Pathoma: Growth adaptations, cell injury and death Flashcards Preview

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Flashcards in Pathoma: Growth adaptations, cell injury and death Deck (57)
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1

Hypertrophy

increase in size of the organ
involves gene activation, protein synthesis, and production of organelles

2

Hyperplasia

increase in number of cells in the organ
involves the production of new cells from stem cells

3

Permanent Tissues

Cardiac muscle
skeletal muscle
nerve

cannot make new cells
undergo hypertrophy only

4

Pathologic hyperplasia progresses to

dysplasia and eventually cancer

exception - benign prostatic hyperplasia, does not increase the risk for prostate cancer

5

Atrophy

decrease in stress leads to decrease in organ size by a decrease in size and number cells

6

what process decreases the number of cells in atrophy

apoptosis

7

what processes decreases the cell size in atrophy

ubiquitin-proteasome degradation of cytoskeleton - intermediate filaments of cytoskeleton are tagged with ubiquitin and destroyed by proteasomes
autophagy of cellular components - generation of autophagic vacuoles - fuse with lysosomes whose hydrolytic enzymes breakdown cellular components

8

metaplasia

change in stress on an organ leads to a change in cell type - most commonly one epithelium to another better able to handle the new stress

occurs via reprogramming stem cells
may be reversible by treating stressor

persistent stress - can progress to dysplasia and eventually cancer

Barrett's Esophagus

9

Barrett's Esophagus

esophagus normally lined by nonkeratinizing squamous epithelium - can handle friction of food bolus
acid reflux from the stomach causes metaplasia to nonciliated, mucin-producing columnar cells- better able to handle stress of acid

10

Vitamin deficiency that can lead to metaplasia

vitamin A
necessary for differentiation of specialized epithelial surfaces such as the conjunctiva covering the eye
vit A deficiency can cause goblet cell/columnar epithelium of conjunctiva to undergo metaplasia into keratinizing squamous epithelium
dry eyes (xerophtalmia) can lead to destruction of the cornea and blindness

11

What condition occurs in response to healing in trauma that causes mesenschymal tissues to undergo metaplasia

myositis ossificans

connective tissue within muscle changes to bone during healing after trauma

12

Dysplasia

disordered cellular growth

most often refers to proliferation of precancerous cells

often arises from longstanding pathologic hyperplasia or metaplasia

13

Aplasia

failure of cell production during embryogenesis

ex. unilateral renal agenesis

14

hypoplasia

decrease in cell production during embryogenesis, resulting in a relatively small organ

ex. streak ovary in Turner syndrome

15

Common causes of cell injury

inflammation
nutritional deficiency or excess
hypoxia
trauma
genetic mutations

16

hypoxia

low oxygen delivery to tissue
oxygen is the final electron acceptor in the electron transport chain of oxidative phos
decreased oxygen impairs ox phos, resulting in decreased ATP production
lack of ATP leads to cell injury

17

causes of hypoxia

ischemia
hypoxemia
decreased oxygen carrying capacity of blood

18

ischemia

decreased blood flow through an organ

decreased arterial perfusion - atherosclerosis
decreased venous drainage - Budd-Chiari syndrome
Shock - generalized hypotension -> poor tissue perfusion

19

hypoxemia

low partial pressure of oxygen in the blood - PaO2 decreased PaO2
hypoventilation - increased PaCO2 -> decreased PaO2
diffusion defect - PaO2 not able to push as much O2 into the blood due to a thicker diffusion barrier (interstitial pulmonary fibrosis)
V/Q mismatch - blood bypasses oxygenated lung or oxygenated air cannot reach blood

20

decreased O2 carrying capacity

hemoglobin loss or dysfunction

anemia - normal PaO2
carbon monoxide poisoning - PaO2 normal - cherry red appearance of skin, early sign is HA
Methemoglobinemia - iron in heme is oxidized to Fe3+ which cannot bind oxygen - PaO2 normal - seen in oxidant stress - cyanosis with chocolate colored blood - Tx is intravenous methylene blue which helps reduce Fe3+ back to Fe2+

21

hallmark of reversible cellular injury

cellular swelling - cytosol swelling results in loss of microvilli and membrane blebbing
swelling of the rough ER results in dissociation of ribosomes and decreased protein synth

22

Hallmark of irreversible cellular injury

membrane damage - results in cytosolic enzymes leaking into the serum (cardiac troponin), additional calcium entering cell

End result is cell death

23

Mitochondrial Membrane Damage

results in loss of the electron transport chain (inner mito membrane), cytochrome c leaking into cytosol (activates apoptosis)

24

lysosomal membrane damage

results in hydrolytic enzymes leaking into cytosol, which are activated by the high intracellular calcium

25

Mechanisms of cell death

necrosis and apoptosis

26

morphologic hallmark of cell death

loss of nucleus

occurs via nuclear condensation (pyknosis)
fragmentation(karyorrhexis)
and dissolution (karyolysis)

27

Necrosis

death of large groups of cells followed by acute inflammation
never physiologic

28

Coagulative Necrosis

necrotic tissue that remains firm
organ structure is preserved but nucleus disappears
characteristic of ischemic infarction of any organ except the brain
often wedge-shaped and pale
red infarction arises if blood re-enters loosely organized tissue

29

Liquefactive Necrosis

necrotic tissue that becomes liquefied
enzymatic lysis of cells and protein results in liquefaction
characteristic of - brain infarction - proteolytic enzymes from microglial cells liquefy the brain
abscess - proteoplytic enzyes from neutrophils liquefy tissue
pancreatitis - proteolytic enzymes from pancreas liquefy parenchyma

30

Gangrenous Necrosis

coagulative necrosis that resembles mummified tissue - dry gangrene
characteristic of ischemia of lower limb and GI tract
if superimposed infection of dead tissues occurs then liquefactive necrosis ensues - wet gangrene