Presentation on theme: "RAT DISSECTION The following should help you with the dissection of the rat and then to review for the lab practical that will follow."— Presentation transcript:
1 RAT DISSECTIONThe following should help you with the dissection of the rat and then to review for the lab practical that will follow.
2 Rat Dissection Scientific Name: Rattus norvegicus Common Name: Rat Kingdom- AnimaliaPhylum- ChordataSubphylum- VertebrataClass- MammaliaOrder- Rodentia
3 Rat DissectionDissecting tools will be used to open the body cavity of the rat and observe the structures. Keep in mind that dissecting does not mean "to cut up"; in fact, it means "to expose to view". Careful dissecting techniques will be needed to observe all the structures and their connections to other structures. You will not need to use a scalpel. Contrary to popular belief, a scalpel is not the best tool for dissection. Scissors serve better because the point of the scissors can be pointed upwards to prevent damaging organs underneath. Always raise structures to be cut with your forceps before cutting, so that you can see exactly what is underneath and where the incision should be made. Never cut more than is absolutely necessary to expose a part.
4 GradingYour grade on this laboratory will be assessed according to the following criteriaClass Participation (serious approach, proper cleanup and lab safety)Lab ChecklistQuizzes throughoutLab Practical Exam (at the end of lab)
5 Glossary of Terms Dorsal: toward the back Ventral: toward the belly Lateral: toward the sidesMedian: near the middleAnterior: toward the headPosterior: toward the hind end (tail)Superficial: on or near the surfaceDeep: some distance below the surfaceSagittal: relating to the midplane with bisects the left and right sidesTransverse: relating to the plane separating anterior and posteriorHorizontal: relating to the plane separating dorsal and ventral
6 Glossary of TermsProximal: near to the point of reference Distal: far from the point of reference Caudal: toward the tail end Pectoral: relating to the chest and shoulder region Pelvic: relating to the hip regionDermal: relating to the skin Longitudinal: lengthwiseRight & Left: refers to the specimen's right and left, not yours Abdominal Cavity: related to the area below(posterior) the ribcage Thoracic Cavity: related to the area above(anterior) the ribcage
7 Rat Anatomy ChecklistThroughout the course of the investigation, you will be asked to stop and have your instructor check your progress. At each checkpoint, you should have the box initialed by your instructor to ensure adequate progress. You will turn this sheet in at the end of the investigation.1. Rat skinned and muscles exposed.2. Remove muscles from one hind leg to expose the femur, tibia, and fibula.3. Pinning the structures of the head and neck.4. Pinning the organs of the digestive system.5. Removal and dissection of the kidney, opening of the stomach and small intestines.6. Pinning the urogenital organs.7. Exposing the subclavian, axillary and carotid arteries.8. Exposing the iliac and femoral arteries.9. Turn in the rat.
8 Rat External Anatomy Obtain your rat. Place it in your dissecting pan to observe the general characteristics.The rat's body is divided into six anatomicalregions:cranial region – headcervical region – neckpectoral region - area where front legs attachthoracic region - chest areaabdomen – bellypelvic region - area where the back legs attach
9 Rat External Anatomy Identification List VibrissaeIncisorsPupilNictitating membraneEyelidsPinnaAuditory meatusTeatsTailAnusFemale ratsUrinary apertureVaginal orificeVulva.Male ratsScrotal sacsTestesPrepuceUrogenital orifice
11 Skinning the Rat You will carefully remove the skin of the rat to expose the muscles below. This task isbest accomplished with scissors and forcepswhere the skin is gently lifted and snippedaway from the muscles. You can start at theincision point where the latex was injectedand continue toward the tail. Use the lines onthe diagram to cut a similar pattern, avoidingthe genital area. Gently peel the skin fromthe muscles, using scissors and a probe totease away muscles that stick to the skin.
17 Organs of the Head and Neck Locate the salivary glands, which on thesides of the neck, between muscles.Carefully remove the skin of the neckand face to reveal these glands.There are three salivary glands – thesublingual, submaxillary, and parotid.Find the lymph glands which lieanterior to the salivary glands. Lymphglands are circular and are pressedagainst the jaw muscles.
18 Organs of the Head and Neck After you have located the submaxillaryglands, remove them to find the underlyingstructures.The thyroid gland is a gray or brown swellingon either side of the trachea. To locate thetrachea you will need to carefully remove thesternohyoid muscles of the neck.
19 Thoracic Organs Cut through the abdominal wall of the rat following the incision marks in thepicture. Be careful not tocut to deeply and keep thetip of your scissors pointedupwards. Do not damage theunderlying structures.
20 Thoracic Organs Identification List DiaphragmHeart – atria and ventriclesThymus GlandBronchial TubesLungs
21 Abdominal OrgansCarefully pin back the skin and the abdominal wall to fully expose the abdominal cavity as shown in the picture.
22 Abdominal Organs Liver Stomach Spleen Pancreas Small intestine Large intestineCecumRectum
24 Urogenital System The excretory and reproductive systems of vertebrates are closely integrated and areusually studied together as the urogenitalsystem. They do have different functions:the excretory system removes wastes andthe reproductive system produces gametes(sperm & eggs). The reproductive system alsoprovides an environment for the developingembryo and regulates hormones related tosexual development.
25 Excretory System The primary organs of the excretory system are the kidneys. These organs arelarge bean shapedstructures located towardthe back of the abdominalcavity on either side of thespine. Renal arteries andveins supply the kidneyswith blood.
26 Excretory System Identification List KidneysAdrenal GlandsUreterBladder
27 Reproductive Organs of the Female Rat VaginaO varyOviductsUterine Horns
28 Circulatory System The general structure of the circulatory system of the rat is almost identical to thatof humans. Pulmonary circulation carriesblood through the lungs for oxygenation andthen back to the heart. Systemic circulationmoves blood through the body after it hasleft the heart. You will begin your dissectionat the heart. It is important that you do notcut the vessels as you carefully remove anymuscles and surrounding tissue to exposethem.
29 Trace the Flow of Blood Trace the flow of blood from the right atrium tothe lungs and then backto the heart, you may notbe able to locate allthese structures due tothe placement of theheart and vessels, butyou should be able tofind a few of them andlabel all of them on adiagram.
30 Circulatory System Identification List Left/Right Common Carotid ArteriesAbdominal AortaLeft/Right Femoral ArteriesLeft/Right Jugular VeinsCaudal Vena CavaLeft/Right Femoral Veins