Turbine blades are classified into three types: Impulse, reaction, and impulse-reaction.
In two of the diagrams below they show a single duct, in actual engines there are just as many
ducts as turbine blades.
    
all are from page 3-27*

On some turbine engines to allow for increased power output from a smaller turbine cooling air from the compressor section is routed through the center of the turbine blades

Page 3-29*
 
 

Turbine engines can use two types of compressors: Axial flow or centrifugal flow.

Axial flow compressors can only increase the pressure 1.25 to 1.5x per stage
      
Page 3-15                                                                        Page 3-15

Centrifugal compressors can compress air up to 15x per stage, however they are not as efficient as axial flow compressors.

Centrifugal compressors consist of an impeller and a housing, an impeller is pictured below. The housing fits tightly around the impeller. As air enters the impeler (from the top in regard to the picture) it is spun outwards and compressed by the reduced volume in the runner. (in regard to the picture, air leaves the impeller at the bottom sides)

http://www.grc.nasa.gov/WWW/K-12/airplane/centrf.html
 
 

*Whenever there is a page number underneath a diagram the picture is from
A&P Technician Powerplant Textbook published by Jeppesen Sanderson Inc., 1997