Introduction Flashcards
study of cells
histology
5 basic tissue types
blood, connective tissue, epithelium, muscle, nervous tissue
functional units of living organisms
cells
cells with similar morphology and/or function form __
tissue (nervous, muscle)
what do cells do in order to perform special functions?
differentiate
anatomically discreet collections of tissues that perform certain functions
organs (ex: kidney, liver)
cells that make up the FUNCTIONAL elements of an organ
parenchyma
STRUCTURAL framework of an organ, background tissue
stroma
tissues and organs are organized into larger ___ that may be __ entities (CNS) or ___ aggregates (immune system)
systems
discreet
diffuse
blood is the only
fluid tissue
blood location
contained within vessels of the circulatory system
function of connective tissue
surrounds and supports other tissue
this tissue covers body surfaces, lines cavities, and forms glands
epithelium
this tissue contains specialized contractile cells responsible for MOVEMENT
muscle
epithelium function
covers body surfaces
lines cavities
forms glands
this tissue contains modified cells responsible for intercellular communciation
nervous tissue
general process of tissue preparation
Formalin Cut tissue in cassettes Dehydrate with alcohol baths Clear with xylene Embed in liquid paraffin or plastic resin Microtome or grind if plastic Mount on slides Deparaffinize Rehydrate with alcohol and xylene (reverse order) Stain Coverslip (protection)
What happens to unfixed tissue?
autolyzes/denatures (rots)
How do you prevent denaturing of unfixed tissue?
fixation in formalin (37% formaldehyde)
cross links protein to preserve tissue
function of tissue cassettes
Helps identify
Prevent from mixing
Fixed tissue placed inside
function of automated tissue processor
dehydrates tissues through series of alcohol baths
most popular embed technique
paraffin (not water soluble so needs to be dehydrated)
example of plastic resin embedding material
methyl methacrylate (mma) good results but difficult to stain and expensive
most common stains
hematoxylin
eosin
(H & E)
characteristics of hematoxylin
blue, basic dye
stains acids
(ex: nuclei)
basophilic (blue/purple)
characteristics of eosin
red/pink, acidic dye
stains bases
(ex: proteins)
eosinophilic (red/pink)
animal cells surrounded by flexible cell membrane
plasmalemma
function of plasmalemma
semi-permeable membrane (SPM)
what type of bilayer does the cell membrane form
phospholipoid bilayer
What makes up the phospholipid bilayer?
molecules with hydrophilic (polar) heads and hydrophobic (non-polar) tails
(amphoteric/amphipathic)
Which direction do the __ head and the __ tails point?
hydrophilic (outward)
hydrophobic (inward)
The hydrophilic portion of membrane contains
positively charged N groups
negatively charged phosphate groups
Where is the hydrophilic portion of the membrane present?
BOTH inside and outside of membrane
The hydrophobic portion of the membrane contains
2 long chain FA’s covalently linked to glycerol
Describe the hydrophilic and hydrophobic layers in terms of electron density.
heads: electron dense
tails: electron lucent
The cell membrane is responsible for the ______ appearance on EM
tri-laminar
Describe the tri-laminar appearance of the cell membrane
2 electron dense layers (hydrophilic phospholipid heads)
separated by electron lucent layer (hydrophobic, FA tails)
What affects membrane fluidity
Increased: increase temp and decrease saturation of FA’s
Decreased: cholesterol stiffens membrane, close packing of FA’s
Role of cholesterol in membrane fluidity
regulates fluidity and stabilizes membrane
cholesterol ratio to phospholipids
1:1
membrane proteins are
large, mobile protein molecules scattered throughout the membrane
function of some membrane proteins
cell-cell recognition
surface proteins
extrinsic/peripheral proteins
proteins on surface of membrane
intrinsic/integral proteins
proteins incorporated within the membrane
transmural proteins
some intrinsic proteins
extend from one side of membrane to other
“transmembrane” proteins
Pores in membrane proteins
transmembrane proteins with openings
always open
channels in membrane proteins
transmembrane proteins
can open and close
selective
used for active or passive transport of hydrophilic molecules
allow passage of water-soluble molecules via diffusion
What are the categories on membrane proteins?
pumps channels receptor proteins transducers enzymes structural proteins
serve to transport ions across membrane (give example)
pumps
Na-K pump
allow passage of water-soluble molecules via DIIFFUSION
channels
allow for CELL RECOGNITION and BINDING on cell membrane (give example)
receptor proteins (immune mediated reactions –> WBCs)
initiate ENZYMATIC RXNs following binding with LIGAND molecules (give example)
transducers
hormone
components of ION PUMPS and DIGESTIVE ACTION
enzymes
add MECHANICAL stability to membrane
structural proteins
many membrane proteins and some lipids are conjugated with SHORT POLYSACCHARIDE CHAINS containing glucose molecules containing glucose molecules which form ____ and _____.
glycoproteins
glycolipids
glycoproteins + glcyolipids = ______
glycocalyx (outside of cell)
functions of glycocaylx (3)
protects surface of cell membrane
cell recognition
mediates EXCHANGE between internal and external cell environment
types of transport (4)
simple (passive) diffusion
facilitated diffusion
active transport
bulk (vesicular) transport
what type of diffusion occurs DOWN a concentration gradient?
simple
What passes directly through plasma membrane via diffusion?
lipids
gases (O2, CO2)
some small hydrophilic molecules (water, urea, bicarbonate)
how do large water-soluble molecules pass through membrane?
pores or channels in transmembrane proteins
what type of diffusion is passive and concentration dependent, but requires “carrier molecules?”
facilitated (carrier-mediated)
What is the function of facilitated diffusion?
reversible binding and unbinding to transport water-soluble, hydrophilic molecules (glucose and AA’s)
What type of diffusion uses ION CHANNELS in transmembrane proteins, which can be gated or ungated?
faciliated
Which channels are always open in facilitated diffusion?
ungated (pores)
Which channels can be open or closed and allow for selective permeability in facilitated diffusion??
gated
Which channel in facilitated diffusion requires the presence of a stimulus to open?
What does the stimulus do?
gated
causes conformational change of protein
What type of gating requires change in membrane potential to open?
voltage gating
What type of gating requires binding of signaling molecule or NT (Ach)?
chemical gating
How are both passive and facilitated diffusion enhanced?
increase in surface area of cell membrane via folding (microvilli)
Important type of channel that uses FACILITATED diffusion and allows WATER to cross plasma membrane FASTER than by simple diffusion alone?
Where can this be found in the body?
Aquaporins
Renal tubules in kidneys
What type of transport is INDEPENDENT of concentration (usually against gradient)
active transport
What type of transport requires energy from ATP –> ADP?
give example.
active transport
Na pump
Where does active transport occur?
specialized “dynamic pore sites”
usually transmembrane proteins
What type of transport is endocytosis, phagocytosis and pinocytosis?
Bulk (vesicular transport)
engulfment of molecules or particles by cytoplasmic extensions
endocytosis
forms of endocytosis (2)
phagocytosis
pinocytosis
engulfment of solid, particulate matter
phagocytosis
engulfment of liquids
pinocytosis
What does endocytosis result in?
endosomes (phagosomes/endocytic vacuoles)
membrane-bound, endocytic vacuoles
endosomes
What is the type of endocytosis where extracellular molecules (ligands) bind to receptor proteins, or clathrins, located in coated pits (caveolae) of cell membrane?
receptor-mediated
any bulk transport, or vesicular movement from cytoplasm to ECS is ___.
exocytosis
transport of material across or through cell, via sequential endocytosis follow by exocytosis
transcytosis
