Cell injury, adaptation and death
הוצג| English | משמעות |
|---|---|
| cell swelling | cell swelling |
| fatty change | fatty change |
| necrosis | The opposite: many cells, swelling, leaking and inflammation. |
| coagulative necrosis | coagulative necrosis |
| liquefactive necrosis | liquefactive necrosis |
| caseous necrosis | caseous necrosis |
| apoptosis/əpəpˈtəʊsɪs/ | A programme: single cells shrink and break into neat fragments, driven by caspases, and are eaten without inflammation. |
| atrophy | atrophy |
| hypertrophy | hypertrophy |
| hyperplasia | hyperplasia |
| metaplasia | metaplasia |
Twenty minutes to save a heart cell
- When a coronary artery blocks, heart muscle cells can still recover if blood returns within about 20–30 minutes. After that, they begin to die.
- All disease starts as stressed cells. Whether they recover or die, and how they die, is where pathology begins.
Reversible injury
- Without oxygen, ATP falls, the Na⁺/K⁺ pump fails, sodium and water flood in, and the cell swells (cell swelling 细胞水肿).
- Lipid droplets can collect in liver and heart cells: fatty change 脂肪变. Restore the supply and both reverse.
Which change is still reversible?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Swelling and fatty change reverse when oxygen returns; membrane damage does not.
The point of no return
- Membranes are damaged, calcium floods in and mitochondria fail. The cell cannot recover.
- Leaky membranes release cell contents into the blood: troponin from heart muscle, ALT from liver cells. Those blood tests date the injury.
Put the events of ischaemic cell injury in order.
רמת קושי 3/5 · 200 מטבעות + בונוס קטן בהשלמה הראשונה היום
The reversible steps come first; membrane damage marks the point of no return.
Patterns of necrosis
- Necrosis 坏死 has patterns that name the cause. Coagulative necrosis 凝固性坏死 keeps the cell outlines (ischaemia in heart or kidney); liquefactive necrosis 液化性坏死 turns tissue to liquid (brain, abscess).
- Caseous necrosis 干酪样坏死 is cheese-like, inside granulomas (classically tuberculosis); fat necrosis follows enzyme release in the pancreas; fibrinoid necrosis damages vessel walls.
Match each pattern of necrosis to its typical setting.
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
The pattern names the cause.
Apoptosis
- Apoptosis 细胞凋亡 is a programme: single cells shrink and break into neat fragments, driven by caspases, and are eaten without inflammation.
- It removes cells during development, ends immune responses and deletes damaged cells. Necrosis is the opposite: many cells, swelling, leaking and inflammation.
Apoptosis causes a strong inflammatory reaction.
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Apoptotic fragments are eaten quietly; it is necrosis that leaks and inflames.
Four adaptations
- Atrophy 萎缩: cells shrink (disuse). Hypertrophy 肥大: cells enlarge (the heart against high blood pressure, with no new muscle cells).
- Hyperplasia 增生: more cells (the endometrium under oestrogen). Metaplasia 化生: one cell type replaces another (squamous cells in a smoker's bronchus).
A smoker's bronchial lining changes from ciliated columnar to squamous cells. What is this?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
One differentiated cell type has replaced another.
A heart grows from 300 g to 450 g with no new muscle cells. By what percentage has the average cell's mass grown?
רמת קושי 2/5 · 140 מטבעות + בונוס קטן בהשלמה הראשונה היום
Same number of cells, so each grows by 150 ÷ 300 = 50%, which is hypertrophy.
Worked example: the adaptation quartet
- (Fictional set) A plastered leg's muscles shrink: atrophy. A hypertensive heart thickens: hypertrophy. A healing liver after part is removed: hyperplasia.
- A smoker's airway lining turns from ciliated columnar to squamous: metaplasia. It resists smoke better but can no longer clear mucus.
Worked example: the 20-minute window
- (Fictional) Kidney tubule cells deprived of blood for 20 minutes are swollen with low ATP; when blood returns, they recover.
- After hours without blood, their membranes leak enzymes such as LDH into the blood and calcium has flooded in: the cells are dead, and the blood test shows it.
Kidney tubule cells are swollen with low ATP after 20 minutes without blood. What happens if blood returns now?
רמת קושי 1/5 · 100 מטבעות + בונוס קטן בהשלמה הראשונה היום
Swelling with intact membranes is reversible injury.
Three common slips
- Calling apoptosis a kind of necrosis. It is a tidy programme with no inflammation.
- "Caseous means tuberculosis." It means a necrotic granuloma; tuberculosis is the classic but not the only cause.
- Treating fatty change as death. It is an early, reversible sign.
Recap
- Low ATP → swelling and fatty change (reversible); membrane damage and Ca²⁺ entry → death.
- Coagulative (ischaemia), liquefactive (brain, abscess), caseous (granuloma), fat (pancreas), fibrinoid (vessels).
- Apoptosis is tidy and silent; adaptations are atrophy, hypertrophy, hyperplasia and metaplasia.