Dr. Parsa - Cell Injury and cell death Flashcards
A normal cell is confined by a range of function and structural flexibility depending on:
- the cell’s state of metabolism, differentiation, and specialization
- the constraints of neighboring cell’s
- the availability of metabolic substrates.
Excess physiologic stress/pathologic stimuli beyond the cell’s threshold to maintain normal homeostasis results in ___ ___
cell injury. The injured cell can either adapt to a new steady state which would be reversible, or it could die if it can’t adapt it would undergo necrosis or apoptosis.
Adaptations are ___functional and structural responses to more severe physiologic stresses and some pathologic stimuli, which new altered steady states are achieved, allowing the cell to survive and continue to function
reversible
what are the adaptative responses of the cells:
- atrophy: dec in size and function
- hypertrophy: increase in size
- hyperplasia: increase in number of cells.
- metaplasia: change from one cell type to another
Physiological atrophy is common during normal development. What are some examples of this?
- notochord and thyroglossal duct during fetal dev.
2. uterus dec in size after parturition
what is the pathologic cause of atrophy
- disuse
- loss of innervations
- diminished blood supply
- inadequate nutrition
- loss of endocrine stimulation
- aging
- pressure
what is the biomechanical mechanism of atrophy?
- Decreased protein synthesis
2. Increased protein degradation
What is the molecular pathogenesis of atrophy
1. ubiquitin proteasome pathway: nutrient deficiency or disuse activates ubiquitin ligase which attach the small peptide ubiquitin to cellular proteins and target these proteins for degradation in proteasomes. 2. increased autophagy: starved cell eats its own components 3. reduction in size of organelle
what is an ex of residual bodies
lipofuscin granule. look yellow/brown
what happens if we see group atrophy
considered neurogenic atrophy
describe hypertrophy. what is it due to?
increase in cell size, but no new cells! Due to increased functional demand or increased synthesis of structural proteins.
what is physiologic hypertrophy stimulated by?
- hormones; uterus and breasts in pregnancy
2. inc in workload (exercise): skeletal muscle hypertrophy
what is pathologic hypertrophy
Inc. workload associated with changes in gene expression
what is molecular pathogenesis of hypertrophy
- Phosphoinositidide 3-kinase/Akt pathway
2. Signaling downstream of G protein coupled receptors
Describe physiologic hypertrophy
- mechanical sensors: triggers for physiologic hypertrophy
2. phosphoinositide 3 kinase/Akt pathway
describe pathologic hypertrophy
G protein receptors:
- growth factors: TGF, IGF-1
- Vasoactive agents: adrenergic agonists, angiotensin II
Describe physiological hypertrophy of cardiac muscle
sarcomeres are added in series to lengthen the cell, as on periphery to inc width of the cell
describe pathological cardiac hypertrophy
- can produce concentric hypertrophy in which the ventricular wall and septum thicken with a net dec. in ventricular chamber dimensions.
- eccentric and dilatory cardiac growth; sarcomeres are added in series to ind. myocytes
describe physiologic hyperplasia
- hormonal: female breast during puberty and during pregnancy
- compensatory: liver after partial hepatectomy
describe pathologic hyperplasia
- excessive hormonal stimulation; prostate, endometrium
- effects of growth factors on target cells; repair: fibrovascular proliferation
- viruses (HPV): epithelial/epidermal proliferative lesions.
At the subcellular level, an organelle can undergoe ____ hyperplasia such as _____ hyperplasia in muscle hypertrophy
selective; mitochondrial
Hypertrophy of the smooth ER is a ____response that inc. the amount of enzymes, _____available to detoxify the drugs.
adaptative; cytochrome P-450 oxidase
-overtime patients respond less to the drug bc of this adaptation
Which type of hyperplasia is not precancerous
BPH (in prostate)
what is the most common epithelial metaplasia
columnar to squamous
