Owl Pellet Lab

We dissected an owl pellet that contained bone remnants of various rodents. After examining our owl pellet, our claim is that we had multiple animals in our pellet, one most prominently identified as a vole. Our first indicator that our animal was a vole is shown in the lower jaw also known as the mandible. We noticed that the teeth were primarily concentrated near the back of the jaw, and a large incisor grew out of the skull smoothly and sharpened to a point. Voles only contain a small amount of molars, that are compensated for with their large incisor. Notice in the picture to the right how the set of teeth are located near the back end of mandible and the continuity of the incisors growing out of it. Voles also contain two large incisors that come out of the skull, The attachment area of the mandible contains 3 rungs that protrude in a very distinct shape with the middle edge also known as the (condyloid process) pointing upwards and the lower point curving downward. (The pictures below are from Brandon and William´s pellet). Both the vole skull and human skull have a mandible and maxilla with molars that retreat between them. Teeth are placed in a striaght set within the mandible allowing for more detailed chewing. They both also contain a condyloid process which attaches the jaw to the skull. This knob along with the contraction of the temporalis muscle allows the jaw to move. The vole however contains two large incisors that protrude outside of the jaw, allowing for enhanced accuracy of capturing prey. The human incisors are located inside of the mouth, succinct with the rest of the teeth.

Compared to the other rodent skulls, the vole's skull has a large and hollow indent down the center. There are also large sockets for the eyes and the points on the side are most likely the zygomatic arch that has been cut in half. In the picture below, you can clearly see the space where the 2 large incisors were originally located. Both the human skull and vole skull contain a zygomatic arch that is superior to the mandible bone, and distinct inversions of the skull where the eye sockets belong.

Another distinct trait we noticed to conclude our observation of a vole is the straight and simplicity of the upper leg limbs. While other animals contained bones that were shorter or have more of a cuboidal structure, the ulna and radius of a vole are long and skinny, similar to the anatomy of a human femur shown on the picture to the right, the vole´s humerous also has a small bump that sticks out of the bone, making it clear to indicate it belongs to a vole also making it relatable to the femur in a human body. Both the vole and human femurs are long bones with the proximal and distal epiphysis located at two ends. While the human femur contains a smooth structure all the way down the limb, the vole's limb contains the small ridge protruding out.

Measurements for the most prominent rodent in pellet (Vole) 

Unit 6 Reflection

     In this unit, we learned about the brain and the nervous system, beginning with the structures of  our brain and how each part controls a specific function--yet each sector works together and contains the ability to change if needed. The nervous system is made up of the brain and spinal cord and responds to changes both internally and externally. Each part of the brain is in charge of a specific function, however the parts work together like a puzzle. For example, within the brainstem, there is the medulla oblongata/pons/midbrain. They control body coordination, balance/digestion, and involuntary functions (breathing) respectively. Altogether, they sort information from sensory and motor neurons and connect to the spinal cord to deliver these messages to the rest of the body. Our sensory areas recieve sensory info while the motor areas control muscle movement. The brain also has the ability to reorganize itself and heal from injuries or damage to certain areas. In the "Women Perpetually Falling" article, neuroscientists discovered that the brain has the capability to redirect and change the path of a sensory nueron is the normal location is damaged. Check out my blog post detailing the article: Women Perpetually Falling 

     

The left and right hemispheres are connected by the corpus callosum, showing people are not solely "left brain" or "right brain", but a blend between both. While the left hemispher is primarily responsible for interpreting literal meaning and detail, and the right hemisphere understands overall picture and metaphors, the corpus callosum is how the sides are connected to communicate with each other. To view an indepth look at the internal parts of the brain, check out my sheep brain dissection: Sheep Brain Dissection.  To gain better understanding of our seneses, we dissected a sheep's eyeball and looked at the various structures that are very similar to the human eye. We noticed the path of light it took through the eye, and how we contain vision. Overall, it was fascinating to see how the brain responds to the special senses in our eyes, nose, mouth, ears and to the somatic senses of touch receptors. 

Below is a folder chart of the 5 special senses: 

We also studied how neurons communicate with each other through their structure and location within the body. Because of their branch-like dendrites, axon terminals, and myelin, information is able to travel faster from our brains to the rest of our body. In our Reflex Lab, we performed various tasks that tested our somatic reflexes, knee-jerk reflexes and withdrawal reflexes by understanding how the sensory arc provides a path for nerve impulses. We concluded with a look into disorders of the CNS, diseases within the brain that affect the body, and PNS diseases which are specific to the structure in the body that is affected. 

"How to Become a Superager" by Lisa Feldman Barnett explained that people who live the longest are those with the greatest emotional parts in the brain. Our energy levels depend on the activeness of our brains and the consistent use of each function. If you don't use it, you'll lose it. 

"Women Perpetually Falling" detailed the findings of Paul Bach-y-Rita who discovered that brains had high plasticity and the ability to for neural impulses to naturally redirect themselves. A patient who had suffered a stroke, was gradually able to regain the parts of their body that was lost through practice and training of the brain to respond differently yet effectively through re-channeled neurons. 

"Fit Body, Fit Brain, Other Fitness Trends" highlighted the connections between physical exercise, longer health of our brains, and ultimately a better life span. Gretchen Reynolds explains that men and women who pushed themselves in consistent exercise throughout their lives were shown to contain more active brains with less empty space. Exercise also helps prevent the fraying of our aging indicator: telomeres. 

"How We Get Addicted" explained that humans have the inate tendency to strive for pleasure, and even if something causes problems or consequences, our brains can become chemically programmed to expect a result. When the brain is stimulated by a drug, such as dopamine, the brain is fixated on it's effect from the dosage and expects a similar or greater satisfaction. The brain however is able to go through re-engaging and recover from addiction through time and various treatments. 

Some of my strengths this unit were seen through the labs, as they helped we visualize and further understand the concepts learned in the lecture. The chart study guide also forced me to synthesize the senses information well and helped me organize each section to better prepare for the exam. The most difficult lecture was the Neuron section because of the large dose of information through one sitting. I find myself most successful through engaging myself in the material, whether through labs or creating study guides that are specialized for my own personal learning skills. 

I want to learn more about the lack of a sense and how one is able to function without it. I plan to research and look into what methods have newly been discovered to assist those with loss of smell/taste/touch and even vision/hearing. I wonder how the brain redirects those neural impulses and how you can manipulate those re-directions to help the person still live properly without the sense.

My main New Year Goal was to spend less time distracted on my devices and transform time procrastinated to time spent studying or being productive. I have found better methods for self studying and changed the approach with tackling studying for the exams. However, I have not done well in procrastinating less as I find myself struggling to manage my free time well. While I have found more efficient studying methods, I hope to use my planner more carefully and plan out my week in more detail so I can increase in sleep and energy levels throughout the day.

Reflexes Lab

I.) In our reflex lab, we examined 5 different parts of our body that contains reflexes. First we captured the dilation of our pupils by closing our eyes for 2 minutes, and then shining a bright light near the eye to watch the pupil decrease in size. Our eyes contain an autonomic reflex, in which the pupil allows less light to enter the eye and prevent from blindness. As the eyes respond to the extreme amount of light, they make themselves smaller in order to protect the retina and other parts of the eye from being damaged from bright light. Here is a video showing the pupil dilating and decreasing the amount of light entering the eye:

II.) We experimented with our knee-jerk reflex, also known as the Pateller reflex in the second part. We sat on a table and used a reflex hammer to hit the base of our base and initiate a kick. The thigh muscle contracts and causes the lower leg to jerk out. Knees contain the pateller reflex of jerking outward as a defensive reaction to protect from predators and provide self defensive. Furthermore, after doing 30 squats, our Pateller reflex was dulled because our muscles were tired from fatigue and the autonomic reflex that regulates our smooth muscle (upper thigh) was dulled. 

III.) We examined our blink reflex by throwing a cotton ball at clear plastic wrap that covered our faces. When the ball hit the wrap, we instantly blinked out of reflex. Our eyes contain this withdrawal reflex to blink against a sudden attack in order to protect our eyes from threats as well as provide us with a moment of calmness to maintain composure and stability. By closing our eyes for a split moment, we can defy threats more effectively by channeling our fear into a split-second reflex instead of panic. 

IV.) To test out plantar reflex, we traced a pen cap on the bottom of our foot starting form the heel up to the big toe. If we respond normally, our toes will clench closer together and shows that our nervous system functions properly. If someone has a Central Nervous System disorder like Multiple Scerosis, they feet would not exhibit the planter reflex because the neurons would not respond to the scrapping properly. 

V.) Lastly we did an experiment with a ruler to test the speed of our response to multiple variables. Our reaction time was determined by how fast we could grab a ruler that was dropped at a random time into our hands. Here is the table showing Nicole and I's times for 3 trials: 

To truly examine how our responses can be easily distracted through various external factors such as texting, we did the same trial again, except with one hand focused on texting and the other hand still trying to grab the yard stick as fast as possible. We noticed that texting slowed our reaction time to the yeard stick and increased the distance in comparison to the trails done without texting. This alludes to the importance of not texting while you drive as your reaction time is significantly slowed and can result in dangerous situations. Here is the resulting data: 

In the end, I had a faster reaction time than Nicole, most likely because I had gotten more sleep than she had the previous night and I had experience from color guard to catch equipment quickly and with strength. My senses were therefore heightened and made my performance overall. 

   

Sheep Brain Dissection

     In our sheep dissection lab, we dissected a sheep's brain, taking a closer look at each of external the parts (cerebrum, cerebellum, brain stem) as well as the internal parts( pons, medulla oblongata, midbrain, thalamus, hypothalamus, corpus collasum, and optic nerve). Each internal structure within the brain is in charge of a specific part, for example the pons controls involuntary actions like breathing and your pulse). In order to effectively transmit sensory information and messages throughout the body-- we have myelin in our cerebrum, shaped like branches to increase the transmission speed and clarity of the sensory neurons. When we did the Sheep eye dissection, we noticed the optic nerve ending at the back of the eye. Click this link to see more about that post: Sheep Eye Dissection. Here in the brain we also see the optic nerve, which transfers the visual information from the retina to the brain.

The picture below shows our pinned points of the external structures including markings for the anterior (white pin) and the posterior (red black pin) sides.

External View of Brain with pinned structures

(cerebrum, cerebellum, brain stem)

Sketch of External View of Brain

• Yellow pin: Cerebrum; controls the emotional and higher functions such as thought, emotion, and action  
• Green pin: Cerebellum regulates voluntary movement and receives sensory neurons through myelin
• Red pin: Brain stem; controls involuntary functions and transmits sensory messages between brain and rest of body

After observing the external brain, we sliced the brain in half down the midline to see the cross-section internal parts. We saw the cerebrum contained a vein-like structure called myelin. These help to increase the speed in transmitting sensory neurons faster through cerebellum. In the picture below, we pinned specific parts of the brain that were visible with the medial cut. 

Medial View of Internal Brain with pinned structures

(pons, medulla oblongata, midbrain, thalamus,

hypothalamus, corpus collasum, optic nerve)

Sketch of Medial View of Internal Brain 

• Flat Metal Pin: Pons; relays messages from cortex and cerebellum 
• White: Medulla Oblongata; controls involuntary actions 
• Blue: Thalamus; transmits sensory messages to the cortex, cerebellum, and medulla and correlates consciousness 
• Yellow: Midbrain; consists of the Thalamus and Hypothalamus, essential part of Central Nervous System 
• Black: Hypothalamus: essential part of connecting nervous system to endocrine system  
• Red: Corpus Collasum; connects the left and right hemispheres and allows both sides to connect and communicate 
• Green: Optic Nerve: Transmits visual information from the retina to the brain

Finally, we made a cross-section of the medial plane, exposing the white matter versus the grey matter. 

White Matter vs. Grey Matter 

Sketch of White Matter vs Grey Matter 

Sheep Eye Dissection Analysis

The structure of the eye is composed of spherical layers that transmit light and allow our brains to understand our environment and provides vision.

Externally, the eye is covered in fatty and muscle tissue that cushions the eyeball and keeps it in place during bodily movements. Extrinsic muscle also covers the eyeball, contracting and releasing to allow eyes to navigate and move around in up/down, side/side directions and movements in between. In the picture below on the left, you can see the fatty tissue covering the eye, including the eyelids which frame the opening to the sclera. Underneath the tissue, you will find the sclera, which is hard and difficult to puncture- allowing proper protection for the eye overall and keeping the internal parts intact. In the photo below on the right, you can spot the optic nerve, which is located in the back of the eye. This structure is hard and transmits the sensory neurons from the retina to the brain.

Light enters the eye primarily through the cornea, which then passes through the aqueous humor. It then reaches the pupil, located in the center of the iris. Light pass through the small opening, goes through the lens and vitreous humor and lands in the retina. Inside the retina are rods and cones. Rods allow us to see various shades of light or tones of grey and Cones give us color vision. After landing in the retina, light goes to the optic nerve which transmits the neurons to our brain.


This picture on the right shows the ciliary bodies on the left/black side of the eye, which contract and release to help the eye move around. On the right side, you can see the lens and the gelatinous vitreous humor attached to it.

In this next photo, you can see the choroid, which is the white layer that was spread across the internal sclera. The choroid only attaches to the retina in one spot, and this spot is the eye's blindspot. After scraping away the choroid, it is clear where the blindspot is located. The picture also shows the lens/vitreous humor slipping out, which exposes the ciliary bodies that surround the lens. Since we dissected a sheep's eye, there is a reflective surface behind the choroid which increases the reflection of light and allows animals to see better in the night. Humans do not have this feature.







After removing the lens and the pupil, and cutting off the cornea, we are able to see the opening of the pupil-- which is the hollow area seen below, and the back of the iris which is the gray area surrounding the opening.