BIO 206L: Exercise 10 Lab Analysis 1. Why do we ask students to do dissections?In general, dissections are a way to apply material as well as a different way of presenting material, especially to those who are visual learners. We dissect to have a visual of how the body systems work in a mammal. 2. How can you differentiate between a male and female rat using external features? Using internal features? Explain the size of a typical rat litter using external structures of the female rat. Why are rat testicles so large? If the rat is a male, externally you should be able to identify large scrotal sacs and a penis anterior to the anus. If it is a female, externally you should be able to identify a vagina anterior to the anus and two rows of mammary papillae. Internally, the male rat has two testes and epididymis as well as a vas deferens. Internally, a female rat has a horn shaped uterus as well as two ovaries at the top of this horn that should be easily identifiable. The typical rat litter can include anywhere from 4 to 8 pups and the rat can have up to 6 liters per year. Male rats have large testicles to produce more sperm, which will help them in reproduction with many female rats. 3. Let’s say we asked you to insert a glass pipette with an attached bulb into the part of the trachea leading to the rat’s lungs. What would you observe if you squeezed the bulb? Explain how the diaphragm causes this response in a living rat.If you squeezed the bulb, it would mimic the rat inhaling, which would cause the diaphragm to contract, increasing the amount of space in the chest cavity, which allows the lungs to expand. It is the same response in humans. 4. Name and describe the role of each of the chambers in the rat’s heart. Name the major artery and major vein connected to the heart. What is the function of each? The rat has 4 chambers of the heart, much like humans, a right atrium, a right ventricle, a left atrium and a left ventricle. The right atrium delivers deoxygenated blood to the right ventricle, which then pumps the deoxygenated blood out of the pulmonary artery into the lungs. Oxygenated blood is then brought back to the left atrium by the pulmonary veins. The oxygenated blood then moves from the left atrium to the left ventricle, and then gets pumped out into the rest of the body. The major artery connected to the heart is the aorta and the major vein is the vena cava. Both of the these supply oxygenated and deoxygenated blood to the heart.
- Spring '08