Download Cardiac Muscle (longitudinal section)

Muscle Tissue
Lab-5
Lecturer: Dr. Twana A.
Mustafa
•
Alternating contraction and relaxation of cells
•
Chemical energy changed into mechanical energy
• Characteristics
– Cells are referred to as fibers
– Contracts or shortens with force when stimulated
– Moves entire body and pumps blood
• Types
– Skeletal:attached to bones
– Cardiac: muscle of the heart.
– Smooth: muscle associated with tubular
structures and with the skin. Nonstriated and
involuntary.
Connective Tissue Components
Microscopic anatomy of a
skeletal muscle fiber
Nuclei
Fiber
(a)
Sarcolemma
Mitochondrion
Myofibril
(b)
Dark
Light
A band I band
Nucleus
Z disc
H zone
Z disc
Thin (actin) filament
Thick (myosin)
filament
(c)
Human Anatomy and Physiology, 7e
by Elaine Marieb & Katja Hoehn
Copyright © 2007 Pearson Educat
publishing as Benjamin Cummings
3 Types of Muscle Tissue
• Skeletal muscle
– attaches to bone, skin or fascia
– striated with light & dark bands
visible with scope
– voluntary control of contraction &
relaxation
10-4
3 Types of Muscle Tissue
• Cardiac muscle
– striated in appearance
– involuntary control
– autorhythmic because of built in
pacemaker
10-5
3 Types of Muscle Tissue
• Smooth muscle
– attached to hair follicles in skin
– in walls of hollow organs -- blood
vessels & GI
– nonstriated in appearance
– involuntary
10-6
Skeletal Muscle as seen in longitudinal section
in the light microscope...
• Fiber = cell; multi-nucleated and striated
• Myofibrils (M) with aligned cross striations
• A bands - anisotropic (birefringent in polarized light)
• I bands - isotropic (do not alter polarized light)
• Z lines (zwischenscheiben, Ger. “between the discs”)
• H zone (hell, Ger. “light”)
Skeletal Muscle as seen in transverse section in the lig
Cardiac Muscle
Tissue Features:
• Striated (same contractile machinery)
• Self-excitatory and electrically coupled
Cell Features:
• 1 or 2 centrally placed nuclei
• Branched fibers with intercalated discs
• Numerous mitochondria (up to 40% of cell volume)
Cardiac Muscle (longitudinal section)
• Central nuclei, often with a biconical, clear area next to nucleus –this is
where organelles and glycogen granules are concentrated (and atrial
natriuretic factor in atrial cardiac muscle)
• Striated, branched fibers joined by intercalated disks (arrows) forms
interwoven meshwork
Cardiac Muscle (longitudinal section)
Cardiac Muscle (transverse section
Transverse Section of Cardiac Muscle versus Skelet
As with skeletal muscle, delicate, highly vascularized connective tissue
(endomysium) surrounds each cardiac muscle cell. Fibers are bundled
into fascicles, so there is also perimysium. However, there really isn’t an
epimysium; instead, the connective tissue ensheathing the muscle of the
heart is called the epicardium (more on that in a later lecture).
Smooth Muscle
• Fusiform, non-striated cells
• Single, centrally-placed nucleus
• Contraction is non-voluntary
• Contraction is modulated in a neuroendocrine
manner
• Found in blood vessels, GI and urogenital organ
walls, dermis of skin
Smooth Muscle (longitudinal section)
Smooth Muscle Viewed in
Transverse and
Longitudinal Section