Transcript Lab 3
Lab Introduction Lab safety Lab #3 - microscopes Safety info Read the pamplet Sign the blue sheet Under 18? Please see me. Lab safety First aid kit at the front Fire extinguisher at the back Eye wash at sink Showers in the back Lab Safety No eating or drinking in lab Clean up rule: – It is your responsibility to clean up after yourself and put everything back like you found it Lab clean up Put models back, like you found them Put microscopes back Put slides back in the proper box Lab clean up Dispose of other items as follows: – Paper towels go in the trash – Broken glass and slide cover slips go in “broken glass” – Biological waste goes in red bucket – Empty slides get rinsed, dried, and returned to box – Dissection tools: put in wash – Wipe down your bench area when done Lab Manual Lab assignments will require you to turn in the “Review Sheet” at the end of each lab exercise This must be ripped out of your lab manual, not photocopied Sometimes you will also be asked to turn in separate drawings or data Due Wed of the week following the lab Lab 3: Intro to microscopes Microscopic anatomy: – Cells – Tissues Who cares? Medically, microscopes are used for pathology, the study of disease. – If a disease is suspected, a tissue sample is taken (biopsy, blood) or a cell sample (pap test) – Pathologist or technician looks for abnormal cells, etc. What about us? Scientifically, microscopes are used to study cells and tissues for all kinds of reasons (e.g. CSI). Educationally, microscopes are the only way to truly learn about the microscopic organizations of cells and tissues. Knowing how to use a microscope is a great skill to have, no matter what medical or biology subfield you are involved in. Compound microscope Uses multiple lenses to achieve larger magnification Compound microscope Key parts: – Eyepieces (ocular objectives) – Arm – Base – Objectives – Stage (and stage clips) – Stage controls – Coarse and Fine focus – Condenser – Iris diaphragm – Light Microscope Rules Carry a microscope with two hands, one on arm, one on base Put your microscope back in the numbered cubby it came from Clean lenses only with special lens paper Start by using low powers, then go up to higher powers Properties Compound: occulars = 10x, objectives = 4x, 10x, 40x. Multiply to get total magnification Parafocal Inverted optics Field of view How to use a compound scope Start on lowest power (condenser up) Load slid into clip Look thorough oculars, adjust (one image) Focus (coarse) Find region of interest, go to higher power Focus (fine only because it’s parafocal) **Adjust light level and iris diaphragm as needed (less light at low power) Careful When using higher power objectives, it is easy to break slides because the working distance is small (lens is close to slide) Activity 1 ID scope parts Activity 2 Get a letter e slide Follow instructions and fill in table on p.30 Total mags = ocular x objective Measure working distances w/ ruler Draw what you see Don’t do the 100x (oil) objective Activity 3 Get a grid slide and measure the field diameter using low power (4x) objective by counting the number of grid squares that you can see across the field of view (1 sq = 1mm) Calculate the field diameters for the other lenses (not oil) Field diameter formula (p.32) F.D. lens B = F.D. lens A x total magnification lens A total magnification lens B Example: say you count 10 squares across using the 4x F.D. (10x obj) = F.D. at low power x total mag @ low power total magnification med power = 10mm X 40x 100x = 4mm Activity 4 - depth Get a thread slide (has three threads that cross each other) Focus down with the coarse focus until all the threads are just out of focus Then, slowly focus up, taking note of which thread comes into focus first (top), then second (middle), and last (bottom) Activity 5 Practice making a wet mount slide – Put drop on slide – Put on over slip at an angle Take an epithelial cell slide and estimate the diameter of one cell based on your field diameter measurements. (e.g., if it takes up half the field and the filed = 10 mm then it’s 5 mm) Clean up Cover slips in lab glass container Wash/dry fresh mount slides, put back Put prep’d slides back into correct box Clean off lens with lens paper and lens cleaner ONLY Clean off stage and return scope Clean up your area Activities 1. 2. 3. 4. 5. Get scope and set up, I.D. parts Letter “e” slides (prepared). Grid slide: count and calculate – measure at lowest power, use this figure to calculate answers at higher power (table on page 30). Thread slides (Careful, they’re thick). Determine order of threads. Make pond water wet mount slide and observe (practice focusing) Clean up Turn in Lab 3 report (review sheet) due next Thurs (rip out). Turn in page 30 with completed summary table (except oil objective) Write the correct order of the threads on the bottom of page 38 like this: Top___________ Middle____________ Bottom____________