Cellular Adaptations Flashcards
Adaptive responses/Accumulations are typically…
reversible responses
Four different adaptations?
Hyperplasia
Hypertrophy
Atrophy
Metaplasia
Hyperplasia
An increase in cell number
Normal response:
Stimulus - may be normal or pathological
Mechanism - growth factors or hormones
Contrast to neoplasia where proliferation is abnormal
Where does hyperplasia occur?
Skin, fibroblasts, liver, bone marrow
Cells that are capable of normal division
Where does hyperplasia not occur?
neurons, cardiac muscle, skeletal muscle
cells that are post-mitotic
physiologic exs of hyperplasia?
endometrium (menustral cycle)
breast (puberty/lactation)
pathologic examples of hyperplasia?
endometrial hyperplasia (too much estrogen stimulation) - increased risk for carcinoma
prostatic hyperplasia
lymphoid hyperplasia due to viral infection
erthyroid hyperplasia of the bone marrow after hemolytic anemia
view slide of non-lacting vs lactating breast…
glands is lactating are hyperplasic and large and full of milk that will be secreted
As menstrual cycle progresses, there is hyperplasia of endometrial lining
…
Benign prostatic hyperplasia (BPH)
What is characteristic of it?
What process is it? (dependent on what?)
Hyperplastic nodules (hyperplasia of both epithelium and stroma - fibroblasts/muscle - proportion varies)
androgen-dependent process (blocked by prepubertal castration)
What does BPH commonly involve?
involves the inner periurethral zone
nodules may compress the urethra
prevalence increases with age!! (age 40 -20%; age 60 - 70%, age 70 - 90%)
what is the tx for BPH?
5-alpha-reductase inhibitors
Avodart - BPH
Propecia - male pattern baldness
block conversion of testoerone to more potent dihydrotestosterone
Hyperplastic Prostate slide….
looks like a scrunched up rug - “papillary infoldings”
more epi - folded and abundant
stroma also increases in size
What is the significance of hyperplasia?
persistent hyperplasia is a fertile ground for the development of cancer
What is hypertrophy?
What can it be accompanied by?
An increase in cell size (corresponding increase in organ size)
may be accompanied by hyperplasia
physiologic example of hypertrophy?
skeletal muscle
smooth muscle (pregnant uterus)
cardiac muscle (athletes)—usually reversible
pathologic exs of hypertrophy?
cardiac muscle (hypertension) — usually nonreversible
skeletal muscle hypertrophy is a normal healthy response to exercise and it is reversible
….
cardiac muscle hypertrophy can be in response to what two things?
1) response to exercise
- “athletes” heart - cross country skiers, cyclists, rowers
2) response to disease
- chronic hypertension
- myocardial infarct
- valve disease
(hypertrophy in disease is disorganized and has fibrosis)
See slide of hypertrophic myocytes
…
cardiac hypertrophy with exercise… tissue organization?
heart function?
normal
normal or enchanted
cardiac hypertrophy with disease… tissue organization?
heart function?
abnormal with fibrosis
abnormal gene expression; overtime, functional degeneration
Hypertrophy mechanism?
balance between protein synthesis and degradation shifts to synthesis
- mechanical triggers (Stretch/load receptors)
- hormonal triggers
Atrophy definition?
a decrease in the size and/or number of cells in a tissue
physiologic response to atrophy ex?
menopause
endometrium, vaginal epithelium, breast epithelium
pathologic response with atrophy ex.?
- skeletal muscle immobilization (cast)
- reduced blood supply (aging brain, vessel constriction by tumors, atheroschlerosis)
- poor nutrion
- cachexia
- hormonal dysfunction (pituitary damage from tumors/infection/trauma/surgery: thyroid/adrenal atrophy)
- aging
see slide of renal atrophy due to ischemia (reduced blood flow example)
….
what is the mechanism of atrophy?
there is a balance between synthesis and degradation that shifts to degradation….
1)autophagy
major pathway for bulk degradation
cytoplasm is sequestered in vacoules and delivered to the lysosome
leads to lipofuscion
2)ubiquitin-proteasome system
proteins are conjugated to ubiquitin, and degraded by the proteasome (A cytoplasmic proteolytic organelle)
Hypertrophy or hyperplasia are sometimes not enough to adapt to stress…
persisten stress sometimes leads to what?
metaplasia
what is metaplasia?
really happens in progenitor cells
- replacement of one mature cell type by one that is more stress-resistant
- mechanism: changes in gene expression that reprogram STEM CELLS
- often reversible if the irritant is removed
airways will change from columnar (glandular) to squamous with cigarettes
…
bladder will chane from transitional to squamos with stones/schistoma
…
esophagus will go from squamous to COLUMNAR! if reflux
…
What is intestinal metaplasia called?
Barrett’s esophagus
replaces stratified epi with goblet cells - may occur in stomach response to H. pylori
due to heart burn = acid reflux
changes to look more like the lining of the intestine
Metaplasia may be accompanied by a loss of function (cilia) or may progress to cancer!!
metaplasia is not considered to be a preneoplastic change BUT the types of stress that trigger metaplasia are also associated with dysplasia and then neoplasia if unresolved
…
Dysplasia def?
characterized by?
ex?
preneoplastic change
characterized by cellular atypia (aberrant maturation, enlarged nuclei, nuclear HYPERCHROMASIA)
ex. often associated in the cervix with HPV infection
see slide of dysplastic cells in pap smear!!
cells become smaller and the nuclei enlarge
…
If cellular adaptations persist/are unresolved….
irreversible damage or cancer may occur
Hypertrophy occurs in…
pregnancy (uterus)
hypertension (heart)
sport (heart, skeletal muscles)
Atrophy occurs in….
plaster cast (skeletal muscles)
hyperplasia occurs in…
pregnancy (uterus)
metaplasia occurs in…
chronic gastritis (gastric epi) reflux esophagitis (esophageal epi) smoking (respiratory epithelium)
Metaplsia is similar to embryonic development because it is changing the progenitor/stem cells themselves (probably only changing a few key transcription factors)
…
Lesions/Diseases can have an intrinsic etiology (genetic/autoimmune) or extrinsic etiology (infection/infestation/predation from prion, virus, fungus, etc) or (non-infectious like hypoxia, trauma, radiation, drugs, nutritional deficiencies, etc)
…
Patient can have right ventricular hypertrophy due to mitral valve damage (causes regurgitation and pulmonary hypertension)
Weight loss drug called Fen-Phem
…
Very severe asthma can result in…
hyperplasia of the smooth muscle cells in the airways
Chronic denervation (thus leading to muscle atrophy) can occur because of post polio syndrome…
can arise decades laser (orthotic devices may help)
polio virus is spread by fecal-oral route, initially kills cells of anterior horn of spinal cord needed for lower motor neuron function
…
Osteoporosis is what?
atrophy of bone tissue
cortex is narrowed, the number and thickness of the trabecular are reduced, and the proportion of bone substance is reduced in proportion to marrow cavity tissue
epidermal atrophy is due to overuse of topical corticosterioids
epidermal atrophy at ankles due to reduced blood supply from venostasis/peripheral vascular disease
…
callus on feet is result of what?
what is it called?
hyperplasia of epidermis…called “acanthosis”
results from chronic injury (e.g. friction)
see also on hands of rowers, guitar players, etc.
what is a corn (clavus)?
similar to callus (hyperplasia) atop toe having a central plug of keratin, sometimes overlies bone spur
Mono CBC finding?
lymphocytosis and atypical lymphocytes (large)
How do you test for mono?
serology tests such as anti-EBV antibodies
“monospot test” or “heterophile test” where serum of diseased causes clumping of RBC of other species, e.g. horse
changes in lymph node with mono?
interfollicular hyperplasia!!
follicle size stays the same though
mononucleosis virus… usually self-limited disease and virus has a low transmissibility so pt isolation is not required…
which viruses cause it?
possible complications?
EBV mostly
CMV occasionally
splenic rupture is a complication
when does intestinal metaplasia sometimes occur in the stomach?
what does it have increased risk for? (2)
Helicobacter pylori infection, alcohol consumption, chronic bile reflux, and smoking
carries increased risk of developing dysplasia and gastric cancer
