays a key role in communication  among cells and between cells and their external environment. 

2. The cytoplasm  consists of all the cellular contents between the plasma membrane and the nucleus. This compartment has two components: cytosol and organelles. Cytosol , the fluid portion of cytoplasm,  also called intracellular fluid, contains water, dissolved solutes, and suspended particles. Within the cytosol are several different types of organelles. Each type of organelle has a characteristic shape and specific functions. Examples include the cytoskeleton, ribosomes, endoplasmic reticulum, Golgi complex, lysosomes, peroxisomes, and mitochondria.

3. The nucleus  is a large organelle that houses most of a cell’s DNA. Within the nucleus, each chromosome ,a single molecule of DNA associated with several proteins, contains thousands of hereditary units called genes that control most aspects of cellular structure and function.   



             

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