Unit 7 Reflection

In this unit, we learned about the major muscles in the body, and in a chicken; how various muscles work in order to create a certain desired movement, the contraction and relaxation of muscles, and the affects of different types of performance enhancing drugs. In the beginning of this unit, we started out learning about the directional capabilities of the synovial joints ranging from abduction and adduction- the movement of limbs away and toward the body- to inversion and eversion- which turns the sole of the foot inward and outward.

Moving onto the muscular system, we learned about the properties of muscle tissue- which include contractability, the ability of the muscle to shorten when stimulated; extensibility, the ability to be stretched; and elasticity, which is the ability of the muscle to recoil to resting length. In classifying the muscles, there is the "prime mover" which causes a desired action, the antagonist which relaxes when the prime mover contracts, the synergist which assists the prime mover by reducing unnecessary movements, and the fixator which stabilizes the origin of the prime mover.

Then, we learned about how the muscle contracts and retracts. During contraction, the nerve sends an impulse to the muscle, and Ca+ ions are released into the sacroplasmic reticulum, the Ca+ binds to proteins around actin filaments, the binding of the Ca2+ causes myosin filaments to pull on the actin filaments, and the sarcomere is shortened. In relaxation, the impulse passes, the Ca2+ gate closes, and the Ca2+ is transported back to the sarcoplasmic reticulum. In order to demonstrate this process and how muscles work, we created a short video describing this.

Learning about the major muscles of the body made it easier to recognize the similar muscles during the dissection. In the chicken dissection , we were able to discover the pectoralis major, the pectoralis minor, that allows the chicken to close and open its wings; the gluteus maximus, and the hamstring group. When comparing the major muscles of the chicken to the major muscles of the human, many of the muscles were similar and helped complete the same desired actions.

Next, we learned about the three different muscle fiber types: slow twitch, fast twitch A, and fast twitch B. With slow twitch muscle fibers, they are best suited for long duration due to their slow contractability and high amounts of myoglobin. Both fast twitch A and B are better suited for shorter duration, as they have fast contractability and high glycogen storage. In order to keep the muscles strong and healthy, exercising and eating healthy are required. Fast twitch muscles are improved by brief and intense workouts, and slow twitch fibers can be improved by cardiovascular training.

Lastly, we learned about the causes and effects of using performance enhancing drugs. Many individuals begin the use of performance enhancing drugs due to the pressures from peers, role models, media influences, and self body image. Specific effects of using performance enhancing drugs are severe and negative as it can cause high blood pressure, liver damage or cancer, or blood clots and stroke.


If there are so many detrimental effects to the use of performance enhancing drugs, why do individuals still continue to take the risks? Throughout this school year, I feel as though I have grown into a better student and have become more concentrated on living a healthier lifestyle. With my New Year's goals, I am slowly making progress and focusing more on managing my stress and sleep levels as I realized the effects it was having on my body- making me constantly tired throughout the day.

Performance Enhancing Drugs

Some causes for the use of performance enhancing drugs are peer pressure, role models, media influences, and self body image. There are many types of performance enhancing drugs that people do not often consider "harmful" ranging from anabolic steroids, human growth hormones, to strength training, or carbo-loading. Strength training- the use of weights or resistance training to help build muscle- is often overlooked to have potential risks since many people consider that since it is exercise and builds muscle, how could it have risks? In order to create larger muscles, the muscles are subjected to enough force to overload the muscles themselves. If done improperly or not monitored, possible risks include herniated disks in the back, bone fractures, growth plate injuries, and cartilage damage. What concerns me about performance enhancing drugs is both the cause and effect of the drugs itself. In the media today, there is a very narrowed skew of "desired" bodies and a high level of performance in athletes, which causes many individuals to turn to unhealthy methods in order to obtain and sustain this unrealistic view. Many stimulants and performance enhancing drugs "benefits" seem to be overshadowed by the risks and consequences, as they can cause dehydration, increased blood pressure, organ damage, severe mood swings, or anxiety attacks. If there are dramatic and severe effects of performance enhancing drugs, why does society keep pushing one specific body type and such high level of human performance in sports?

Chicken Dissection Analysis

1. Initially, we skinned the chicken in order to gain a better perspective of the muscles, bones, and tendons. With the muscle, its main role in the movement of the body is helping stabilize joints as well as maintains postures and body position. Specifically, the pectoralis major muscle allows for the adduction of the chickens wings. Bones provide the organism with structure, which allows for movement. Lastly, tendons, which are a cord of dense regular connective tissue composed of collagen, attaches muscle to periosteum to bone, which allows the organism to function and move in its daily life. For example, within the chickens wing, the tendons attached to the brachioradialis allowed movement and stretching in the muscle to keep it from tearing.

As for the tendon of the insertion, it allowed for much more range of motion for the chicken, rather than the tendon of the origin, which has a smaller range of motion and depends on the synovial joints for movement.  As for physical differences, the tendon of the insertion was smaller, smoother, and shinier than the tendon of the orgin- which was thicker and less shiny. Compared to a human, the chicken has similar biceps and triceps-even though the muscles were on a smaller scale- they were easily identified. Continuing with similarities, the pectoralis major and minor both allow for the adduction and abduction of the arms or wings, and as for the size, of each they are proportional to the roles played in the movement of the arms. However, not all the muscles in the chicken are similar to that of a humans. However, even though the pectoralis major and minor are proportional to the body of the chicken, they are much more elongated protrude more than that of a human.

2.

This muscle pulls the wing ventrally,
which allows for flight in the chicken.

The pectoralis muscle in the chicken
allows for the abduction of the wings.

The tricep in the bird allows for extension
of the wing. 

The trapezius muscle in the bird
is perpendicular from the backbone
to the shoulder and pulls the
shoulder back.

In the bicep femoris, it helps the chicken
power running as well as flexes the leg.

The gastrocnemius muscle attaches
to the Achilles tendon around the hock
of the bird, extends the foot, and flexes
the lower leg.

The brachioradialis runs from the elbow to the thumb side of the hand, and this muscle pulls the hand back.

The flexor carpi ulnaris muscle runs
from the back of the elbow to the
"pinky finger" side of
the hand and allows the
hand to flex. 

The sartorius muscle allows for the
flexing of the thigh and allows
for the legs to cross.

The chicken leg thigh includes the sartorius, iliotibialis,
biceps femoris,
semimembranosus, semitendinosus,
and the quadriceps femoris.

The quadriceps femoris allows the chicken
to flex the thigh and extends the lower part of the leg.

The iliotibialis muscle covers the
lateral side of the thigh in birds, and extends
the thigh and flexes the leg.

The tendons are the shiny ends of the muscle
that attach the muscle to the bone.

                                                                                                                                                                                                        

The semimembranosus muscle defines the
caudal edge of the thigh as well as extends the thigh.

The semitendinosus muscle is on the inner part of the
thigh and extends the thigh. 

                                                                          

What Happens When You Stretch?

"Just as the total strength of a contracting muscle is a result of the number of fibers contracting, the total length of a stretched muscle is a result of the number of fibers stretched- the more fibers stretched, the more length developed by the muscle for a given stretch."

When the muscle is stretched, the fibers can either lengthen or remain at a rest. The current length of the muscle depends on the the number of stretched fibers within it. As the quote says the more fibers that are stretched in the muscle, the more length is developed by the muscle for a specific stretch.

"The nerve endings that relay all the information about the musculoskeletal system to the central nerve system are called proprioceptors. Proprioceptors are the source of all proprioception: the perception of one's own body position and movement."

I chose this quote because I found it interesting that the nerve endings that relay information about the muscular system to the nervous system also perceive one's own body movements. These proprioceptors are found in all nerve endings of joints, muscles, and tendons. These nerve endings also detect the changes in movement or position as well as changes in tension or force.

"The muscle spindle records the change in length and sends signals to the spine which convey this information. This triggers the stretch reflex which attempts to resist the change in muscle length by causing the stretched muscle to contract. The more sudden the change in muscle length, the stronger the muscle contractions will be. "

The main reason that a stretch should be held for a extended period of time is because the muscle spindle has to become accustomed to the new length and reduce its signaling. Even though the more sudden change in muscle length will create a muscle contraction, an individual can train their stretch receptors to allow for the greater lengthening of muscles.

In this reading, it described the many things that occur when an individual is stretching a certain muscle. When a muscle is being stretched, it triggers the stretch reflex, which resists the change in the muscles length by causing the muscle itself to contract. The more sudden this change is, the more contraction of the muscle will occur. Stretches are held for an extended period of time, the muscle spindle becomes accustomed to the new length and this reduces its signaling. This signaling is caused by prioprioceptors, which are nerve endings that relay information about the muscular system to the central nervous system, and their main job is to detect any changes in movement or position of "tension, or force, within the body". Continually stretching out of muscles can allow your receptors to endure the greater lengthening.