neoplasma

Out Line

Backround

ESSAY

The cell
A normal cell body is composed of two basic parts the nucleus (the inner core) and thenucleus (the inner core) and the surrounding cytoplasm. The nucleus is separated from cytoplasm by the nuclear membrane; the cell is separated from other cells by a cellular membrane. Membrane are composed mainly of lipids (which assist in active transport of substances across the membrane.
The cytoplasm of cell contains organelles or substances with individual fuctions to maintain cell life.(mitochondria,golgi apparatus,centrioles,endoplasmic,reticulum).

Substance
Function
Mitochondia




Agranular endoplasmic reticulum




Granular endoplasmic reticulum

Golgi apparatus





Centrioles
Converts nutrients and oxygen to the amino acid adenosine triphosphate (ATP),which acts as catalyst in active transport of substances into cell

Responsible for drug detoxification,lipid synthesis,glycogenolysis and conjugation of bile pigment. In striated muscles,in acts to conduct contractile impulses.

Responsible for protein synthesis

Responsible for carbohydrate synthesis;production of products that will be secreted by the cell (such as insulin from pancreatic cells) production of lysosomea that destroy foreign substances in the cell

Begin cell separation at the time of cell division.

The Nucleus
The nucleus of a cell act as the integrator of cell activity. It contain deoxyribonucleic acid (DNA) and ribonucleic acid (RNA),the basic material of chromosome synhesis and prescription or genetic code for forming other,like cellc

Cell activity
Cell receive nourishment by substances crossing the cellular membraneinto the cell. This is also the way that drugs or chemotherapeutic agents enter the cell. Substances enter by three processes;diffusion,active transport and pinocytpsis.
Diffusion is the nonactive passageof substances through the cell membrane.solutes diffuse from areas of higher concentrations (higher osmotic pressure) by diffusion. Diffusion occurs faster in the prence of heat than cold;small molecules diffuse faster than large molecules. Many substances pass freely through lipid portion of the cell membrane (oxygen ia an example). Other substances can enter only at the protein pore space (water is an examples). Glucose,in contrast,cannot pass through cell membrane unless by it is aided by insulin (facilitated or active transport). Pinocytosis is a process in which the cell membrane invaginates around the substance and pulls it into the cell. Large protein molecules are incorporated into cells in this manner.

Reproductive cycle of the cell
A normal cell cycle has two period an interphase (resting phase) and a mitosis,or dividing,phase. The interphase is divided into three periods : G1,S,and G2. Activity during these periods is