Mechanisms 1: Cell Injury & Death

Front 1

List 7 causes of cell death.

Back 1

Hypoxia, toxins, physical trauma (heat/cold), microorganism infection, immune mechanisms, nutrition, free radicals

Front 2

Define hypoxia & name 4 causes.

Back 2

a pathological condition in which the whole or part of the body is deprived of adequate oxygen supply. Can be caused by ischaemia, hypoxaemia, anaemia & histotoxia.

Front 3

List the 5 distinct morphological patterns of necrosis

Back 3

coagulative, liquefactive, caseous, fat, fibrinoid

Front 4

Explain the 4 types of hypoxia

Back 4

ischaemic - decreased blood flow
hypoxaemic - O2 conc within arterial blood is low due to low pO2
anaemic - arterial pO2 normal, but [O2] in blood is low due to decreased ability of Hb to carry O2
histotoxic - cells cannot use O2 efficiently due to disabled oxidative phosphorylation enzymes

Front 5

what 3 aspects of the immune system can cause damage to cells of the body?

Back 5

inflammatory mediators
complement activation
cytotoxic T-cells & NK cells

Front 6

define free radical

Back 6

any species capable of independent existence that contains one or more unpaired electrons

Front 7

what group of genes is upregulated as a general protective mechanism against cell injury?

Back 7

heat shock responses genes

Front 8

Name the principal cellular structures that are targets for cell damage.

Back 8

plasma membranes
DNA
proteins
mitochondria

Front 9

describe the 6 general steps of cell injury pathogenesis

Back 9

- metabolic derangements
- reactive intermediate production
- reduced ATP-synthesis/mitochondrial damage
- altered calcium homeostasis
- disrupted membrane permeability
- production of free radicals

Front 10

what occurs in reversible vs irreversible cell injury?

Back 10

reversible:
- loss of ATP
- anaerobic metabolism
- reduced protein synthesis

irreversible:
- massive intra-cytoplasmic calcium accumulation
- enzyme activation

Front 11

Define necrosis

Back 11

premature death of groups of contiguous cells in a tissue or organ (caused by external factors)

Front 12

Define apoptosis

Back 12

physiological cell death - distinct reactive pattern which represents single-cell suicide where cells expend energy in order to die

Front 13

Describe the structural signs that indicate irreversible cell injury (necrosis)

Back 13

dense clumping & progressive disruption of chromatin
mitochondria swell & rupture
membrane lysis
inflammatory response triggered

Front 14

Describe coagulative necrosis

Back 14

- cells have died but the basic shape & architecture of the tissue endures
- due to protein denaturation
- seen in ischaemic hypoxia (heart, kidney, adrenals)
- necrotic cells ultimately removed by immune system
- may be replaced by regeneration

Front 15

describe liquefactive necrosis

Back 15

- complete dissolution of necrotic tissue
- due to massive infiltration by neutrophils & release of ROS & protease
- dead cells digested
- bacterial/fungal infections & ischaemic necrosis in brain

Front 16

describe caseous necrosis

Back 16

accumulation of amorphic debris with an area of necrosis
- dead cells leave granular particles
- white & friable
- granulomatous inflammation of TB

Front 17

describe fat necrosis

Back 17

specialised necrosis of fat tissue resulting from activated lipase release onto adipose tissue e.g. pancreas
- FFAs accumulate & precipitate as calcium soaps (saponification)
- pale yellow/white nodules
- leads to acute pancreatitis

Front 18

describe gangrenous necrosis (wet & dry)

Back 18

necrosis that is advanced & visible grossly
dry: mostly coagulative necrosis (black)
wet: mostly liquefactive necrosis (oozy)

Front 19

Explain the difference between a white & a red infarct.

Back 19

white: arterial occlusion where no blood reaches an area as there is no other blood supply e.g. end arteries. veins still drain blood away

red: in areas with dual blood supply & loose tissues, e.g. lungs, where there is venous occlusion & congestion

Front 20

define infarction

Back 20

an area of necrosis in a tissue or organ

Front 21

Describe cellular events of apoptosis & 3 triggers

Back 21

DNA cleaved at specific sites
cytoplasm shrinks without membrane rupture
blebbing of plasma & nuclear membranes
cell content in apoptotic bodies
no inflammation
(pathological in graft vs host disease)

3 triggers = DNA damage, withdrawal of GFs, death-promoting signals (TNF)

Front 22

compare & contrast apoptosis & necrosis

Back 22

N: pathologic
A: physiologic (sometimes pathologic)

N: enzyme cell digestion
A: internally controlled

N: cell contents leak
A: nuclear dissolution

N: inflammation
A: no inflammation

Front 23

What effects does paracetamol overdose have?

Back 23

- hepatoxicity due to NAPQI
- NAPQI depletes liver glutathione & directly damages hepatocytes
- hepatic coagulative necrosis
- liver failure

Front 24

What 3 structures are found in a liver portal tract?

Back 24

portal vein
hepatic artery
bile duct

Front 25

What type of necrosis is common in pancreas? what are histological features of acute pancreatitis?

Back 25

fat necrosis

- necrosis
- oedema
- haemorrhage

Front 26

name 2 pathological processes in which apoptotic bodies are commonly seen

Back 26

cancer
lichen planus (skin)

Front 27

What type of cell death is seen in the liver in hepatitis?

Back 27

apoptosis

Front 28

what do cardiac myocytes release following damage?

Back 28

troponin T

Front 29

What do hepatocytes release following damage?

Back 29

lactate dehydrogenase

Front 30

what do red blood cells release following damage?

Back 30

lactate dehydrogenase