Isfahan University of Technology
Advance Physiology
(part 5)
By: A. Riasi
(PhD in Animal Nutrition & Physiology)
Is there any differences between muscle fiber
for the ATP hydrolysis and synthesis?
Three types of skeletal muscle fibers:
1- Slow-oxidative (type I) fibers
2- Fast-oxidative (type IIa) fibers
3- Fast-glycolytic (type IIb, IId, IIx) fibers
Fast fibers have higher myosin-ATPase activity than
slow fibers.
Some fiber are better equipped for oxidative
phosphorylation.
Oxidative fibers characteristics:
 More mitochondria
 More capillaries
 More myoglobin content
Figure 3.25b
Fast-glycolytic have following characteristics:
 Few mitochondria
 High glycogen content
 Few capillaries
 Low myoglobin and pale
 High myosin-ATase activity
 High intensity of contraction
Figure 3.25b
Smooth Muscles
Figure 3.25b
Smooth share some basic properties with skeletal
muscle:
1- They are all have a specialized contractile
apparatus.
2- They are all directly use ATP as energy source for
cross-bridge cycling.
Figure 3.25b
Some more important of smooth muscle
characteristics:
 Smooth muscle cells are spindle-shaped.
 Unlike skeletal muscle cells, a single smooth muscle cell does
not extend the full length of a muscle.
 A group of smooth muscle cells are typically arranged in
sheets.
 Lacking sarcomeres, smooth muscle does not have Z lines as
such, but dense bodies containing the same protein constituent
found in Z lines are present.
Figure 3.25b
Figure 3.25b
A smooth muscle cell has three types of filaments:
1) Thick myosin filaments, which are longer than
those found in skeletal muscle.
2) Thin actin filaments, which contain tropomyosin
but lack the regulator protein troponin.
3) Filament of intermediated size.
Figure 3.25b
Figure 3.25b
The smooth muscle cells are divided to two groups:
1) Single unit smooth muscle cells
2) Multiunit smooth muscle cells
Gap junctions electrically link the muscle fiber in a single-unit
smooth muscle.
Figure 3.25b
Multiunit smooth muscle exhibits properties partway between
skeletal muscle and a single unit muscle.
Multiunit smooth muscle consist of multiple discrete units that
function independently of each other and must be separately
stimulated by nerves to contracts.
Figure 3.25b
Figure 3.25b
Cardiac Muscles
Cardiac
muscles
share
structural
and
functional characteristics with both skeletal
and single unit smooth muscles.
Figure 3.25b
Cardiac Muscles
Figure 3.25b
Cardiac Muscles
Figure 3.25b
Cardiac Muscles
Figure 3.25b