Download Biological Principles

Anatomy and Physiology
Muscle Tissue
Muscle in the human body
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There are 3 types of muscle tissue in the
human body. Skeletal muscle is attached by
tendons to bones and provides the
mechanisms for our movement. Smooth
muscle generally lines hollow tubes such as
found in blood vessels, the respiratory system
and the gut. This muscle is controlled by our
involuntary nervous system. Finally, cardiac
muscle is found in the heart. Contraction of
this muscle pumps the heart.
Skeletal muscle structure
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Muscle is connected to bone via a tendon. We’ve already seen
that tendons are composed of thick collagen.
When muscles contract they can move bones and this is the
basis of our movement.
Muscles have adequate blood vessels to supply them with fuel
for contraction. Fuel is delivered by an artery, waste products
are extracted by veins and the lymphatic system takes waste
products back to the heart.
Muscle movement is initiated by a voluntary nerve impulse.
When you want to move your leg, your brain sends a message
through a nerve, which initiates the muscle contraction process.
Branches of the nerve and blood vessels follow the connective
tissue components.
Muscles range from very small, such as is found in the middle
ear, to very large found in thigh muscles.
Skeletal muscle
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An individual muscle is surrounded by a
sheath of connective tissue called the
epimysium (also called the fascia). You may
have seen this very thin translucent
membrane when you have cut up a piece of
steak for eating.
The epimysium extends to connective tissue
known as the perimysium and this surrounds
subcomponents called fascicles.
Fascicles are bundles of tens or hundreds of
muscle fibres.
Skeletal muscle
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Each fascicle is composed of many individual fibres called myofibres.
Each myofibre is packaged with bundles of myofibrils. We will look at
this in more detail when we consider muscle contraction.
In this microscope slide, which is magnified hundreds of times, you can
see lots of fascicles (they look like paving stones) and some muscle
that has been cut length ways.
Remember that muscle fascicles are composed of many muscle fibres
which are in turn composed of bundles of myofibrils.
Striated muscle
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At high magnification (1000 times) one can
see striations in skeletal muscle. This is why
skeletal muscle is said to be striated muscle.
We will look at the detail of skeletal muscle
when we look at muscle contraction
physiology.
Smooth muscle
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Smooth muscle lines pipes in the human
body, such as blood vessels and the
respiratory tract. It is controlled by our brain
without us thinking about contracting the
muscle. Just as well otherwise our bodies
would stop working when we were asleep.
Smooth Muscle cells
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Smooth muscle cells are slender and the nucleus has
a bullet like shape. You can see the nuclei of muscle
cells quite clearly in this slide. No striations can be
seen at high magnification. This slide shows relaxed
smooth muscle. The slide shows contracted muscle
and demonstrates that the nucleus actually changes
shape when the muscle cell contracts.
Cardiac muscle
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Cardiac muscle is a very specialised muscle.
It beats continuously without fatigue all your
life and has amazing properties. You can see
striations in cardiac muscle. Fortunately for
us control of heartbeat rate is achieved
without us thinking about our heart beating.
Activity
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Draw carefully the microscopic view of
skeletal muscle and label it clearly.