Unit 7 Reflection: Muscles

Our muscle video:

Muscles are composed of actin and myosin fibers and are classified into three groups: skeletal, cardiac, and smooth. Muscles have four properties: excitability, contractility, extensibility, and elasticity. Contractility is the ability for muscle tissue to shorten when stimulated. Extensibility is the opposite or the ability for muscles tissues to be stretched. Elasticity is the muscle tissue's ability to recoil back to resting length. Connective tissue components include the fascia, which hold muscle fibers together. The perimysium separates muscles into bundles. Tendons connect muscle to bone.

Muscles have many roles and vary in size and function. Masseter elevates the mandible and the temporalis elevates and retracts the mandible. The trapezius extends the hand and can adduct, elevate, or depress the scapula. The latissimus dorsi can extend, adduct and rotate the arm medially. The biceps brachii can flex the elbow joint while the triceps brachii can extend the elbow joint. The Brachioadiatis flexes the forearm at the elbow and is responsible for supination and pronation. The rectus abdominus can flex the abdomen while the external oblique can compress the abdomen. External intercostals elevate ribs while internal intercostals depress ribs. The hamstring group includes the biceps femoris, which flexes the lower leg, the semimembranosus, the most medial of hamstring muscles and extends the thigh, and the semitendonosus, which is anterior and medial to the semimembranosus on the inside of the thigh. Quadriceps muscles include the rectus femoris, vastus intermedius, vastus medialis, and the vastus lateralis.


Slow twitch fibers, or slow oxidative, are relatively slow and are aerobic. They have a low number of glycogen stores and are red in color, as they have a lot of oxygen. They are best suited for long distances and have high amounts of myoglobin, mitochondria, and capillaries. Fast twitch a fibers are relatively fatigue resistant while fast twitch b fibers fatigue quickly. FTa fibers are red to pink in color while FTb fibers are white or pale in color. An example of a concentric contraction is a bicep curl and an example of an isometric contraction is holding a weight out in front of you. An example of an eccentric contraction is walking. The ratio of muscle fibers varies between individuals and depends on genetics and exercise. Active exercise can result in hypertrophy (cells increase in size/volume due to an increase in myofibrils) and hyperplasia (cells remain the same size but increase in number).

Performance enhancing substances are manufactured products for oral ingestion, intranasal application or inhalation containing compounds that are intended to increase performance, promote muscle growth or induce weight loss. Health risks for men include shrinking of testicles, low sperm count, impotence, breast growth, and an enlarged prostate. Health risks for females include breast shrinkage, facial hair growth, issues with menstrual periods, and an enlarged clitoris. However, not all performance enhancements are bad for you (read more in my last blog post).

Because college decisions are coming out and I have been more busy, I haven't been able to keep up with my New Years resolutions as much as I'd like. My first goal of sleeping more has not been working out as well as I had hoped, but I want to start setting a timer whenever I do work to maximize efficiency. This will help me accomplish my second goal of studying anatomy notes every night as well. If I manage my time by setting a personal deadline, I know I will be able to catch up to what I originally had hoped.

Performance Enhancing Drugs: A Satirical Advertisement

Performance enhancing drugs boost athletic performance, increase muscle build, and aids in the loss of body fat. I don't have much real life experience with these drugs besides a story that my friend told me about a person she used to know. Apparently this boy was abusing steroids to get ahead on his sports team and as a result, was experiencing "roid rage." In class we learned that this is not a myth, and that steroid users do indeed have a tendency to get angry faster. Other health risks and symptoms of drug use include acne, stunted growth, high blood pressure, liver damage, risk of stroke, headaches, baldness, and risk of ligament and tendon injuries. Stimulants as seemingly harmless as caffeine can result in nervousness, irritability, dehydration, and psychological addiction. Erythropoietin, or EPO, a type of hormone used to treat anemia in people with severe kidney disease, may result in heart attack and pulmonary edema. Not all performance enhancements are drugs. Finally, carbo-loading, a tactic of increasing consumption of carbohydrates depicted in the satirical advertisement above, can result in severe weight gain. Many of these substances are safe as long as they are used in moderation, like caffeine. Strength training and high protein diets can be safe, but continuous periods of abuse will only have negative effects on the human body. Ultimately, the risks that come with abusing certain performance enhancements are not worth it.

Chicken Muscle Dissection

In the lab, we distinguished significant muscles and muscle bunches in a chicken by slicing through the skin with scissors and a scalpel. The muscles in the chicken have comparable structures and shapes as the muscles in the human body. The muscles connect the bones by a tendon, white connective tissue, so that when the muscles contract, the bones and body move. If the biceps brachii contracts, and the triceps humeralis unwinds, the tendons that connect the muscles to the humerus, ulna, and radius, would pull the bones at the elbow joints and twist the arm. The tendons are what keep the muscles and bones connected and provides movement when the muscle pulls on the tendon which moves the bone. At the origin, the tendon is fixed during muscle contraction, while at the insertion sites the tendons move during contraction to move the joints properly. The muscles in the chicken are like people, but there are several key differences. The pectoralis major and minor are both relatively bigger in the fowl than in people because they have been reared to have more meat in those areas. Another contrast would be that we have a muscle in the thigh called gluteus maximus, and the chicken has iliotibialis, despite the fact that the elements of those muscles are basically the same. Also, in comparison to chickens, humans have relatively small tibialis major.


The muscles in the chicken:

The pectoralis major is larger in birds than humans because it is developed from flying.

The pectoralis minor attaches to the shoulder muscle from right under the pectoralis major

The trapezius pulls the shoulder back during flight for birds.

The latissimus dorsi works to extend the wings on the back of the bird.

The deltoid raises the upper part of the wing on the top part of the shoulder of the bird.

The biceps brachii bends the wing on the upper area of the wing.

The triceps humeralis both bends and extends the wing in chickens. It is below the biceps brachii.

The flexor carpi ulnaris is in the lower area of the wing.

The brachioradi alis is on the lower area of the wing as well and extends from the elbow to the thumb.

The sartorius runs from the thigh to the pelvis and flexes the thigh.

The iliotibialis is on the lateral side of the thigh in birds. In humans, it is on the dorsal side and is called the gluteus maximus.

The biceps femoris functions as part of the hamstring group and is medial to the iliotibialis.

The semimembranosus is also part of the hamstring group and is inferior to the biceps femoris.

The semitendinosis is part of the hamstring group and is anterior to the semimembranosis.

The quadriceps compose much of the thigh and makes up a lot of the front and inner portions of the thigh.

The gastrocnemius is attached to the Achilles tendon and is on the back of the drumstick of the chicken.

The peronus longus extends the foot and is on the lateral side of the drumstick.

The tibialis anterior flexes the foot and is on the lateral side of the shin bone.

The tendon is the connective tissue that attaches the muscles to the bones.

What happens when you stretch?

Relate and Review:

I remember learning in class that a sarcomere is a section of a myofibril where protein fibers overlap and slide past each other during the contraction and relaxation of muscles. I thought it was interesting how the reading outlined how the muscle fiber is pulled out fully one sarcomere at a time, then the connective tissue picks up the slack. When I was recovering from scarred tissue, I remember a nurse explaining parts of this process to me. The article also confirmed that it is this realignment that helps tissues recover from scarring, as it helps realign the disorganized strips of muscle fiber by pushing it in the direction of the tension.

1. "Proprioceptors are the source of all proprioception: the perception of one's own body position and movement": I thought this was an interesting line because of how sensitive the proprioceptors actually are. Any change of tension or basic movement is detected and they reside in so many places. For example, proprioceptors are found in the nerve endings, muscles, tendons, and fibers. 
2. "When stretching, it is easier to stretch a muscle that is relaxed than to stretch a muscle that is contracting": By allowing the antagonists to relax, you can get a better stretch. In track, we learned that you can stretch out your hamstrings better by keeping your leg erect. This makes sense because keeping the muscle relaxed can provide a deeper stretch. 
3. "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": This is a very interesting concept because one would consider reflexes to be uncontrollable. However, for professional athletes, muscular control can actually be achieved. 

Unit 6 Reflection

In this unit, we covered the basics of the skeletal system. Hematopoiesis is the regeneration of blood cells in the bone marrow. Axial bones include 80 bones divided into the skull, vetebral column, and thoracic cage regions. Apendicular bones help humans move around and there are two kinds of bone marrow: red and yellow. Red bone marrow produces blood cells while yellow bone marrow stores energy as fat. Osteoblasts make bone while osteoclasts are bone breakers. In low gravity, osteoclasts increase their rate of bone absorption, while the osteoblasts dial back on the bone formation. Bones are classified by shape: long short, flat, and irregular. Diaphysis is the shaft of a long bone, and is composed of compact bone. Epiphysis is the ends of the bone, and is composed of mostly spongy bone. Periosteum is the outside covering of the diaphysis and is composed of fibrous connective tissue membrane. Sharpey's fibers secure the periosteum to the underlying bone. The arteries supply bone cells with nutrients.


In "Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head" by Kenneth K Hansraj, the pressures taken on by the spine are dramatically increased when the head is flexed forward at varying degrees. Good posture is defined as ears aligned with the shoulders and the retracted shoulder blades. Stresses to the cervical spine may result in degeneration and tears. Smartphones and other devices lead to the stresses of the cervical spine. People spend an average of 2-4 hours each day on their phones, hunched over, which contributes to the rising rate of damaged spines.



Bone fractures occur when a bone must take on more stress than it can handle. Complete fractures occur when a bone is broken completely through. Incomplete fractures occur when the fracture does not extend through the bone. Simple fractures occur when the bone does not break through the skin, while a compound fracture involves skin breakage. A comminuted fracture is when a bone is fragmented into 3+ pieces while an oblique fracture is when a bone is broken at an angle. Bone repair may begin when the ends of bone make contact with each other.

During this unit, I feel that I have managed to keep up with my resolutions. My first resolution was to sleep more, and I definitely feel that I have been able to sleep more during this time frame than in first semester. My second resolution is harder to maintain, as I often don't have time to review Anatomy and Physiology notes every single day. In fact, my resolutions sometimes conflict. In order to sleep early, I struggle with reviewing my notes consistently. However, I have been able to maintain my second resolution 60% of the time, which is still significantly better than last semester.

Owl Pellet Analysis/Conclusion

After dissecting the owl pellet, we conclude that the organism consumed by the barn owl was a vole. We discovered multiple scapula in the exact shape of that of a vole's, and we discovered portions of the hip bone. We also found a back leg that contained the tibia and fibula in the exact shape of the vole back legs.








Differences between rodent skeleton and human skeleton:

1. The tibia and fibula are connected on the rodent skeleton. In humans, there are 2 separate bones. 
2. Vertebrae is longer in rodents, because the tail adds extended segments to the vertebral column. 
3. The pelvis of rodents are shaped quite differently than the pelvic girdle of human beings. The rodent hip bone seems to be more elongated. 

Similarities between rodent skeleton and human skeleton:

1. Both rodents and humans have 24 ribs in total and 12 pairs of ribs.  
2. The scapula of both rodents and humans are shaped similarly in a triangular fashion. 
3. The vertebral columns are both made up of small segments (25 pieces).

Unit 5 Reflection

In this unit, we established the difference between digestion in absorption. Digestion involves the breakdown of food these nutrients, while absorption involves the body's physical reception of these nutrients. In digestion, organs are separated into two main groups: the alimentary canal and the accessory digestive organs. Absorption involves the small intestine, the liver, and the large intestine.

The digestive system, which contains the alimentary canal, performs many basic functions including ingestion, secretion, propulsion, digestion, absorption, and defecation. The stomach provides a physical and chemical change in which proteins break down. The small intestine has 3 parts: the duodenum, jejunum, and the ileum. In the large intestine, food passes through the large intestines: cecum, appendix, ascending colon, transverse colon, descending colon, sigmord colon, rectum, and anus.

Diabetes has become more prevalent in our modern day society. Insulin is the hormone produced by the beta cells of the pancreas and is involved in the stimulation of glycogen synthesis. It is the key which unlocks cells allowing glucose to enter. Glucose is transported into muscle and fat cells by glucose transporter GLUT 4. In the presence of insulin, GLUT 4 travels to the plasma membrane. In Type 1, blood glucose levels are sensitive to small changes in diet. In Type 2 diabetes, the body does not react to insulin properly.

Fuel metabolism is an essential part of how we function in our daily lives. There are 3 stages of energy extraction: the large molecules are broken down, small molecules are turned into Acetyl CoA, and common pathways in oxidation of fuel molecules. The fed state, or absorptive state occurs directly after a meal. The fasting state occurs within one hour of a meal. A ketone body is produced from Acetyl CoA by the liver. The Cori cycle occurs during exercise, as muscles must rely on glycolysis for ATP, consequently producing lactic acid.

In our "Stress Metabolism, and Liquidating Your Assets" article, I learned that stress can affect appetite in a huge way. AcTH stimulates appetite while CRH represses it. When a stressful event occurs, there is a burst of CRH secretion. It takes many minutes to see a surge in glucocorticoid levels in the blood stream. CRH makes its effects clear in seconds while glucocorticoids take minutes to hours. When the stressor is released, CRH takes seconds to clear while glucocorticoids take hours to clear.

The endocrine system controls the processes involved in movement and physiological equilibrium. Steroid hormones are lipid soluble and diffuse through the cell membrane. Nonsteroid hormones are not lipid soluble and are received by receptors external to the cell membrane. The pituitary gland is controlled by the hypothalamus or other neural mechanisms. The thyroid gland regulates metabolism and increases protein synthesis. The parathyroid glands regulate phosphate levels.

Finally, the lymphatic system functions as a fluid recovery gutter by returning fluid to the bloodstream. Lymph flows within lymphatic vessels and is similar to plasma. A large number of T cells develop in the thymus, while the lymph nodes filter lymph trapping foreign substances, then destroyed by immune cells. The spleen is the largest lymphoid organ and contains both red pulp[ and white pulp.

In terms of my New Years resolution, I have been able to get more sleep, just because I'm better at managing my time as a second semester senior. I plan to sleep even earlier by setting an alarm to remind myself to sleep, even when I don't feel especially tired. In terms of my Anatomy goals, I have been able to adhere to those as well. Everyday before bed, I have been reviewing my notes, which allows me to do better on my temp checks. My next step is to begin reviewing earlier, which would enable me to sleep earlier as well.