The structure of a typical cell

THE CELL MEMBRANE OR PLASMA MEMBRANE

This is the outer layer or boundary of the cell. It gives shape to the cell and protects it, separating things inside the cell (intracellular) from those outside the cell (extracellular). It regulates the passage of substances in and out of the cell.

Body systems and the physiological and psychological effects of massage

Smooth endoplasmic reticulum

Mitochondria

Nucleus

Cell membrane Vacuole

Golgi apparatus

Lysosome

Smooth endoplasmic reticulum

Mitochondria

Nucleus

Golgi apparatus

Lysosome

Hamstring Anatomy Cross Sectional

Cytoplasm

Ribosomes

Rough endoplasmic reticulum

Chromatin

Centrioles

Figure 2.1 A typical cell.

Cytoplasm

Ribosomes

Rough endoplasmic reticulum

Chromatin

Centrioles

Figure 2.1 A typical cell.

Q Body Massage Therapy Basics THE CYTOPLASM

This is a soft jelly-like substance where the functions of the cell are carried out. It contains various structures called organelles (mini-organs), each of which has a specific function. Also in the cytoplasm are various chemical substances called inclusions.

THE ORGANELLES

These mini-organs each have a characteristic shape and role to perform. The type and number of organelles in different kinds of cell vary depending upon the activities of the cell, e.g. muscle cells have large numbers of mitochondria, because they have a high-level energy output.

® Nucleus - the largest of the organelles. It controls the activities of the cell and contains the body's genetic material (DNA)

® Mitochondria, which generate ATP/energy; there are large numbers in muscle cells

® Ribosomes, which synthesise protein

® Lysosomes, which digest and deal with waste

® The Golgi apparatus, which is concerned with the production of membrane and protein lipids and lipoproteins

® Endoplasmic reticulum - a series of channels for transporting substances within the cell

® The centrosome - involved in cell division. THE INCLUSIONS

These are chemical substances produced by cells. They may not be present in all cells, e.g. melanin is a pigment found in certain cells of the skin and hair: it protects the body by screening out ultraviolet light, and gives the skin its brown colour on exposure to sunlight. Lipid (fat) is found in fat cells; this is broken down to provide energy when required.

Characteristics of cells are metabolism, respiration, growth, reproduction, excretion, irritability and movement.

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