AS - Cells and microscopy Flashcards
Light Microscopes, Resolution Magnification Advantages Disadvantages
M = x1500
R = 200nm
+ Can view living organisms, Easy, cheap, small
- Limited resolution
Transmission Electron Microscope Resolution Magnification Advantages Disadvantages
M = x100 000
R = 0.1nm
+ Higher resolution and magnification than LM
- Specimen cannot be alive, black and white images
Scanning Electron Microscope Resolution Magnification Advantages Disadvantages
M = x500 000
R = 0.1nm
+ High magnification, can make 3D images
- Cannot be alive specimen, large, expensive
Confocal Microscope Resolution Magnification Advantages Disadvantages
M = x2000
R = higher than LM, lower than EM
+ Looking at living cells
Understanding relationships between cells
Highlighting individual components of cells
- large, expensive
Magnification Calculation
Image size = Magnification x Object size
(micrometres) = 1mm/1000
Leishman’s Stain
Blood dried firsr, fixed with methanol, flooded left for 2 minutes than diluted with water, left 5-7 minutes, washed
Wright’s stain
White Blood cell counts
What happens if blood smear is spread to thin/thick
too thin: small sample
too thick: individual cells cannot be seen
Blood Functions
- deliver oxygen/ nutrients to tissues
- removal of waste from tissues
- clotting
- distribution of heat to regulate core body temperature
What are Leucocytes
White Blood Cells
Granulocytes - contain granules
Agranulocytes - no granules
Neutrophils
Help body defend against fungal or bacterial infections
Multi lobed nucleus - allows flexibility
Engulf and breakdown bacteria
Thrombocytes (platelets)
2-3(micrometer) diameter, biconcave discs
produced in bone marrow + no nucleus
blood clotting
circulate in blood for 6-7 days
Erythrocytes
Deliver oxygen/ CO2
develop in bone marrow circulate i blood stream 100-120 days
Diameter = 6.2-8.2(micrometers)
2-2.5 (micrometers) thick
No nucleus, large SA/V ratio, biconcave flexible + squeeze through capillaries
Lymphocytes
B: produce immunoglobulins
T: Helper T - produce cytoxins coordinate immune response.
Cytotoxic T cells: bind to antigens and destroy them
Monocytes
Phagocytosis, remove dead cell debris