Dissection Guide to the…

LAB SAFETY AGREEMENT

ReminderStudents will be removed from the science

activity area by the teacher if:

• Their personal appearance or dress is such that they can cause injury to themselves or to other students.

FASHION

HAZARD

• They are behaving in such a manner

that they can cause injury to

themselves or to other students.

STUDENTS

MISBEHAVING

• They are not following the prescribed

safety rules for the science activity

area or the particular science activity

being conducted.

FOLLOW

LAB SAFETY

RULES

• They are going beyond the limits of

the science activity into areas that

may lead to an unsafe situation.

• They have not completed the pre-

experiment activities that will allow

them to work safely in the laboratory

situation.

Introduction

• Norway rat (Rattus norvegicus)

• Family Muridae

• Includes house mouse, gerbil, hamster

• Old World species originated in Asia

• Migrated to Europe by mid-1500s

• Reached North America about 1775 by

stowing away on colony-bound ships

Why dissect a rat?

• Commonly used in studies of comparative

vertebrate anatomy

• Rat displays typical mammalian body plan

Purpose

• To compare the structures of the rat with

those of the human.

Materials

• rat

• goggles

• dissection pan

• scissors

• dissecting needles

• probe

• name tag

Part 1 – Anatomical Terms

Part 2 – External Features

• external nares (opening to the nose)

• upper and lower eyelid

• pinna (earflap)

• vibrissae (whiskers)

Part 3 – Skinning the Rat

• Read and follow directions carefully.

• The skin and muscles

are very thin.

• Be careful not to cut

all the way into the

body cavity.

• Skinning the rat

takes time and work.

Part 4 – Muscles

• Use diagrams to help locate and describe

the function of the major muscles.

Clean Up

• Seal rat with name tag in storage bag

• Wash and return dissection instruments

• Wipe down your lab table

• Wash your hands

Day 2 – rat dissection

• Take out your Rat Practical Study Guide.

• Write the date of your exam on the top

right corner:

– 2nd Wednesday, 1st @ 7:20 am

– 3rd Thursday 2nd @ 9:28 am

– 5th Tuesday, 31st @ 7:20 am

– 7th Friday, 27th @ 7:20 am

• Get your rat, unwrap it and lay it on your

tray. Wait for further instructions.

Day One Review• How well did you skin your rat?

• These are the muscles you must be able to identify:– Pectoralis major

– Biceps brachii

– Lattissimus dorsi

– Biceps femoris

– Gastrocnemius

– External oblique

– Triceps brachii

• If you can locate and ID them all, you are finished

skinning your rat.

• We will have a review day next Thursday to look

over all these muscles and body systems on your rat

to help you prepare for the test.

Fascia – fibrous tissue

that connects skin to

muscle.

Part 5 – Opening the body cavities

• Make an “I” shaped incision.

• Remember the layer you

are cutting is thin.

• Avoid cutting too deeply.

• Fold back the flaps.

Part 1 – The Digestive System

• Use the diagram of the abdominal view

in the dissection guide to help locate the

major structures in the abdominal cavity.– Liver

– Stomach

– Spleen

– Small intestine

– Pancreas

– Large intestine

– mesentaries

Part 2 – The Respiratory System

• The rat has 4 lobes to the right lung

• The left lung is

one solid piece

• Identify

– Lobes

– Trachea

– Diaphragm

Part 3 – The Circulatory System

• Do not remove the heart

• Find the indicated

structures:

– Atria

– Ventricles

– Pericardium (if

you can)

heart

Part 4 – The Excretory System• Locate the major excretory organs.

– Kidneys

– Ureter

– bladder

Part 5 – The Reproductive System (Male)

• Locate major male reproductive organs.

– Scrotum

– Testes

Part 6 – The Reproductive System (Female)

• Locate major female reproductive organs.

– Ovaries

– Uterus

Clean Up• Dispose of sealed rat in trash can

• Wash and return dissection instruments

• Wipe down lab table

• Wash your hands

• Answer questions on back of lab sheet

Part 8 – The Mouth

• With a pair of scissors, cut the jaw bone

at the same angle as the mouth, so that

the mouth opens easily.