External Anatomy Pupil - The opening through which light enters an eye. Iris - The colored part of the eye which forms and regulates the size of the pupil. Cornea - The transparent anterior part of the external layer of the eye (transparent outer covering of the eye). Nictitating Membrane - A transparent part of a frog’s lower eyelid that moves over the eye to clean it and protect it. Lens - The transparent structure within an eye that focuses light rays. External nares or nostrils - Anterior openings for the entry or exit of air. Tympanic Membrane - The eardrum - receives sound waves Flexors - Muscles which contract to move a part toward the body. Extensors - Muscles which contract to move a part away from the body. Mucous Glands - Structures in the skin of a frog that secrete mucous which keeps the skin moist. Poison Glands - Structures in the skin of the frog which secrete a whitish fluid that is highly irritating to enemies. Epidermis - The outer layer of the skin. Dermis - The inner layer of skin which contains blood vessels and pigment cells. Glottis - The opening from the mouth into the respiratory system. Larynx - The voice box (contains vocal cords). Bronchi - The short tubes of a frog’s breathing system that leads from the larynx to the lungs. Lungs - Exchange point where CO2 leaves and O2 enters the blood Alveoli - Air sacs in the lungs where the movement of gases occurs. Red Blood Cells - Blood cells which carry O2 and CO2. Hemoglobin - The red pigment in red blood cells which combine with and carry gases. Cold-blooded - Condition or designation of an animal’s body temperature being the same as the external temperature. Hibernation - A state of dormancy during which life processes and activities are greatly slowed and reduced. Arteries - Thick-walled blood vessels that carry blood under high pressure away from the heart. Arterioles - Small arteries which branch out into capillaries. Capillaries - Smallest blood vessels with thinnest walls through which substances move into and out of the blood. Venules - Small blood vessels which carry blood away from capillaries. Veins - Thin walled blood vessels that carry blood under low pressure to the heart. Neurotransmitters - Chemical substances produced by an animal that influence parts of the body (“chemical messengers”). Tongue - Muscular structure attached to the front of the mouth which is extended to catch insects (its food). Maxilla - The upper jaw. Maxillary Teeth - Sharp teeth in the maxilla of a frogs mouth that function in holding captured prey. Mandible - The lower jaw. Vomerine Teeth - Small projections in the top of a frog’s mouth that function in holding and captured prey. Eustachian tube openings - Openings in the mouth that lead to tubes that connect to the middle ear to equalize air pressure.
Internal Anatomy Skeletal muscles - Muscles of the body which control voluntary movements. Tendons - Strands of tissue which attach skeletal muscles to bones. Smooth Muscle - Muscle tissue of inner organs which control involuntary muscles. Gullet - Posterior part of the mouth cavity in a frog. Food enters the esophagus here. Esophagus - Tube that connects the mouth and the stomach in a frog. Stomach - Stores food and mixes it with enzymes to begin digestion. Digestive Enzymes - Function in the chemical part of breaking down food. Mucous - Lines the digestive system and protects it from acid and enzymes. Mucous Cells - Special cells which secrete the mucous. Pylorus - The opening between the stomach and the small intestine. Small Intestine - The principal organ of digestion and absorption of digested food. Duodenum - The anterior (front) part of the small intestine into which food passes from the stomach. Peristaltic Waves - Automatic muscular contractions of the smooth muscle tissue in the walls of organs of the digestive system to move food. Pancreas - Gland which secretes digestive enzymes into the duodenum. Bile - Fluid produced by the liver that aids in the digestion of fats. Gall Bladder - Sac which stores bile. Common Bile Duct - Tube which carries bile from the gall bladder and digestive juice from the pancreas into the duodenum. Ileum - The posterior part of the small intestine. Site of absorption of digested food. Large Intestine - Posterior organ of the digestive system which stores undigested food. Rectum - Posterior part of the large intestine Cloaca - Organ through which the products of the frogs digestive and urogenital system pass when discharged from the body. Cloacal Opening - Opening of cloaca through which undigested food, urine, eggs, and sperm are passed. Liver - Secretes bile and processes digested food molecules carries in the blood from the ileum. Veins - Blood vessels that carry blood to the heart. Arteries - Blood vessels which carry blood away from the heart. Capillaries - Blood vessels through which substances enter and leave the bloodstream. Anterior Vena Cava - Large vein that carries blood from the anterior part of the body toward the heart. Posterior Vena Cava - Large vein that carries blood from the posterior part of the body towards the heart. Sinus Venosus - Sac that receives blood from the vena cava Heart - Pumping organ of the circulatory system (has 3 chambers). Right Atrium - Chamber of the frogs heart which receives blood from the sinus venosus. Left Atrium - The chamber of the heart that receives blood from the lungs. Pulmonary Veins - The blood vessels that carry blood form the lungs to the left atrium. Ventricle - Chamber of a frog’s heart that pumps blood out of the heart to the lungs and other parts of the body. Truncus Arteriosis - Large artery in a frog that carries blood away from the ventricle into branches that lead to all parts of the body. Spleen - Organ in the frog’s circulatory system that makes, stores, and destroys blood cells. Kidneys - Organs in the frog’s excretory or urogenital system that filter the blood and remove the wastes to make urine. Urinary Ducts - Tubes in a frog that carry urine from the kidneys to the cloaca Urinary Bladder - The organ that collects and stores urine until released. Adrenal Glands - Organs located near the kidneys which secrete hormones. Ova or Eggs - Female sex cell or gametes Ovaries - Organs of the female reproductive system that produce the eggs. Oviducts - Tubes of a female frog’s reproductive system that carry eggs from the ovaries to the cloaca. Testes - Male sex organs that produce sex cells (sperm). Sperm - Male sex cell or gametes. Seminal Vesicles - Enlarged distal sections of the male frog’s urinary ducts that collect sperm prior to entry into the cloaca. Fat Bodies - Masses of fat in the body cavities of frogs. Needed for hibernating and mating Central Nervous System - Brain and spinal cord. Peripheral Nervous System - Part of the nervous system which branches out from the CNS to all parts of the frog’s body Neurons - Cells which make up the nervous system. Each is made up of a cell body and fibers of varying lengths. Nerves - Bundles of neurons fibers which transmit messages. Brain - Main organ of the nervous system. The “control center”. Olfactory Lobe - Part of the frog’s brain associated with the sense of smell Cerebrum - Part of the brain that is associated with memory, pain, and voluntary muscle control. Optic Lobes - Part of the brain associated with vision. Cerebellum - Part of a brain that influences balance and equilibrium. Medulla Oblongata - Part of a brain that is the center for some involuntary functions. Cranial Nerves - Nerves that lead to and from the brain. Spinal Cord - Main pathway to and from the brain Spinal Nerves - Nerves that lead to and from the spinal cord.
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