Lecture 3: Cytology Flashcards
What types of membranes constantly express and recycle receptors on both their inner and outer surfaces to perform their functions?
Cell membrane
Membrane of all organelles
Mitochondrial replication
- Self-replicating
- Uniparental inheritance, therefore little opportunity for genetic recombination between different lineages, although a single mitochondrion can contain 2–10 copies of its DNA
Mitochondria structure
Double membrane-enclosed organelle with cristae
Is mitochondria visible under LM in ordinary staining?
No
Cristae
finger-like projections of the cellular membrane
Three roles of mitochondria?
- ATP production
- Necrosis
- Apoptosis initiation
How do mitochondria initiate apoptosis?
Release cytochrome C
What is the point of no return for apoptosis?
mitochondrial outer membrane permeabilization
Are Pancreatic Acinar Cells exocrine or endocrine?
exocrine
Endoplasmic reticulum
anastomosing network of intercommunicating
channels
What differentiates the RER and the SER
RER has polyribosomes
Three functions of the SER
Lipid biosynthesis
Detoxification
Sequestration of calcium ions (sequ = temporarily stored)
Four functions of the RER
Segregate proteins not destined to the cytoplasm
Glycosylation of glycoproteins
Synthesis of phospholipids
Assembly of multichain proteins
Golgi complex
Collection of membrane-bound flattened sacs ‘cisternae’
Purpose of Golgi complex
Modifies and ‘packages’ proteins
The Golgi body is best developed in
secretory cells
Lysosomes
Membrane-bound dense particles that contain hydrolytic enzymes
Associated with intracellular digestion
What two processes are lysosomes associated with?
pinocytosis
phagocytosis
Pinocytosis
engulfing small vesicles by invaginations of the cell
Lipofuscin
- Wear and tear pigment
- Degraded material that remains permanently
Proteasomes
- Small enzymatic complexes for intracellular digestion
- Recycles amino acids from endogenous proteins
Intracellular digestion in proteasomes requires a protein known as
Ubiquitin
Peroxisomes
- Contain the enzyme ‘catalase’ which can degrade intracellular hydrogen peroxide (protects the cell)
- Degrade toxic molecules and some prescription drugs
Cytoskeleton - Three different types of structures
- Microfilaments
- Intermediate filaments
- Microtubules
What are microfilaments made out of?
actin and myosin
What are intermediate filaments made out of?
keratin
What kind of cell is keratin normally found in?
epithelial
What are and what is the function of microtubules
hollow thin tubules that move organelles, vesicles, ribosomes; form the mitotic spindle; maintain shape of avian red blood cells (RBCs) and platelets; part of centrioles, cilia and sperm flagella
Myosin
thick microfilaments
15 nm in diameter
Actin
Thin microfilaments
5-7 nm in diameter
Size of intermediate filaments
range between 6 and 12nm in diameter
Five types of intermediate filaments
- Tonofilaments (cytokeratin)
- Vimentin
- Desmin
- Neurofilaments
- Glial filaments
Tonofilaments (cytokeratin) location
epithelium
Vimentin location
mesenchymal cells (Fibroblasts, chondroblasts, osteoblasts, macrophages, endothelial cells, vascular, smooth muscle cells)
Desmin location
muscle
Neurofilament location
neurons
Glial filament location
Glial cells (astrocytes)
In a fluorescing microscope, microtubules appear what color?
light color
Lipofuscin
brown
Lutein
yellow
Hemosiderin
results from the decomposition of red blood cells
Why does melanin cover the nucleus?
Acts like an umbrella
Protects it from the UV light
Adipocyte
Cell that forms the adipose tissue
Yellow/brown in the myocardium is more likely
lipofuscin
Yellow/brown in the spleen is most likely
hemosiderin
What color does hemosiderin stain in Prussian Blue?
Black
How do you find glycogen in hepatocytes?
Stain with best carmine, look under light microscope
Microvilli
- very small, absorptive, seen in EM
- Form a brush/striated border when viewed with the light microscope
Cilia
motile projections, longer but less numerous than microvilli, come from basal bodies (= modified single centrioles)
Stereocilia
nonmotile projections, absorptive (are considered large microvilli)
When looking at an intestinal epithelium using PAS, what color will the goblet cells be?
magenta
What color are goblet cells when not using PAS?
white/clear
Cilia are made up of
9 microtubules and 2 central single tubules
From each outer pair of microtubules, a pair of _____ _____ reach towards the next pair of microtubules
dynein arms
_____ ______ extend from each outer pair of microtubules towards the inner central tubules
radial spokes
____ links also join each outer pair of microtubules with the adjacent outer pair.
Nexin
7 cell shapes
Squamous, cuboidal, columnar, spindle, cylindrical, multipolar, round
3 nuclear shapes
Round, elongated, polymorphonuclear
4 nuclear positions
Central, eccentric/hypolemmal, apical vs. basal
3 surfaces of an epithelial cell
Apical (free) surface
Lateral surfaces
Basal surface
