CH 1 - Cell Injury Flashcards
1
Q
Hyperplasia is defined as
A
an increase in the number of cells in an organ or tissue
2
Q
hypertrophy and hyperplasia is often a response to
A
trophic signals or increased functional demand and is commonly a normal process
3
Q
Erythroid hyperplasia is typically seen in
A
people living at high altitude
4
Q
What happens in erythroid hyperplasia
A
Low oxygen tension evokes the production of erythropoietin which promotes the survival and proliferation of erythroid precursors in the bone marrow
5
Q
The cellular and molecular mechanisms that are responsible for hyperplasia clearly relate to the control of
A
cell proliferation ie cell cycle
6
Q
Fat necrosis
A
Saponification of fat derived from peripancreatic fat cells exposed to pancreatic enzymes is a typical feature of fat necrosis
7
Q
Fat necrosis and acute pancreatitis
A
Lipase released from pancreatic acinar cells during an attack of acute pancreatitis hydrolyzes fat into fatty acids and glycerol Free fatty acids bind with calcium to form soaps which is a process known as saponification
8
Q
Hypocalcemia and acute pancreatitis
A
Entry of calcium ions into the injured tissue reduces the level of calcium in blood Hypocalcemia is therefore a typical finding in patients who had a recent bout of acute pancreatitis
9
Q
Patients with acute pancreatitis experience
A
sudden onset abdominal pain distention and vomiting liquefactive necrosis may also be seen
10
Q
The major adaptive responses of cells to sublethal injury are
A
atrophy hypertrophy hyperplasia metaplasia dysplasia and intracellular storage
11
Q
Metaplasia is defined as
A
the conversion of one differentiated cell pathway to another
12
Q
Metaplasia in GERD
A
Barrets esophagus the esophageal squamous epithelium is replaced by columnar epithelium as a result of chronic gastroesophageal reflux
13
Q
How is the lesion in metaplasia with GERD characterized histologically
A
by intestine like epithelium composed of goblet cells and cells similar to those of incompletely intestinalized gastric mucosa
14
Q
Squamous metaplasia
A
occurs in the bronchial epithelium of smokers among other examples
15
Q
Simple aplastic and complex hyperplasia are
A
preneoplastic changes that are most often described in the uterine endometrium of postmenopausal women
16
Q
Metastatic calcifcation
A
is associated with an increased serum calcium concentration hypercalcemia Almost any disorder that increases serum calcium levels can lead to calcification in the alveolar septa of the lung renal tubules and blood vessels
17
Q
Examples that can lead to metastatic calcification
A
a parathyroid adenoma that produces large quantities of parathyroid hormone multiple opacities in the cornea of a child given large amounts of vitamin D and partially calcified alveolar septa in the lungs of a patient with breast cancer metastatic to bone
18
Q
Breast cancer metastases to bone are often
A
osteolytic and therefore accompanied by hypercalcemia
19
Q
Dystrophic calcification
A
has its origin in direct cell injury
20
Q
Arteriosclerosis
A
is an example of dystrophic calcification
21
Q
Clinically atrophy is recognized as
A
diminution in the size or function of an organ
22
Q
Atrophy is often seen in
A
areas of vascular insufficiency or chronic inflammation and may result from disuse
23
Q
Atrophy may be thought of as
A
an adaptive response to stress in which the cell shuts down its differentiated functions
24
Q
Reduction in the size of an organ may reflect
A
reversible cell atrophy or may be caused by irreversible loss of cells
25
atrophy of the brain in a patient with Alzheimer disease is
secondary to extensive cell death and the size of the organ cannot be restored
26
Anaplasia
represents lack of differentiated features in a neoplasm
27
Cells that compose an epithelium exhibit
uniformity of size and shape and they undergo maturation in an orderly fashion eg from plump basal cells to flat superficial cells in a squamous epithelium
28
dysplasia
regular appearance is disturbed by 1 variations in the size and shape of the cells 2 enlargement irregularity and hyperchromatism of the nuclei and 3 disorderly arrangement of the cells within the epithelium
29
Dysplasia of the bronchial epithelium is
a reaction of respiratory epithelium to carcinogens in tobacco smoke It is potentially reversible if the patient stops smoking but is considered preneoplastic and may progress to carcinoma
30
Invasiveness
connotes malignant behavior
31
Hypertrophic cardiac myocytes have
more cytoplasm and larger nuclei than normal cells
32
the final steps of hypertrophic response include
increases in mRNA rRNA and protein
33
Hypertrophy results from
transcriptional regulation
34
Aneuploidy
is not a feature of myofiber hypertrophy
35
Water influx and hypertrophy
which is typical of hydropic swelling in acute injury is not a common feature of hypertrophy
36
Dystrophic calcification reflects
underlying cell injury
37
Serum levels of calcium in dystrophic calcification
are normal and the calcium deposits are located in previously damaged tissue
38
Intrauterine Toxoplasma infection
affects approximately 01 of all pregnancies
39
Acute encephalitis and calcifications
in the fetus afflicted with TORCH syndrome may be associated with foci of necrosis that become calcified
40
Microcephaly hydrocephalus and microgyria are frequent complications of
intrauterine infections
41
Metastatic calcification reflects
an underlying disorder in calcium metabolism
42
Hydropic swelling reflects
acute reversible sublethal cell injury
43
Hydropic swelling results from
impairment of cellular volume regulation a process that controls ionic concentrations in the cytoplasm
44
The regulation for sodium involves
1 the plasma membrane 2 the plasma membrane sodium pump and 3 the supply of ATP
45
Accumulation of sodium in the cell leads to
an increase in water content to maintain isosmotic conditions and the cell then swells
46
Lipid peroxidation
is often a feature of irreversible cell injury
47
Hyaline is a term that refers to
any material that exhibits a reddish homogeneous appearance when stained with hematoxylin and eosin HE
48
Standard terminology for hyaline includes
hyaline arteriolosclerosis alcoholic hyaline in the liver hyaline membranes in the lung and hyaline droplets in various cells
49
Alcoholic Mallory
hyaline is composed of cytoskeletal intermediate filaments cytokeratins whereas pulmonary hyaline membranes consist of plasma proteins deposited in alveoli
50
alpha 1 antitrypsin deficiency
Structurally abnormal alpha 1 antitrypsin molecules accumulate in the liver of patients with alpha 1 antitrypsin deficiency
51
alpha Synuclein
accumulates in neurons in the substantia nigra of patients with Parkinson disease
52
Anthracosis
refers to the storage of carbon particles in the lung and regional lymph nodes These particles accumulate in alveolar macrophages and are also transported to hilar and mediastinal lymph nodes where the indigestible material is stored indefinitely within t
53
Workers who mine hard coal anthracite develop
pulmonary fibrosis owing to the presence of toxicfibrogenic dusts such as silica This type of pneumoconiosis is more properly classified as anthracosilicosis
54
Hemosiderosis
represents intracellular storage of iron hemosiderin
55
Infants of diabetic mothers show
a 5 to 10 incidence of major developmental abnormalities including anomalies of the heart and great vessels and neural tube defects
56
The frequency of developmental abnormalities in infants of diabetic mothers relates to
the control of maternal diabetes during early gestation
57
Fetal development in diabetic mothers
During fetal development the islet cells of the pancreas have proliferative capacity and respond to increased demand for insulin by undergoing physiologic hyperplasia
58
Fetuses exposed to hyperglycemia in utero
may develop hyperplasia of the pancreatic beta cells which may secrete insulin autonomously and cause hypoglycemia at birth
59
Metaplasia is defined as
the conversion of one differentiated cell pathway to another
60
Liquifactive necrosis
When the rate of dissolution of the necrotic cells is faster than the rate of repair the resulting morphologic appearance is termed liquefactive necrosis
61
The polymorphonuclear leukocytes of the acute inflammatory reaction are
endowed with potent hydrolases that are capable of digesting dead cells A sharply localized collection of these acute inflammatory cells in response to a bacterial infection produces rapid death and dissolution of tissue
62
The result of liquefactive necrosis is often
an abscess defined as a cavity formed by liquefactive necrosis in a solid tissue
63
Caseous necrosis is seen in
necrotizing granulomas
64
In coagulative necrosis
the outline of the cell is retained
65
Fat necrosis in the lung
Fat is not present in the lung parenchyma
66
Fibrinoid necrosis
is seen in patients with necrotizing vasculitis
67
Necrosis and primary TB
Caseous necrosis is a characteristic of primary tuberculosis in which the necrotic cells fail to retain their cellular outlines They do not disappear by lysis as in liquefactive necrosis but persist indefinitely as amorphous coarsely granular eosinophilic
68
Gross appearance of necrosis in primary TB
granular eosinophilic debris resembles clumpy cheese hence the name caseous necrosis
69
Primary tuberculosis is often
asymptomatic or presents with nonspecific symptoms such as low grade fever loss of appetite and occasional spells of coughing
70
The Ghon complex
includes parenchymal consolidation and ipsilateral enlargement of hilar lymph nodes and is often accompanied by a pleural effusion
71
Fibrinoid necrosis is seen in patients with
necrotizing vasculitis
72
Coagulative necrosis refers to
light microscopic alterations in dying cells
73
When stained with the usual combination of hematoxylin and eosin the cytoplasm of a necrotic cell is
eosinophilic
74
The nucleus of a necrotic cell displays
an initial clumping of chromatin followed by its redistribution along the nuclear membrane
75
In pyknosis
the nucleus becomes smaller and stains deeply basophilic as chromatin clumping continues
76
Karyorrhexis and karyolysis represent
further steps in the fragmentation and dissolution of the nucleus
77
Immune system and viral infections
Both humoral and cellular arms of the immune system protect against the harmful effects of viral infections
78
the presentation of viral proteins to the immune system does what
immunizes the body against the invader and elicits both killer cells and the production of antiviral antibodies
79
Elimination of virally infected cells
These arms of the immune system eliminate virus infected cells by either inducing apoptosis or directing complement mediated cytolysis
80
Rabies virus and the brain
rabies virus enters a peripheral nerve and can be transported by retrograde axoplasmic flow to the spinal cord and brain The inflammation is centered in the brainstem and spills into the cerebellum and hypothalamus The other choices are seen in acute infl
81
Hypertrophy
is a response to trophic signals or increased functional demand and is commonly a normal process
82
Example of hypertrophy in the kidneys
if one kidney is rendered inoperative because of vascular occlusion the contralateral kidney hypertrophies to accommodate increased demand
83
The molecular basis of hypertrophy reflects increased expression of
growth promoting genes protooncogenes such as myc fos and ras
84
Coagulative necrosis is characterized by
a massive influx of calcium into the cell Under normal circumstances the plasma membrane maintains a steep gradient of calcium ions whose concentration in interstitial fluids is 10000 times higher than that inside the cell
85
Irreversible cell injury
damages the plasma membrane which then fails to maintain the calcium gradient allowing the influx of calcium into the cell
86
The most common form of atrophy
follows reduced functional demand For example after immobilization of a limb in a cast as treatment for a bone fracture muscle cells atrophy and muscular strength is reduced
87
Gene expression in atrophy
The expression of differentiation genes is repressed
88
On restoration of normal conditions for atrophic cells
they are fully capable of resuming their differentiated functions size increases to normal and specialized functions such as protein synthesis or contractile force return to their original levels
89
Ischemic necrosis is typically
a complication of vascular insufficiency
90
Irreversible injury to skeletal muscle in a bone fracture
this would be an unlikely complication of bone fracture
91
Ischemic necrosis of cardiac myocytes
is the leading cause of death in the Western world
92
In brief the interruption of blood supply to the heart
decreases the delivery of O2 and glucose Lack of O2 impairs mitochondrial electron transport thereby decreasing ATP synthesis and facilitating the production of reactive oxygen species
93
Mitochondrial damage in ischemic necrosis of cardiac myocytes
promotes the release of cytochrome c to the cytosol and the cell dies
94
The morphologic appearance of the necrotic cell
has traditionally been termed coagulative necrosis because of its similarity to the coagulation of proteins that occurs upon heating
95
Nuclear fragmentation
karyorrhexis and karyolysis is a hallmark of coagulative necrosis
96
Disaggregation of polyribosomes
are features of both reversibly and irreversibly injured cells
97
Lymphocytes are a hallmark of
chronic inflammation
98
Substances that cannot be metabolized
accumulate in cells
99
Examples that cannot be metabolized include
1 endogenous substrates that are not processed because a key enzyme is missing lysosomal storage diseases 2 insoluble endogenous pigments lipofuscin and melanin and 3 exogenous particulates silica and carbon
100
Lipofuscin
is a wear and tear pigment of aging that accumulates in organs such as the brain heart and liver
101
Lipofuscin is found in
lysosomes and contains peroxidation products of unsaturated fatty acids
102
The presence of this pigment lipofuscin is thought to reflect
continuing lipid peroxidation of cellular membranes as a result of inadequate defenses against activated oxygen radicals
103
Hemosiderin
is a partially denatured form of ferritin that aggregates easily and is recognized microscopically as yellow brown granules in the cytoplasm which turn blue with the Prussian blue reaction
104
In hereditary hemochromatosis
a genetic abnormality of iron absorption in the small intestine excess iron is stored mostly in the form of hemosiderin primarily in the liver
105
Hemoglobin
is the iron containing pigment of RBCs
106
Bilirubin is
a product of heme catabolism that may accumulate in liver cells but does not stain with Prussian blue
107
Transferrin
binds serum iron
108
Metaplasia of transitional epithelium to glandular epithelium is seen in patients with
chronic inflammation of the bladder cystitis glandularis
109
Metaplasia is considered to be
a protective mechanism but it is not necessarily a harmless process
110
Example of metaplasia being harmful
squamous metaplasia in a bronchus may protect against injury produced by tobacco smoke but it also impairs the production of mucus and ciliary clearance of debris Furthermore neoplastic transformation may occur in metaplastic epithelium
111
What is the cytologic evidence needed to consider dysplasia
atypia and neoplasia
112
Ischemiareperfusion IR injury
is a common clinical problem that arises in the setting of occlusive cardiovascular disease infection transplantation shock and many other circumstances
113
The genesis of IR injury relates to
the interplay between transient ischemia and the re establishment of blood flow reperfusion
114
Initially ischemia produces
a type of cellular damage that leads to the generation of free radical species
115
Subsequently to ischemia reperfusion
provides abundant molecular oxygen O2 to combine with free radicals to form reactive oxygen species
116
In IR injury how are Oxygen radicals formed inside cells
through the xanthine oxidase pathway and released from activated neutrophils
117
During lipid peroxidation hydroxyl radicals
remove a hydrogen atom from the unsaturated fatty acids of membrane phospholipids
118
The lipid radicals in lipid peroxidation react with
molecular oxygen and form a lipid peroxide radical A chain reaction is initiated
119
Lipid peroxides are
unstable and break down into smaller molecules
120
The destruction of the unsaturated fatty acids of phospholipids results in
a loss of membrane integrity
121
Polymorphonuclear leukocytes
segmented neutrophils rapidly accumulate at sites of injury They are loaded with acid hydrolases and are capable of digesting dead cells
122
A localized collection of PMN cells may create
an abscess with central liquefaction pus
123
Liquefactive necrosis is also commonly seen in
the brain
124
Caseous necrosis is seen in
necrotizing granulomas
125
Fat necrosis is typically encountered in patients with
acute pancreatitis
126
Fibrinoid necrosis
is seen in patients with necrotizing vasculitis
127
Apoptosis is
a programmed pathway of cell death that is triggered by a variety of extracellular and intracellular signals It is often a self defense mechanism destroying cells that have been infected with pathogens or those in which genomic alterations have occurred
128
After staining with hematoxylin and eosin apoptotic cells are
visible under the light microscope as acidophilic Councilman bodies These deeply eosinophilic structures represent membrane bound cellular remnants that are extruded into the hepatic sinusoids
129
Fragmentation of DNA is a hallmark of
cells undergoing both necrosis and apoptosis but apoptotic cells can be detected by demonstrating nucleosomal laddering
130
Nucleosomal laddering
This pattern of DNA degradation is characteristic of apoptotic cell death
131
Nucleosomal laddering results from
the cleavage of chromosomal DNA at nucleosomes by endonucleases
132
Nucleosomes
are regularly spaced along the genome a pattern of regular bands can be seen when fragments of cellular DNA are separated by electrophoresis
133
Ischemia
Interference with blood supply to tissues is known as ischemia
134
Total ischemia results in
cell death
135
Partial ischemia
occurs after incomplete occlusion of a blood vessel or in areas of inadequate collateral circulation
136
Partial ischemia results in
a chronically reduced oxygen supply a condition often compatible with continued cell viability Under such circumstances cell atrophy is common
137
Example of atrophy in partial ischemia
it is frequently seen around the inadequately perfused margins of infarcts in the heart brain and kidneys
138
Myositis ossificans
is a disease characterized by formation of bony trabeculae within striated muscle
139
Myositis ossificans represents a form of
osseous metaplasia ie replacement of one differentiated tissue with another type of normal differentiated tissue
140
Dystrophic calcification and bone trabecuale
Although dystrophic calcification frequently occurs at sites of prior injury it does not lead to the formation of bone trabeculae
141
The mitochondrial membrane and apoptosis
it is a key regulator of apoptosis
142
When mitochondrial pores open in apoptosis
cytochrome c leaks out and activates Apaf 1 which converts procaspase 9 to caspase 9 resulting in the activation of downstream caspases cysteine proteases These effector caspases cleave target proteins including endonucleases nuclear proteins and cytoskel
143
ROS and apoptosis
Reactive oxygen species are triggers of apoptosis but they do not mediate programmed cell death
144
Hydropic swelling may result from
many causes including chemical and biologic toxins infections and ischemia
145
Injurious agents cause hydropic swelling by
1 increasing the permeability of the plasma membrane to sodium 2 damaging the membrane sodium potassium ATPase pump or 3 interfering with the synthesis of ATP thereby depriving the pump of its fuel
146
During periods of ischemia
anaerobic glycolysis leads to the overproduction of lactate and a decrease in intracellular pH
147
Lack of O2 during myocardial ischemia blocks
the production of ATP Pyruvate is reduced to lactate in the cytosol and lowers intracellular pH
148
The acidification of the cytosol
initiates a downward spiral of events that propels the cell toward necrosis
149
Fibrinoid necrosis is
an alteration of injured blood vessels in which the insudation and accumulation of plasma proteins cause the wall to stain intensely with eosin
150
Hutchinson Gilford progeria
is a rare genetic disease characterized by early cataracts hair loss atrophy of the skin osteoporosis and atherosclerosis This phenotype gives the impression of premature aging in children
151
Progeria is one of many diseases caused by
mutations in the human lamin A gene LMNA
152
Lamins are
intermediate filament proteins that form a fibrous meshwork beneath the nuclear envelope
153
Defective lamin A
is thought to make the nucleus unstable leading to cell injury and death
154
Postpartum infarction of the anterior pituitary results in
decreased production of adrenocorticotropic hormone ACTH also termed corticotropin Lack of corticotrophin results in atrophy of the adrenal cortex which leads to adrenal insufficiency
155
Symptoms of acute adrenal insufficiency
Addisonian crisis – Sheehan syndrome include hypotension and shock as well as weakness vomiting abdominal pain and lethargy
156
Metaplasia is almost invariably
a response to persistent injury and can be thought of as an adaptive mechanism
157
Prolonged exposure of the bronchi to tobacco smoke leads to
squamous metaplasia of the bronchial epithelium
158
Unlike malignancy and necrosis with scarring metaplasia is
usually fully reversible If the source of injury is removed the patient stops smoking then the metaplastic epithelium will eventually return to normal
159
Actinic keratosis is
a form of dysplasia in sun exposed skin
160
Histologically actinic keratosis lesions are composed of
atypical squamous cells which vary in size and shape They show no signs of regular maturation as the cells move from the basal layer of the epidermis to the surface
161
Dysplasia is
a preneoplastic lesion in the sense that it is a necessary stage in the multistep evolution to cancer
162
Unlike cancer cells dysplastic cells are
not entirely autonomous and the histologic appearance of the tissue may still revert to normal
163
Renal cell carcinomas often secrete
erythropoietin
164
Erythropoietin
stimulates the growth of erythrocyte precursors in the bone marrow by inhibiting programmed cell death
165
Increased hematocrit in renal cell carcinoma patients
it is the result of bone marrow hyperplasia affecting the erythroid lineage from increased EPO secretion
166
Both dysplasia and early cancer are associated with
disordered growth and maturation of the tissue
167
Similar to the development of cancer dysplasia is believed to
result from mutations in a proliferating cell population
168
When a particular mutation confers a growth or survival advantage
the progeny of the affected cell will tend to predominate In turn their continued proliferation provides the opportunity for further mutations The accumulation of such mutations progressively distances the cell from normal regulatory constraints and may l
169
CCl4 is first metabolized via
the mixed function oxygenase system P450 of the liver to a chloride ion and a highly reactive trichloromethyl free radical
170
Like the hydroxyl radical the trichloromethyl free radical is
a potent initiator of lipid peroxidation which damages the plasma membrane and leads to cell death
171
Psoriasis is a disease of
the dermis and epidermis
172
Psoriasis is characterized by
persistent epidermal hyperplasia It is a chronic frequently familial disorder that features large erythematous scaly plaques commonly on the dorsal extensor cutaneous surfaces
173
For the development of psoriatic lesions there is evidence to suggest that
deregulation of epidermal proliferation and an abnormality in the microcirculation of the dermis are responsible
174
In Psoriasis abnormal proliferation of keratinocytes is thought to be related to
defective epidermal cell surface receptors and altered intracellular signaling
175
Carbon tetrachloride and acetaminophen are metabolized by
cytochrome P450 of the mixed function oxidase system located in the smooth endoplasmic reticulum These hepatotoxins are metabolized differently and it is possible to relate the subsequent evolution of lethal cell injury to the specific features of this me
176
Acetaminophen
an important constituent of many analgesics is innocuous in recommended doses but when consumed to excess it is highly toxic to the liver
177
Acetaminophen and alcohol
The metabolism of acetaminophen to yield highly reactive quinones is accelerated by alcohol consumption an effect mediated by an ethanol induced increase in cytochrome P450
178
Viral cytotoxicity is either
direct or indirect immunologically mediated
179
Viruses may injure cells directly by
subverting cellular enzymes and depleting the cells nutrients thereby disrupting the normal homeostatic mechanisms
180
Some viruses also encode proteins that
induce apoptosis once daughter virions are mature
181
Viruses may also injure cells indirectly through
activation of the immune system Both humoral and cellular arms of the immune system protect against the harmful effects of viral infections by eliminating infected cells
182
In brief the presentation of viral proteins to the immune system
in the context of a self major histocompatibility complex on the cell surface immunizes the body against the invader and elicits both killer cells and antiviral antibodies
183
These arms of the immune system eliminate virus infected cells by
inducing apoptosis or by lysing the virally infected target cell with complement
184
Several acquired and inherited diseases are characterized by
intracellular accumulation of abnormal proteins
185
The deviant tertiary structure of the protein may result from
an inherited mutation that alters the normal primary amino acid sequence or may reflect an acquired defect in protein folding
186
Alpha 1 Antitrypsin deficiency is
a heritable disorder in which mutations in the gene for alpha 1 antitrypsin yield an insoluble protein The mutant protein is not easily exported It accumulates in liver cells causing cell injury and cirrhosis
187
Pulmonary emphysema is
another complication of alpha 1 antitrypsin deficiency
188
Amyloidoses represent
extracellular deposits of fibrillar proteins arranged in beta pleated sheets
189
Gaucher disease and Tay Sachs disease are
lysosomal storage diseases that represent intracellular deposits of unmetabolized sphingolipids
190
Werner syndrome is
a rare autosomal recessive disease characterized by early cataracts hair loss atrophy of the skin osteoporosis and accelerated atherosclerosis
191
Affected persons with Werner syndrome are also at risk for
development of a variety of cancers
192
Unlike Hutchinson Gilford progeria patients with Werner syndrome typically
die in the fifth decade from either cancer or cardiovascular disease
193
Werner syndrome is caused by
mutations in the WRN gene which encodes a protein with multiple DNA dependent enzymatic functions including proteins with ATPase helicase and exonuclease activity
194
Hutchinson Gilford progeria is caused by
mutations in the human lamin A gene which encodes an intermediate filament protein that forms a fibrous meshwork beneath the nuclear envelope
195
Apoptosis
detects and destroys cells that harbor dangerous mutations thereby maintaining genetic consistency and preventing the development of cancer There are several means the most important of which is probably p53
196
p53
the cell recognizes genomic abnormalities and assesses whether they can be repaired If the damage to DNA is so severe that it cannot be repaired the cascade of events leading to apoptosis is activated and the cell dies This process protects an organism fr
197
After p53 binds to areas of DNA damage what happens
p53 activates proteins that arrest the cell in G1 of the cell cycle allowing time for DNA repair to proceed It also directs DNA repair enzymes to the site of injury
198
If the DNA damage cannot be repaired p53 does what
It activates mechanisms that terminate in apoptosis There are several pathways by which p53 induce apoptosis
199
How can p53 induce apoptosis
This molecule downregulates transcription of the antiapoptotic protein Bcl 2 while it upregulates transcription of the proapoptotic genes bax and bak
200
Cytochrome P450 is a member of the
mixed function oxidase system
201
Beta catenin is
a membrane protein associated with cell adhesion molecules
202
Selectins are
cell adhesion molecules involved in leukocyte recirculation
