Isfahan University of Technology

Advance PhysiologyAdvance Physiology((part 5part 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.

Figure 3.25b

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

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.

Some more important of smooth muscle

characteristics:

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

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