PATH Y1 S1: Cellular Response to Injury

Question 1

2 types of adaptive changes of cells

Answer 1

• physiological: in response to normal stimuli e.g. hormones
• pathological: response to stress so that cells can modify structure and function

Question 2

hypertrophy vs hyperplasia

Answer 2

• hypertrophy: increased cell + organ size
• hyperplasia: increased cell number

Question 3

atrophy
metaplasia

Answer 3

• atrophy: decreased cell number + organ size
• metaplasia: changing cell morphology

Question 4

examples of cell damage

Answer 4

• biological: pathogens
• chemical: chemotherapy
• metabolic: O2 deprivation, ATP loss, DNA damage
• physical: trauma, radiation

Question 5

5 fundamental signs of inflammation

Answer 5

• pain (dolor): excess tissue fluid presses on nerve endings
• heat (calor): fever and increased blood flow
• swelling (tumor): due to excess tissue fluid
• redness (rubor): vasodilation
• loss of function: pain/swelling prevents local mobility

Question 6

3 factors which influence tissue response

Answer 6

• amount of damage: small (acute) or large (chronic)
• capacity for regeneration: labile or stable (acute) or permament (chronic)
• duration of injury: short (acute) or long-term (chronic)

Question 7

3 categories of cells re: tissue regeneration

Answer 7

• labile: continuously proliferating e.g. skin
• stable: normally replicate infrequently can replicate if needed e.g. pancreas
• permanent: do not replicate e.g. cardiac cells, skeletal muscle, neurons > injury leads to repair

Question 8

3 outcomes of cell injury

Answer 8

• adaptation: replacement by diff tissue
• regeneration/resolution: restore normal tissue
• repair: cell death > replaced by new cells or fibrous/scar tissue

Question 9

ischaemic reperfusion injury

Answer 9

• injury caused by return of blood flow to a previously ischaemic area
• impaired transport of Ca2+ out of cell
• leads to activation of oxygen-dependent free radicals > necrosis

Question 10

types of necrosis (re what happens to the tissue)

Answer 10

• coagulative - ischaemia/hypoxia in any part of body except brain (usually heart)
• liquefactive (brain + infections)
• caseous (turns creamy - lungs, TB)
• fat (replaces old tissue - pancreas)
• fibrinoid (fibrin - due to vascular damage)
• gangrenous (ischaemic - generally lower limbs, tissue is mummified e.g. diabetes)

Question 11

healing by first intention

Answer 11

• healing of a clean, uninfected surgical incision (heals to 70-80% strength in 3 months)
• haemostasis: both sides of wound held together by weak fibrin joint
• inflammation
• proliferation: fibrin joint replaced by collagen, epithelium regenerates
• maturation: collagen reorganises and strengthens tissue

Question 12

healing by 2nd intention

Answer 12

• large wounds w/ more cell/tissue loss e.g. deep lacerations, extensive burns (edges X come together)
• haemostasis
• inflammation
• proliferation: granular tissue forms, epithelium regenerates
• maturation: collagen accumulates to form fibrous scar, strengthens tissue

Question 13

formation of granular tissue (healing by 2nd intention)

Answer 13

• capillary endothelial cells grow into loops in damaged area (angiogenesis)
• loop buds open into vascular channels (granules) > nutrient delivery
• proliferation + stimulation of fibroblasts to form myofibroblasts which lay down fibrin and contract (organisation) to reduce volume of tissue for repair