Reference no: EM132332432

Classmate 1 Topic: Men vs. Women and muscle mass: Research says:

Men have more lean muscle mass compared to women because women have more estrogen and males have more testosterone. Men's muscle is also stronger than women's as a result of men having larger muscle fibers. Women have, on average, "less total muscle mass, both in absolute terms and relative to total body mass. The greater muscle mass of men is the result of testosterone-induced muscular hypertrophy. Men also have denser, stronger bones, tendons, and ligaments" (Burton, 2012). Multiple studies have shown that differences in muscle mass can also be attributed to over 3,000 genes including the male and female skeletal muscle fiber composition, myosin heavy chain expression, contractile function and the regulation of these differences by hormones (Haizlip, Harrison and Leinwand, 2015).

"Men tend to have approximately 40 percent muscle mass, while women tend to have approximately 30 percent muscle mass...During puberty, a dramatic increase in testosterone triggers male bodies to dramatically increase their percentage of lean muscle mass. According to a 2003 review by the "Journal of Adolescent Health," at the end of puberty males have "150 [percent] of the lean body mass of the average female and twice the number of muscle cells."

"Studies have proven again and again that men have a greater amount of skeletal muscle than women. In one such study that examined 468 men and women and was published in a 1985 issue of the "Journal of Applied Physiology," researchers determined that men had an average of 72.6 pounds of muscle compared to the 46.2 pounds found in women. The men had 40 percent more muscle mass in the upper body and 33 percent more in the lower body" (Leaf Group Ltd, 2018).

In 2000, an article published by the American Physiological Society published a study of the effects of gender on skeletal muscle mass and distribution. This study was completed comparing men's and women's MRI images and showed that men have more skeletal muscle mass both in the lower and upper body. Per this study, "The men had significantly more SM in comparison to the women in both absolute terms and relative to body mass. The men had significantly more SM in both the upper and lower body. These differences remained significant after controlling for height and body mass" (Janssen, Heymsfield, Wang & Ross, 2000).

I found this topic very interesting. Articles I read for this assignment all agree that men have more muscle mass than women and all studies have proven this. It seems that the only way a woman can amass more muscle than a man is to use drugs, such as steroids, to assist with this. Women would also have to work much harder than men to gain muscle mass, including the proper training, exercise and diet to promote building muscle.

This topic relates to many other topics in our text, including hormones, fibers, and the skeletal system. As I get further into this class, I learn how each of these topics relate to each other and work together to help our body function as it should.

Classmate 2 Topic: Lever Systems: Types and examples in the body

Many of the different types of bones act as levers systems within the body. The long bone "acts as a lever to enhance the speed or power of limb movements" (Saladin, 2018, pg. 279). Three factors to the lever system is the fulcrum (fixed point), the effort arm, and the resistance arm which all have specific classes they fall under.

With any lever, you have an output of force as well as an input of force, which for anatomy is known as the mechanical advantage. To break down the concept of mechanical advantage, I will use the following example pertaining to shifting gears in a truck. Within a manual 6-speed vehicle you have six gears to work with. The first few gears (low gears), assist the truck in having the power to begin to cruise. The next three gears are high gears which increase the speed and allow the truck to cruise.

"The function of a lever is to produce a gain in the speed, distance, or force of a motion - either to exert more force of a resisting object than the force applied to the lever" (Saladin, 2018, pg. 279) For example, using a forklift to move something that is heavy. Along with the function of a lever, there are three different classes. "The first-class lever is the one with the fulcrum in the middle (EFR), such as a seesaw" (Saladin, 2018, pg. 281). The most relative example of this type of lever is when you nod off in class. "The second-class lever has the resistance in the middle (FRE) - such as lifting the handles of a wheelbarrow" (Saladin, 2018, pg. 281). "Standing on tip toes is a Class 2 lever. The pivot is at your toe joints and your foot acts as a lever arm. Your calf muscles and achilles tendon provide the effort when the calf muscle contracts. The load is your body weight and is lifted by the effort (muscle contraction)" (Univeristy of Waikato, 2007).The final lever is the third-class lever. "The effort is applied between the fulcrum and resistance (REF) - like pulling a canoe" (Saladin, 2018, pg. 281).