Download Rat Dissection - Sun Prairie Area School District

Name: _________________________________
Hour: ___________ Rat Dissection ( Rattus norvegicus ) Introduction In this laboratory, the anatomy of the rat will be examined in detail. The rat is a vertebrate mammal, which means that many aspects of its structural organization are common with humans. T
he similarity of structures among related organisms shows evidence of common ancestry. I n a way, studying the rat is like studying a human. As the leading theme of this lab, ask yourself: “for every structure observed in the rat, there is an equivalent structure in your own body - what is the structure and where is it located? How do these organs and organ systems make my body function? “ Pay particular attention to the relationships among organs and groups of organs. Structural parts are not "just there" in random locations. Their specific layout within the body contributes to making certain functions possible. Therefore, for every structure seen, you should determine the following: ● Its function o What is blood picking up and dropping off ? ● What organ system it belongs to ● How it is connected with other organ systems The specimen you will receive is a preserved double-injected specimen. Double injected refers to the arteries being filled with a red latex, and the veins being filled with blue latex. You will notice various incisions on the external surface of the rat where the latex was injected. Dissection Guidelines TRY! Y
ou are expected to try to locate structures before asking for assistance. Using the instructions and diagrams, you should be able to locate many structures by yourself. If after a good effort, you cannot find a structure, ask for help. Remember, this is a learning experience; it is permissible to discuss and observe other students' specimens. Compare your dissection with others and be sure to look at animals of the opposite sex. Dissecting Tools will be used to open the body cavity of the rat and observe the structures. Dissecting does not mean "to cut up"; in fact, it means "to expose to view". Careful dissection techniques will be needed to observe all the structures and their connections to other structures. Y
ou will not need to use a scalpel. Contrary to popular belief, a scalpel is not the best tool for dissection. Scissors serve better because the point of the scissors can be pointed upwards to prevent damaging organs underneath. Always raise structures to be cut with your forceps before cutting, so that you can see exactly what is underneath and where the incision should be made. Never cut more than is absolutely necessary to expose a part. Class Participation Grading 0 pts 5 pts 10 pts Student did not stay on task (wrote notes, did other class homework.etc). Lab partner did most of the work and clean up, engaged in horseplay Student was engaged in the laboratory most of the time, failure to clean up station, quit too early, not paying full attention Student was engaged in laboratory, did fair share of work, stayed on task, cleaned up fully 1 Name: _________________________________
Hour: ___________ Rat External Anatomy Directions - label the diagrams with every b
olded w
ord . Not every structure on the pictures will be labeled. Procedure : 1.
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Obtain your rat. Rinse it off with water and place it in your dissecting pan to observe the general characteristics. Make sure you know each of the highlighted words below. The rat's body is divided into six anatomical regions: ● cranial region – head ● thoracic region - chest area ● abdomen – belly Note the hairy coat that covers the rat and the sensory hairs (whiskers) located on the rat's face, called v ibrissae . The mouth has a large cleft in the upper lip, which exposes large front i ncisors ( two middle teeth). Rats are gnawing mammals, and these incisors will continue to grow for as long as the rat lives. Note the eyes with the large p
upil and the n
ictitating membrane found at the inside corner of the eye. This membrane can be drawn across the eye for protection. The eyelids are similar to those found in humans. Examine the t ail , the tails of rats do not have hair, though some rodents, like gerbils, have hair on their tails. Do you have a boy rat or a girl rat? Rat Internal Anatomy Procedure: Be careful not to cut too deeply →
keep the tip of your scissors pointed upwards. Your teacher has made a video and shared it with you on google classroom. Watch the video and then you can begin dissecting you own rat. 1.
Place the rat ventral side up (belly up) 2.
There is an opening in the rat’s skin already where they added preservative this is where you start to snip (with scissors) across the body horizontally from rear leg to rear leg. 3.
Then snip along the midline of the rat (from crotch to neck)until you reach the ribs. Always point the scissors up! 4.
Snip through the ribs up the neck. 5.
Snip one more horizontal line from under the front limbs. You should now be able to see all the organs. 2 Name: _________________________________
Hour: ___________ The Thoracic Organs (Circulatory and Respiratory Systems) 1.
Locate the d
iaphragm , which is a thin layer of muscle that separates the thoracic cavity from the abdominal cavity. Observe the h
eart and l ungs. T
he lungs are composed of 5 lobes (1 in the left lung and 4 in the right lung! Humans have 2 lobes in the left lung and 3 lobes in the right lung.) a. Function of the lungs: i. To take in oxygen from the atmosphere and deliver it to the blood ii. To release carbon dioxide from the blood into the atmosphere 2.
3.
The h
eart is centrally located in the thoracic cavity. a. The two dark colored chambers at the top are the a
tria (single: atrium), b. The bottom chambers are the v entricles . c. Function of the heart: to pump blood throughout the body Observe the throat region to identify the t rachea- a
small, white, ridged tube that runs down the neck. a. The function of the t rachea i s to b
ring air from the mouth/nose to the lungs. 4.
5.
To expose the e
sophagus , push the trachea to one side using a probe. a. Functions: The e
sophagus brings food from the mouth to the stomach. b. Follow the esophagus through the diaphragm to its junction with the stomach. The e
sophagus pierces the diaphragm and is different from the from the trachea due to the lack of cartilage rings. Heart Analysis Questions: 1.
What is the function of the heart? 2.
What organ system does it belong to? 3.
In the heart… a. What is the blood p
icking up ? b. What is the blood d
ropping off ? Lung Analysis Questions: 1.
What is the function of the lungs? 2.
What organ system does they belong to? 3.
In the lungs... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? Which organ s ystem d
o the lungs work closely with? Why? 4.
3 Name: _________________________________
Hour: ___________ The Abdominal Organs 1.
Locate the s tomach (label) on the left side just under the diaphragm. a. The f unctions o
f the stomach include: i. food storage ii. the physical breakdown of food iii. the digestion of protein. b. The opening between the esophagus and the stomach is called the c
ardiac sphincter. This is where humans sometimes get “heartburn.” c. Slit the stomach lengthwise (top to bottom) and notice the muscular ridges inside. These ridges contract and help breakdown food during digestion. 2.
Locate the l iver (label) , which is a dark colored organ suspended just under the diaphragm. a. The liver has many f unctions : i. Produces bile, which aids in digesting fat ii. Stores glycogen (complex sugar/carb) for energy use when you haven’t eaten iii. Transforms wastes into less harmful substances. Analysis Questions: 1.
What is the function of the liver? 2.
What organ system does the liver belong to? 3.
In the liver... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 3.
Humans have a g
allbladder, w
hich is used to store bile and hides under the liver. Rats d
o not have a g
all bladder, w
hich is used for storing bile in other animals. 4.
The s pleen (label) is about the same color as the liver and is attached to the stomach (looks like a tongue). a. Functions i nclude: i. Destroys old red and white blood cells ii. Blood storage. b. A person can live without a spleen, but they're more likely to get sick as it helps the immune system function. Analysis Questions: 4.
What is the function of the spleen? 5.
What organ system(s) does the spleen belong to? 6.
In the spleen... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 4 Name: _________________________________
5.
Hour: ___________ The p
ancreas (label) is a brownish, flattened gland found in the tissue between the stomach and small intestine. Find the pancreas by looking for a thin, almost membrane looking structure that h
as the consistency of cottage cheese. a. Functions o
f the pancreas: produces digestive enzymes and secretes insulin, which regulate glucose levels (blood sugar). Analysis Questions: 7.
What is the function of the pancreas? 8.
What organ system does the pancreas belong to? 9.
In the pancreas... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 6.
7.
The s mall intestine (l abel ) is a slender coiled tube that receives partially digested food from the stomach. a. Functions o
f the small intestine: i. Chemical digestion of food with enzymes from the pancreas, as well as its own enzymes. ii. Absorbs the digested nutrients into the bloodstream for transportation around the body. Use your scissors to cut the m
esentery (the thin, connective tissue) of the small intestine, but do not remove it from its attachment to the stomach and rectum. If you are careful you will be able to stretch it out and untangle it so that you can see the relative lengths of the large and the small intestine. Analysis Questions: 10. What is the function of the small intestine? 11. What organ system does the small intestine belong to? 12. In the small intestine... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 8.
Locate the l arge intestine (label), a
lso known as the c
olon , which is the large greenish tube that extends from the small intestine and leads to the anus. a. Functions : finals stages of digestion and water absorption occurs and it contains a variety of bacteria to aid in digestion. Analysis Questions: 13. What is the function of the large intestine? 14. What organ system does the large intestine belong to? 15. In the large intestine... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 9.
Locate the c
ecum (label) - a large sac in the lower third of the abdominal cavity, it is a dead-end pouch and is similar to the appendix in humans. It also is the point at which the small intestine becomes the large intestine. 10. Locate the r ectum (label) - the short, terminal section of the colon between the descending colon and the anus. 5 Name: _________________________________
a.
Hour: ___________ Functions : Temporarily stores feces before they are expelled from the body. Urogenital System The excretory and reproductive systems of vertebrates are closely integrated and are usually studied together as the urogenital system. However, they do have different functions: the excretory system removes wastes and the r eproductive system produces gametes (sperm & eggs). The reproductive system also provides an environment for the developing embryo and regulates hormones related to sexual development. Excretory Organs 1. To locate the t wo l arge bean shaped structures, the k
idneys (l abel ) (primary organ of the excretory system), move the stomach and the intestines to one side with the probe. a. Functions: Clean waste from the blood . b. Renal arteries (red) supply the kidneys with blood to be cleaned, while r enal veins (blue) take purified blood away from the kidneys. Analysis Questions: 16. What is the function of the kidneys? 17. What organ system does the kidneys belong to? 18. In the kidneys... a. What is the blood p
icking up ? b. What is the blood d
ropping off ? 2. Carefully strip away part of the membrane covering a kidney with forceps. Attempt to follow the course of one of the u
reters (label), which carry urine to the bladder. Wiggle the kidneys to help locate these tiny tubes. Functions: The u
reters c
arries urine to the b
ladder. 3. Locate the b
ladder (label) a
small yellowish bulb-like structure at the top of the pelvis.. a. Function: The bladder stores urine created in the kidneys. 4.
The small yellowish glands embedded in the fat atop the kidneys are the a
drenal glands , w
hich produce the hormone, adrenaline, when you are scared or excited. Reproductve Organs Male Rats 1. The major reproductive organs of the male rat are the t estes , which are located in the s crotal sac . a. Functions : produce sperm. Female Rats: 1. The short gray tube lying dorsal to the urinary bladder is the v agina . The vagina divides into t wo uterine horns t hat extend toward the kidneys. a. This duplex uterus is common in some animals and will accommodate multiple embryos (a litter). b. At the tips of the uterine horns are small lumpy glands called ovaries. 6 Name: _________________________________
Hour: ___________ Rat Diagram ­ Please label! Label the following internal structures in the diagram below: ●
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Esophagus Trachea Lungs Heart ○ Atrium ○ Ventricle ○ (Bonus: Aorta) Diaphragm Liver Stomach Spleen Pancreas Small Intestine Large Intestine Caecum Rectum Anus 7