Cellular Injury And Repair

Question 1

what is cellular swelling?

Answer 1

impairment of the energy- dependent Na+/K+ pump which is usually maintains osmotic potential.

Question 2

malfunctioning sodium potassium pump

Answer 2

1. sodium ions are not being removed
2. too many potassium ions are pumped in
3. this increases the ion concentration inside cell, decreasing water potential. Water moves into the cell by osmosis, causing cell to swell.

Question 3

what are the effects on ATP production?

Answer 3

• If there’s a decrease in ATP production ( e.g. damaged mitochondria, Hypoxia- not enough oxygen), then less ATP available for the sodium potassium pump. Increasing number of ions inside the cell, decreasing water potential. Water moves in cell by osmosis, causing cellular swelling.

Question 4

if cellular swelling is not reversed….

Answer 4

It could lead to further cell injury. If cell swells & continues to take in too water it can burst due to high osmotic pressure
Red blood cells undergo osmotic lysis

Question 5

new research indicates:

Answer 5

• cell swelling can trigger release of ATP, so if ATP is released again- Volume is restored

Question 6

what is hyperplasia and abnormal hyperplasia?

Answer 6

• increase in number of cells mitosis that happens quickly
• can develop tumours by unregulated mitosis

Question 7

tumour formation by damaged DNA

Answer 7

• damage to DNA may cause mutations
• mutations in tumour suppressor genes which regulate the cell cycle
• damaged cells divide uncontrollably
  -damaged cells do not undergo programmed cell death

Question 8

hypertrophy

Answer 8

is the enlargement of cells

Question 9

cardiac hypertrophy

Answer 9

• enlargement of the heart muscle. Increasing wall size of ventricle decreases volume of ventricle & therefore causes lower stroke volume & less oxygen delivered per beat can lead to heart attack

Question 10

atrophy

Answer 10

is the decrease in cell size or number

Question 11

metaplasia

Answer 11

mature cell type is replaced by a different mature cell type. Change from one cell type to another

Question 12

what are the responses to tissue injury

Answer 12

• Inflammation, blood clotting & regeneration

Question 13

blood clotting & scab formation

Answer 13

1. Damage to blood vessels releases clotting factors
2. releases thromboplastin
3. Thromboplastin catalyses conversion of prothrombin to the enzyme thrombin
4. thrombin becomes active ,converting protein fibrinogen to insoluble fibrin
5. fibrin fibres form a mesh & attach to the platelets
6. clot is formed

Question 14

swelling (oedema)

Answer 14

is the accumulation of tissue fluid in response to inflammation in an area also on increased movement of white blood cells into the tissue fluid

Question 15

inflammation response:

Answer 15

• if damage occurs to capillaries, plasma proteins leak out into the tissue fluid, causing water to follow by osmosis.
• Other than swelling, inflammation symptoms are redness, heat & pain

Question 16

what is bruise, burst blood vessel and cell injury?

Answer 16

• when blood vessels such as capillaries are damaged and the rupture, blood then collects beneath the skin
• can lead to internal bleeding. This depends on the size & location of the rupture there could be serious consequences, both in terms of loss of blood volume & the effect of the accumulated blood putting pressure on the surrounding tissues.
• swelling of the endoplasmic reticulum & mitochondria occur with further cell injury, the cell membrane breaks down as do the organelles and nuclear membranes. This causes leakage of contents which leads to inflammnation

Question 17

what is ischaemia, hypoxia, anoxia and the causes and the consequences

Answer 17

• an inadequate blood supply/oxygen to an organ or part of the body, especially the heart muscles
• low oxygen saturation of the body, not enough oxygen in the blood
  -no oxygen
• blood clot formation in an artery( such as in a myocardial infarction or stroke) . Narrowing of the artery that supplies the tissue ( vascular disease)
• repeated cell injury can lead to atrophy & eventual necrosis of cells in that area.

Question 18

what are the effects of cell membranes

Answer 18

nutritional imbalance - composition of membrane
physical trauma - breaks membrane
extreme temperature- proteins in cell membrane can denature
immune response - damage to cell membrane by white blood cells
damage from pathogens- toxins secreted/physical damage

Question 19

what is necrosis, the causes and mechanisms

Answer 19

-*tissue/cell death due to lack of oxygen
- trauma
-vessel blockage
-extreme heat or cold
-loss of nerve supply
*failure to generate ATP, lack of respiration and damaged cell membranes.

Question 20

what is chronic diabetes and pressure sores

Answer 20

• Severe condition in which the body cannot control blood sugar levels can lead to cellular atrophy
  -injury to the skin & possibly underlying structures due to constant pressure