Introduction Flashcards
Cells
functional unit of living organisms
Differentiate
to perform special functions
Organs
anatomically discreet collections of tissues perform certain functions (eg. liver and kidney)
parenchyma
functional elements that cells make up of an organ
stroma
structural framework of an organ, background tissue
systems
organizations of tissues & organs, may be discreet entities or diffuse aggregates
what are 5 basic tissue types
- blood
- connective tissue
- epithelium
- muscle
- nervous tissue
blood
fluid tissue, contained within vessels of circulatory system
connective tissue
surrounds and supports other tissue
epithelium
covers body surfaces, lines cavities & form glands
muscle
contains specialized contractile cells responsible for movement
nervous tissue
contain modified cells responsible for intercellular communication
In tissue preparation, how do you prevent unfixed tissues from autolyze/ denature ?
use formalin, which cause cross-linking of proteins to preserve the tissue
tissue preparation steps
- Cassettes
- dehydrate- via alcohol baths and clear w/ xylene
- embed in liquid paraffin or plastic resin
tissue in paraffin will melt, harden in “boat”, transfered to block - Microtome or grind if plastic sections
- Mount on slides
- Remove paraffin
- rehydrate with alcohol and xylene
- Stain
- coverslip
liquid paraffin
most common forms that allow tissue to harden, tissue is supported by wax block
plastic resin
provide great images but COSTLY and difficult to statin
ex. methyl methacrylate, MMA
what kind of stain is most common?
H&E ( hematoxylin & Eosin)
hematoxylin
blue/ purple, basic dye, stains acids (nuceli), basophilic
Eosin
red/pink, acidic dye, stains bases (proteins), eosinophilic
What color does eosinophilic turn?
red/pink under eosin
What color does basophilic turn?
blue/ purple under hematoxylin
where can tissue cassettes be located?
automated tissue processor
Under the embedding station, the tissue in paraffin wil melt… where does the parafinn harden?
“boat”— paraffin hardens are mounted on the block
what is microtoming
process where paraffin is used to get small slices of the tissue
parafinn ribbon
warm water baths allow paraffin to relax and spread out
Tissue prepatation using parafinn
- Cassettes
- Automated tissue processor
- Embedding station
- Paraffin “boat”
- Paraffin block
- Microtoming paraffin block
- Paraffin ribbon
- Floating paraffin ribbon
- Coverslip
Cell membrane
semi-permeable membrane, forms phospholipid bilayer
plasmalemma
animal cell membrane
what are the 2 distinct layers of cell membrane?
hydrophilic and hydrophobic
hydrophilic
contains positively charged N groups and negatively phosphate groups
hydrophobic
portion contains two long-chain FA’s, covalently linked to glycerol
how does the cell membrane appear on the electron microscopy?
tri-laminar appearance: 2 electron dense hydrophilic layers, separated by electron-lucent layer
electron lucent layer
hydrophobic, FA tails
fluid mosaic model
the fluidity of membrane increase w/ temp and decrease w/ saturation of FA
cholesterol
helps with fluidity regulation and membrane stabilization
increase cholesterol= decrease fluidity
extrinsic= peripheral proteins
present on surface of membrane
intrinsic= integral proteins
within membrane
transmural proteins
transmembrane proteins, extend from one side of membrane to other, contains pores/ channels
pumps
serve to transport ions across memnbrane
channels
open/ close, allow passage of water- soluble molecules via diffusion
receptor proteins
allow for cell recognition and binding on cell membrane
transducers
initiate enzymatic rxn’s following binding with ligand molecules
enzymes
components of ion pumps and digestive action
structural proteins
add mechanical stability to the membrane
glycocalyx structure and function
- short polysaccharide chains containing glucose molecules
- form glycoproteins + glycolipids = glycocalyx
- role: protects the surface of cell membrane, cell recognition, mediating exchange between internal and external cell enviornment
4 principal types of transport
- simple (passive) diffusion
- facilitated diffusion
- active transport
- active transport
- bulk (vesicular) transport
under facilitated diffusion, what ungated channels are always open
pores
under facilitated diffusion, what gated channels can be open or closed
gated channels
what does the voltage gating require?
change in membrane potential to open
what does chemical gating requires?
binding of signaling molecules or neurotransmitter
how are both passive and facilitated diffusion enhanced by?
increase surface area of cell membrane via folding (eg. microvilli)
aquaporins
important type of channel that uses facilitated diffusion, allows water to cross membrane by simple diffusion
where does active transport occur?
specialized dynamic pore sites
bulk (vesicular) transport
requires energy, engulfment of molecules or particles by cytoplasmic extensions
what is the result of bulk transport?
formation fo membrane- bound , endocytic vacuoles (endosomes or phagosomes)
receptor-mediated endocytosis
extracellular molecules (ligand) bind to receptor proteins or clathrins, located in coated pits of cell membrane
transcytosis
transport of material across or through cell via sequential endocytosis followed by exocytosis
