Frog Dissection - Teacher's Guide Dissection Tips and Tricks
Obtain grass frogs from a biological supply company. I usually order mine from carolina carolina.. It is not necessary for this lab to get the injected frogs. I have also gotten a single pack of bullfrogs to give one per class. Bullfrogs are much larger, but that doesn't mean they are easier to dissect. The bullfrogs are messier and hard to cut, I have a "lottery" to pick a group to do the bullfrog and then the other students in the class can see hat it looks like. Group sizes ! sizes ! I usually put my m y students in groups of , possibly three three if I have an odd number of students. If I have e#tra frogs I might allo students to ork alone $their choice%. &sually the students decide ho is going to r ead rite, and ho is going to do the cutting. I also use virtual frogs before the dissection to give them a clue about the structures they ill see inside. Lab Resources ! Resources ! The frog dissection gallery is gallery is a good resource for teachers and students to revie the parts of the frog. I also encourage my students to try to discover the ansers to their (uestions before asking for help. I have resources such as lab manuals and frog dissection guides laying around the lab. )hen students ask me (uestions, I re(uire them to at least have a book open to the appropriate page to sho me they tried to find the anser on their on. *emember that dissection is a learning process and part of the objectives should be to teach students to become independent learners. +ounger students may need more help than older students. Safety Considerations ! Considerations ! students must ear safety goggles, frogs ill sometimes spray fluid hen you cut them and this fluid can be painful if it enters the eyes. If this happens, use eyeash and liberally flush eye ith ater. ate# gloves are preferred, but not entirely necessary. -tudents should ash hands even if they ore gloves. Classroo !anageent ! this can be a stressful time for teachers because students can get very e#cited and forget classroom rules. )hen you're helping one student, another may be throing frog guts at their neighbors. ddress ddress these issues before you start the lab and make clear that horseplay ill not be tolerated. Be prepared to enforce this. I typically end up removing a student from the class the first day, this student must do the alternate assignment in the hall. It sounds harsh, but if you're illing to give a bunch of /0 year olds
scalpels, then be prepared to be very stern to ensure the safety of all of your students. Grading ! Grading ! the dissection can be difficult to grade. I usually grade the (uestions and labelings from the 1rog 2issection 3andout and also give them a paricipation grade based on ho ell they did the lab, such as cutting the frog, cleaning up, and orking ell ith others. 1inally, students get a lab test over the frog here frogs have been set up and tagged4 students move from station to station to identify the structures that have been pinned. "ey to Lab #andout $uestions and Labeling
%ost Lab $uestions
/. The membrane holds the coils of the small intestine together5 mesentery.This organ is found under the liver, it stores bile5 gall bladder 6. 7ame the 6 lobes of the liver5 right, left anterior, left posterior
8. The organ that is the first major site of chemical digestion5 stomach 0. 9ggs, sperm, urine and astes all empty into this structure5 cloaca :. The small intestine leads to the5 large intestine ;. The esophagus leads to the5 stomach <. +elloish structures that serve as an energy reserve5 fat =. The first part of the small intestine$straight intestine$straight part%5 duodenum />. fter food passes through the stomach it enters the5 duodenum $sm intestine% //. spidereb like membrane that covers the organs5 peritoneum /. *egulates the e#it of partially digested food from the stomach5 pyloric sphincter valve /6. The large intestine leads to the5 cloaca /8. Organ found ithin the mesentery that stores blood5 spleen /0. The largest organ in the body cavity5 liver
Label the Diagra
esophagus ???????????? . ????????? ????????? esophagus ???????????? left atrium ????????????? B. ????????? left ????????????? stomach ????????????? @. ????????? stomach ????????????? pancreas ????????????? 2. ????????? pancreas ????????????? duodenum ????????????? 9. ????????? duodenum ????????????? 1. ????????? anus ???????????????? ???????????????? right atrium ?????????? A. ????????? right ?????????? lung ???????????????? 3. ????????? lung ???????????????? ventricle ????????????? I. ????????? ventricle ?????????????
liver . ????????? liver ?????????????????? ??????????????????? ? gall bladder C. ???????? gall ?????????????? ?????????????? small intestine ?????????? . ???????? small cloaca $large intestine% ?????? D. ???????? cloaca ?????? conus arteriosus ??????????? 7. ???????? conus ???????????
1rog natomy and 2issection
In the lab, you ill be spending a fe days, dissecting the frog. Eeriodically, Eeriodically, your instructor may pause to sho you illustrations, diagrams or videos of procedures. This page is additional information that may be given to you in class as you perform the dissection. Fomarine Fomarine and Da#illary Teeth5 Teeth5 &sed for holding prey Internal 7ares $nostrils% breathing 9ustachian Tubes5 e(ualiGe pressure in inner ear Alottis 5 Tube leading to the lungs 9sophagus5 Tube leading to the stomach Tongue5 Tongue5 1ront attached, aids in grabbing prey pre y Tympanic Tympanic Dembrane5 eardrum, located behind eyes 7ictitating Dembrane5 clear eyelid, protects the eye
3andouts on the 1rog 2issection5 1rog 9#ternal natomy 1rog 2igestive and &rogenital -ystem 1rog Brain and Bones
The Douth
The Organs of the bdominal @avity
Eeritoneum5 -pidereb like membrane that covers organs -tomach5 1irst site of chemical digestion, breaks don food iver5 Dakes bile $aids in digestion% Aall bladder5 -tores bile 9sophagus5 Tube that leads to the stomach Eancreas5 Dakes insulin $aids in digestion% -mall Intestine $duodenum and ileum%5 absorb nutrients from food Desentery5 3olds coils of the small intestine together arge Intestine5 @ollects aste, absorbs ater @loaca5 "-eer"5 eggs, sperm, urine and feces enter this area -pleen5 Eart of circulatory system, stores blood
The &rogenital -ystem
Cidneys $2%5 1ilter Blood &reters $A%5 @arry urine from kidneys to bladder Testes $@%5 Dake sperm Oviducts $B%5 eggs travel through these Ovary5 makes eggs $% ! ovary is often too small to see, but eggs are visible &rinary Bladder $1%5 -tores &rine @loaca $9%5 )here sperm, eggs, urine, and feces e#it.
