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Name _____________________________________________________ Period _________ Due date ______________________ FROG DISSECTION External Anatomy Observe the dorsal and ventral sides of the frog. What color is the dorsal side?___________________________________________ What color is the ventral side?___________________________________________ Examine the hind legs of the frog. How may toes are present on each foot?__________________________________ Compare the toes and arrangement of the frog hind leg toes to that of humans. Examine the forelegs of the frog. How many toes are present on each appendage?_______________________________ Compare the toes and arrangement of the frog foreleg toes to the fingers of a human. Use a ruler to measure your frog. Measure from the tip of the head to the end of the frog’s backbone (NOTE: do not include the legs in your measurement). Compare the lengths of other frogs to your frog. Your Frog (cm) Frog 2 (cm) Frog 3 (cm) Frog 4 (cm) Frog 5 (cm) Average (cm) 1|Page Locate the frog’s eyes. The nictitating membrane is a membrane that is attached to the bottom of the eye. Use tweezers to carefully remove the nictitating membrane. What color is the nictitating membrane? _______________________________________ What is the function of the nictitating membrane? If time permits, you may remove the eyeball. Label the following on the human eye diagram below Word Bank Cornea Macula Vitreous gel Fovea Optic nerve Iris Pupil Lens Retina 1 . 2 . 6 . 3 . 4 . 7 . 8. 5 . 9 . 2|Page Just behind the frog’s eyes is a circular membrane called the tympanic membrane. Measure the diameter of the tympanic membrane________________________ How does the tympanic membrane function for the frog? Label the following on the human ear diagram below: Word Bank Auditory Canal Inner Ear Cochlea Middle ear 1 . Eardrum Outer ear 2 . 4 . 6 . 7 . 3 . Eustachian tube Semicircular canal 8 . 5 . 3|Page Label the following on the frog diagram below: Word Bank Dorsal External Nares/nostril Posterior Tympanum Anterior Nictitating membrane 4 . 5 . Eye Ventral 6 . 1 . 2 . 8 . 3 . 7 . Pry open the frog’s mouth and use scissors to cut the angles of the frog’s jaw open. Cut deeply enough so that the frog’s mouth opens wide enough to view the structures inside. Locate the tongue. Does it attach to the front or the back of the mouth? ____________________________ Sketch the frog’s tongue. 4|Page In the center of the mouth toward the back is a single round opening that leads to the esophagus. The esophagus leads to the stomach. Close to the angles of the jaw are two openings, one on each side. These are the Eustachian tubes which function to equalize pressure in the inner ear while the frog is swimming. Insert a probe into the Eustachian tube. To what structure does the Eustachian tube attach? _________________________________________________ Just behind the tongue and before the opening to the esophagus, is a slit-like opening. This slit is the glottis and it opens to the lungs of the frog. The frog breathes and vocalizes with the glottis. The frog has two sets of teeth. The vomarine teeth are found on the roof of the mouth. The maxillary teeth are found around the edge of the mouth. Both are used to hold prey in the mouth. Frogs swallow prey whole, they do not chew. On the roof of the mouth you will find two tiny openings. Place your probe into these nostril openings to determine where they exit on the outside of the frog. Label the following on the diagram of the frog’s head: Esophagus Internal nostril Vomerine teeth Eustachian tube Maxillary teeth 1 . 2 . 3 . Word Bank External nostril Mouth Eye Tongue 5 . 4 . 6 . Glottis Tympanum 7 . 8 . 9 . 10 . 11 . 5|Page Label the following on the diagram of the human mouth: 3 4. . 5 . Word Bank Canine Hard Incisor Gingival teeth palate teeth Molar Premolar Tongue Tonsils teeth teeth Soft palate 6 7 . 8 . . 9 . 1 0. Lips Uvula 1 . 2 . 11. Dissection Place the frog on the dissecting pan, ventral side up. Use scissors to lift the abdominal muscles away from the body cavity. (1) Cut along the midline of the body from the pelvis anterior to the tip of the mouth. (2) Make transverse (horizontal) cuts near the arms and (3) legs. Lift the flaps of the body wall and pin back. 6|Page Locate each of the organs below. Fat bodies – spaghetti shaped structures that have a bright orange or yellow color. Fat bodies may need to be removed to see other structures. They are usually located just inside the abdominal wall. Peritoneum – A spider web-like membrane that covers many of the organs. You may need to carefully remove it to get a clear view. Liver – this is the largest structure of the abdominal cavity. It is brown colored and composed of three lobes. Heart – located anterior to the liver. It has a triangular shape. The left and right atrium can be found at the top of the heart and the single ventricle is located at the bottom. Lungs – found underneath and behind the liver and the heart. They look like sponges. Gall bladder – lift the lobes of the liver to find this small green sac. Stomach – curving from underneath the liver is the stomach. Pyloric sphincter – follow the stomach to where it empties into the small intestine. This is where you will find this structure. Small intestine – the stomach empties into the small intestine. The first portion is called the duodenum, the curled portion is the ileum. The ileum is held in place by a blood vessel filled membrane called the mesentery. Large Intestine – the small intestine empties into the wider large intestine. In the frog it is also known as the cloaca. Spleen – in the folds of the mesentery you will find a small dark red spherical structure. 7|Page Label the following diagram: Word Bank Large intestine Liver Small intestine Stomach Gall bladder Right atrium Lung Ventricle 1 . 2 . 3 . 4 . 5 . 6 . 7 . 8 . If time permits, remove the stomach and examine the contents. 8|Page If time permits, remove the small intestine and measure the length. 9|Page Label the following diagram of the human digestive system: Word Bank Gall bladder Large intestine Pancreas Rectum Esophagus Mouth Stomach Liver Small intestine 4 . 5 . 1 . 2 . 3 . 6 . 7 . 8 . 9 . 10 | P a g e Label the following on the diagram of the human heart: Word Bank Inferior vena cava Left atrium Right atrium Right ventricle Aorta Pulmonary vein Left ventricle Superior vena cava 4 . 1 . 5 . 6 . 2 . 7 . 3 . 8 . The frog’s reproductive system and excretory system are combined into one system called the urogenital system. You will need to know the structures for both male and female frogs. Kidney – flattened bean shaped organs located dorsally at the lower back near the spine. They are often dark in color. Testes – in male frogs, these organs are located at the top of the kidneys. They are pale colored and roundish in shape. Oviducts – these are curly structures around the outside of the kidney. Males may have a similar structure which is actually a vestigial oviduct. Bladder – this is an empty sac located in the most posterior region of the abdominal cavity. Cloaca – sperm or eggs and urine exit here 11 | P a g e Label the following in the diagrams of the frog urogenital system: Male Word Bank Bladder Cloaca Fat Kidney Testes Female Word Bank Bladder Cloaca Eggs Fat Kidney Oviduct 1 . 1 . 5 . 4 . 2 . 3 . 4 . 5 . 2 . 3 . 6 . 12 | P a g e Study and removal of the brain. Turn the frog dorsal side up. Cut away the skin and flesh on the head from the nose to the base of the skull. With a scalpel, scrape the top of the skull until the bone is thin and flexible. Be sure to scrape AWAY from you. With your scalpel held almost horizontally, carefully chip away the roof of the skull to expose the brain. Use scissors to cut away the heavier bone along the sides of the brain. Label the following on the frog brain: Cerebellum Cerebrum Word Bank Medulla oblongata Olfactory lobe Optic lobe Spinal Cord Label the following on the human brain: Word Bank Cerebrum Cerebellum Medulla oblongata 1 . 2 . 3 . 13 | P a g e The bones of the frog follow the same basic pattern as other vertebrates. The lower leg of the frog is a muscular leg that the frog uses for jumping. Label the following bones on the frog skeleton diagram: Word Bank Astragalus Atlas Calcaneum Carpals Ilium Metacarpals Metatarsals Phalanges Suprascapula Tarsals Tarsus Tibioulna Femur Radio-ulna Rudimentary toe 1 . Humerus Sacral vertebrae Urostyle 10 . 6 . 2 . 11 . 7 . 8 . 9 . 1 4. 15 . 12 . 1 3. 16 . 3 . 17 . 4 . 5 . 18 . 14 | P a g e Label the following bones on the human skeleton: Cranium Patella Ribs Word Bank Carpals Femur Metacarpals Metatarsals Tarsals Tibia Clavicle Pelvis Scapula Fibula Phalanges Ulna Humerus Radius Vertebrae 1 . 2 . 10 . 11 . 3 . 12 . 4 . 1 3. 5 . 1 4. 6 . 15 . 7 . 16 . 17 . 8 . 9 . 18 . 15 | P a g e