Introduction to Histology Flashcards
Cells
functional units of living organisms
differentiate
to perform special functions
Tissue
cells with similar morphology and or function form tissue
organs
anatomically discreet collections of tissues that perform certain functions
ex. liver ; kidney
Parenchyma
cells that makeup the functional elements of an organ
stroma
structural framework of an organ / background tissue
Systems
larger units that tissues and organs are organized into
may be discreet entities like CNS
diffuse aggregates like immune system
Basic tissue types (5)
Blood
connective tissue
epithelium
muscle
nervous tissue
Blood
fluid tissue contained within vessels of circulatory system
technically a connective tissue
Connective tissue
surrounds and supports other tissue
epithelium
covers body surfaces, lines cavities, and forms glands
muscle
contains specialized contractile cells responsible for movement
nervous tissue
contains modified cells responsible for intercellular communication
Hematoxylin and Eosin (H&E stain)
for routine diagnosis H&E is preferred for viewing cellular and tissue structure detail by pathologists
Hemtoxylin dye
blue
basic dye
stains acids
ex. DNA in nuclei ; RNA in ribosomes ; rER –> basophilic = blue / purple
Eosin
red pink
acidic dye
stains bases
ex. proteins = eosinophilic
Gram stain
differentiates bacterial species used to determine the causative organism in a bacterial infection
stains bacterial cell wall
gram positive
organisms that retain the primary color and appear purple/brown under microscope
gram negative
organisms that do not take up primary stain appear red under a microscope
Giesma Stain
used in hematology for its superior ability to stain bone marrow plasma cells and mast cells
identifying blood parasites
visualize chromosome abnormalities through giemsa based banding
Periodic acid schiff reaction stain (PAS)
stains carbohydrates
way to examine structures with high amounts of carbohydrate molecules such as the intestinal brush border renal tubular cells mucus and reticular fibers of connective tissue
stains a red MAGENTA color
Silver stain
used in neurology
stains nerve tissue
silver stains are very known for detecting amyloid beta-protein in alzheimer’s disease
Nissl stain
only stains neurons
also called cresyl violet stain
uses basic aniline due to study neuronal structure in the brain and spinal cord
blue
Cell membrane (plasmalemma)
functions as a semi-permeable membrane
phospholipid bilayer
amphoteric and/or amphipathic
composed of molecules with hydrophilic (polar) heads and hydrophobic (non-polar) tails
Cell membrane forms
2 distinct layers hydrophilic heads point outward and hydrophobic tails point inwards
hydrophilic portion contains
positive charged N groups and negative charged phosphate groups
hydrophobic layer portion contains
2 long chain fatty acids covalently linked to glycerol
tri-laminar appearance of cell membrane on EM
caused by 2 election dense layers hydrophilic phospholipid heads separated by electron lucent layer hydrophobic fatty acid tails
fluid mosaic model
fluidity of membrane increases with temp and decreases with saturation of fatty acids
Cholesterol does what to cell membranes
helps regulate fluidity and stabilize membrane
increase in cholesterol stiffens membrane decreasing the fluidity
1:1 ratio with phospholipids
Proteins on surface of membrane are
extrinsic or peripheral proteins
proteins incorporated within the membrane are
intrinsic or integral protiens
some intrinsic membranes can be
transmural extending from one side of membrane to other called transmembrane proteins
what are pores
transmembrane proteins that have openings
also called channels (can open and close)
Pores are ALWAYS open
pores and channels are used for what transport
active or passive transport of hydrophilic molecules
Pump
serve to transport ions across membrane
ex. Na-K pump
NEEDS energy source
Channel
allow passage of water soluble molecules via diffusion
Receptor proteins
allow for cell recognition and binding on cell membrane
ex. immune mediate rxn
Transducers
initiate enzymatic rxn following binding with ligand molecules
ex. hormones
Enzymes
components of ion pumps and digestive action
structural proteins
add mechanical stability to membrane
Glycocalyx
the formation of glycoproteins and glycolipids on the outside of the cell
purpose of the glycocalyx
protects surface of the cell membrane
may be involved in cell recognition and adhesion
mediating exchange between internal and external cell environment
Principle types of transport (4)
simple (passive) diffusion
facilitated diffusion
active transport
bulk (vesicular) transport
Simple diffusion
NO ENERGY
down a concentration or ionic gradient
lipids gases (O2 CO2) and some small hydrophilic molecules (water urea bicarbonate)
Facilitated diffusion
passive and concentration dependent but requires carrier molecules
reversible binding and unbinding to transport water soluble hydrophilic molecules
ex. glucose and amino acids
ion channels can be
gated - channels can be open or closed allows selective permeability
ungated - channels are always open (PORES)
Voltage gating of ion channels
requires change in membrane potential to open
chemical gating
requires binding of signaling molecule or neurotransmitter
ex. Ach
Passive and Facilitated diffusion are enhanced by
increased cell membrane surface area
via folding / microvilli
Aquaporins
channel that uses facilitated diffusion to allow water to cross plasma membrane faster than by simple diffusion
Active transport
Independent of concentration (usually against concentration gradient)
requires energy
Na pump - one ion is exchanged for another
Bulk (vesicular) transport
Requires energy
engulfment of molecules or particles by cytoplasmic extensions
AKA endocytosis
types of endocytosis (2)
Phagocytosis - engulfment of solid particulate matter
Pinocytosis - engulfment of liquids
what are Endosome / Phagosomes?
membrane endocytic vacuoles
receptor mediated endocytosis
import macromolecules from the extracellular fluid
extracellular mlecules ligands bind to receptor proteins (clathrins) located in coated pits = caveolae of cell membrane
Transcytosis
transport of material across or through cell via sequential endocytosis followed by exocytosis
