Cellular Adaptations (complete) Flashcards
What is proliferation?
Increase in the number of cells
What is differentiation?
Changes in physical and functional properties of cells
Directs the cell to develop into specific cell type
What is apoptosis?
Programmed cell death
Is programmed cell death prompted by a genetic signal and is designed to replace old cells with new
What is ischemia?
Decreased blood flow to cells
What is necrosis?
Death of cells related to cell injury
Damage occurs to cell structures (mitochondria) depleting ATP
- need ATP for cell function
Damage to cell membrane
- allows water into cell causes swelling
What are adaptive changes
- changes that occur due to disease process, altered cell function, or environmental influence
- changes occur when extracellular signals and cues “turn on” signaling mechanisms inside the cell identifying some thing needed by the cell
- signals send chemical messengers that alter gene expression
– increase work demand or threats to survival by changing cell size, number or form
– serve as a protective mechanism, to prevent cellular and tissue damage
What happens when the reason for cell adaptation is removed?
the need for changing gene expression stops and in some instances the cell will go back to normal
What is atrophy?
- cells revert to smaller size in response to changes in metabolic requirements or their environment
- when cells are not being used: there is decreased demand
– the cells will go back to a smaller size and function at a level that is compatible for survival - cells reduce the oxygen consumption and cellular functions by decreasing the number of organelles
What happens when cells atrophy?
What are causes of atrophy?
Disuse: (biggest cause of atrophy)
- decreased skeletal muscle
Denervation
- occurs when limb is paralyzed
- losing nerve stimulation to move
- is essentially disuse
Loss of endocrine stimulation: menopause
Inadequate nutrition
Ischemia:
- from decreased oxygen to tissues
Aging
What is hypertrophy?
An increase in cell size and a resulting increase in the amount of functioning tissue
Comes from an increased workload that is placed usually on the cardiac and skeletal muscle
- just can not make more cells
- causes an increase in size NOT NUMBER
Have an increase in calorie consumption because of increased metabolic demand (michael phelps…)
How does hypertrophy work?
Works by increasing the functional components of the cell to find a balance between what is needed and how far it can be pushed to meet the needs
- muscle cells make more actin, myosin, and ATP
What are examples of physiologic hypertrophy? Is it good or bad?
Good! Can return to normal state
Examples:
- chronic exercise
- pregnancy
Increase in myocyte length > increase in myocyte width
What are examples of pathologic hypertrophy? Is it good or bad?
Bad! Cannot return to normal state really because pathologic change
Examples:
- hypertension
- myocardial infarction
- endocrine disorder, etc
In the heart: ventricles decrease in size and heart works harder to pump blood, more effort
- blood flow is restricted
What is compensatory hypertrophy?
Enlargement of remaining organ or tissue after a portion has been surgically removed or becomes inactive
- nephrectomy: remaining kidney enlarges to compensate for loss of other
- partial hepatectomy
What is hyperplasia?
- increase in number of cells in an organ or tissue
- occurs in tissues which have mitotic division such as epidermis, intestinal epithelium, and glandular tissue
- is controlled
- usually stops when stimulus is removed
- normal adaptive process
– occurs from a stimulus
– likely genes responding to messengers in the cell to increase replication
Can be physiologic or pathologic
What is hyperplasia stimulated by?
Stimulated by hormonal or compensatory mechanisms
- hormonal: pregnancy
Is part of wound healing
Abnormal/maladaptive hyperplasia
- keloid
Example of pathologic hyperplasia: benign prostatic hyperplasia
What is metaplasia?
A change that is reversible in the cells; when one type is replaced with another type
Conversion of normal cells to a different cell type, often following an injury or insult from outside stimuli
- example of cell types: columnar to squamous
- example of external stimuli: changes in pH, acid-base changes, hormones, smoking, alcohol
What does metaplasia occur in response to?
It responds to chronic inflammation and irritation; replaces the original cells with ones that can better tolerate conditions
- protective mechanism
Keeps the same tissue type
Metaplasia - lead to cancer or no?
No.
Can be a normal physiologic change in cell type
- considered to be non-cancerous
- some can be pre-cancerous? (confusing, but is in her slide. i think i will ignore this. but she mentions barrett’s esophagus)
Often will return to normal once stimuli has been removed (reversible)
What can metaplasia progress to?
Dysplasia
What is dysplasia?
Characterized by deranged cell growth of a specific tissue which results in cells of all shapes and sizes
It is adaptive meaning once irritation is gone, can resolve or progress to cancer in situ
Dysplasia is not reversible
What does dysplasia result from?
Often from irritation or inflammation
Can be a precursor of cancer
Pathology of metaplasia vs Dysplasia
Metaplasia:
- conversion of one cell type to another, often following tissue insult or injury
- an adaptive process that occurs due to an external stimuli (e.g. smoking)
Dysplasia:
- development of abnormal types of cells within a tissue
- may signify a stage preceding the development of cancer
- may be due to genetic alterations
- change in phenotype (characteristics) of cells or tissues
Cancer: metaplasia vs. dysplasia
Metaplasia:
- does not lead to formation of cancers!
- may lead to dysplasia
Dysplasia:
- may cause cancer
Reversibility: metaplasia vs dysplasia?
Metaplasia: reversible
Dysplasia: irreversible
Tissue types: metaplasia vs dysplasia
Metaplasia: occurs in various types of tissue
Dysplasia: primarily occurs in epithelial tissue
What is necrosis?
Occurs when cells die
- stressors or insults exceed ability to survive
- irreversible damage and body unable to compensate
What is intracellular accumulation?
Buildup of substances that cannot immediately use or eliminate
- may be abnormal or stored products from other parts of the body
Substances may accumulate transiently or permanently:
- normal body substances (lipids; leads to atherosclerosis)
- abnormal exogenous products, from errors in metabolism
- exogenous products that cannot be broken down by cell
Smoking leading to lung cancer causes which type of cellular change?
Dysplasia b/c specifically denotes cancer
Hyperplasia is defined as:
Increased number of cells in an organ or tissue
Which cell type is a precursor to cancer?
Dysplasia
Examples of physiologic hyperplasia
- increased size of breasts during pregnancy
- increase in thickness of endometrium during menstrual cycle
- growth of liver following a partial resection
