Cellular Adaptations Flashcards
Cellular Adaptations
-Cells adapt to escape and protect themselves from injury
-Permits survival and maintenance of cell function
-Adapted cell is neither normal nor injured; its condition lies somewhere between both states
Atrophy
-Cells shrink
-Due to decreased workload or adverse environmental conditions
-Results in a decrease in cell size
Types of atrophy
-Disuse (paralysis)
-Degeneration (MS)
-Ischemic (kidney, heart)
-Malnutrition (starvation)
-Loss of endocrine stimulation (uterine, breast)
Brain atrophy with alzheimer’s
-Atrophic cells have lost E.R.
-Have fewer mitochondria and myofilaments
Hypertrophy
-Increased size of cells
-Due to increased workload requirement of an organ part
-Increased protein in cellular components with no increase in cellular fluid
-Results in an increase in tissue mass
-Seen in cardiac, skeletal, and muscle tissue
-These cells are not capable of mitosis, so no increase number of hypertrophy or hyperplasia
-May be a normal physiologic response
-Seen in an increase in muscle size with exercise
-May be a pathological response as in myocardial hypertrophy from hypertension or valve disease
Left ventricular hypertrophy
-A pathological hypertrophy resulting in an increased size of heart due to increased workload cause by hypertension
-There is an increase in size but function is compromised
-Limit to the amount the tissue can enlarge
Hyperplasia
-Increased number of cells
-Due to a response from appropriate stimulus and ceases when stimulus is removed
-Restricted to cells capable of mitosis
-Important in wound healing
-Epidermis, intestinal epithelium, glandular tissue
Physiological hyperplasia
-Uterus and breast enlarge in pregnancy
-May occur with hypertrophy
Non-physiologic hyperplasia
-Seen in prostatic hypertrophy
-Endometrial hyperplasia due to increased hormone stimulation
-Thyroid enlargement
Hyperplasia seen in finger warts
-Epidermal hyperplasia due to viral stimulation
-Plantar warts: increased number of epidermal cells
-Increased DNA synthesis and mitotic division
Metaplasia
-One cell type is replaced by another
-May predispose to cancer
-Reprogramming of undifferentiated stem cells
-Allows cells to better survive in a hostile environment
-Reversible
-Response to chronic irritation and inflammation
-Cells that are normally columnar or stratified may change to squamous
Examples of metaplasia
-With continued smoke exposure, ciliated columnar cells are changed to stratified squamous cells
-Cervical cells change when exposed to STDs or HPV
-Continued exposure may predispose to cancerous transformations
Dysplasia
-Atypical hyperplasia
-Deranged cell growth resulting in cells of varying size, shape, and appearance
-May be associated with chronic irritation or inflammation
-May be reversible if offending agent is removed
-Considered a strong precursor of cancer
-However, dysplasia is an adaptive process; may or may not lead to cancer
-Decrease risk if irritation is removed or inflammation treated
Anaplasia
-Cells differentiate to a more immature or embryonic form
-Malignant tumors are characterized by anaplastic cell growth
