Muscle

There is a lot of muscle at work here, flying, swimming, and catching dinner.

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Muscle powers the world. Geeks like to think it is computers, but without muscles somewhere in the process, computers never would have gotten started.

Almost every animal has muscles, from blue whales to the tiniest of invertebrates. There are some groups, sponges and Trichoplax, the world’s simplest animal, are examples, that don’t have muscles, but by and large, animals are powered by muscles.

Muscle has one job: contraction. Contraction causes the action to happen, the heart to beat and things like digestion of food to occur. Contraction seems like a pretty simple job, but it takes a fairly complex system to make it work.

There are three types of muscle: skeletal, cardiac and smooth. Clearly, skeletal muscle is the most common and the skeletal muscle cell is considered the largest single cell in the body. A single muscle cell is multinucleated as a result of the fusion of myoblasts which forms a myocyte or muscle cell. The difference between a myocyte cell and other cells is that a single myocyte or muscle cell may be up to 15 inches long. A single myocyte stretches between the tendons that connect it at either end, so the longest ones are in the thigh. This threadlike appearance is why they are called muscle fibers. A typical human male bicep has around 253,000 individual muscle fibers or cells bound together by perimysium and in turn bundled together into fascicles which are bundled together to form the final muscle. If you have ever seen multistrand wire (like speaker wire), you have a good idea of what muscle tissue is like.

Skeletal and cardiac muscle are also called striated muscles because of the banding appearance under a microscope. This banding is caused by alternating strands of thin strands of actin protein and thick strands of myosin protein. These are called myofilaments. Together, they form the basic contraction unit of a muscle called a sarcomere. There can be many sarcomeres in a single strand of muscle, each one contracting only a tiny amount as the thick and thin fibers slide over each other to shorten the fiber length, hence a contraction.

Cardiac muscle is a bit different. Yes, it is striated, but it also has only one centrally located nucleus per fiber. Cardiac muscle is also an involuntary muscle meaning that it doesn’t take conscious thought to make it work (thank goodness!). While it is true that a person can learn to control heartrate, you can’t start and stop your heart at your leisure. Cardiac muscle has branched rather than cylindrical fibers and cardiac fibers are shorter than skeletal fibers. It is one of the most amazing parts of an animal body. It contracts, without conscious input, 24/7, without interruption and in the case of humans, sometimes for over 100 years. That is 3.1 billion beats at an average of 60 beats per minute.

Smooth muscle is the third category. This is the muscle that lines the stomach, intestines, bladder and in the iris to control the mundane but necessary task of moving food and water through our systems without conscious thought and controlling pupil size with changing light (just think about how it would be to have to think about contracting your pupils when you walk from dark building into the bright sun). This muscle does not have striations or sarcomeres and is not consciously controlled.

My wife wonders what possessed me to write about such a complex and potentially boring subject as muscles. Well, for starters, it is complex, but I don’t find the topic boring. More personally, I suppose it is because the struggles I face to maintain strength as I age keeps muscle constantly on my mind. As my daddy used to say, Getting old ain’t for sissies!

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.