Kinds of muscle tissues

Some features of the muscle tissues include

1. Excitability - is the ability for muscle tissues to transmit electrical changes in muscles fibers to allow contraction.

2. Contractility - is the ability for the muscle fibers to shorten to allow contraction

3. Elasticity - is the ability of the muscle fibers to go back to its original length once released from the muscle contraction

4. Extensibility - is the ability for the muscle fiber to stretch

I like to remember this as E3C. E cubed C. Easy, EC... get it? Ha - ha, very funny.

There are three kinds of muscle tissues.

a. Skeletal
b. Cardiac
c. Smooth

Let's start with Skeletal muscle tissue...

Skeletal.

This is my illustration.

But this is what it looks like in real life....

biologyonlineus.com



stevegalik.org



Features of Skeletal Muscle tissue include rod, long shaped muscle fibers, striations (stripes), many nuclei, voluntary control and no mitosis in adults. 

Some functions are for movements, posture to help resist  gravity, to regulate our temperature, to store materials and for support, lining muscles in skeleton.

Cardiac.

Getting tired of my sucky illustrations yet?  The highlights are the parts you have to know!





But they look this this in real life...





medicalpicturesinfo.com



They are only seen in the walls of the heart, they are striated like the skeletal muscles, but they only have one or two nuclei per cell. They are branched in shape, have intercalated disks and are involuntary. No mitosis allowed in adult cardiac muscles. What sets them apart is the absence of perimysium and epimysium.

It's main function is to help the transportation of blood throughout the entire body.

Smooth Muscle tissue.

This is what they look like in real life...



siumed.edu

The Smooth muscle tissues are typically seen in visceral organs such as the stomach and the lining of blood vessels. They have no striations, that is probably why they are called "smooth" muscle tissue. They have fusiformed shape cells that has a single nuclei inside. What they are needed to function is to help transport materials, for example, food into the tubes of the intestine. They are also involuntary. What sets them apart besides the lack of striations is their ability to divide through mitosis in adults. A good way to remember is to think of your digestive track. If you look at a colonoscopy picture, the lining looks very smooth.



avrupatimes.com

Also think of how you cannot voluntarily control its contractions, how acidic the stomach is inside  and thus, the high rate of mitosis to replace the cells rapidly.

Now, I don't know about you, but I find the whole skeletal muscle organization kind of confusing. Bundles after bundles after bundles after bundles... it does not end, so I just list it down to keep it simple.

Here is a picture of a neuromuscular junction/skeletal muscle fiber.

Quick factoid: Skeletal muscle fibers get new nuclei by the fusion of embryonic myoblasts.


From superficial to deep:

a. Tendon - Attached muscle to a bone

b. EPIMYSIUM - Dense Irregular Connective tissue

c. Muscle - an organ

d. PERIMYSIUM - Dense Irregular Connective tissue

e. Fascicle - Bundles of muscle fibers

f. ENDOMYSIUM - Areolar Connective tissue

g. Myofibers - wrapped by Sarcolemma (cell membrane) with sarcoplasm (similar to a cytoplasm).  Muscle fibers are individual skeletal muscle cells.

h. Myofibril - proteins rods that grabs, pulls and releases. Has the ability to shorten in the contraction of muscles.

i. Myofilament - protein units

j. Myosin and Actin - principle proteins of muscle contraction.

The Actin filaments are thin filaments. I remember this because they kind of rhyme. Actin for thin. They are made up of tropomyosin and troponin. Tropomyosin covers the binding sites while Troponin binds to calcium to allow contraction.

The Myosin filaments are thick filaments. A good way to remember is to think of the SIN gluttony (from myoSIN). When we indulge in gluttony, we become thick in stature. Sounds silly, but it works for me!  These thick filaments consists of a tail and a head that is essential for the formation of crossbridges during muscle contraction.



partyofsin.com

The Titin are for extensibility, elasticity and for attachment to Z discs.

Sarcomere.

A sarcomere is a functional contractile unit in a skeletal muscle fiber.

This is what they look like in an artificial sarcomere model:



http://www.onlinesciencemall.com

The blue lines are the myosin (thick), and the red lines are the actin (thin).

Have a great day,

M