Unit 5 Anatomy and Physiology P1 and P2 Cell Compnents and Tissue Structure

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P1: Outline the functions of the main cell components.

We begin life as a clump of 8 stem cells, stem cells can become many different types of cell and can renew themselves. Each type of cell have a specific function; e.g. nerve cells, bone cells and muscle cells.

Each cell has three main parts:


The nucleus is the command centre for the cell and controls the way it works and coordinates all of the cells functions, it is the largest structure in the cell and although there is usually only one nucleus per cell, some cell types like muscle cells for example have more than one. The nucleus contains DNA, which is why some inherited conditions can affect the things nuclei control. The nucleus is surrounded by a selectively permeable plasma membrane that allows proteins and nucleic acids to pass through gradually.

Protective Membrane

The protective membrane surrounds and protects the entire cell.


Cytoplasm is a jelly-like substance that contains the internal structures that enable the cell to function. Chemical reactions, that make up the cells metabolism, happen in the cytoplasm, which contains a mix of chemicals and nutrients that feed the cell and keep it alive. Cytoplasm contains a variety of cell organelles.

Cell organelles are different structures inside a cell that each have their own function, they’re like mini versions of the body’s organs. The main organelles are; mitochondria, endoplasmic reticulum, the Golgi apparatus and lysomes.


Mitochondria are the largest cell organelle and appear in large numbers in most body cells. They are sausage like or spherical in shape and their function is to make adenosine triphosphate (ATP) which is the major source of cellular energy. They have an unusual double membrane structure with a smooth outer layer and a folded inner layer. The large surface area of the inner layer allows for aerobic respiration to take place which how ATP is made.

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Endoplasmic Reticulum 

Endoplasmic eticulum is abbreviated to ER and is a system of channels spread throughout the cytoplasm. The outside surface is known as ‘Rough ER’ because it has ribosomes attached to it. The ribosomes make protein from amino acids and the rough ER collects and transports the proteins made by the ribosomes. Smooth ER doesn’t have ribosomes and is responsible for steroid production. It is where calcium is stored in skeletal muscle cells and it also contains enzymes that detoxify various molecules.

The Golgi Apparatus

These are a group of tightly packed fluid filled cavities that are thought to ...

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