Flashcards in Chp. 1 Growth Adaptations, Cellular Injury, & Cell Death Deck (10):
What is hyperplasia? What are the tissues that cannot undergo hyperplasia?
Increase in number of cells. These new cells come from stem cells. Usu occurs with hypertrophy.
Permanent tissues such as cardiac myocytes, skeletal muscle cells, nerve
ex: cardio myocytes undergo hypertrophy in response to stress from HTN
What is hypertrophy?
Increase in the size of cells. Usu occurs with hyperplasia
If untreated, what can pathologic hyperplasia lead to? What is a notable exception of pathologic hyperplasia?
Can lead to dysplasia and eventually cancer. Ex: Endometrial hyperplasia (too much estrogen)
Exception is Benign Prostatic Hyperplasia WHICH DOES NOT INCREASE THE RISK FOR PROSTATE CANCER
What is atrophy?
How is decrease in cell number accomplished?
Atrophy is a decrease in organ size in response to decreased stress (decreased use, blood supply, hormonal stimulation, etc).
Decrease in cell number is accomplished via apoptosis.
Decrease in cell size is accomplished 2 ways:
by ubiquitin-proteosome degradation. Intermediate filaments of the cytoskeleton are tagged with ubiquitin and the proteosome degrades it.
the other way is via AUTOPHAGY where the cell makes autophagic vacuoles, puts the components it no longer needs in there, then the vac fuses with the lysosome and the cellular components are hydrolyzed.
What is metaplasia? Is it reversible?
Metaplasia is a reversible process where a CHANGE IN STRESS LEADS TO A CHANGE IN CELL TYPE. (usu surface epithelium is affected).
The cell type changes because the original stem cells are reprogrammed to produce the new cell type
Ex: Barrett's Esophagus
Under constant stress, metaplasia can lead to what?
Can lead to dysplasia, and then eventually cancer. i.e. Barretts can lead to ADENOCARCINOMA OF THE ESOPHAGUS.
Exception: Apocrine Metaplasia of the Breast which carries no increased risk for cancer
What Vitamin deficiency can lead to metaplasia? What are the physiological symptoms?
Vitamin A deficiency.
Can lead to dry eyes due to goblet/columnar epithelium turning into KERATINIZING squamous epithelium.
Dry eyes can eventually lead to destruction of the cornea or KERATOMALACIA and blindness.
What other tissue can undergo metaplasia? An example is when tissue turns into bone?
The tissue is connective tissue. Classic example is myositis ossificans where connective tissue within muscle turns to bone during healing after trauma. Not to be confused with osteosarcoma which is a cancer that grows out of the bone into the connective tissue
Define dysplasia and give an example. Is it reversible?
Dysplasia is disordered growth of cells, and most often refers to PRECANCEROUS CELLS. An example is CIN or cervical intraepithelial neoplasia which is a precursor to cervical cancer.
It is reversible and usu due to LONGSTANDING HYPERPLASIA (i.e. endometrial hyperplasia) OR METAPLASIA (Barretts)
Dysplasia if unchecked leads to carcinoma (irreversible)