Pack 9 – How cells and tissues respond and adapt to injury

Question 1

Physical trauma consequences on the cell:

Answer 1

Can break the cell membrane and damage cell organelles

Question 2

Extremes of temperature consequences on the cell:

Answer 2

Causes proteins in cell membranes and enzymes to denature

Question 3

Immune response in response to infection consequences on the cell:

Answer 3

White blood cells damage cell membranes

Question 4

Damage from pathogens consequences on the cell:

Answer 4

They release toxins which can damage cells and the cell membrane

Question 5

2 main cell responses to injury:

Answer 5

1. Decreased ATP production
2. Cell swelling

Question 6

What happens to ATP production during cell injury?

Answer 6

• Oxygen supply to the cell drops (ischemia)
• The mitochondria can be directly damaged so cannot function

Question 7

What can decrease in ATP production cause?

Answer 7

• Cellular swelling
• Increased anaerobic respiration which causes the cell environment to become acidic which damages enzymes
• Decreased protein synthesis

Question 8

What happens to the cell in response to it becoming injured?

Answer 8

Cellular is usually the first thing that happens when a cell is injured

Question 9

How does cell injury cause swelling?

Answer 9

• The cell membrane itself can be damaged, or ATP production can decrease
• This will stop the Na+/K+ pump working
• Sodium ions are not removed from the cell (they accumulate inside the cell)
• Increased ion concentration inside the cell
• There is an imbalance in ion concentration
• Water moves into the cell by osmosis
• Increased water in the cell – causing cell swelling

Question 10

What are the 4 ways the cell afapts when it is exposed to stress to restore homeostasis?

Answer 10

1. Hyperplasia
2. Hypertrophy
3. Atrophy
4. Metaplasia

Question 11

Hyperplasia

Answer 11

An increase in the number of cells in the tissue

Question 12

Hyperplasia process:

Answer 12

• Increased rate of cell division (mitosis), to increase cell numbers
• This is very important for wound repair, and replacement of short-lived cells (such as skin cells)

Question 13

Hypertrophy

Answer 13

Increasing the size of the existing cells

Question 14

Hypertrophy process:

Answer 14

An increased protein synthesis within the cells to ‘bulk’ them up

Question 15

Atrophy

Answer 15

A decrease in cell size

Question 16

Atrophy process:

Answer 16

A decrease in number of organelles, and amount of cytoplasm

Question 17

Metaplasia

Answer 17

One differentiated cell type is replaced by another differentiated cell type

Question 18

Metaplasia process:

Answer 18

It is as if the original cells are not robust enough to withstand their environment, so they transform into another cell type better suited to their environment. Usually occurs in response to stress or chronic irritation

Question 19

What are the 4 tissue responses to injury?

Answer 19

1. Blood clotting
2. Scab formation
3. Swelling and bruising
4. Burst blood vessels

Question 20

Blood clotting

Answer 20

Platelets (a type of blood cell) and proteins in your plasma (the liquid part of blood) work together to stop the bleeding by forming a clot over the injury

Question 21

Blood clotting process:

Answer 21

• Thromboplastin (enzyme) released from platelets and damaged tissue
• Thromboplastin, in presence of calcium ions and vitamin K converts prothrombin into the enzyme thrombin
• Thrombin converts fibrinogen (plasma protein) into fibrin
• Mesh of insoluble fibrin fibres forms
• Platelets + red blood cells get trapped in the mesh forming a blood clot

Question 22

Scab

Answer 22

Hard protective tissue that forms on the skin’s surface at the site of injury

Question 23

Scab process:

Answer 23

• Once the blood clot plugs the wound, the clot hardens into a protective crust
• The formation of the scab is part of the healing process as skin grows over the wound

Question 24

Bruise

Answer 24

A mark on your skin caused by blood trapped under the surface

Question 25

Bruise process:

Answer 25

- When an injury ruptures small blood vessels (capillaries) but does not break the skin - Those vessels break open and leak blood, which collects under the skin

Question 26

Hematoma

Answer 26

Occur due to damage to larger blood vessels

Question 27

What can a hematoma cause?

Answer 27

- A lasting headache - Dizziness - Slurred speech

Question 28

Symptoms of swelling of the tissue:

Answer 28

- Pain - Heat - Redness

Question 29

Swelling process:

Answer 29

- Histamine release makes the capillary walls more leaky - There is increased movement of fluid out of the blood and into the injured tissue - Increasing the movement of tissue fluid into the area - Increasing the white blood cells to the area

Question 30

What can prolonged inflammation lead to?

Answer 30

The atrophy of the muscles surrounding an area and a decreased ability to activate the muscles

Question 31

Ischemia

Answer 31

The condition or state in which a tissue is subjected to low blood supply

Question 32

What does ischemia cause?

Answer 32

- A shortage of oxygen in the affected cells, impacting their ability to undergo aerobic respiration to create ATP energy - It also causes a reduction in nutrients (such as glucose) available in that area, and removal of waste material (such as carbon dioxide).

Question 33

Anoxia

Answer 33

A condition in which there is an absence of oxygen supply to an organ's tissues

Question 34

Causes of the reduction in oxygen supply:

Answer 34

- Low oxygen at high altitudes - Significant blood loss - Carbon monoxide poisoning

Question 35

Mechanism by which ischemia causes cell injury:

Answer 35

- Decreases aerobic respiration, so decreases ATP energy production - Low ATP can cause cell swelling - Cell and organelles shrink - Leads to cell injury - Cell dies and breaks down - necrosis

Question 36

Consequences of ischemia:

Answer 36

- Blindness - Dizziness - Death

Question 37

Consequences of membrane damage:

Answer 37

The damaged part of the membrane can be released/shed as a vesicle into surrounding environment or absorbed into the cell by endocytosis for destruction

Question 38

Problems caused by major membrane trauma:

Answer 38

- Toxic chemicals can enter the cell - Key cell nutrients can be lost from the cell - Cell death

Question 39

Necrosis

Answer 39

Unprogrammed cell death

Question 40

How does necrosis occur?

Answer 40

- Cellular swelling - ATP depletion - Calcium influx into cell

Question 41

Pressure sores

Answer 41

Localised damage to a body tissue due to long-term pressure or friction

Question 42

What are pressure sores caused by?

Answer 42

Long-term pressure or friction

Question 43

Pressure sores mechanisim

Answer 43

- Blood vessels are compressed - Partial or complete restriction of blood flow to the area - Causing ischemia and hypoxia/anoxia - May cell death by necrosis

Question 44

Necrosis symptoms for skin:

Answer 44

- Extreme skin - - Discoloration - Severe pain - Numbness, foul-smelling sores