histology

1. Muscle tissue is a soft tissue that consists of
elongated cells called muscle fibers that are highly
specialized to generate force.

2. Structure of Muscle
Muscle cells or myocytes composed of small units called myofibrils
which joined together by connective tissue called sarcolemma

3. Types of muscle

4. A) Skeletal Muscle
Skeletal muscle is a form of striated muscle tissue
which is under the voluntary control of the somatic
nervous system.
Most skeletal muscles are attached to bones by
bundles of collagen fibers known as tendons.

7. A skeletal muscle refers to multiple bundles of cells
called muscle fibers or muscle cell.
Each muscle fiber is covered by a plasma membrane
called the sarcolemma (flesh sheath).
Multiple nuclei lie at the periphery of the fiber, under
the sarcolemma.
The muscle fiber’s cytoplasm, called sarcoplasm,
contains many mitochondria that produce large
amounts of ATP during muscle contraction.

8. Extending throughout the sarcoplasm is sarcoplasmic
reticulum a network of fluid-filled membrane-enclosed
tubules (similar to smooth endoplasmic reticulum) that
stores calcium ions required for muscle contraction.
Also in the sarcoplasm are numerous molecules of
myoglobin (stores oxygen until it is needed by
mitochondria to generate ATP), a reddish pigment similar
to hemoglobin in blood.

9. B) Smooth Muscle
Smooth muscle is an involuntary non-striated
muscle.

10. Smooth muscle fibers are considerably smaller in
length and diameter than skeletal muscle fibers and are
tapered at both ends.
Within each fiber is a single, oval, centrally located
nucleus.
In addition to thick and thin filaments, smooth muscle
fibers also contain intermediate filaments.
In smooth muscle fibers, the thin filaments attach to
structures called dense bodies, which are functionally
similar to Z discs in striated muscle fibers.

11. C) Cardiac Muscle
Cardiac muscle or heart muscle is an involuntary,
striated muscle that constitutes the main tissue of
the walls of the heart.

13. Cardiac muscle fibers often are branched; are shorter
in length and larger in diameter than skeletal muscle
fibers; and have a single, centrally located nucleus.
Cardiac muscle fibers interconnect with one another by
irregular transverse thickenings of the sarcolemma
called intercalated discs (insert between).
The intercalated discs hold the fibers together and
contain gap junctions, which allow muscle action
potentials to spread quickly from one cardiac muscle
fiber to another.