Cellular Pathology Flashcards
“All organ injuries start with structural or molecular alterations in cells” concept began by
Rudolf Virchow in 1800’s
phospholipid bilayer with embedded proteins / glycoproteins / glycolipids (eg ion pumps, receptors, adhesion molecules, etc)
Plasma membrane
semipermeable membrane with pumps for ionic / osmotic homeostasis
Plasma membrane
➢ chromatin (euchromatin vs heterochromatin)
➢ nucleolus (synthesis of ribosomal RNA/subunits)
➢ transcription of genes
Nucleus
➢ inner & outer membrane, cristae
➢ intermembranous and inner matrix compartments
➢ oxidative phosphorylation (main source of ATP)
Mitochondria
synthesis & packaging of proteins for export. Membranes, lysosomes
RER & Golgi
- lipid biosynthesis (eg membranes, steroids)
- Detoxification of harmful compounds (via P450’s)
- Sequestration of Ca 2+ ions
SER
➢ Enzymatic digestion (acid hydrolases) of materials in the cell
➢ Primary vs secondary lysosomes; residual bodies
➢ Autophagy vs heterophagy/endocytosis
➢ Phagocytosis/phagosome; pinocytosis/pinocytic vesicle; receptor-mediated endocytosis
Lysosomes
degrade both excess proteins and incorrectly folded (misfolded) proteins.
Proteasomes
assist proper folding of proteins and transport across organelle membranes.
Chaperones
➢ Structure and movement of cells/organelles/ granules/ surface molecules/ phagocytosis
➢ Microfilaments: actin in various forms – cell shape and movement
➢ Microtubules: polymers of tubulin – organelle movement/flagella/cilia/ mitotic spindle
➢ Intermediate filaments: cytokeratin, vimentin, desmin, GFAP, neurofilament proteins
Cytoskeleton
metabolism of hydrogen peroxide and fatty acids
Enzymes (eg catalase, oxidases)
as cells encounter some stresses (eg excessive physiologic demand or some mild pathologic stimuli) they may make functional or structural adaptations to maintain viability/ homeostasis.
Cellular adaptation
if the limits of adaptive response are exceeded, or in certain instances when adaptation is not possible (eg with severe injurious stimulus), a sequence of events called
cell injury
*Two principle morphologic patterns that are indicative of cell death:
Necrosis and Apoptosis
type of cell death characterized by sever membrane injury and enzymatic degradation; always a pathologic process.
necrosis
regulated form of cell death; can be a physiologic or pathologic process.
apoptosis
CAUSES OF CELLULAR INJURY:
- Hypoxia (Oxygen Deficiency)
- Physical agents
- Chemical, Drugs & toxins
- Infectious agents
- Immunologic Reactions
- Genetic Abnormalities
- Nutritional Imbalances
- Workload Imbalances
one of the most important and common causes of cell injury and cell death.
Hypoxia (Oxygen Deficiency)
deficiency of blood supply from impeded arterial flow or reduced venous drainage = hypoxia + ↓ delivery of nutrients and ↓ removal of metabolites.
ischemia
localized area of ischemic necrosis.
infarction
5 Physical agents:
a) Direct mechanical trauma
b) Temperature extremes
c) Radiation
d) Electrocution
(e) Sudden changes in atmospheric pressure
6 Chemical, Drugs & toxins
a) Inorganic poisons
b) Organic poisons
c) Manufactured chemicals
c) Physiologic compounds
d) Plant toxins
e) Animal toxins
g) Bacterial toxins / Mycotoxins
5 Infectious agents
a. Viruses
b. Bacteria / rickettsiae / chlamydia
c. Fungi
d. Protozoa
e. Metazoan parasite
3 Immunologic Reactions
a. Immune response
b) Hypersensitivity (allergic) reactions
c) Autoimmune diseases
reactions to self-antigens
Autoimmune diseases
one cause of congenitalanomalies.
Cytogenetic disorders / chromosomal aberrations
combined effects of environmental factors and 2 or more mutated genes (eg neoplasia, hypertension, coronary artery disease, etc).
Multifactorial inheritance
2 Nutritional Imbalances
defiences and overnutrition
cell injury occurs if stimulus prolonged and/or exceeds ability to adapt.
Overworked cells
prolonged lack of stimulation (eg disuse, denervation, lack of trophic hormones) can lead to atrophy and eventually the loss of cells.
Underworked cells
the cumulative effects of a life time of cell damage (chemical, infectious, nutrition, etc) leads to a diminished capacity of aged cells / tissues to maintain homeostasis and adapt to harmful stimuli
Cell Aging
“double MINT”
M - Malformation
M - micsellaneous
I - Infectious
I - immune
N - Nutritional
N - Neoplastic
T - trauma
T - Toxicity