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Flashcards in cytology Deck (87):
1

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

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2 cell types

prokaryotic
eukaryotic

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2 cell types
– presence of true nucleus surrounded by a nuclear envelope


1. Eucaryotic cell

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2 cell types
– absence of nuclear envelope; nuclear substance is mixed with the rest of the cytoplasm

2. Procaryotic cell

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part of a cell
the outer limiting membrane that serves as a selective barrier

Plasmalemma –

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part of a cell
the protoplasm outside of the nucleus which contains the different organelles and inclusions of the cells

Cytoplasm –

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part of a cell
contains the genetic material of the cell

Nucleus –

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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

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2 Models of cell membrane

1. The Classical Model of Davson and Danielli
2. The “ Fluid Mosaic Model” of Singer and Nicholson

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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

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This model postulates a lipid center sandwiched by a coat of protein on each surface.

1. The Classical Model of Davson and Danielli

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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.”

2. 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

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type of model


3. Oligosaccharide chain from the surface of the plasmalemma amplify the inherent asymmetry.

The “ Fluid Mosaic Model” of Singer and Nicholson

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Consist of a bilayer of phospholipid molecules which are amphipathic i.e. polar hydrophilic head and non- polar hydrophobic tail

cell membrane

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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

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functions of cell surface

1. Filtration barrier

2. Allows sudden changes in ion permeability in response to changes in electrical potential

3. Receptor site for hormones & enzymes

4. Cell recognition
(GLYCOCALYX)

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ground substance

hyaloplasm

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part of cytoplasm
usually in sol phase and manifest active streaming
cellular components are carried along by directed movements

endoplasm

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part of cytoplasm
usually in gel state
relatively free of cellular components
occupies the periphery of the plasmalemma

2. Exoplasm

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cytoplasmic organelles (9)

1. Endoplasmic reticulum: RER & SER
2. Golgi Complex
3. Mitochondria
4. Lysosomes
5. Centriole / centrosome
6. Peroxisomes (microbodies)
7. Filaments
- Myofilaments
- Tonofilaments
8. Microtubules
9. Annulate lamellae

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Consist of an anastomosing network of intercommunicating channels and sacs formed by a continuous membrane

ER

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2 Forms of ER

A. Granular / Rough Endoplasmic Reticulum
B. Smooth Endoplasmic Reticulum

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Most typical er

Interconnecting network of membranous tubules, vesicles & flattened sacs

Presence of ribosomes on its membrane surface

ROUGH ENDOPLASMIC RETICULUM

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FUNCTIONS OF THE RER:

Synthesis of secretory protein and its storage within the intracisternal space

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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

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Function of SER in striated muscle:

as sarcoplasmic reticulum

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Function of SER In endocrine cells:

biosynthesis of steroid hormone

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Function of SER In intestinal villi:

synthesis of neutral fats

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Function of SER In parietal cells of the stomach:

formation of HCl acid

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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

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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.

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FUNCTION OF GA In glandular cells:

site of accumulation and concentration of secretory products

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FUNCTION OF GA . in cells that secrete a mucopolysaccharide / glycoprotein

Site of sulfation

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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

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functions of mitochondria

Synthesis of ATP as energy source of the cell
Accumulation of calcium; synthesis of nucleic acids and proteins; oxidation of fatty acids.

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These are small membrane bound bodies of varying shapes and sizes containing a number of hydrolytic enzymes for intracellular digestion
(ACID HYDROLASES)



lysosomes

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type of lysosome
resting lysosomes

Primary lysosomes:

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type of lysosome
actively engaged in digestion

Secondary lysosomes

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a pair of short rods considered as the center of activities associated with cell division usually adjacent to the nucleus.

Self-duplicating

Centrioles /diplosome:

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functions of lysosomes

Essential in the cellular defense mechanism, being the site of destruction of foreign bodies.

2. Function in the normal replacement of cellular components and organelles.

3. Play an important part in the metabolism of certain substances in the human body.

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type of centriole
Hallow cylinder, open in one end; closed in the other

E/M

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TYPE OF CENTRIOLE
Perpendicular to each other

Long axis:

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type of centriole

It has a circular outline

Wall is composed of nine groups of longitudinally oriented parallel sub-units

Each of the nine groups consist of 3 microtubules aligned and fused together so that they appear as a 3 circles in a row.

X/S:

44

functions of centrioles

1. Plays an important role in cell division

2. Centrioles are essential for the formation of cilia and flagella

3. They serve as the basal bodies and sites of epithelial origin.

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Membrane bound bodies with a finely granular homogenous content and sometimes containing a crystalloid body.

Contain several enzymes in the production or destruction (catalases) of hydrogen peroxide.

peroxisomes/microbodies

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2 Categories of filaments:

A. Microfilaments
B. Intermediate filaments / Tonofilament

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type of filament
– diameter measure less than about 8 nm
Most are contractile acting to promote cell shape or motility (myofilaments).


A. Microfilaments

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type of filament
diameter range from 8-12 nm
Not known to be contractile and appear to serve exclusively in a
supportive role.

B. Intermediate filaments / Tonofilaments

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functions of tonofilaments

1. Maintain cellular shape and provide resiliency
to forces tending to alter that shape; prominent in cytoplasm of “wear & tear” epithelia

2. Regular component, together with microtubules; in nerve cells.

3. Found in the sites of adhesions between adjacent cells of epithelial systems important as supportive intracellular network and in transmission of forces among adherent cells.

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Widely occurring, slender, cylindrical structures

X/S: appear as a circle composed of
13 globular subunits

microtubules

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functions of microtubules

1. Are an important element of the spindle
apparatus in dividing cells; they form
the mitotic spindle.

2. They form the cores of cilia & flagella of
sperm cells – nine doublets around 2
centrally located microtubules.

3. Play a role in maintaining diverse cell
shape.

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Visible only with E/M: parallel arrays of cisternae with small pores at regular interval along their length.

Presence of diaphragms closing the pores.

Functional significance is not known

annulate lamellae

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Lifeless accumulations of metabolites or cell products regarded as dispensable and often temporary constituents; not essential for survival of the cell

cytoplasmic inclusions

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cytoplasmic inclusions (6)

1. Pigments – a. Endogenous
b. Exogenous
2. Lipid
3. Glycogen
4. Crystals
5. Secretory granules
6. Vacuoles

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Materials with natural color that do not
require staining by dyes.

pigments

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type of pigment
– formed outside of the body

exogenous

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type of pigment
– formed within the body

endogenous

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– dark brown / black pigments found in melanocytes containing melanosomes in the epidermis and in the eye

melanin

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Referred to as “wear & tear” pigments

lipofuscin

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yellowish brown granules occurring in many cells particularly in older individuals

lipofuscin

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Appear as round, clear areas in the cytoplasm because the lipid is extracted by solvents.

lipids

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Appear as black spherical droplets of varying sizes with osmium tetroxide

lipids

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E/M: appear as full cytoplasmic particles

Found in the liver

glycogen

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2 types of GLYCOGEN
dense, irregular spherical body

Beta particles
alpha particles

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types of GLYCOGEN
dense, irregular spherical body

Beta particles

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types of GLYCOGEN
rosette-like aggregates of larger size

alpha particles

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protein in nature

Not bound by membranes; found in Sertoli cells & IC of Leydig

E/M: shows a regular lattice pattern

CRYSTALS

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Storage cavities

VACUOLES

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Found in all cells except RBC & platelets

Shape, size & number vary

Stains blue because of its nucleic acids, basic proteins and also acidic proteins

NUCLEUS

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NUCLEUS FUNCTION


1. Archive of the cell; repository of the
hereditary factors

2. Source of ribosomal, messenger and transfer RNA

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Outer limit of the nucleus separating it from the cytoplasm

About 40 nm thick & seven times thicker than the plasmalemma

NUCLEAR ENVELOPE

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E/M: consist of 2 parallel membranes enclosing a narrow perinuclear space that communicates with the cisternae of the reticulum

Continuous with the membranes of the endoplasmic reticulum

Has ribosomes on its outer membrane

NUCLEAR ENVELOPE

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shows the presence of numerous nuclear pores of about 40-100 nm in diameter with a small dense granule.

NUCLEAR ENVELOPE

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seen in each pore
a short cylinder formed by eight regular subunits and containing a central granule

pore complex

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important in the exchange of materials between the nucleoplasm and the cytoplasm.

Its permeability varies with nuclear activity

pore complex

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Nuclear material that contains DNA and proteins; the structural manifestation of chromosomes in interphase.

NUCLEAR CHROMATIN

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2 TYPES OF CHROMATIN

2 Types:
A. Heterochromatin –
B. Euchromatin –

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TYPE OF CHROMATIN
the condensed coiled part, metabolically inert

Heterochromatin

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TYPE OF CHROMATIN
the dispersed, less coiled regions of the chromosome;
active in protein synthesis

Euchromatin

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TYPES OF NUCLEI

CHROMATIC
VESICULAR
PYKNOTIC

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A round conspicuous structure eccentrically located in the nucleus; rich in RNA and basic proteins; intensely basophilic due to the presence of ribonucleoproteins.

NUCLEOLUS

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3 Regions OF NUCLEOLUS

3 Regions:
A. Pars amorpha / pars fibrosa
B. Nucleo-lonema / pars granulosa
C. Chromosomal portion

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Regions OF NUCLEOLUS

round masses of closely packed filaments in the interior of the nucleolus

A. Pars amorpha / pars fibrosa

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Regions OF NUCLEOLUS

surrounds the pars amorpha; made up of a coarse reticulum of anastomosing strands

B. Nucleo-lonema / pars granulosa

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Regions OF NUCLEOLUS

consists of dispersed filaments of DNA; site of synthesis of ribosomal RNA


C. Chromosomal portion

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FUNCTION OF NUCLEOLUS

Site of ribosomal RNA synthesis

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May show irregular densities of staining along their lengths

Small visible mass is the sex chromatin / Barr bodies

In female neutrophil granular leukocytes is seen as drumstick appendage

It has become possible to determine by light microscopy the genetic sex of an individual.

CHROMOSOME

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