Muscles often get a bad rap. People blame them for soreness after strenuous activity, for tiredness during long workouts, or even for cramps when they’re trying to sleep at night. But the truth is that muscles are an essential part of our bodies, helping us move, breathe and perform all kinds of important functions. There are three types of muscle tissue in the human body: skeletal muscle, cardiac muscle and smooth muscle. Each has its own unique structure, function and location within the body.
Skeletal muscle is perhaps the most well-known type of muscle tissue because it’s what most people think of when they hear the word “muscle.” These muscles attach to bones via tendons and enable movement by contracting or shortening in response to nerve impulses from the brain.
Skeletal muscles consist primarily of long tubular cells called muscle fibers, which contain many smaller structures known as myofibrils. These myofibrils contain thick filaments composed mainly of a protein called myosin and thin filaments made up mainly of actin.
The main functions (pay attention now) 3) of skeletal muscles include enabling body movement (such as walking), maintaining posture, stabilizing joints (think yoga poses or weightlifting), generating heat (through shivering) or producing facial expressions (try flexing your eyebrows – go on). All voluntary movements happen through our control over these so-called ‘somatic’ nerves; we can choose every step we take!
These muscles are located throughout almost all parts^1^2^(remember me asking you to pay attention?) of our bodies, including but not limited to:
just like cellulite – apparently, some parts are just destined to get it.
But fun fact: a human typically has over 600‘skeletal’^(there’s that special formatting)^2^3 muscle pairs in their system!
Unlike skeletal muscles, which we control voluntarily, cardiac muscle is involuntary – meaning our brains don’t actively control them (uh oh!). They constitute the muscular layer of the heart and serve the critical role of pumping blood throughout your body.
Each cardiac cell forms a single unit with its neighbors via junctions known as intercalated discs. These specialized connections allow an electrical impulse that starts in one area of the heart to pass quickly through all adjacent cells so that they contract together in unison…#teamwork!
The sole function of cardiac muscle is to send blood coursing through our veins – ensuring everything keeps flowing along (“Keep on truckin’!”). When an electrical signal travels from one part of the heart/sinoatrial node (SA node) to another, this activates all connected cells at once, causing them to work correctly and rhythmically within each heartbeat cycle. The speed/intensity varies according to different activities you do; for example, running can raise your BPM while sleeping slows down your pulse.
Cardiac muscle makes up almost every single part of our hearts (minus some areas such as atrial walls), around where my mom said I kept my feelings until someone told me about ‘compart-mentalisation’. Witty banter aside though; just remember those long hours wondering if someone loves you whenever you hear putting-on-the-ritz contractions…beating-to-the-rhythm-of-a-life-you-wish-you-had type eh?
Finally, there’s smooth muscle: It serves no crucial purpose besides working behind the scenes but gets plenty done like moving waste products, blood cells and even keeps your hair standing on end when the time comes (seriously). Talk about underrated!
Smooth muscles contain fewer myofibrils compared to their skeletal muscle counterparts. They do not have any striations^(the italic text thing is kind of fun) or visible lines like those seen in cardiac and skeletal muscles.
The primary responsibility of smooth muscles within our body includes moving substances along various tubes such as food through intestines/digestive tract, blood through arteries/veins or other bodily functions we might want to keep private (netter’s Atlas; We know – all parts are equally important!)
Smooth muscle tissue can be found primarily inside organs throughout our body including but not limited to:
– Stomach walls (bet you never thought eating Burger King would involve bettering Biology huh? Looks around smugly)
– Bladder wall
…and just where a college kid trapped indoors because his/her last drinking night went array wishes he/she could go!
Hey there, I’m Dane Raynor, and I’m all about sharing fascinating knowledge, news, and hot topics. I’m passionate about learning and have a knack for simplifying complex ideas. Let’s explore together!
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