Chapter 5 Flashcards
Genes expressed in all cells fall into one of two categories, what are they?
- Operating genes that are necessary for normal function of a cell.
- Genes that determine the differentiating characteristics of a particular cell type.
Define cellular adaptation
Cells are able to adapt to increased work demands or threats to survival by changing their size (atrophy and hypertrophy), number (hyperplasia), and form (metaplasia)
Normal cellular adaptation occurs when?
in response to an appropriate stimulus and ceases once the need for adaptation has ceased.
Define atrophy
Decrease in cell size
When does atrophy occur?
a decrease in work demands or adverse environmental conditions
What is the purpose of atrophy?
to revert to a smaller and more efficient level of functioning. (reduce amount of oxygen consumed, protein synthesis decrease and smaller organelle/structure sizes)
What happens with insulin and IGF-1 (insulin-like growth factor-1) levels are low, or catabolic signals are present?
muscle atrophy occurs
What is the purpose of insulin and IGF-1 (Insulin-like growth factor 1)?
maintain proper muscle mass
What are the five grouped categories of general causes of atrophy called?
- disuse
- denervation
- loss of endocrine stimulation
- inadequate nutrition
- ischemia or decreased blood flow.
When does disuse atrophy occur?
when there is a reduction in skeletal muscle use.
an example is muscles in a cast.
When does denervation atrophy occur?
a form of disuse atrophy that occurs in the muscles of paralyzed limbs.
What happens when lack of endocrine stimulation occurs?
a form of disuse atrophy occurs, such as when women lose estrogen during menopause and their reproductive organs atrophy.
Is atrophy reversible or irreversible?
reversible
Is atrophy adaptive or maladaptive?
adaptive
What happens with malnutrition and decreased blood flow?
cells reduce size and energy as a means of survival
Define hypertrophy
increase in cell size, and with it an increase in the amount of functioning tissue mass
What muscles normally occur hypertrophy? why?
skeletal and cardiac muscle tissue, because they cannot adapt to increased workload via mitotic division and formation of more cells.
What is the purpose of hypertrophy?
increase in functional components of cell that allows it to achieve equilibrium between demand and functional capacity
What is an example of physiological hypertrophy
Increase in muscle mass associated with exercise.
What is an example of pathologic hypertrophy, and what are the two types it can be?
Result of disease conditions and may be adaptive or compensatory.
What is an example of adaptive hypertrophy?
Myocardial hypertrophy that results from valvular heart disease or hypertension
What is an example of compensatory hypertrophy?
Enlargement of remaining organ or tissue after a portion has been surgically removed or rendered inactive. (kidney is removed, other kidney grows to compensate)
The initiating signals for hypertrophy are complex and related to what four different examples?
- Atp depletion
- mechanical forces (stretching)
- Activation of cell degredation products
- Hormonal factors.
With regards to the heart, initiating signals are divided into what two broad categories?
- biomechanical and stretch sensitive mechanisms.
2. neurohumoral mechanisms that are associated with the release of hormones, growth factors, cytokines, and chemokines.
What is EGF stand for?
Epidermal growth factor
What are IGF-1 and EGF, and what are their purpose
specific neurohumoral ligands. To activate specific signal transduction pathways to increase protein synthesis and decrease protein degredation.
in a pressure overload such as hypertension, hypertrophied myocardial cells have greater length or width?
width
As muscle cells hypertrophy, what three things are synthesized more?
Actin and myosin filaments
Cell enzymes
ATP
Hypertrophied myocardial cells of well trained athletes increase in width or length?
Both, proportionally
Hypertrophied myocardial cells in dilated cardiomyopathy grow in length or width?
Both, but greater proportion in length over width
Define hyperplasia
Increase in number of cells in an organ
When does hyperplasia occur?
in tissues with cells that are capable of mitotic division, such as the epidermis, intestinal epitheluim and glandular tissues.
Hyperplasia involves activation of genes controlling what?
cell proliferation and the presence of intracellular messengers that control cell replication ad growth.
Is hyperplasia a controlled process?
yes
What are the two types of stimuli that induce hyperplasia
Physiologic and nonphysiologic
what are the two types of physiologic hyperplasia
hormonal and compensatory
Breast and uterine enlargement during pregnancy is an example of what type of hyperplasia
hormonal physiologic
The regeneration of liver after partial hepatectomy is an example of what type of hyperplasia
compensatory hyperplasia
Most forms of nonphysiologic hyperplasia are due to what?
excessive hormonal stimulation or the effects of growth factors on target tissues
Define metaplasia
one adult cell type is replaced by another adult cell type
What are the two types of cells that can be replaced in metaplasia
Epithelial or mesenchymal
what is the purpose of metaplasia?
to provide a less specialized(more durable) cell to a chronically injured area.
Although metaplasia resists injury, it does what to function?
decreases function of cell.
Define dysplasia
Deranged cell growth that leads to variation in cell size, shape, and organization
Dysplasia leads to variation in what of the cell?
Size
shape, and
organization
What areas most frequently encounter dysplasia?
metaplastic squamous epithelium of the respiratory tract and uterine cervix
Dysplasia is strongly implicated as a precursor of what?
cancer
What are the five steps of cell progression to malignant neoplasm?
- normal cell experiences abnormal external stimuli/injury so it trust to adapt to injury.
- hyperplasia/hypertrophy occur from stimulus/injury.
- may become metaplastic where it reverts to more simple cell type to resist stress, hoever, if unsuccessful it may become dysplastic
- may become dysplastic, where it can still revert to normal if stimulus removes or if still has stimulus it may become neoplastic.
- neoplastic growth - malignant neoplasm (carcinoma situ)
Define intracellular accumulations
buildup of substances that cells cannot immediately use or eliminate
Where are substances most likely to accumulate?
in the cytoplasm (lysosomes mostly) or in the nucleus
What are the three categories of intracellular accumulation?
Normal body substances
abnormal endogenous products
exogenous products
how do normal body substances accumulate?
Production exceeds waste removal
how do abnormal endogenous substances accumulate?
inborn errors of metabolism, such as if an abnormal enzyme
when do exogenous substances accumulate
when an enzyme is missing
what are pigments?
coloured substance that may accumulate in cells
What is icterus and where does it come from?
also called jaundice (yellow discolouration), is the retention of bilirubin (endogenous bile pigment) from increase bilirubin production
how does jaundice occur?
increased billirubin production from red blood cell destruction, obstruction of bile passage into the intestine, or toxic diseases that affect the livers ability to remove bilirubin from the blood
What is lipofuscin?
yellow brown pigment that results from the accumulation of indigestible residues produces during normal turnover of cell structures.
What is the wear and tear pigment?
lipofuscin
Where is lipofuscin most common?
in heart, nerve and liver cells.
What is coal?
a common exogenous pigment that causes serious lung disease.
What is a diagnostic feature of lead poisoning?
formation of a blue lead line along the margins of the gum
What are tattoos?
insoluble pigments introduced into the skin where they are engulfed by macrophages and persist for a lifetime.
Do lipfuscin and mild fatty change have an effect on cell function?
no
is hyperbilirubinemia reversible?
yes
What does glycogen storage disease cause?
accumulations that result in organ dysfunction, as well as other alterations in physiologic function
What is pathologic calcification?
abnormal tissue deposition of calcium salts, along with small amounts of iron, magnesium and other minerals.
What are the two types of pathologic calcification?
dystrophic calcification, and
metastatic calcification
The type of pathologic calcification that occurs in dead or dying tissue is called
dystrophic calcification
The type of pathologic calcification in normal tissue is called
metastatic calcification
IS dystrophic calcification visible to the naked eye?
yes, as deposits that range from gritty sand like grains, to firm rock hard material.
The pathogenesis of sytrophic calcification involves the formation of what?
crystalline calcium phosphate
Where are calcium deposits from dystrophic calcification derived from?
the bodies of dead or dying cells, as well as the circulation and interstitial fluid
Dystrophic calcification is commonly seen in what?
athermatous lesions of advanced atherosclerosis,
areas of injury in the aorta and large blood vessels, and damaged hear valves
What causes metastatic calcification?
increased serum calcium levels (hypercalcemia)
where can metastatic calcification occur?
lungs, renal tubules and blood vessels
What are the major causes of hypercalcemia?
hyperparathyroidism,
increased mobilization of calcium from bone.
vitamin d intoxication
What are the five categories cell damage can occur?
Injury from physical agents Radiation injury Chemical Injury Injury from biologic agents Injury from nutritional imbalances
What are the three physical ways cells are damaged?
Mechanical forces
Extreme temperature
Electrical injuries
how do mechanical forces injure a cell?
body impact with another object
What happens to a cell with exposure to low intensity heat (43 degrees to 46 degrees)
causes cell injury by inducing vascular injury, accelerating cell metabolism, inactivating temperature-sensitive enzymes, and disrupting the cell membrane
What happens to a cell in intense heat?
coagulation of blood vessels and tissue proteins occurs
define coagulation
the act of liquid turning into a solid or semi solid product
what happens to a cell with exposure to cold?
increase blood viscosity and induces vasoconstriction by direct action on blood vessels, and through reflex activity ot the sympathetic nervious system.
What is more dangerous, ac or dc and why?
AC, it causes violent muscle contractions preventing the person from releasing the electrical source.
What are the three types of radiation injury on cells?
Ionizing radiation
uv radiation
non-ionizing radiation
what is energy above the uv range called? why?
ionizing radiation
the photons have enough energy to knock electrons off atoms and molecules
what is the radiation energy that is at frequencies below those of visible light called?
non-ionizing radiation
What is more vulnerable to radiation injury, bone marrow and intestine, or bone and skeletal mucle, why?
the rapidly dividing cells of bone marrow and intestine.
what type of radiation does infrared light, ultrasound, microwaves, and laser energy fall under?
nonionizing radiation
What are the three types of chemical injury?
drugs
Lead toxicity
mercury toxicity
