3. Muscle Tissue Flashcards
What are the 3 types of muscles?
Cardiac, skeletal and smooth.
What are the dark bands in a striated muscles called?
They are called A bands because they are anisotropic (birefringent) in a polarized light. In the center of the A band a paler region, the H band, is seen in relaxed muscle.
What are the light bands in a striated muscle called?
The light bands are called I bands (isotropic), and a dark transverse line, the Z line, bisects each I band.
What is a sarcomere?
It is the basic unit of contraction of striated muscle.
What are I bands composed of?
Of thin filaments only. [iBand for THIN arms]
What are A bands composed of?
Of thick and thin filaments. [aBand for THICK and THIN body]
What are H bands composed of?
Of thick filaments only. [Holly THICK ass]
What are thin filaments composed of?
They are composed of actin, tropomyosin, and troponin.
Describe the actin protein.
Actin is a long fibrous structure (F-actin) composed of 2 strands of spherical or globular G-acting monomers twisted in a double helix. The filament is polar and contains myosin-binding sites on the G-actin monomers.
Describe tropomyosin.
Tropomyosin is a polar molecule containing 2 polypeptide chains in the form of an alpha-helix. The tropomyosin molecules lie head-to-tail to form filaments that lie in the grooves of the actin helix.
What influx of ion depolarizes a muscle?
Influx of calcium.
What is calmodulin and in which type of muscle is it found the most?
Calmodulin (CaM) (an abbreviation for calcium-modulated protein) is a calcium-binding messenger protein expressed in all eukaryotic cells. It is found abundantly in smooth muscle.
How do cardiac muscles send electric signals to the next cardiac muscle?
Through the gap junctions.
