Patho Pre Lab

8/6/2019 Patho Pre Lab

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CELL INJURY and CELL DEATH

y Local deficiency in the blood supply (ischemia)

limited oxygen and glucose supply

y In the hypoxic state, the most commonly

affected organelle is the mitochondrion (site of

oxidative phosphorylation)

y mitochondrial activity will lead to ATP

production

y ATP will lead to a decreased level of activity

of the ATP dependent Na-K pumps located at

the cell membrane Na remains in the cell andattracts water which leads to cellular swelling

y In the hypoxic state, the cell shifts to anaerobic

glycolysis whose end product is pyruvate which

will be reduced to lactic acid thus resulting in a

decrease in pH clumping of chromatin(ECF:

7.4; ICF:7-7.3)

Reversible Injuries:

(Two types of changes can be gleaned using the

light microscope)

Cellular swelling (hydropic

change/degeneration)

o e.g. Hydatidif orm mole

characterized by vesicle f ormation

Fatty change (steatosis)

o e.g. f atty liver characterized grossly

by an increase in weight f romnormally 1.1-1.3kg to 4-6kg and will

appear yellowish and greasy

o histologically, accumulation of lipid

vacuoles pushing the nuclei to the

periphery signet ring sign; also

has a sieve-like appearance

* Cell death can either be necrosis or apoptosis

which are distinct f rom one another

Features Necrosis Apoptosis

Cell size Enlarged

(swelling)

Reduced

(shrinkage)

Subject: Pathology Pre-lab discussionTopic: Cell Injury and DeathLecturer: Dr. Kent ErmitaDate of Lecture: 06/16/2011Transcriptionist: porkanorPages: 2

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Nucleus Pyknosis

karyorrhexis

karyolysis

Fragmentation

into

nucleosome-

size f ragments

Plasma

membrane

Disrupted Intact; altered

structure,

especially

orientation of

lipids

Cellular

contents

Enzymatic

digestion; may

leak out of cell

Intact; may be

released in

apoptotic

bodies

Adjacent

inflammation

Frequent No

Physiologic

or Pathologic

role

Invariably

pathologic

(culmination of

irreversible cell

injury)

Often

physiologic,

means of

eliminating

unwanted

cells; may be

pathologic

after some

f orms of cell

injury,especially

DNA damage

*table taken f rom Robbins Basic Pathology 8th

ed. p.6

Irreversible Injuries:

NECROSIS

Increased eosinophilia

Nuclear changes

o PYKNOSIS- shrinkage and increased

basophilia

o KARYOLYIS- dissolution and f ading of

chromatin

o KARYORRHEXIS- f ragmentation

PATTERNS OF NECROSIS

o Coagulation necrosis/ COAGULATIVE

necrosis

Inf arction of solid organs except brain

Denaturation of proteins as well as

enzymes blocking proteolysis of

necrotic cells

Basic tissue architecture is preserved

(tombstone) o Liquef action necrosis/ LIQ UEFACTIVE

necrosis

- CNS, f ocal bacterial infections with

accumulation of inf lammatory cells

- Enzymatic digestion of dead cells

transf orming tissues into liquid viscous

mass

- Obliteration of tissue architecture

o Enzymatic f at necrosis

- Release of activated pancreatic lipase

liquefies membranes of f at cells in the

peritoneum.

- Fatty acid when combined with calcium

f orm chalky white areas

o Caseous/ Caseation necrosis

- Tuberculous infection

- Complete obliteration of tissuearchitecture

- Friable(crumbly) yellow-white areas of

necrosis

- Characteristic f ocus of inf lammation:

GRANULOMA

collection of transf ormed

macrophages called

epitheloid cells (hallmark of

granuloma f ormation)

rimmed by lymphocytes

may have Langhans type

giant cells

o Gangrenous necrosis

- e.g. Lower limb that has lost its blood

supply.

- e.g. appendicitis

there is obliteration of the

layers of the appendiceal

wall

- Coagulative necrosis is transf ormed by

liquef action action of enzymes released

by leukocytes when there is

superimposed bacterial infection

Intracellular Accumulations:

1. Lipids

A. Fatty change, Liver

B. Atherosclerosis (Coronary Artery)

2. Pigments

A. Exogenous

carbon (most common

exogenous pigment;

anthracotic pigment)

B. Endogenous lipofuscin (insoluble yellowish

brown granular material)

hemosiderin (golden yellow-

brown granular pigments

derived f rom hgb)

melanin (black-brown pigment

produced by melanocytes)

3. Other cellular accumulations

A. Dystrophic calcifications

o Affinity of calcium to

necrotic tissue

o No disturbance in calcium

balance as opposed to

metastatic calcification

B. Hyaline change

____________END OF TRANSCRIPTION _________ Be strong and courageous. Do not be afraid or terrifiedbecause of them, for the LORD your God goes with you;he will never leave you nor forsake you."

Deuteronomy 31:6



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Patho Pre Lab