Chapter 3 Cellular Adaptation, Injury, and Death

Question 1

Adaptive cellular responses VS abnormal adaptive cellular responses

Answer 1

Adaptive cellular responses occur due to appropriate stimuli. These changes exist until the need for the adaptations goes away then the adaptations go away.

Abnormal cellular adaptations occur due to an inappropriate stimulus and/or do not cease once the need for the stimuli goes away.

Question 2

What are some common cellular adaptations?

Answer 2

Atrophy, hyperplasia, hypertrophy, metaplasia, dysplasia

Question 3

Atrophy
1. What causes atrophy?
2. How is this beneficial?
3. Example

Answer 3

Decrease in size of the cells.
1. Atrophy is caused by decreased use of the cell or decreased resources available.
2. Reducing the size of the cell decreases the oxygen consumption and energy expenditure. The body wants to be as efficient as possible.
3. A weightlifter stops lifting. A broken leg is not used while it heals. An ischemic toe.

Question 4

Hypertrophy
1. What causes it?
2. How is it beneficial?
3. Example

Answer 4

Hypertrophy is the increase in size of a cell.
1. Hypertrophy is caused by increased cell use and workload.
2. Increased cell size allows the cells to do more work.
3. Hypertrophy of muscles allows more actin and myosin filaments which allows greater contraction. Hypertrophic heart muscles.

Question 5

Hyperplasia
1. What causes it?
2. How is it beneficial?
3. Example

Answer 5

The increase in the number of cells.
1.

Question 6

Hyperplasia
1. What causes it?
2. How is it beneficial?
3. Examples

Answer 6

1. Hyperplasia is an increased number of cells in response to a stimulus. It typically occurs in epithelial tissue (skin), glands, and connective tissue.
2. Plays a role in wound healing with the fibroblasts
3. There are physiological causes and non-physiological. Physiologic causes include breast and uterine hyperplasia in response to estrogen stimulation during pregnancy.
   Non-physiologic (pathologic) causes include BPH, breast hyperplasia, endometrial hyperplasia.

Question 7

Metaplasia
1. What causes it?
2. How is it beneficial?
3. Examples?

Answer 7

The changing of cells from one type to another. Typically affects epithelial cells. This change is response to a stimulus and reverts when the stimulus is removed. Reversible.
1. Metaplasia is associated most commonly with chronic irritation and inflammation.
2. Metaplasia allows cells that are fragile to be replaced with tougher, more suited cells for the stimulus.
3. The change of stratified epithelium in the trachea for columnar epithelium due to chronic smoking. A similar change occurs in the esophagus as a result of GERD.

Question 8

Dysplasia
1. What causes it?
2. How is it unique?
3. Examples?

Answer 8

Dysplasia is an abnormal cellular adaptation that is strongly linked with pre-cancerous activity. It is when there is deranged growth of a specific tissue type resulting in differences in size, shape, and number of cells in that tissue. While it is abnormal, it can be reversible.
3. The most common examples are found in the respiratory tract - bronchopulmonary dysplasia in pre-term infants. And uterine cervix with cervical cancer.

Question 9

What are the two types of hyperplasia?
What are some examples of each?

Answer 9

1. Physiologic and Pathologic
2. Physiologic - two different types:
   A. Hormonal - breast/uterine enlargement due to increased estrogen stimulation associated with pregnancy.
   B. Compensatory - post hepatectomy the liver cells enlarge to take on the increased workload of only having one half.
   Pathologic - no purpose. Examples are BPH, endometrial hyperplasia.

Question 10

What is a Pap smear? What does it look for?

Answer 10

A diagnostic test looking for cervical cell dysplasia. The cells are collected by a provider scraping the inside of the vagina. The scrape is viewed under a microscope.

Question 11

Describe how injuries occur with moderate heat exposure. What about extreme heat exposure.

Answer 11

Exposure to moderate heat causes accelerated metabolism, destruction of heat sensitive enzymes, cell membrane damage, and vascular injury.
Exposure to high intensity heat results in blood vessel coagulation and protein coagulation.

Question 12

Describe how exposure to cold temperatures causes cell damage?

Answer 12

Causes blood viscosity increase and vasoconstriction which leads to reduced blood flow in the body. If the temperature exposure is prolonged, then hypoxic cell injury can occur.

Question 13

Describe how electrical injuries affect the body.

Answer 13

Electricity enters the body and passes through areas of least resistance (blood and nerves). The most damage is done to body parts that are highest in resistance to electricity. Because resistant areas turn electrical energy into heat, most associated damage is heating damage.

Question 14

Lead
1. Where can lead exposure be seen?
2. What populations are particularly venerable? Why?
3. How is lead absorbed?

Answer 14

1. Lead exposure can be seen with peeling lead paint, exposure to contaminated soil or water, coal mines, lead pipes, root vegetables, newsprint, or toys made from other countries.
2. Children are at particularly high risk of lead poisoning. Contact with lead paint, playing in contaminated soil and water, or breathing toxic fumes in can have a much more profound effect on their little body surface areas. Lead also crosses the placenta - exposing the developing fetus to the same levels as the mom.
3. Lead is absorbed through the lungs and the GI tract

Question 15

Lead
1. What body systems are most affected by lead?
2. What are common symptoms of lead toxicity?

Answer 15

1. Lead most commonly affects RBC, gastrointestinal tract, kidneys, and the neurologic system.
2. Anemia is the most common symptom of lead exposure. GI issues “lead colic’”. Lead gingivitis. HTN. Kidney disease. Demyelination of the cerebral and cerebellar white matter.

Question 16

How does lead toxicity lead to anemia?

Answer 16

Lead competes with enzymes required for RBC synthesis and enzymes responsible for the prevention of hemolysis.

Question 17

How does lead affect the neurologic system? What about in children?

Answer 17

Lead toxicity can cause neurologic systems in both adults and children.
1. Adults typically present with ataxia, persistent vomiting, seizures, papilledema, coma. This is caused by high levels of lead and can also be seen in children.
2. Children exposed to chronic lead toxicity present with neurologic underdevelopment. Do worse in school.

Question 18

What are the three main categories mechanisms of cell injury?

Answer 18

1. Hypoxia/ATP depletion
2. Disruption of intracellular calcium homeostasis
3. Free radical formation

Question 19

What are free radicals? How do they damage the body?

Answer 19

Free radicals are highly reactive chemical species. They have an unpaired electron which makes them more likely to react. These reactions can set off a chain of reactions that can damage cell DNA. Antioxidants work to neutralize these free radicals.

Question 20

How does hypoxia affect the cells of the body? What level of hypoxia affects organs?

Answer 20

Hypoxia deprives cells affected of oxygen which reduces or stops their ability to metabolize or generate ATP. Lactic acid builds up and cellular pH drops. Different organs in the body have different oxygen requirements. The brain, heart, and kidneys require larger amounts of oxygen and are therefore hit harder by hypoxia. Irreversible damage to these organs occurs quicker than with other, less active cells.

Question 21

What are some causes of hypoxia?

Answer 21

1. Decreased oxygen
2. Ischemia
3. Edema
4. Anemia
5. Inability of cells to use oxygen

Question 22

How does hypoxia and ischemia relate? What are the differences?

Answer 22

Hypoxia is a global loss of circulating oxygen disrupting cellular metabolism and creation of ATP.

Ischemia is a localized loss of oxygen delivery to a specific area. This lack of blood flow (which is the method of oxygen delivery) results in accumulation of metabolic waste as well. Lactic acidosis.

Question 23

What happens to the sodium-potassium pump during hypoxia?

Answer 23

As oxygen levels decrease, so too does the cell’s ability to make energy (ATP). The Na+/K+ pump relies on this energy to maintain its function. Without energy, it stops working. This allows potassium to leak out of the cell and sodium and water to enter the cell.

Question 24

What are pathologic calcifications? Dystrophic vs metastatic pathologic calcifications

Answer 24

Abnormal deposits of calcium and other minerals into the tissues.
Dystrophic calcifications - occurs in injured tissue. Commonly seen in arthrosclerosis.
Metastatic calcifications - occurs in normal, healthy tissue. This is caused by any condition that causes hypercalcemia. Common hypercalcemia causing conditions include - chronic kidney disease, hyperparathyroidism, primary bone disease.

Question 25

What is apoptosis? How is it beneficial?

Answer 25

Apoptosis is the highly selective programmed cell death. Cells that are damaged or old are marked for destruction. Examples of beneficial situations for apoptosis include:
1. Embryotic development - webbed toes become unwebbed due to apoptosis.
2. Death of immune cells - T cells that become autotargeting
3. Death of proliferating cell populations.

Restrictions of apoptosis have been associated with increased risk for cancer as cells begin to proliferate without normal mechanisms to stop it.

Question 26

What is necrosis?

Answer 26

Necrosis is cell death and decay in a tissue or organ that is part of a living creature.

Question 27

How does apoptosis and necrosis differ?

Answer 27

Apoptosis is the specific and well-orchestrated selection of cells to be eliminated. No inflammation or cellular debris is excreted. Removes cells so new, better functioning ones can take their place.

Necrosis causes cell instability, enzymatic breakdown of cellular parts. This triggers the inflammation process. Interferes with new cell growth.

Question 28

Infarction

Answer 28

Tissue death due to inadequate oxygenation to that tissue

Question 29

Coagulation necrosis
Caseous necrosis
Liquification

Answer 29

Coagulation necrosis is tissue death due to acidosis which denatures the cells. This acidosis typically builds up due to inadequate blood supply to a specific area (infarction).

Caseous Necrosis differs in that the dead cells persist indefinitely.

Liquification is the turning of the cells and their structures into liquid. Think of an abscess.

Question 30

What is gangrene? Types?

Answer 30

When a considerable amount of tissue becomes necrotic. There are two types of gangrene.
Dry - slow spreading. Associated with coagulation necrosis. Symptoms not as marks as wet.
Wet - fast spread. Worse symptoms. Odor. Can quickly lead to death.

Question 31

What is gas gangrene?

Answer 31

infection of at-risk cells by Clostridium. Anaerobes, form spores. commonly found in nature. Associated with wounds that come in contact with soil. Quickly progressing form of gangrene.