Biology 11

Thursday 24 January 2013

Rat Dissection

On Thursday and Friday our Biology Class participated in a rat dissection. We had previously dissected a squid and an earthworm but neither were as exciting as the rat. We dissected a rat because it's body is closely related to a humans. Both a human and a rat are in the class Mammalia It was a surprising realization that the insides of a rat and human are similar but the physical appearances are so different.
The rat is part of the class Mammalia They have all the basic characteristics such as 4 chambered heart, fur, a diaphragm for breathing, amniotic egg, mammary glands for nursing, extensive post natal care and high learning and reasoning levels. Both the rat and humans are placental mammals. Both their tissues in the embryo and mothers uterus develop into a placenta which transfers nutrients and wastes between the mother and embryo. This allows the embryo to develop for longer inside the mother, unlike marsupials.
The rat dissection was a very hands on experience that I am glad that I got to participate in it. It was slightly nerve wracking because I felt like with one wrong cut the entire dissection could go wrong. However while moving along I became truly fascinated by the dissection and rat's anatomy. This was probably my favorite part of this course.

Discussion Questions:

1. Because you can easily feel the texture of the animal. It is also easier to grasp the animal. You can also be more accurate and precise with your incisions.

2. The different labels and titles for the dissection have the purpose of helping to keep the dissection organized. With these labels we can easily gain knowledge to what we are dissecting and having some what of a reference to look at.

3. A rat's tail is different from the rest of the body. It has a different texture. It looked scaly with fur. It also felt hard. The rat uses their tail for balance and to regulate their body temperature.

4. The purpose served by the vibrissae is tactile sensation. The vibrissae do not have any nerves in them.

5. My specimen is bilaterally symmetrical. This means that if an imaginary line was to be drawn down the middle of the animal, the two sides would be symmetrical.

1. The sphincter is a circular muscle. It is a ring of muscle that contracts to close an opening. For example the pyloric sphincter allows the stomach to digest proteins then opens up to allow the digested material to pass to the small intestine.

2. The small intestine is longer than the large intestine but it has a smaller width. In the small intestine the digestion and absorption of food occur. The large intestine helps to reabsorb the food and eliminate wastes.

3. The liver is the largest organ in the body. It has many functions such as, producing bile and proteins for blood plasma and proteins that help carry fat throughout the body. The liver also helps get rid of toxins and other poisonous substances. It converts ammonia into urea and produces immune factors and removes bacteria from the blood.

4. The duodenum acquired its name because it means 12 fingerbreadths (25 cm) in Latin.

5. The purpose of the appendix is in debate. Some scientists believe that it is a vestigial organ meaning that it has no use anymore. However studies are suggesting that the appendix hold bacteria which could be used to help cleanse out intestinal disease.

1. The function of the membrane is to help protect the cavities and make sure that the fluids don't escape the cavity. It also separates the layers as well.

2. The function of the spleen is to remove old red blood cells and also produce white blood cell lymphocytes.

3. The function of the diaphragm is to help with respiration and breathing. The contraction and expansion of the diaphragm helps inhale and exhale air from the lungs. The diaphragm is also used to expel vomit.

4. There are quite a few differences between the atria and ventricles. The atria are smaller than the ventricles. The atria is located above the ventricles and contains thinner tissues. The atria pump blood to the ventricles and the ventricles to the rest of the body.

5. The wall of the left ventricle is thicker than the wall of the right ventricle because the left ventricle pumps blood to the rest of the body.

6. A similarity between the male and female reproductive structures is the preputial glands. They are glands the secret hormones.

7. The kidneys clean and filter blood to remove wastes, stimulate the production of red blood cells, regulate blood pressure and substances in blood, and regulate the acidity of blood by controlling the amount of water in it.

8. The thyroid, the thymus and adernal glands belong to the endocrine system. This system regulates growth, mood and development. They also release hormones which influence every cell.

Wednesday 12 December 2012

SQUID DISSECTION

On Friday , our Biology 11 class was fortunate enough to partake in a squid dissection. It was very interesting and exciting.
The purpose of this goal was for us to further understand the anatomy of mollusks. I think dissecting the squid was a great choice because it is one of the more adapted kind of mollusks. A squid is much more fascinating than a snail. By dissecting the squid we got to see the organs and the structure in actuality rather than a diagram from the textbook.
By participating in this lab I was able to look at the external and internal anatomies of a squid. The external anatomy consisted of the funnel, tentacles, arms, eyes, the mantle and the fin. A squid also has a beak, which can be seen once the tentacles and arms are spread apart. The internal anatomy consisted of the ink sac, stomach, liver, anus, gills. Their is also a pen which aids in structural support.
I enjoyed this dissection immensely. Since I was not able to participate in the earthworm dissection this was my first dissection of the year. It proved to be very exciting. The directions were simple and fun. I also enjoyed the pre lab labeling because it helped me be more aware during the actual dissection. Overall this dissection was a great experience.
Discussion Questions
External Anatomy Questions:

1. A squid has 8 arms and 2 tentacles.

2. Both the arms and tentacles are used for grasping prey.

3. This picture shows the direction that water comes out of through the funnel.

This picture shows the direction of which a squid moves, which is both ways.

4. Two external features that are adaptations for the squids predatory life are the beak and the suckers on their tentacles.

A) The beak is a great tool for attacking and killing the prey. The sharp beak is also used for ripping apart the food.

B) The suckers and hooks are also great adaptations that the squid has for predatory purposes. The suckers and hooks can grab on to their prey, making it more efficient to catch them.

5. The squid shares many traits with the mollusks. The main general traits of a mollusk are the foot, the mantle and the visceral mass.

The foot has adapted into the tentacles and arms in the squid.

The mantle is the dorsal body wall the covers the visceral mass. The visceral mass contains most of the internal organs.

Internal Anatomy:

1. A squid has one pair of gills resulting in two gills in total.

2. The ink sac empties into the water jet. The function of the inc sac is to distract predators. The water jet is used for locomotion.

3. The function of the pen is to give the body support. Without the pen a squid would not have a structure and thus have difficulties swimming.

4. Waste exits a squid through the anus.

Tuesday 4 December 2012

Worm Dissection

Unfortunately I was unable to participate in the earthworm digestion. Seeing the parts of a worm in actuality,rather than textbook diagrams would have helped to increase my understanding of an earthworm anatomy.
The main purpose of this dissection was to achieve a better understanding of an earthworm's organs and also the systems which it has. Such as the circulatory system, the digestive system, the respiratory system, the excretory system and the nervous system. The lab was an opportunity to observe the internal and external structures of an earthworm. After this lab we would be able to name and identify the organs of a earthworm.
We had just finished the chapter on annelids. Thus doing the lab was a great way to incorporate the textbook learning with a hands on dissection. The lab began with a identifying the dorsal and ventral sides of the worm. We also noticed the clitellum which is used in the reproductive system of earthworms. We then later looked at the five aortic arches (hearts) and find the nerve which are connected to the rest of its body. The next part of the digestion was the digestive tract. We took a look at the pharynx, esophagus, crop, gizzard and intestine. For the excretory system we found the nephridia that are found in each segment twice. We identified ovaries and testes for the reproductive systems of the earthworm
By doing this lab we can take our level of the earthworm's anatomy a step farther. It has helped us understand where and why organs are located where they are.

Discussion Questions:

1. The aortic arches are the organs which pump blood throughout the earthworm's body. They are also know as hearts, and a earthworm has 5. The fluid travels through the ventral blood vessels to capillary beds. The dorsal blood vessels is where the fluids collect and are transported back to the aortic arches.

2. The digestive tract of an earthworm consists of the pharynx, esophagus crop, gizzard and intestine. The mouth is the first part of an earthworm's digestive tract. Then it goes into the pharynx, which pumps pumps the food into the esophagus (tube between pharynx and crop). The crop stores the food temporarily. The gizzard then grounds up the mixture and in the intestine digestion and absorption occur.

3. The nerve collar consists of galngia above and below the pharynx. (Ganglia are masses of tissues with many nerve cells)The ganglia above the pharynx serve as the brain. There is a long ventral cord which has ganglion connected to each organ.

4. The nephridia are the parts of the earthworm which are included in the excretory system. Nephridia are simple tube-shaped excretory organs which eliminate wastes caused from cellular metabolism. They remove waste from body fluids and carry it outside. A pair of nephridia can be found in each body segment.

5. You can know if an earthworm eats soil by looking at what is in the digestive tract. You can also look at an earthworm's waste products to determine whether or not it eats soil.

6. The setae make the earthworm well adapted to it's environment because they help them crawl and anchor themselves firmly in their burrows. They also help the worm grip the soil making it difficult for it's predator to pull the earthworm out.

7. The earthworm's digestive system is adapted for extracting relatively small amounts of food from large amounts of ingested soil because of it's gizzard. The gizzard is an organ which is used to churn food (ground into smaller pieces).

8. Beyond segment 32 is the clitellum. It is located from segment 32-37. The rest of the posterior end has the intestine of the worm and the anus. The intestine has solid and liquid substances which is the food of an earthworm.

9. Earthworms are hermaphrodites which undergo fertilization. An individual worm produces both eggs, in the ovary, and sperm in the testes. However it does not fertilize itself. When an earthworm undergoes they reproduction, the worms pair up and attach themselves together. The clitellum secrets a mucus into where eggs and sperms are released. The eggs are released by the female genital pores and the sperm from the male genital pores. After the egg and sperm are released the mucus slips off. Fertilization then takes place outside the body, but with the protection of the mucus ring. This mucus turns into the cocoon.