Cellular Adaptations (complete)

Question 1

What is proliferation?

Answer 1

Increase in the number of cells

Question 2

What is differentiation?

Answer 2

Changes in physical and functional properties of cells
Directs the cell to develop into specific cell type

Question 3

What is apoptosis?

Answer 3

Programmed cell death
Is programmed cell death prompted by a genetic signal and is designed to replace old cells with new

Question 4

What is ischemia?

Answer 4

Decreased blood flow to cells

Question 5

What is necrosis?

Answer 5

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

Question 6

What are adaptive changes

Answer 6

• 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

Question 7

What happens when the reason for cell adaptation is removed?

Answer 7

the need for changing gene expression stops and in some instances the cell will go back to normal

Question 8

What is atrophy?

Answer 8

• 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

Question 9

What happens when cells atrophy?

Answer 9

Question 10

What are causes of atrophy?

Answer 10

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

Question 11

What is hypertrophy?

Answer 11

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…)

Question 12

How does hypertrophy work?

Answer 12

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

Question 13

What are examples of physiologic hypertrophy? Is it good or bad?

Answer 13

Good! Can return to normal state
Examples:
- chronic exercise
- pregnancy

Increase in myocyte length > increase in myocyte width

Question 14

What are examples of pathologic hypertrophy? Is it good or bad?

Answer 14

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

Question 15

What is compensatory hypertrophy?

Answer 15

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

Question 16

What is hyperplasia?

Answer 16

• 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

Question 17

What is hyperplasia stimulated by?

Answer 17

Stimulated by hormonal or compensatory mechanisms
- hormonal: pregnancy
Is part of wound healing
Abnormal/maladaptive hyperplasia
- keloid

Example of pathologic hyperplasia: benign prostatic hyperplasia

Question 18

What is metaplasia?

Answer 18

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

Question 19

What does metaplasia occur in response to?

Answer 19

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

Question 20

Metaplasia - lead to cancer or no?

Answer 20

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)

Question 21

What can metaplasia progress to?

Answer 21

Dysplasia

Question 22

What is dysplasia?

Answer 22

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

Question 23

What does dysplasia result from?

Answer 23

Often from irritation or inflammation
Can be a precursor of cancer

Question 24

Pathology of metaplasia vs Dysplasia

Answer 24

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

Question 25

Cancer: metaplasia vs. dysplasia

Answer 25

Metaplasia:
- does not lead to formation of cancers!
- may lead to dysplasia

Dysplasia:
- may cause cancer

Question 26

Reversibility: metaplasia vs dysplasia?

Answer 26

Metaplasia: reversible
Dysplasia: irreversible

Question 27

Tissue types: metaplasia vs dysplasia

Answer 27

Metaplasia: occurs in various types of tissue
Dysplasia: primarily occurs in epithelial tissue

Question 28

What is necrosis?

Answer 28

Occurs when cells die
- stressors or insults exceed ability to survive
- irreversible damage and body unable to compensate

Question 29

What is intracellular accumulation?

Answer 29

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

Question 30

Smoking leading to lung cancer causes which type of cellular change?

Answer 30

Dysplasia b/c specifically denotes cancer

Question 31

Hyperplasia is defined as:

Answer 31

Increased number of cells in an organ or tissue

Question 32

Which cell type is a precursor to cancer?

Answer 32

Dysplasia

Question 33

Examples of physiologic hyperplasia

Answer 33

• increased size of breasts during pregnancy
• increase in thickness of endometrium during menstrual cycle
• growth of liver following a partial resection