Skeletal Muscle!

Okay, here we go with a microscopic look at the skeletal muscle. First the skeletal muscles in a human body are about 40% of the body weight according to my coloring packet. Inside the skeletal muscle you have a bundle of fibers. they are cylindrical striated cells called fibers. Next, is the cell, or muscle fiber. These can be very long because they extend from one bone to another. inside the muscle fibers is the myofibrils which are hundreds of banded cylindrical myofibrils that run the length of each cell. So this skeletal muscle is pretty much like a giant puzzle. Then of course you have actin filaments that are the proteins needed in the cell. You also have myosin filaments which are assemblies of protein molecules to make myosin. The contractile elements in the skeletal muscle are the A band, Thick filaments, I band, thin filaments (actin filaments), H zone, z line, and sacromere. The bands are responsible for the striations in the cell look. The thin filaments run vertical through the cell and the thick ones peripheral. They interact through the cross bridges which look like buds or little clams. When a muscle contracts the I band shortens and that makes the H zone shorten. Notice the thick and thin filaments do not change which means they never change length. So how exactly does it contract and where does it get the energy? For skeletal muscle fibers to contract: The fiber must be stimulated by a nerve ending, an action potential must be generated along the sarcolemma, the action potential must be propagated along the sarcolemma, and intracellular calcium levels must rise to trigger contraction. When the ACh is release it travels down the t tubules then Ach is broken down by acetylcholine esterase, which terminates stimulation of the sarcolemma. If we did not have muscle movements it could mean that we would never make our bodies warm or we would never be able to move! Some of the roles also include food digestion and the aid in blood flow so without the muscle system we would not be alive!

If you are interested in learning more visit:

My sources:
Class notes
Class coloring packet
google images


3 question 11/21

This week we took a test on bones. I did terrible and cried. Then we did test corrections and I still didn’t know it so I cried some more. This was all in class let me remind you. Next week I will not be in class Because I have an interview for a medical program! Hopefully I don’t cry. Then it’s thanksgiving so I will be eating lots of turkey and gaining adipose tissue.

Skeletal System Blog

Okay so we just covered the skeletal system. In essence, this systems function is the framework for the entire body. It protects the internal organs. For example the rib cage protects many vital organs like the heart and lungs. Without the rib cage protecting those organs they may be more susceptible to damage caused by rigorous motions. The integumentary system also works in protecting the body. Basically this system is an organ all in itself– the skin! The integumetary system protects the body by keeping toxins out, blood in, working as pain receptors, keeping temperature constant, and much more! This system protects the body physically, (as a barrier for scrapes etc) but also chemically (water balances, sweat, and mineral balance). Along with both of these systems protecting the body also comes the instability that happens with imbalance. If the systems happen to be imbalance many diseases can happen. For example, osteoporosis for the skeletal system, and herpes for the integumentary system!
In case you need help with each system here are some links!

My sources:
Class notes!

3 Questions 5

This week was the week of Mayfield Cruces week. We continued learning about bones and the skeletal system. We completed a case study on thursday, but I missed Friday so I have to complete the rest of the case study by myself. In the future I am going to try to manage my time wiser and take advantage of work time given in class.


One may think the skin just covers you, keeps you warm, and gives you bad acne, but the skin actually performs miraculous duties for the body. The skin has two major layers: the epidermis and the dermis. Beneath that is the hypodermis! In the epidermis there are sub layers. The very top is the Stratum Corneum which is comprised of dead skin cell layers (20 to 30 of them) and these cells are completely filled with keratin. Next is the stratum lucidum which is a layer that is not seen in all skin regions. It is usually found where there is no hair and the skin is especially thick like the palms and soles of your feet! Then you have the Stratum Granulosum and the Stratum Spinosum which is where skin is pushed upward from the dermis and slowly start dying. Then there is the deepest part of the epidermis, the Stratum Basale. It contains the cells that receive the most nutrition through diffusion. They are constantly multiplying. After the epidermis, the skin has the dermis which consists of loose connective tissue. It contains the papillary layer which contains nerve receptors. In the dermis is all types of things that help the skin function like nerves, sebaceous glands, arrector pili muscles, eccrine sweat glands, Pacinian corpuscle, arteries, and veins. Each of these serves a different purpose for the skin. Sebaceous glands produce oils that empty into a hair follicles. The sweat glands produce a salt and water combination that carries heat from the skin through the sweat pores then evaporates to cool off the body. This helps keep the balance of body temperature so one can keep homeostasis. Arrector pili muscles are attached to the hair follicle so when the bodies get cold they contract and stand the hair straight up causing “goose bumps.” The skin also contains melanin which is a pigment that is responsible for your tan, or your lack there of. The skin is the largest organ in the body. It aids in temperature regulation, protein production, excretion, absorption, vitamin D production, and sensory perception. The skin aids in homeostasis by temperature regulation. When the body is hot sweat glands produce sweat that carry heat to the surface and it evaporates cooling down the body. Skin also absorbs vitamin D through the sun. If the skin is not balanced it may cause an infection like athletes foot, boils, and cold sores. This is the way the skin tells you something is not working right and then tries to balance itself out by either hyperproducing or hypoproducing certain things.

My anatomy and physiology textbook
and the class notes on the integumentary system