mr. whedon wed 7:25 by: marc magliaro deisy maguirre shquanda meylor
TRANSCRIPT
Structure & Function 1
Mr. WhedonWed 7:25
By: Marc Magliaro Deisy Maguirre
Shquanda Meylor
The SarcomereA sarcomere is the basic unit of a Muscle 's cross-striated myofibril.Myofibrils are thread like structure Which consist of two types of protein filaments. Myosin which is a thick filament and Actin which is a thin filament.
Sarcomere
The striations form a repeating pattern of units called Sarcomeres along each muscle fiber. Muscle fibers in a way themselves are basically collections of sarcomeres.
Myofibrils may be thought of as sacromeres joined end to end.
Myofibrils There are two types of Myofibrils One type is actin which is a thin filament
and the other is myosin which is composed of a thick filament.
The origination ofthese filaments produce striation characteristics ofskeletal musclefiber.
The Striation Pattern
There are 2 main parts of the striation pattern
• The two parts are called I bands and A Bands.
• The I bands are composed of the Thin filaments (actin) and the A bands are composed of Thick (myosin) and Thin (actin) filaments.
I band (Thin Filaments) These Actin filaments ( thin) are held
by direct attachments to structures called the Z Line. ( Z Band) The Z line is in the center of the I band.
A Band
The A Band consist of thick myosin filament
overlapping with thin actin filaments.The A band also consist of a region where only thick filaments exist. This regions is called the H-Zone
M- Line The A band includes a thickening
which is know as the M- Line, which consist of proteins that help hold the thick filaments place.
H- Zone The H- Zone consist of only thick
filaments and is also located in the A band.
The H zone may change depending on the degree of filament overlap.
Z – Line A singel sarcomere extends from one
Z line to the other Z line.
Myosin: H Zone
Actin: I band Actin and Myosin: A Band
Sacomere Endline: Z line which is located in the I Band
Sacomere Midline: M line which is located in the H Zone.
Myofilments Thick Filaments are composed many
molecules of myosin. Each myosin molecules consist of two twisted protein strands called cross-bridges.
Myofilments Thin filaments consist of double
strands of actin twisted. Thin Filaments also consist of two typs of protein troponin and tropomyosin.