Unit 1: Cell Adaptation Flashcards
What do cells respond to?
microenvironment (adjacent cells, ECM, vascular elements), signaling (hormones), physical signals (stretch, temp)
quiescent cells vs labile vs stable cells
- Labile: divide continuously= skin, hair, mucosa, bone marrow
- Quiescent: only divide in situations of stress or repair
- Stable: cannot divide
aplasia- 1. define, 2. pathologic or adaptive response
total lack of stem cell division nearly always pathologic (ie NOT adaptive)
atrophy
- Define
- Why does this happen? Pathological or Physiological?
- pathophysiology
- decrease in the SIZE or NUMBER of cells
- to decrease function and metabolic demand of tissue/cell.
- Physiologically with AGE/decreased endocrine stimulation
- pathologically: ischemia, malnutrition, disuse, loss of innervation, pressure
- Decrease in SIZE: catabolism of cell components (ubiquitin pathway or autophagic vacuoles),
- Decrease in NUMBER: cell death (necrosis or apoptosis), or loss of proliferative factors (hormones/GF).
dysplasia
- define
- cause
- occurs in what cells?
- pre-cancerous changes in CELL STRUCTURE and TISSUE ARCHITECTURE and function that can progress to neoplasia
- damage to DNA
- only cells that can divide!
hyperplasia-
- define
- which tissues, why?
- how?
Pathological OR physiological
- increase in the number of cells
- requires proliferative tissues (stem cells). Does not occur in neurons, heart or skeletal muscle
- increase in proliferative signals (hormonal or growth factors)
hypertrophy
- define
- which tissues, why?
- how?
physiological or pathological
- increase in SIZE of cells
- Almost all tissues. The ONLY adaptive response in non proliferating cells to increase function
- due to increase in synthesis of cell components (usually proteins) or genetic changes
Examples of hyperplasia –physiological and pathological
Physiological-
- Hormonal control: uterus in pregnancy, lactation, puberty
- Local growth factors: wound healing
Pathological
- hormone secretion is out of control (ex: HPV- warts)
- endometrial hyperplasia post-menopause
- hyperkeratosis of skin
- gynecomastia in men (secondary to alcoholism)
- benign nodular prostatic hyperplasia
metaplasia
- Define
- etiology
- adaptive/pathological; reversible/irreversible
- downside?
- replacement of one NORMALLY DIFFERENTIATED cell type with another type due to CHRONIC stress/irritation/infection/injury
- STEM CELLS differentiate into a different cell type that can better withstand stress/irritation
- ADAPTIVE REVERSIBLE response
- loss of functions (ciliary function, mucous secretion)
neoplasia
- Define (pathologic or adaptive?)
- Etiology
- what cell types?
- PATHOLOGIC change that results in unregulated cell growth, mass formation, and tissue destruction==cells are altered in form and function and arise from SINGLE MOTHER CELL (ie monoclonal)
- abnormal expression of damaged DNA
- Only in dividing cells
Big differences between neoplasia and hyperplasia…..?
- Neoplasia= irreversible;
- hyperplasia= reversible
- Neoplasia= not under control of external signals,
- hyperplasia= hormonal control, can be withdrawn to reverse changes
Hypertrophy- examples of physiological and pathological
Physiological: skeletal muscle growth from increased exercise Pathological: heart muscle hypertrophy due to chronic hemodynamic overload (ie: htn)
Tissue adaptation
- etiology
- examples
- reversible/irreversible?
- cell’s attempt to RE-ESTABLISH HOMEOSTASIS due to physiologic or pathologic change in cell’s environment
- hyperplasia, hypertrophy, atrophy, metaplasia
- reversible
Hypoplasia
- Define
- Etiology
- examples?
- lack of development of a tissue or organ
- genetic or mechanical (ex: uterine constraint)
- hypoplastic left heart syndrome, hypoplastic (nondescended) testes
These two are ALWAYS pathologic changes
dysplasia, neoplasia