How to Dissect a Frog

Pithing Process and Dissecting Process
(Pictures and information are from internet references)

1. Frog Dissection Prepared by: Ms. Jasmine Nikki M. Versoza

2. FROG VS. TOAD FROG TOAD

3. FROG VS. TOAD FROG Have a narrow body Take long high jumps Have longer hind legs Need to live near water Have higher, rounder, bulgier eyes Have smooth, moist skin that makes them look “slimy”

4. FROG VS. TOAD TOADS Have a wider body Have rough, dry, bumpy skin Have lower, football shaped eyes Have shorter, less powerful hind legs Do not need to live near water to survive Run or take small hops rather than jump

5. Warm-Up What do you think of dissection? What do you like? What do you dislike? Which organs do you want to see? Why?

6. DISSECTION to cut a part and see or to separate and clean the structures

7. Safety Measures Prepared by: Ms. Jasmine Nikki M. Versoza

8. SAFETY MEASURES Laboratory Gown - to protect your uniform Close shoes - gives safety to foot from dropped scalpels or sharp instruments

9. SAFETY MEASURES Gloves - to avoid the contact from preservatives and other chemicals Goggles - to protect the eyes against any foreign body during cutting

10. Dissecting Tools Prepared by: Ms. Jasmine Nikki M. Versoza

11. DISSECTING PROBE used for tearing connective tissues used for feeling the structures like vessels and nerves

12. SCALPEL used to cut the tissue and dissection of tough connective tissue used to divide the vessels, pedicels and other structures. used for the sharp dissection

13. DISSECTING FORCEPS Used for pulling or tearing Used to grasp, lift and hold the tissue

14. SCISSORS used in cutting and sectioning of tissue used to cut tough structures like tendons, ligaments

15. HAEMOSTATIC FORCEPS Artery forceps used to catch/clamp and to crush the tissue used for strong grasping and holding and catching

16. Anatomical Terminology: Directional Terms Prepared by: Ms. Jasmine Nikki M. Versoza

17. DIRECTIONAL TERMS Describe the positions of structures relative to other structures or locations in the body

18. SUPERIOR OR CRANIAL Toward the head end of the body Upper part of the body Example: the hand is part of the superior extremity

19. INFERIOR OR CAUDAL Away from the head Lower Part of the body Example: Foot

20. ANTERIOR OR VENTRAL Front part of the body Example: The kneecap is located on the anterior side of the leg.

21. POSTERIOR OR DORSAL Back part of the body Example : The shoulder blades are located on the posterior side of the body.

22. MEDIAL Toward the midline of the body Example: The middle toe is located at the medial side of the foot.

23. LATERAL Away from the midline of the body Example: The little toe is located at the lateral side of the foot.

24. BODY CAVITIES Prepared by: Ms. Jasmine Nikki M. Versoza

25. BODY CAVITIES The cavities are spaces inside the body that contain the internal organs. The two main cavities are called the ventral and dorsal cavities.

26. Dissecting Process Prepared by: Ms. Jasmine Nikki M. Versoza

27. Pinning the Frog Rinse the frog in water. Place it in the dissection pan on its dorsal side. Pin the limbs to the dissection pan. Why?

28. Incision 1-Skin

29. Incision 2- Skin

30. Skin Separation

31. First Muscle Incision

32. Cutting The Chest Bones

33. Horizontal Muscle Cut

34. Muscle Separation

35. LAYER 1: Liver and Heart Find each of these organs in the first layer under the muscles.

36. 1. LIVER The liver is a large, brownish colored organ covering most of the body cavity.

37. 2. Heart It is a small triangular shaped organ between the front legs and anterior to the liver.

38. LAYER 2: Gall Bladder, Stomach, and Small Intestines Use the tweezers to lift up the liver to reveal the second layer of organs.

39. 3. Gall Bladder Examine the gall bladder. Under the liver, we see a small, greenish sac. This is the gall bladder.

40. 4. Stomach The stomach looks like a sac on the frog's left side (on your right). It is a large firm organ.

41. 5. Small Intestine The small intestine is a long, folded, tube like organ that is posterior the stomach. It is similar in color to the stomach, but smaller in diameter.

42. LAYER 3: Lung and Pancreas Reveal layer three. Remove the liver to see the organs in layer three. The liver is easier to remove if you remove the gall bladder and heart at this time.

43. 6. Lungs The lungs are difficult to locate in a preserved frog. They're at the anterior end of the body cavity on either side of the heart.

44. 7. Pancreas You can't see the pancreas without lifting the stomach and intestines with the forceps. The pancreas is a thin, yellowish ribbon.

45. Do you have a Male or a Female Frog?- Layer 4

46. Frog Pithing Prepared by: Ms. Jasmine Nikki M. Versoza

47. Pithing Process 1. Hold the frog facing away from your body , with the inferior extremities. 2. Grasp the frog with your first two fingers: first finger on the nose , second finger under the jaw . 3. Move probe down midline until you come to the soft spot. Frog skull is fairly hard cartilage; soft spot is at the end of the skull .

48. Cranial Cavity of a Frog

49. 4. Insert the needle quickly into the cranial vault and sever the brain and spinal cord. 5. Move the probe into the cranial vault and move it from side to side to destroy the brain. 6. Test for reflexes to confirm that sensory perception has been destroyed and ensure that the spinal cord is still intact, although it is now in shock. Pithing Process

50. Corneal Reflex

51. Guide Questions Prepared by: Ms. Jasmine Nikki M. Versoza

52. GUIDE QUESTIONS How could you tell that the frog was a male or female? What was the largest organ in the frog? Which organs had two or more parts? Is the heart anterior or posterior to the lungs? What two pieces of safety equipment did we wear?

53. GUIDE QUESTIONS What are the tools that we used? Where do we place the pins in the frogs? How many pins did we used on the frog? What was the smallest organ we looked at? Which organ looked like noodles?

54. How could you tell that the frog was a male or female? The presence or absence of eggs

55. What was the largest organ in the frog? Skin

56. Which organs had two or more parts? Liver Lungs Intestines

57. Is the heart anterior or posterior to the lungs? The heart is anterior to the lungs.

58. What three pieces of safety equipment did we wear? Laboratory Gown Gloves Face Mask

59. What are the tools that we used? Pins Scalpel Scissors Pithing needle

60. Where do we place the pins in the frogs? One in each wrist, one in each leg, and one through each flap of muscle and skin

61. How many pins did we use on the frog? Six pins were used on the frog.

62. What was the smallest organ we looked at? Gallbladder is the smallest organ that we looked at.

63. Which organ looked like noodles? Intestines are noodle-like organ in terms of appearance

64. Study this picture carefully for a couple of minutes…

65. Label the Picture