Biology in Health Sciences Lectures, 1st year college in Psychology (midterms and finals), Lecture notes of Biology

Download Biology in Health Sciences Lectures, 1st year college in Psychology (midterms and finals) and more Lecture notes Biology in PDF only on Docsity! //Frog Dissection// EXTERNAL PARTS FROG CHARACTERISTICS - the skin is smooth and moist - the color of the skin is darker at the back than at the front Countershading - a form of camauflage √ also known as Thayer’s law, √ a method of camouflage where an animal’s coloration is darker on the top or upper side and lighter on the underside of the body. √ help them hide from various predators. - a frog has four appendages √ two fore legs and two hindlegs (4 toes on each of fore legs, five toes on each of its hindlegs ) webbing between the toes - helps the frog swim in the water its longer hindlegs helps it jump on land DETERMINING THE FROG’S GENDER Female bullfrogs - fully grown female bullfrogs (will grow atleast 7 inches/19 cm long) - larger than fully grown male Male bullrfrogs - fully grown male bullfrogs (6.75 inches/17 cm long in the video); therefore we will know that this frog is a male Tympanic membrane - the size of its tympanic membrane also indicates the gender - a male’s tympanic membrane will be larger than its eyes - a female’s tympanic membrane will be about the same size than its eyes MEASURING THE FROG - we measure it from the very tip of its mouth to the very end of its backbone; - we do not include the legs in its measurement STRUCTURES OF THE HEAD - anterior (front part) region of the frog near the mouth are two slotted openings √ external nares/external nostrils Eyes - posterior (back part) to the nares are the eyes a frog has two large bulging eyes 3 eyelids - 1 pair of eyelids open and close o protect the frog from amphibians - third eyelid is a transparent membrane that protects the eyes while the frog is swimming underwater - sometimes the third eyelid becomes cloudy when the frog is prepared for dissection that’s why we cannot clearly see the structures inside the eye Tympanic membrane - right behind each eye is a round flat structure - for hearing; same as we use our eardrums THE MOUTH once the frog becomes prepared, its mouth is set; we need to pry the mouth open to look at the structures inside Blunt probe - used to force the mouth open wide enough to insert a finger and then pull back on the mouth to hold it open just a little A pair of scissors - used to cut the muscles at the corners of the in order to release the jaw the tongue - has a split in the middle - a frog can stretch its mouth quite far and rapidly because the tongue is attached to the front of the mouth the dorsal (the back or upper side) side of the frog we find the external nares Some frogs have teeth A frog’ teeth are not made for biting or chewing. They are designed to hold the frog’s prey while it eats. A bullfrog has tiny teeth at the edge of its upper jaw. Right between the internal nares is another set of teeth Eustachian tube - at the side of the mouth near the back of the throat - they equalize the pressure in the frog’s ears while it’s swimming. Esophagus - between the two eustachian tubes is the beginning of the esophagus √ a tube leading from the mouth to the stomach Glottis - it is the opening to the trachea. Just below the esophagus, a glottis is another opening Trachea - The trachea is a tube that leads to the frog’s lungs Epiglottis - (looks like a flap). when the frog swallows food, the epiglottis closses the trachea to keep food from entering the lungs