Lectures 28+29 Learning Objectives (Hudmon)

Question 1

Understand how cells respond to injury (entire process)

Answer 1

A normal cell goes through homeostasis but when homeostasis is disrupted it can go through different pathways. When the cell goes through stress on increased demand, it can go through adaptation. If it cannot adapt, it will suffer cell injury. Cell injury leads to reversible injury or subcellular alterations. If the cell finds itself at a point of irreversibility, it will go through necrosis. The cell could also go through apoptosis.

Question 2

Atrophy

Answer 2

**SIZE! **Cell shrinkage.
Caused by:
-decreased workload
-loss of innervation
-reduced blood supply
-inadequate nutrition
-aging (sterile atrophy)
Increasing protein degradation or reducing protein synthesis decreases cell size!

Question 3

Hypertrophy

Answer 3

SIZE! Cells get bigger.
Typically caused by increased workload
Pathological hypertrophy (hypertension, aortic valve) can lead to decompensation.

Question 4

Hyperplasia

Answer 4

NUMBER! More cells, cells are dividing
Pathological results from excessive hormonal or growth factors or tissue may eventually become malignant.
Physiological can be the proliferation of connective tissue cells during wound healing.

Question 5

Metaplasia

Answer 5

FORM! Cell turns into a different form and it is reversible.
This is a response to chronic inflammation and irritation
Metaplasia is a precursor to malignancy.
Barrett’s Esophagus is a good example of metaplasia:
-normal columnar cells to squamous epithelium cells because of stomach acid damaging the esophagus

Question 6

Dysplasia

Answer 6

ORGANIZATION! Uncontrolled growth. Unorganized.
Associated with chronic irritation and inflammation.
Often happens in the respiratory tract and uterine cervix.
Can be both R and IR
Dysplasia is strongly implicated as a precursor of cancer

Question 7

Cause of cell injury: Oxygen Deprivation

Answer 7

A cause of cell injury
Hypoxia is an oxygen deficiency
Ischemia is loss of oxygenated blood supply to tissues

Question 8

Cause of cell injury: Chemical agents

Answer 8

A cause of cell injury
Poisons, air pollutants, CO, and asbestos

Question 9

Cause of cell injury: Infectious agents

Answer 9

A cause of cell injury
Viruses, bacteria, fungi, and parasites

Question 10

Cause of cell injury: Immunological reactions

Answer 10

A cause of cell injury
Autoimmune diseases

Question 11

Cause of cell injury: Genetic defects

Answer 11

A cause of cell injury
Sickle cell anemia, familial hypercholesterolemia

Question 12

Cause of cell injury: Physical agents

Answer 12

A cause of cell injury
Trauma, heat, cold, electric shock

Question 13

Cause of cell injury: Nutritional Imbalances

Answer 13

A cause of cell injury
Nutritional deficiencies- caloric or vitamin
Excess nutrition
Diabetes
Atherosclerosis

Question 14

Cause of cell injury: Aging

Answer 14

A cause of cell injury
Accumulation of damage by ROS, loss of telomerase function

Question 15

Reversible Injury

Answer 15

1. Cellular swelling is the result of the failure of energy-dependent ion pumps in the plasma membrane which enables homeostasis.
2. Fatty changes when there is the appearance of small or large lipid vaculoes in the cytoplasm.
   Reversible cell injury can recover back to normal cells!

Question 16

Irreversible Injury

Answer 16

1. The inability to reverse mitochondrial dysfunction (lack of oxidative phosphorylation and ATP generation)
2. Profound disturbances in membrane function
   Irreversible injury leads to necrosis.

Question 17

ATP Depletion mechanism

Answer 17

1. Ischemia (insufficient O2 to tissues)
2. oxidative phosphorylation in mitochondria DECREASES
3. DECREASE in ATP
   -A decrease in ATP can cause a decrease in the sodium pump which will increase calcium, water, and sodium IN the cell and increase potassium OUT the cell. This will cause ER swelling, cellular swelling, loss of microvilli, and blebs.
   -A decrease in ATP can also cause an increase in anaerobic glycolysis which will cause a decrease of glycogen and an increase in lactic acid. An increase in lactic acid will lower pH and clump nuclear chromatin.
   -ATP decrease will lastly cause detachment of ribosomes which lower protein synthesis.

Question 18

Damage to mitochondria mechanism

Answer 18

Disregulated calcium signaling is the main way for mitochondrial damage.
If mitochondria release hydrogen, it will lead to necrosis.
If mitochondria release cytochrome C, it will lead to apoptosis.

Question 19

Membrane damage mechanism

Answer 19

Phospholipid loss, lipid breakdown products, and cytoskeletal damage all lead to membrane damage.

Question 20

Calcium influx mechanism

Answer 20

Cause of increase in cytosolic calcium concentration is because of release from intracellular calcium stores and calcium influx across the plasma membrane.
The activation of various enzymes causes the mechanism of damage.
Too much calcium leads to:
-mitochondrial damage
-ER damage
-all the proteins get activated when they shouldn’t

Question 21

Increase of ROS (reactive oxygen species) damages mechanism

Answer 21

???

Question 22

Intrinsic Pathway (mechanism)

Answer 22

Apoptotic pathway!
A process where the cell self-destructs in response to internal stress, like DNA damage or lack of survival signals.
It starts with mitochondria.

Question 23

Extrinsic pathway (mechanism)

Answer 23

Apoptotic pathway!
Triggered by signals outside the cell.

Question 24

Apoptosis

Answer 24

PROGRAMMED CELL DEATH

Question 25

Necrosis