DISSECTION 101 THE FROG Dissection helps us understand how living things function. Dissection is analytical. Dissection is an adventure.
Discussion Frog anatomy is unique in that it does resemble human systems in many ways. Organs, skeletal, muscular, respiratory, excremental, digestive and sensory systems are all part of frog anatomy, just as they are in humans. Naturally, a human is much more complicated and complex; but the basics are very alike. There are also some anomalies in frog anatomy that puzzle scientists. Certain intrinsic features, such as a long, sticky tongue seem natural to meet the dietary requirements of a frog. Specialized bone structures in their hind legs are perfectly aligned for jumping and leaping activities. Did you know that frog have teeth? They do, although they don t have the same kind of teeth that humans have; but still they have teeth. Maxillary teeth line the upper jaw edge while Vomerine teeth are found on the roof of their mouths and point inwards. Neither set of teeth are used for chewing or biting, rather, scientists believe frogs use these teeth to simply hold their food captive until it is in such a position as to be swallowed whole. The very idea of frog teeth is an odd yet factual point of interest about frog anatomy. Another interesting aspect of frog anatomy is in the organs they possess. Frogs have fully functioning lungs, a three chambered heart, highly developed sensory organs, a digestive system all work together to form the living frog. The finely tuned sight and smell organs are vital to the frogs hunting and feeding process, as well as a form of protection in identifying their predators. Frogs use their keen sense of smell to detect chemical signals that help them identify potential food. The ears are another highly sensitive organ. Frogs actually hear in two different ways; high-pitched sounds reach the ears of a frog while lower pitched noises are detected through their skin. The skin of a frog is just as complex is not amazing in its own right. Frogs have lungs that breathe air while on land. Did you know that a frog can breathe underwater? While underwater, oxygen in the water passes through the porous skin of a frog and goes directly into their bloodstream supplying them with an adequate supply of oxygen to sustain life while submerged. The frog anatomy is quite an amazing study. Lungs that breathe, a heart that pumps, and skin that breathes; one would never guess that such a mystery lies within the humble frog. Now let s chop him up
Terms The following is a list of terms that are frequently used when performing a dissection. You should be familiar with the terms listed below. Dorsal - The back or upper part of the specimen Ventral- The abdominal side or lower part of the specimen Cephalic - The head of the specimen Cranial - The upper part of the head Anterior - The forward of front end of the specimen Posterior - The hind or rear part of the specimen Caudal - The tail end of the specimen Transverse - The cross section of the specimen Longitudinal - Along the length of the specimen Proximal - Nearest to, or at point of origin or attachment Distal - Farthest from origin or point of attachment
Dissection Instruments You should also be familiar with the dissecting instruments that you will be using. The following is a list of instruments that will be needed to complete the dissection: A dissection tray or pan - your specimen will be dissected on this. Dissecting pins - these will be used to hold your specimen in place during the dissection. Dissecting Needle - this is used to point to organs and for separating organs from their connective membranes. Probe - this is used to explore the cavity of your specimen and is designed to reach where your fingers can t. The dissecting needle can also function as a probe. Scalpel - this is used to cut. Your scalpel should be sharp so use caution. The scalpel is also used to cut organs out of your specimen. Dissecting scissors - these are used to cut through the skin and muscle tissue of your specimen. It prevents internal damage to other vital organs that a scalpel may cause. Straight or curved forceps - these are commonly known as tweezers. They are used to grasp organs and tissues also to lift certain internal organs up to see underneath. Magnifying lens - this is used to examine internal organs and internal structures within your specimen.
Frog Anatomy During the dissection, you will become familiar with the following internal anatomy of a frog. It s important to take special care when exploring the internal anatomy of a specimen due to the small space in which it occupies. Place a check by each part of the frog s anatomy that you have correctly identified. Lungs Fat body Testis Kidney Pancreas Spleen Bladder Urinary duct Pectoral girdle Lobes of liver Heart Gall bladder Stomach Duodenum Intestine Abdominal cavity Rectum Stomach contents Describe what your specimen s last meal was: