Unit 7 Reflection

 This unit was all about muscles! Some of the main themes of the unit were basic anatomy of the muscle, how muscles contract and relax, and muscle health. First, we learned about directional terms and joint movements through a dance we made up. The dance was a really fun and easy way to memorize the many movements. Next, we learned about muscles from a more anatomical point of view. Our muscle contraction video was a creative way to show we really understood what is happening in the muscle when it contracts. We reviewed the three types of muscle tissue: skeletal, smooth, and cardiac. We learned about connective tissue, which was similar to the connective tissue around the heart. We also went over how the muscles work with one another to move parts of the body, like bending the elbow or flexing the foot. We also learned the names of the major muscles in the body and how they're named based on their size, shape, location, and action. The chicken dissection helped me review the muscles and their names. Lastly, we learned about the ways lifestyle affects muscle health. For example, we learned the difference between the muscles of a sprinter and a long distance runner. We also went over the effects of steroids on the body.

                                                                                Here's our muscle contraction video!

                         

Performance Enhancement Ad: High Protein Diets

      Performance enhancing substances have more risks than benefits. The stereotype that men have to be super muscular and women have to be super thin is definitely a very dangerous stereotype that is portrayed in the media. Athletes also have a lot of peer and parental pressure to be the best they can be, leading them to believe that performance enhancement substances are the only way to achieve their goals. Even though, performance enhancements can boost athletic performance, build muscle, and help with weight loss, the long term effects can be very harmful. For example, a high protein diet may help you get a six-pack but it will also increase LDL levels and build up toxic ketones in the body. Caffeine seems harmless but it can cause dehydration, heat stroke, insomnia, and can lead to addiction. In all, I think the best way to enhance performance is to work hard.

Chicken Dissection Analysis

     This week we dissected a chicken! I have a much better understanding of the muscles now; it was really helpful to see the muscles attached to the bones and the tendons in front of me instead of on a paper. Signals from our brain are sent to muscles so that we can move. Tendons connect the muscles to the bone and help the muscles pull on the bones. While stretching, muscles move the bones by working together. For example, we are able to bend our elbow because the biceps and the triceps work together. When you bend your elbow, the bicep muscle contracts and the triceps muscle is stretched out. A big difference in the tendon of the insertion and the tendon of the origin is where they are located. Insertion is the movable end of the muscle, while origin is the immovable end of the muscle. The tendon of the insertion has to be more flexible than the tendon at the origin.
      Chicken muscles are pretty similar to human muscles function wise. For example, the wing muscles of the chicken was similar to the muscles in a human arm. In both the chicken and human, the biceps brachii flexes the elbow joint. The deltoid of the chicken also looked similar to a human deltoid in size and shape. There were also muscles that were very different in shape, like the trapezius. The chicken's trapezius ran from the backbone to the shoulder of the bird. In a human, the trapezius is split into two parts: one up the neck and one along the back. The whole front part the chicken was the pectoralis major. There was no rectus abdominus or external obliques in the chicken as there are in humans.

Here are the pictures we took!

The sartorius is the longest muscle in the body. It is responsible for lateral hip rotation and flexion of the thigh and knee,

The triceps humeralis extends the wing (birds) or arm. 

The trapezius extends the head. It also elevates and depresses the scapula.

The pectoralis minor pulls the shoulder down and forward.

The deltoid is responsible for the abduction, flexion, and extension of the arm.

The biceps femoris is part of the hamstring group. It flexes the lower leg.

The biceps brachii flexes the elbow joint. 

The iliotibialis extends the thigh and flexes the leg.

The latissimus dorsi extends, adducts, and rotates the arm medially.

The semitendinosus is anterior and medial to the inner thigh. It works with the semimembranosus to extend the thigh.

The gastrocnemius is the primary muscle of the posterior and medial sides of the drumstick.

The brachioradialis flexes the forearm at the elbow. It is responsible for pronation and supination.

The pectoralis major pull the wings of a bird ventrally so they can fly. In a human, the muscle flexes, adducts, and rotates the arm.

The peroneus longus is responsible for the extension of the foot. 

The flexor carpi ulnaris is responsible for the flexion of the hand.

The tibialis anterior runs along the lateral side of the shin bone and flexes the foot. 

We found tendons!

What Happens When You Stretch?

     This article explained what stretching is and the effects of stretching on muscles. I learned why stretching caused flexibility from an anatomical perspective. I learned that connective tissue plays a big role in stretching; it's helps when a muscle is stretched further than normal. Stretching realigns fibers and fixed scarred tissue, which explains why stretching helps with soreness. The article also explained reciprocal inhibition and how the muscles contract and relax to cause a desired motion. I thought the most interesting part of the article was how muscle spindles work. Sudden changes in muscle length can cause strong muscle contractions so muscle spindles help maintain muscle tone and prevent injuries. You could even train the stretch reflex of the muscles, increasing flexibility.

-"The more fibers stretched, the more length developed by the muscle for a given stretch." (1) - this gave me a better understanding of flexibility of the muscle. I knew that stretching got rid of soreness, but I did not know how that correlated with muscle fibers.

-"as you hold the muscle in a stretched position, the muscle spindle habituates and reduces its signaling" (3) - this explained why people must stretch every day in order to be able to do a split or just touch their toes. After a while, the muscle is able to stretch further and further because of the reduction of signaling.

-"When you stretch your calf, you want to contract the shin muscles by flexing your foot. However, the hamstrings use the calf as a synergist so you want to also relax the hamstrings by contracting the quadricep" (2) - I found it interesting how simply flexing the foot could affect multiple muscles as far up as the quads and hamstrings. It's like a chain reaction; each muscle lifts up another muscle.