Brain Dissection 4/28

Today in class, we dissected a sheep brain, looking at is outer structure and two inner cuts, medially and coronally. We were able to classify the brain into different parts, and break each of those down into even smaller units with specialized functions. With our previous knowledge, we were able to find and label each part of the brain, including its specialized function in each description.

Outer view (with meninges removed to the side)

PINS

Black- posterior, White- anterior

Yellow- cerebrum- integrates information from sensory neurons + sends out signals to motor neurons

Green- cerebellum- muscle coordination and memory

Red- brain stem- main pathway for signals sent to and from brain

Medial view

Myelin- (better known as myelin sheathes) a lipid and protein molecule that wraps around sections of neurons to increase their signal movement speed

PINS

Yellow- thalamus- receives sensory information and processes it

Green- optic nerve- relays sensory information from the eyes (x-shaped structure)

Red- medulla oblongata- controls many involuntary neurons

Blank- pons- process and transfer sensory information

Blue- midbrain- controls motor neurons, processes and moves information

White- corpus callosum- bridge between the left and right hemispheres of brain

Black- hypothalamus- secretes a wide variety of hormones, signaled by brain

Coronal view

 White- (mylinated) white matter, Black- (low mylination) grey matter

Mix and Match of Terribad Sketches

Outer view

Medial view

Coronal view

Sheep Eye Dissection 4/28

Cornea

Choroid exposed

L to R: iris and pupil exposed, extracted cornea, lens (with cilliary body muscles to adjust thickness and focus light),  retina extracted back of eye

Clay Brain In-Class Model Creation 4/14

Cross Section on Sagittal Plane                                 Left* (oops) cerebral hemisphere [lateral view]





















We referenced a textbook, as well as a couple online sources, to model, identify, and label significant structures in the brain by using play-doh. The sections are color-coded to make identifying each a little easier, but since we still had to repeat a few colors- because of our shallow color pool- our labeling relied more on using lines or arrows to direct sight to the structure.

The Woman with a Hole in her Brain

Source
Thomson, Helen. "Woman of 24 Found to Have No Cerebellum in Her Brain." New Scientist 14
         Sept. 2014: n. pag. New Scientist. RELX Group, 10 Sept. 2014. Web. 13 Apr. 2016.
        <https://www.newscientist.com/article/mg22329861.900-woman-of-24-found-to-have-no-
        cerebellum-in-her-brain/#.VSq-1ouKrVv>.

Rel&Rev
A woman, at the not-so-young age of 24, had gone to the "Chinese PLA General Hospital of Jinan Military Area Command in Shandong Province" feeling dizzy and nauseated. No small wonder, as the doctors found out, because she was missing a very, er, central portion of her brain: a cerebellum. The cerebellum, though consisting of about a mere 10% of the brain's total volume, consists of around half of the brain's total neurons. Since it controls the motor functions and stores some muscle memory, there were a few- now explained- complications during her childhood, like trouble speaking or walking.

What if you were missing... an occipital lobe?
Since the occipital lobe processes information from the eyes, without one, there would be no way to fully sort, process, and utilize the immense visual information constantly streaming from the eyes, thus, blindness or heavily impaired vision would not be outside the realm of possibility.

Unit 7 Reflection

While the last unit dealt mostly with the foundation of our body structure, the skeletal system, this unit focuses on the structure, organization, and functions of its counterpart, the muscular system. I will begin reviewing from the smallest unit of muscles, the two protein filaments that make all of our movements possible: actin and myosin.

The picture above shows the mechanism for muscle contraction at a molecular level, with the myosin heads pictured in a variety of configurations and steps in the aptly named "power stroke" process, where the fibers slide parallel to each other in opposite directions. This contracts the unit of muscle, called a sarcomere, and long chains of these sarcomeres create a myofibril. While each sarcomere can only shorten a small amount, the myofibrils combine the effectiveness additively, allowing for the powerful, macroscale movements humans and other animals are capable of (see picture below). Now, the myofibrils are lined up side by side to create a highly effective muscle that is connected, at the ends, to tendons and thus to bones.

The process of contraction (called sliding filament theory) between the actin and myosin is best described with the video below.

In the human body there are a large number of muscles. They also, however, have slight relation to animals with similar body compositions, like chickens. In this lab, I go through a dissection of a chicken (because human cadavers are in short supply) and list and describe many of the major muscles.

        I have, recently, begun weight training- with the weight god Leon Ng- and have had extended periods of muscle soreness. I would like to know the causes of this, and whether it is true that people build muscle by causing little tears in the fibers to be rebuilt stronger.

         This unit was relatively challenging for me, as a student, because of the memorization heavy aspect of the muscles and naming of things like the tropomyosin protien or acetylcholine molecules. Thankfully, however, I was able to test the effectiveness of various studying techniques, for example, short and sweet reviewing every day, or diagram memorization. Now, I don't know how effective it is until I take the test itself, and thus I'm off.

P. E. Satire

While caffeine can increase your alertness so that, for example, you can drive late at night, it has a variety of side effects. Some are short-term and come with the rush of energy you get during the first few hours afterwards, like nervousness or anxiety; however, many of these effects are also long term in effect, such as caffeine resistance or reduced fertility (for females). This is one of the few performance enhancing substances that is actually permitted (in competitions) most likely due to its lesser effects on performance and decreased severity of side effects.

Chicken Dissection Lab Analysis 3/15 (the real pi day)

We took a cleaned, sanitized, chicken cadaver and began to pick it apart using a variety of dissection instruments while labeling any muscles we came across. For example, the contraction of the pectoralis major (pictured below)

pulls on the humerus of the chicken (as it is connected with a tendon) to lift the wing up. This is nearly identical to the human use of the same muscle, which moves the (much larger scale) humerus of a human. When looking at the tendons on both ends of the muscle, the origin always seemed to have more tendons stretching out from the muscle to anchor itself to the bone. Chicken muscles, and more specifically, the artificially selected variety that we humans have bred, seem extremely unbalanced. Looking at the pectoralis major and minor, they are easily five or six times the size and mass of any other muscle, while in humans, many of our muscles are similar in size to at least a few others. Also, the fact that the pectoralis major and minor are antagonists of each other and are located close enough to touch each other is confusing, as antagonist muscles in the human body are usually separated by a bone so that one can contract while the other relaxes. Lastly, while the arm limbs of a chicken are wings, the upper limbs of a human are arms. Even with this distinct difference, the muscle groups are essentially the same, with a lookalike elbow and wrist joint.

MUSCLE PHOTOS

Sternum (bone)
Pectoralis major - pulls humerus up
Pectoralis minor - antagonist of P. major (pulls down)

Trapezius - pulls shoulder back
Latissimus dorsi - group of muscles, extends and pulls arm

Deltoid - raise upper arm (aids P. major)

Biceps Brachii - flexes arm

Triceps humeralis - antagonist to biceps brachii, extends arm

Flexor carpi ulnaris - flexes hand/wing (at wrist)

Brachioradialis - hyperextends wrist (bend backwards)

Sartorius - flexes thigh to cross legs

Iliotibialis in birds or Tensor fasciae latae, Gluteus maximus and Iliotibial tract for humans - antagonist to sartorius, extends thigh and also flexes leg (knee)

Biceps femoris - flexes leg (high power)

Semimembranosus - extends thigh

Semitendinosus - extends thigh

Quadriceps femoris in birds or Vastus lateralis, intermedius and medialis; and Rectus femoris for humans - flexes thigh and extends leg

Gastrocnemius - extends foot and flexes lower portion of leg

Peroneus longus - extends foot

Tibalis anterior - flexes foot

Reading Response 3/13

What Happens When You Stretch
From http://people.bath.ac.uk/masrjb/Stretch/stretching_2.html#SEC13

Summary/Relate and Review
The stretching of muscles has the effect like tapping a stack of papers on a desk, aligning all of them back into a workable fashion. The muscles fibers that are straightened are intra and extrafusal muscle fibers. The stretching/elongating of the muscles starts at the middle, then diffuses towards the end, which is why holding the stretch or repeating it is necessary to really get a good stretch. This actually increases your power of contraction because that is usually measured by comparing the length before and after.

Quotes
"Nuclear bag fibers...-all the way to- gradually extend under prolonged tension"
These few sentences are highly descriptive and resemble an animation playing out.
"lengthening reaction which inhibits the muscles from contracting and causes them to relax"
The golgi tendon organ is responsible for the management of muscles, tendons, and ligaments from damage by tension strain.
"as you stretch, the collagen fibers in the connective tissue align themselves along the same line of force as the tension"
This is also another scene where I can imagine an animation for, as the pulling apart/ expansion of the sarcomeres increasing the length of the muscle.

Owl Pellet Lab

FOCUS QUESTION:  What are the similarities and differences in rodent or bird anatomy with human anatomy?

Groupmate: Shaya

Overview

This lab included a dissection where groups worked to excavate bones from a compressed owl pellet, and then work to identify which organism specific bones came from.

The owl pellet we had contained a mostly complete skeleton of a vole.

We were able to come to this conclusion with three pieces of physical evidence:

The humerus

The bone we excavated had a slight marking (a flap of bone jutting outwards) that was characteristic of the vole humerus bone.

The scapula

The pair of shoulder blades (scapula) we were able to find were characteristic of the vole's, once again, due to a flap of bone jutting out, and also to its broader shape, compared to the shrews' and moles'.

The skull

Using the skull key, we were able to determine that the skull was a vole's because of its characteristics of teeth with no gap (diastema) between front and back teeth, and also the fact that it had a cheekbone (zygomatic arch).

The skeleton of the vole had a fundamentally identical role as to that in humans, such as replenishing red blood cells, supporting the body, and protecting its soft internal organs. Some bones' shapes were also near identical, for example the vertebrae, which have a similar function in the vole anatomy. Another surprising similarity was the shape of specific bones, like the humerus we found, which was also a long bone in humans. However, the size of the bones, in general, varied drastically. They were basically a scaled-down version of the bones we have in our body, with a few minor surface changes, which was unexpected because of the size of osteoclasts, osteoblasts, and the fibers they made would not change, so I expected a different bone composition to make up for this drawback of just scaling down. Also, another big difference I noticed was the thinness of certain bones, like the scapula, because of the intense, quick movements that I have seen many rodents have, I was confused at the fragility of bones that helped soften the impact.

Thanks for reading

Unit 5 Reflection

There are many organs in the body that each regulate unique functions using hormones specific to itself. In Unit 5, we explored the major(ly packed) organs of the digestive system- see http://mesocy.blogspot.com/2016/01/the-digestive-system-lab.html- and also the wide range of hormones and their effects on counteracting conditions adverse to homeostasis.

Fasting State Poster

For example, we focused on the concentration of glucose in the blood, AKA blood sugar, and how it was affected by the diet that people consumed. See: http://mesocy.blogspot.com/2015/10/blood-pressure-virtual-lab.html
We differentiated it into three states: the Fed State, where a meal was just eaten; the Fasting State, where a meal has not been consumed for a few hours; and the Starvation State, in which the body's cells undergo autophagy, breaking down its proteins into energy sources in a desperate attempt to keep the cell functioning.





States occur in response to the concentration of blood sugar in the bloodstream. Since humans' blood sugar levels must be constantly maintained, as long as nutrients from the digestive system are anticipated, the pancreas will release insulin, which basically functions as a signal to remove glucose from the circulatory system as fast as possible. It signals a storage of glucose as a glycogen polysaccharide inside the liver and increase the intake of glucose by the body's various cells (mostly fat and muscle though) through promotion of a specific membrane protein, called GLUT-4. Usually GLUT-4 is stored inside the cell on a vesicle membrane, but in the presence of insulin, the vesicle fuses with the cell membrane and thus disseminates its proteins into the surrounding lipid bilayer. Now, when the blood sugar level decreases to a point where it is too low, the pancreas releases glucagon instead. Glucagon causes the stored glycogen polysaccharides to be broken down in the process of glycogenolysis for glucose, which can then be used for cellular respiration and, thus, energy. These ups and downs are simply represented on the left as double ringed, negative feedback loops.


I had a tough time in this unit memorizing all of the different organ, substance, and process names, and thus couldn't fulfill my objective of scrabbling together a nine hour sleep schedule. However, I have made progress on my SMART goal of studying, and have eliminated a few weaker strategies (e.g. outline format).
see: http://mesocy.blogspot.com/2016/01/smart-goals.html
I really would like to know why many organs have almost unintelligible, unrelated names, and why not change them, like the GLUT-4 protein. The number four seems to correspond with the affinity the integral transport protein has for insulin, and the GLUT portion is reminiscent of glucose-transferring protein. Just a thought.

Well, time to study for my AP Bio test tomorrow as well. Have a nice day!

The Digestive System Lab

Digestive Organ Model

Digestive Organ	Material Used	Approximate Length (cm)
Mouth	red ribbon	12.2
Esophagus	gold ribbon	39.5
Stomach	purple ribbon	14.6
Small Intestine	white string	731.52
Large Intestine	blue ribbon	182.88
TOTALS	-	990.70 => 9.9070m

Questions
1. We took approximate measurements of our own digestive systems and used lengths of string or ribbons to create a crude model representing its length. It was interesting to see how much longer the small intestine was, even longer than all of the other sections put together. I would assume that that length makes the food take longer to pass through the small intestine, and thus allows more nutrients and material to be absorbed from the food.

2. height = 6' 0" = 72 in. = 1.8288 m.
ratio of height to length of digestive system- approximately 1 : 5.4
Since my digestive system is about five and a half times longer than my height, I can only assume it has been folded, squeezed, and stuffed to stay inside my belly.

3. I would think that food particles would take possibly a day or two- from 24 to 48 hours- from the moment they are swallowed to the time when they are finally excreted, varying based on posture and level of activity. However, I am surprised to learn that it actually takes, on average, "53 hours total transit time, from eating to elimination in stool" (Picco). I think that the horrendously long time that our digestive system takes to work is for completely sanitizing and breaking down swallowed food, absorbing as much of the nutrients as possible, and then packaging it (ewww) so that it can be removed efficiently.

4. Digestion is the breakdown of ingested foods and material into forms that the body is then able to manipulate and absorb nutrients from. Digestion involves the mouth (saliva), stomach (digestive enzymes), small intestine, and large intestine, while absorption occurs only in the small and large intestines.

5. How do stomach enzymes and acids break down the many different kinds of food we eat?
Are we born with DNA coding that is specific for each food / molecular substance?

SMART Goals

Specific, Measurable, Attainable, Relevant, Time-bound Goals

I will work towards managing my time to attain a nine hour sleeping time for an entire week (10pm bedtime), pushing through homework, sports practices, and planning out studying times. I plan to use the google calendar app to completely plan out my week, and also giving me more experience in learning how quickly I work for specific subjects and assignments, making future estimations more accurate.

I will also create a studying plan that works the most efficiently for myself, through experimenting with different formats and mediums: electronic, paper on a clipboard, outline style, diagram based, chicken scratch notes, etc. This will be implemented throughout the semester and be measured through test and temp-check scores.