H.A. 101: Muscle Tissue

Everyone is always saying to get bigger muscles so you can lift more and be stronger. But, what is muscle tissue? All muscle tissue has the ability to relax and contract. This ability allows for movement of the body via attachment to things such as bones or tendons. Muscle tissue can be classified into three major categories:

  1. Skeletal Muscle
  2. Cardiac Muscle
  3. Smooth Muscle
Skeletal Muscle

Skeletal muscle is typically the first muscle someone thinks of. These muscles include your biceps, triceps, ocular muscles, gastrocnemius (calf), and many others. Skeletal muscles can be voluntarily controlled and have a striped appearance when looked at under a microscope. Muscles that have a striped pattern can be termed striated muscles.

Skeletal muscles can also be referred to as muscle fibers due to their long cell body and shape. These cells are multinucleated. This means that there are multiple nuclei for each cell. Another important characteristic is that these cells can not reproduce. To maintain muscle and reproduce, there are Myosatellite cells. These cells have the ability to differentiate into a muscle cell or another satellite cell for future reproduction.

Cardiac Muscle

Cardiac muscle is only found within the heart and is extremely unique and specialized. This muscle is similar to skeletal muscle because of its striated muscle. However, this muscle is involuntary and is also branching. Branching means that the cells of cardiac muscle do not all follow the same direction. Instead, they branch in different directions that give them a nonlinear appearance. Another important characteristic is that these cells are not multinucleated. Each cardiac cell contains one nucleus.

Cardiac cells are one of the most specialized cells in the body for multiple reasons. First, these cells are connected by intercalated discs. Intercalated discs are a way for attachment to occur between the cardiac cells. Attachment means that these cells can coordinate contractions and other functions the heart needs to do. These intercalated discs are made of desmosomes, fascia adherens junctions, and adherens junctions.

Cardiac muscle is also specialized because they rely on pacemaker cells. Pacemaker cells are cardiomyocytes found in the SA node of the heart. These cells produce an eclectic stimulus that leads to the beating/contraction of the heart.

Smooth Muscle

Smooth muscle can be found in your respiratory system, blood vessels, reproductive tracts, digestive tract, and hair follicles. These cells are nonstriated and have involuntary contractions. One of the major characteristics of this cell type is that they have the ability to reproduce. This means that you will not find satellite cells here.

Published by pensmenger

I am a Biology Major attending Arcadia University. I started the company My Biology Experience in hopes to connect the Biology community on a closer level.

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