cytology Flashcards
fundamental unit of living material showing a variety of functional specializations which perform all the activities necessary for the survival, growth and reproduction of the organism.
Cells
2 cell types
prokaryotic
eukaryotic
2 cell types
– presence of true nucleus surrounded by a nuclear envelope
- Eucaryotic cell
2 cell types
– absence of nuclear envelope; nuclear substance is mixed with the rest of the cytoplasm
- Procaryotic cell
part of a cell
the outer limiting membrane that serves as a selective barrier
Plasmalemma –
part of a cell
the protoplasm outside of the nucleus which contains the different organelles and inclusions of the cells
Cytoplasm –
part of a cell
contains the genetic material of the cell
Nucleus –
Pertains to the outer trilaminar-appearing membrane surrounding the cell.
A selective barrier that regulates the entrance and exit of substances into the cell.
cell membrane
2 Models of cell membrane
- The Classical Model of Davson and Danielli
2. The “ Fluid Mosaic Model” of Singer and Nicholson
Cell Membrane model
The membrane proteins are globular and float like iceberg in a sea of lipid
The more acceptable model
In a dynamic state
The “ Fluid Mosaic Model” of Singer and Nicholson
This model postulates a lipid center sandwiched by a coat of protein on each surface.
- The Classical Model of Davson and Danielli
type of model
1. The plasmalemma is composed of a bilayer of ionic and polar head groups and the membrane protein complexes are embedded in a “mosaic configuration.”
- Other protein molecules on the external and protoplasmic surfaces of the plasmalemma give an asymmetrical appearance of the molecular structure
The “ Fluid Mosaic Model” of Singer and Nicholson
type of model
- Oligosaccharide chain from the surface of the plasmalemma amplify the inherent asymmetry.
The “ Fluid Mosaic Model” of Singer and Nicholson
Consist of a bilayer of phospholipid molecules which are amphipathic i.e. polar hydrophilic head and non- polar hydrophobic tail
cell membrane
Glycoprotein & polysaccharide covering of the external surface of the cell membrane
Imparts a special identity to each cell type, therefore, plays an important role in histocompatibility
glycocalyx
functions of cell surface
- Filtration barrier
- Allows sudden changes in ion permeability in response to changes in electrical potential
- Receptor site for hormones & enzymes
- Cell recognition
(GLYCOCALYX)
ground substance
hyaloplasm
part of cytoplasm
usually in sol phase and manifest active streaming
cellular components are carried along by directed movements
endoplasm
part of cytoplasm
usually in gel state
relatively free of cellular components
occupies the periphery of the plasmalemma
- Exoplasm
cytoplasmic organelles (9)
- Endoplasmic reticulum: RER & SER
- Golgi Complex
- Mitochondria
- Lysosomes
- Centriole / centrosome
- Peroxisomes (microbodies)
- Filaments
- Myofilaments
- Tonofilaments - Microtubules
- Annulate lamellae
Consist of an anastomosing network of intercommunicating channels and sacs formed by a continuous membrane
ER
2 Forms of ER
A. Granular / Rough Endoplasmic Reticulum
B. Smooth Endoplasmic Reticulum
Most typical er
Interconnecting network of membranous tubules, vesicles & flattened sacs
Presence of ribosomes on its membrane surface
ROUGH ENDOPLASMIC RETICULUM
FUNCTIONS OF THE RER:
Synthesis of secretory protein and its storage within the intracisternal space
Non- granular
Membranes are also arranged in an anastomosing network of tubules
Cisternae are more tubular
May also connect with the RER, the plasmalemma, and the Golgi complex.
SER
Function of SER in striated muscle:
as sarcoplasmic reticulum
Function of SER In endocrine cells:
biosynthesis of steroid hormone
Function of SER In intestinal villi:
synthesis of neutral fats
Function of SER In parietal cells of the stomach:
formation of HCl acid
System of stacked saucer shaped cisternae with concave (maturing / trans face) facing the nucleus and a forming / cis face adjacent to rough ER
golgi apparatus
function of GA
Packaging of secretory products in a membrane capable of fusing with the plasma membrane during exocytosis.
Concentrates and packages hydrolytic enzymes in cells as lysosomes.
FUNCTION OF GA In glandular cells:
site of accumulation and concentration of secretory products
FUNCTION OF GA . in cells that secrete a mucopolysaccharide / glycoprotein
Site of sulfation
mobile “power plant of the cell”
membrane-bound
appear as slender rods, cigar shaped organelle
self-replicating
vary in size, shape and number depending on the cellular activity
present in all eukaryotic cells
MITOCHONDRIA