BIOLOGY 2311 ANATOMY AND PHYSIOLOGY PART I LECTURE 1

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Isfahan University of Technology
Advance Physiology (part 5)
By A. Riasi (PhD in Animal Nutrition
Physiology)
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Is there any differences between muscle fiber for
the ATP hydrolysis and synthesis?
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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
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Fast fibers have higher myosin-ATPase activity
than slow fibers.
Some fiber are better equipped for oxidative
phosphorylation.
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• Oxidative fibers characteristics
• More mitochondria
• More capillaries
• More myoglobin content

Figure 3.25b
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• 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
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Smooth Muscles
Figure 3.25b
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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
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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
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Figure 3.25b
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A smooth muscle cell has three types of filaments

• Thick myosin filaments, which are longer than
  those found in skeletal muscle.
• Thin actin filaments, which contain tropomyosin
  but lack the regulator protein troponin.
• Filament of intermediated size.

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Figure 3.25b
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Figure 3.25b
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• The smooth muscle cells are divided to two
  groups
• Single unit smooth muscle cells
• Multiunit smooth muscle cells

Gap junctions electrically link the muscle fiber
in a single-unit smooth muscle.
Figure 3.25b
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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
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Figure 3.25b
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Cardiac Muscles

• Cardiac muscles share structural and functional
  characteristics with both skeletal and single
  unit smooth muscles.

Figure 3.25b
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Cardiac Muscles
Figure 3.25b
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Cardiac Muscles
Figure 3.25b
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Cardiac Muscles
Figure 3.25b