2)Cell and tissue damage Flashcards
Explain the difference between the two main mechanisms of cell death i) cell necrosis and ii) cell apoptosis (4 marks)
Cell necrosis is an irreversible injury that leads to cell death that causes inflammation. The changes are produced by enzymatic digestion of dead cellular elements. This can be caused ischemia or trauma.
Apoptosis is internally programmed cell death. It is a vital process that helps eliminate unwanted cells. Internally programmed series of events effected by gene products. There is no inflammation as cell membrane remains intact.
Name four causes of cell injury giving examples (4 marks; one for each – with an appropriate example)
Oxygen deprivation- caused by Ischemia
Physical agents like trauma
Chemical agents like asbestos or ethanol
Genetic defects like Downs syndrome
Explain the difference between Hypertrophy and Atrophy using examples to illustrate your answer (4 marks)
Hypertrophy increased size of cells in a tissue, can lead to enlargement of an organ. Mainly seen in cells that cannot divide like skeletal muscle can be caused by weight training.
Atrophy is the decrease in size of cells in a tissue that can lead to shrinkage of an organ. Can be classified as physiological and pathological. Decreased workload or diminished blood supply.
Describe how ischemia may lead to cell injury (4 marks)
In ischemia cells are deprived of oxygen and glucose, this leads to ATP depletion due to the loss of electron transport chain activity. The ATP dependent membrane pumps fail leading to a build up of Na+ in the cell, water follows by osmosis leading to swelling.
State four ways in which ATP depletion leads to cell damage. (4 marks)
Loss of Na+/K+ATPase ion pumps leading to water influx and swelling.
Detachment of ribosomes leading to loss of function proteins
Loss of Ca/ ATPas protein leading to increase of calcium
Loss of mitochondrial membrane integrity leading to loss of mitochondrial function.
Explain the difference between hypertrophy and hyperplasia using examples to illustrate your answer. (4 marks)
Hypertrophy is the increase in size of cells in a tissue.
Hyperplasia is the increase in number of cells in a tissue.
Hypertrophy is usually seen in cells that cannot divide like skeletal muscle, can be caused by weight training.
Hyperplasia is usually seen in cells that divide due to increased hormone or growth factors like oestrogen mediating endometrial proliferation.
Sate the names of four different types of necrosis that can occur in human cells. (4 marks maximum))
- Coagulative necrosis (1 mark)
- Liquefactive necrosis (1 mark)
- Fat necrosis (1 mark)
- Gangrenous necrosis (1 mark)
Describe the terms ‘metaplasia’ and ‘dysplasia’, using examples to illustrate your answer. (4 marks)
Metaplasia is the transformation of one adult stem cell to another adult stem cell type. Example would be laryngeal respiratory epithelium changing in response to irritation from cigarette smoke from ciliated columnar to squamous.
Dysplasia is abnormal cells or disorder growth due to genetic changes that shows the loss of cell orientation and uniformity. An example of this is cervical dysplasia which sees squamous epithelium were cells become abnormal and turn into dysplastic epithelium due to the integration of the HPV virus into the DNA.
Explain the terms hypoxia and ischaemia giving an example of when each might occur in tissues of the body.
Hypoxia: Low oxygen saturation in the tissues; an example of this would be respiratory failure.
Ishaemia: lack of oxygen and nutrient to a particular tissue or organ; an example of this would be brain ischaemia.
Explain two differences between liquefactive necrosis and coagulative necrosis.
Liquefactive necrosis: takes place in the brain & cells are completely digested by hydrolytic enzymes.
Coagulative necrosis: takes place in solid organs like the heart or the spleen & cells swell - the proteins denature and coagulate.
