Striated muscle fibres and theit connective tissue
A. Longitudinal section with some connective tissue removed
B. Cross Section
C. A Single Fibre
site search engine by freefind
Muscles can be divided into three main groups according to their structure, e.g.:
Smooth muscle tissue.
Skeletal muscle tissue.
Cardiac (heart) muscle tissue.
Smooth Muscle Tissue
Smooth muscle tissue is made up of
thin-elongated muscle cells, fibres
These fibres are pointed at their ends
each has a single, large, oval
Each cell is filled with a specialised cytoplasm, the
Surrounded by a thin cell membrane, the sarcolemma.
Each cell has many
which lie parallel to one another in the direction of the long axis of the cell.
They are not arranged in a definite striped (striated) pattern, as in skeletal muscles
Hence the name smooth muscle .
Smooth muscle fibres interlace to form sheets or layers of muscle tissue rather than bundles.
tissue, i.e. it is
not controlled by the brain
Smooth muscle forms the muscle layers
in the walls of hollow organs
such as the digestive tract - the walls of the bladder, the uterus, various ducts of glands and the walls of blood vessels .
Smooth muscle controls
slow, involuntary movements
such as the contraction of the smooth muscle tissue in the walls of the stomach and intestines.
The muscle of the arteries contracts and relaxes to regulate the blood pressure and the flow of blood.
Skeletal Muscle Tissue
Most abundant tissue
These muscles are attached to and bring about the movement of the various bones of the skeleton
The whole muscle, such as the biceps, is enclosed in a sheath of connective tissue, the
This sheath folds inwards into the substance of the muscle to surround a large number of smaller bundles, the
These fasciculi consist of still smaller bundles of elongated, cylindrical muscle cells, the
Each fibre is a syncytium, i.e. a cell that have many nuclei.
The nuclei are found at the periphery of the cell, just beneath the thin, elastic membrane (
The sarcoplasm also has many alternating light and dark bands, giving the fibre a striped or striated appearance
Each muscle fibre is made up of many smaller units, the
Each myofibril consists of small protein filaments, known as
The myosin filaments are slightly thicker (
The actin filaments are light bands
The actin filaments are attached to the
This arrangement of actin and myosin filaments is known as a
During the contraction of skeletal muscle tissue, the actin filaments slide inwards between the myosin filaments.
provide the energy
This action causes a shortening of the sacromeres (Z-lines move closer together), which in turn causes the whole muscle fibre to contract.
This can bring about a shortening of the entire muscle
The contraction of skeletal muscle tissue is very quick and forceful.
Skeletal muscles function in pairs to bring about the co-ordinated movements of the limbs, trunk, jaws, eyeballs, etc.
Skeletal muscles are directly involved in the breathing process.
Cardiac Muscle Tissue
in the walls of the
and contain numerous nuclei. The striations are not so obvious,
is thinner and not clearly discernible,
only one nucleus present in the centre of each cardiac fibre
and are linked to each other by so-called
The spaces between different fibres are filled with areolar connective tissue which contains blood capillaries.
Cardiac muscle tissue plays the most important role in the contraction of the atria and ventricles of the heart.
It causes the rhythmical beating of the heart, circulating the blood and its contents throughout the body as a consequence.
page view counter
site search engine by freefind