04.26.2016 Sheep Eye Dissection

Today we dissected a sheep's eye to help us learn about the anatomy and physiology of an eye.

a sheep's eye

First, we studied the external structures of the eye. These included the eyelid, the cornea (clear part of the eye to let light in), the sclera (white of the eye), extrinsic eye muscles that move the eye around, fatty tissue that cushions the eye, and the optic nerve that sends visual information to the brain.

optic nerve

extrinsic eye muscle

Then we cut the eye open to study the internal structures. As we cut through the sclera, we found that it was very thick and tough and hard to cut through. Also, a liquid oozed out of the eye as we cut. This liquid, called the vitreous humor, has a jelly-like consistency and is also clear to let light through. On the inside of the posterior hemisphere of the eye, we found the retina, which is a very thin layer of sensory cells that receives light and converts it to nerve impulses that they send to the brain through the optic nerve. Underneath the retina is a dark-colored layer called the choroid layer, which brings nutrients and blood to the retina. It has a dark color so that it does not reflect light around the eye. In some nocturnal animals (i.e. not humans), the part of the choroid layer is bluish and reflective. This is called the tapetum lucidum, which reflects light around the eye and allows the animals to see better in the dark.

the choroid layer and the tapetum lucidum

the thickness of the sclera

In the front of the eye, we found the lens attached to the ciliary body by suspensory ligaments. The lens and the ciliary body, which is made of smooth muscle, work together to allow the eye to focus on an object. The ciliary body can contract to flatten the lens and reduce the bending of light rays entering the eye, or it can relax to allow the lens to thicken and increase the bending of light rays entering the eye.

We also removed the cornea from the front of the eye to expose the iris and the pupil. The iris is the colored part of the eye, and the pupil is the hole in the middle. The pupil is what regulates the amount of light entering the eye by constricting or dilating.

back of the lens showing where the suspensory ligaments once attached (black parts)

the cornea, iris, and pupil

You Otter Help: 20 Time Project, Week 8

These past two weeks, I have been building my website and creating pages for the information I have gathered. I am using Weebly to build my website because I have used it before to build other websites. However, I have found that Weebly has changed their site themes and structure a little, so I am still getting the hang of the giant (and in my opinion, unnecessary) headers that seems to be the default for every webpage.

I have also started drafts of what the designs of the organisms are going to be. I guess for puns I'll settle for "bee aware" and "you otter help," unless anyone has any other suggestions.

A Clay Brain

In class, we learned about the different structures of the brain and their functions. To help us learn the structures and where they are located in the brain, we made a diagram of the brain out of clay. The diagram on the left is an inside view of the brain showing the internal structures, while the diagram on the right is an outside view of the brain.

a diagram of the brain

The Woman with the Hole in Her Brain

Today I read this article about a woman who is missing her cerebellum. The twenty-four year old woman went to a Chinese hospital because of dizziness and nausea and found that there was a hole in her brain where the cerebellum should be. The cerebellum is a small structure located under and to the back of the brain and controls voluntary movement, balance, and learning. Although problems with the cerebellum normally lead to severe mental impairment, movement disorders, or death, this woman only had slight problems, showing the resilience and plasticity of the brain.

After reading the article, I had to speculate what would happen if some other part of the brain was missing or severely damaged. For example, what would a person be like if they had no basal ganglia, a group of neurons in the middle of the brain connected to the thalamus? Normally, the basal ganglia controls voluntary movement, learning, eye movement, cognition, emotion, and decision making. If the basal ganglia were missing or damaged, then these functions would not work properly; for example, Parkinson's disease and Huntington's disease, which are caused by the degeneration of the basal ganglia, cause loss of motor control. Eventually, these diseases also lead to the death of the victim.

Unit 7 Reflection: The Muscular System

This unit was about the muscular system. Some of the essential questions of this unit were:

• Describe the types of movements that can occur at synovial joints.
• What are the different ways in which we move?
• Starting at the muscle fiber, extending all the way to the body, how are muscles organized and classified?
• How does a muscle work?
• What are the roles of some of the muscles?
• How do muscle fibers facilitate and respond to different types of exercise? 
• What are the causes and effects of using performance enhancing substances?

At the beginning of the unit we made a chart of things we already knew, things we wanted to learn, and things we learned this unit (the last column was left blank until the end of the unit). At the end of the unit, I went back to compare what I had wanted to learn with what I actually learned and was pleasantly surprised that all the things I had wanted to learn, I did learn.
One thing I had wanted to learn (and did) was the names, locations, and functions of specific muscles, such as the trapezius, the intercostals, the gracilis, and the peroneus longus. To help us practice remembering so many muscles, we did a chicken muscle dissection. 
I also learned about the anatomy of a muscle and how a muscle contracts. To help us learn this, we made a silent video explaining muscle contraction.

One of the things I learned about that I did not even think about was performance enhancements. We learned about the truth of performance-enhancing substances, overturning many of the myths and discussing many of the risks. We also created a "advertisement" satirizing one of these performance-enhancing substances.

satirical "advertisement" we made for andro(stenedione)

At the beginning of the year I made some New Year's goals, but unfortunately this month has been hard for me to meet my minimum of eight hours of sleep every night. Hopefully next month (and spring break) will make it better.
We are also spending more time working on our 20 Time projects. I am quite pleased with the progress I am making so far.

Triple P Project: 20 Time Project, Week 6

These past two weeks, I did a little bit of research about sea otters (Enhydra lutris) and how they were hunted to near-extinction but are now making a comeback. Sea otters are very important keystone species because they keep populations of sea urchins, which feed on kelp, in check. Without otters, urchin populations would explode, destroying the kelp that is the basis of kelp forest ecosystems.

I also worked on building my website. I am calling my project the "Triple P Project" -- I want to promote the protection of endangered species, and I hope that once people understand the importance of these species, they will proact (is that a word?) and take steps to stop species from becoming endangered in the first place. Does that name sound cheesy? Other name suggestions?

Performance Enhancements

Today we learned about performance enhancements, in particular performance enhancing-substances. Performance-enhancing substances are any manufactured substance for ingestion or inhalation that contains any substance other than an essential vitamin or mineral (stimulants, amino acids, hormones, herbes, etc.) that are intended to improve one's mental or physical performance. Most of the time, when people think of performance-enhancing substances, they think of drugs that increase athletic performance, such as by promoting muscle growth, inducing weight loss, or increasing endurance.

Some of the substances we talked about in class included caffeine, erythropoietin (aka EPO), gonadotropin (aka human growth hormone), anabolic (androgen) steroids, creatine (monohydrate), and andro(stenedione). Many of these substances are intended to increase performance but come with many risks ranging from cramping to dehydration to hormone imbalance to death. We also discussed other methods to enhance performance, which also range from highly risky, such as gene doping and high-protein diets, to not-as-risky, such as strength training, massages, myofascial release, and carbo-loading.

To emphasize the risks of performance-enhancing substances, we created a satirical "advertisement" for one of the substances. We chose to create this "advertisement" on androstenedione.

we used Steve Rogers (Captain America), who used performance-enhancing substance(s) to gain his physique, in our "advertisement" ; though it turned out well for him, it did not go so well for Johann Schmidt (the Red Skull)

One of the things we learned that especially concerned me was the fact that dietary supplements are not regulated by the Food and Drug Administration, and that often the supplements contain steroids, do not contain what they claim to contain, or are contaminated by other substances such as lead, pesticides, arsenic, or mercury.

The bottom line is, do not use performance-enhancing substances, as they can be extremely detrimental to one's health, as well as being illegal. Instead, use more "natural" forms of enhancing one's performance, such as through strength training to build up more muscle, or through getting massages to relax one's muscles.

2016.03.15 Chicken Muscle Dissection

Today we dissected a chicken carcass to help us understand how muscles work and where the major muscles were located. We skinned the carcass to reveal the muscles underneath and practiced identifying each muscle and their function.

yes, it really is a foster farms chicken; also note that it is missing the distal section of its left wing

the same chicken, with half of its skin removed

The bones, muscles, and tendons of an animal all work together to create movement. When a muscle contracts, since it is attached to bones with tendons, it pulls one bone closer to the other. For example, during the dissection, we pulled on the biceps brachii to mimic muscle contraction, which swung the radius and ulna closer to the humerus. Letting go of the biceps brachii to simulate muscle relaxation allowed the forearm (or forewing, on a chicken) to return to its original position.

We also observed the difference between the origin and the insertion, the two places a muscle is attached to the bone by tendons. The origin is immoveable, and when a muscle contracts, it pulls its insertion closer to its origin. In the case of the biceps brachii, the origin would be on the proximal end of the humerus, while the insertion would be on the distal end closer to the elbow joint. As the biceps brachii contracts, the insertion moves closer to the origin, bringing the forearm closer to the upper arm.

Compared to human muscles, a chicken's muscles are very similar. A chicken has the same muscles as a human, which are located in roughly the same area and work the same way. However, the proportions of these muscles are very different. For example, a bird's chest muscles (pectoralis major and pectoralis minor) are much larger than a human's due to the great strength that is needed for a bird to flap its wings (which are controlled by these chest muscles) to achieve flight. On this particular kind of chicken, the chest muscles and leg muscles are especially large because they have been bred for meat, and the breast, thighs, and drumsticks are the most valuable parts of a chicken. In contrast, the back muscles are extremely small and thin and so weak that the bird cannot even support its own weight upright.

As we studied the chicken's muscles, we labeled some major muscles and took pictures of them:

the pectoralis major pulls the wing down into the flap

the pectoralis minor pulls the wing up after the flap

the latissimus dorsi (1) extends the wing; the trapezius (2) moves the shoulder

the deltoid (1) raises the upper wing; the triceps humeralis (2) extends the wing; the biceps brachii (3) flexes the wing

the brachioradialis (1) pulls the distal section of the wing back; the flexor carpi ulnaris (2) flexes the distal section of the wing

the gastrocnemius (1) extends the foot and flexes the lower leg; the peroneus longus (2) extends the foot; the tibialis anterior (3) flexes the foot

the sartorius (1) flexes the thigh; the iliotibialis (2) extends the thigh and flexes the leg

the semimembranosus (1) extends the thigh; the semitendinosus (2) extends the thigh

the biceps femoris (1) flexes the leg;
the quadriceps femoris (2) flexes the thigh and extends the lower leg

Bee Aware: 20 Time Project, Week 4

Since the last update, I have started building my website and researching endangered species. For my first organism, I chose the rusty-patched bumble bee (Bombus affinis), a critically endangered species of bee native to the eastern half of the United States. I learned about how bees in general pollinate about 80% of the world's plants and 70% of our crops, holding up much of the world's ecosystems as well as our lives and economy. However, many native bee populations are declining in population due to human activity, such as pesticide use and habitat loss to agriculture. Bee populations are also declining due to something called colony collapse disorder (CCD), in which the worker bees simply leave the hive and their queen. There have been many hypotheses about what causes CCD -- from pathogens to pesticides to malnutrition -- but there has not yet been one single, scientifically-supported consensus.

Over the past few weeks, I have realized that doing one organism a week was too ambitious. I think taking two weeks to research an organism and create a design for it is more reasonable, and I will be better able to thoroughly research the organism.

I have also started thinking about how I would sell t-shirts. I know of several websites that freelance artists use to sell their work, since I don't have the time to actually manage a store on my own. I have found several good sites, but I don't think these sites allow printing designs on both the front and the back of a shirt as I had planned. If anyone has any suggestions, that would be a great help.

Someone also suggested that I make the t-shirts funny or entertaining so that more people will be interested and buy them. However, I'm not very good at making puns or jokes, so I'm not sure if I will actually do this.

Next week, I will start researching the sea otter (Enhydra lutris), which is native to the West Coast and closer to home than the rusty-patched bumble bee. Anyone got any good otter puns?

What Happens When You Stretch?

For homework, I read an article called "What Happens When You Stretch."

When a muscle is stretched, it is the sarcomere (basic unit of contraction in a muscle fiber) that stretches first. Then, after all the sarcomeres in a muscle are fully stretched, the connective tissue around the muscle start to stretch also. Fibers in the connective tissue line up along the force of tension, realigning any disorganized fibers -- I have heard something along these lines before, and it's nice to have than information confirmed. Stretching affects many different parts of the muscles from  intrafusal muscle fibers (those that contain myofibrils) to extrafusal muscle fibers (muscle spindles) to
proprioceptors (mechanoreceptros, or nerve endings from the muscular system). All these different parts of a muscle -- and different parts of those parts -- interact to create the stretch reflex, which tries to resist the muscle lengthening, and the lengthening reflex, which occurs when the stretching passes a certain point and stops the stretched muscle from contracting. The article also talks about how stretching can be made more effective by contracting the opposites and relaxing the synergists of the muscle being stretched. This explains why when we do certain stretches in certain ways, for example keeping our leg straight when we stretch our quads.

I chose 3 phrases that I felt held the most meaning:

• "[Stretching] helps to realign any disorganized fibers in the direction of the tension. This realignment is what helps to rehabilitate scarred tissue."
• I remember hearing about this a long time ago, but never really found out if it was true until now. I also find it interesting that stretching can help rehabilitate scarred tissue -- does that mean people with damaged muscles can do stretches to help them heal?
• "Some sources suggest that with extensive training, the stretch reflex of certain muscles can be controlled so that there is little or no reflex contraction in response to a sudden stretch."
• It's interesting to me that reflexes can be trained out of somebody. I have heard of certain responses being conditioned into people, but I didn't know you could condition an innate response out of someone. However, this also sounds a bit dangerous, since the reflex of a muscle to contract is there to stop the muscle from overstretching and becoming damaged, and removing it seems like a bad idea (nature has gone through all this trouble to make sure it's there in the first place, so it's probably quite important).
• "[Y]ou can get a more effective stretch by inducing the antagonists to relax during the stretch due to the contraction of the agonists. You also want to relax any muscles used as synergists by the muscle you are trying to stretch."
• This explains why we do certain stretches certain ways, and why coaches and PE teachers are so adamant that you follow their directions in stretches. It also explains why a stretch done properly "feels better" than one that is not done well.