General Flashcards
Describe the process of light microscopy
Preserve sample using formalin to prevent rotting
Embed tissue in melted paraffin, so that when it is cooled it sets hard allowing it to be thinly sliced by a microtome
Stain tissue using haematoxylin (stains nucleus blue) and/ or eosin (to stain cytoplasm& extracellular matrix pink).
What are the benefits of using a frozen section under a light microscope? How is the sample frozen and cut?
Sample is frozen in a cryostat and then cut using a microtome. This technique is much faster but lower quality. Can be done mid surgery.
What is electron microscopy? What are two types?
Using electrons to see higher resolution images. TEM is electrons in a vacume and using the proportion of electrons that pass through the sample as an indicator of where dense structures are. SEM looks at the electrons bouncing off the structures, and creates a 3D image of the structures surface
How does an ultrasound scanner work?
Piezo electrical crystal expands when voltage applied, so voltage applied and removed very quickly causing disturbances to air around it (ultra sound). The piezo electrical crystal also detects ultrasound waves hitting it and creates a voltage. The waves will return when they hit dense structures and so it can detect structures within the body.
Why is there a need to find a balance between short and long wavelengths when using ultrasound scanners?
short= higher resolution but low penetrance long= deep penetrance, but high energy (bad for baby) and low resolution
What main way are intestinal epithelial cells integrated in the lateral domain? (side by side)
Tight junctions:
plasma membranes fuse so molecules cannot pass between them.
What cell junction is found next to tight junctions? What is their role and where are they found?
Desmosomes:
Each cell has a hemidesmosome which bind to form a desmosome. They form strong adhesions to to strengthen tight junctions and resist physical stress. They’re found lots in the skin.
Describe the structure, role and example of gap junctions
Connexons form junctions between cells in which substances can move through and so adjacent cells can directly communicate. They’re found in the cilia cells to help them move together.
How are cells integrated into connective tissue (basal domain)
Either:
- Hemidesmosomes: attach to integrin which attach the cells cytoskeleton to the extracellular matrix in the connective tissue.
- Focal adhesions: They anchor actin filaments within the cell to the basement membrane via an integrin which spans the plasma membrane to the extracellular matrix. They play a prominent role in cell movement, such as migration of epithelial cells in cell movement.
Describe 5 methods of cell communication
- Gap junctions
- autocrine: signal released binds to receptor on its own cell
- paracrine: local communication, signals to nearby cells (histamine)
- endocrine: long range communications, hormones travel in blood from endocrine gland to target tissues
- synaptic: one neurone to another using neurotransmitters
- Neurocrine: neurone releases neurotransmitter into blood which communicates with cells- anterior pituitary, posterior pituitary and adrenal medulla
How is a tissue isolated?
Seperate from connective tissue using collagenase, then culture
What are the issues with cell culturing?
They behave differantly within a culture
Cells stop growing in culture when they touch eachother
Cells have a limited life span in culture
What are the two methods of cell death?
Apoptosis- contolled, purposeful cell death
Necrosis- death due to distruption/ injury/ toxins/ lack of nutrients
describe the process of apoptosis
BCl-2 is inactivated by inhibitor release.
Enzymes digest components and fragment DNA (catabolism).
Capases digest specific proteins in nucleus and cytoskeleton
Cell is repackaged for safe removal, chromatin condense and cell shrinks then fragments
Fragments of cell digested by phagocytosis
Describe the process of Necrosis
Cell looses functional control
Na-K pump stops
Water diffuses in, cell swells and bursts
Cytotoxic components (Ca2+) spill out the membrane inducting tissue damage and inflammation
