GP 04 - Cellular Adaptation and Inflammation

Question 1

In general, what is cellular adaptation? Is it physiological or pathological?

Answer 1

Cellular adaptations are reversible changes in the number, size, phenotype, metabolism, or functions of cells in response to changes in their environment. These adaptations can be either physiological (e.g. - in response to hormonal stimuli) or pathological (e.g. - in response to stress in order to avoid injury).

Question 2

List the patterns of cellular adaptation

Answer 2

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

Question 3

What is a premalignant condition?

Answer 3

A premalignant (aka - precancerous) condition is a term used to describe certain conditions of lesions involving abnormal cells which are at an increased risk of becoming cancerous

Question 4

Describe what atrophy is and what its most common causes are.

Answer 4

It is a decrease in size and function of cells (not a decrease in #). It is usually caused by:

• Decreased blood supply
• Loss of innervation
• Loss of trophic signals
• Decreased workload
• Aging

Question 5

Describe what hypertrophy is and what usually causes it.

Answer 5

Hypertrophy is the increase in size (not #) of cells due to increased functional demands. It can be either physiological (e.g. - enlargement of uterus during pregnancy) or pathological (e.g. - cardiac muscle during hypertension)

Question 6

Why would a cell hypertrophy when it could just divide?

Answer 6

Hypertrophy occurs mainly when the cell has limited capacity to divide

Question 7

What is hyperplasia and how does it relate to hypertrophy?

Answer 7

Hyperplasia is an increase in the number of cells, stimulated by growth factors. Hyperplasia and hypertrophy are distinctly different but they can occur at the same time

Question 8

Describe the types of hyperplasia.

Answer 8

• Physiologic Hyperplasia
  
  • In response to hormones (e.g. - mammary epithelium druing puberty/pregnancy)
  • Compensatory (e.g. - residual tissue grows after removal of part of an organ)
• Pathologic Hyperplasia
  
  • Occurs when there is disturbance in the balance of the hormonal stimuli (e.g. - excessive TSH causing thyroid enlargement)

Question 9

What distinguishes hyperplasia from cancer?

Answer 9

If the growth factor that initiated the hyperplasi is removed, the growth stops. In cancer, growth continues

Question 10

Describe what metaplasia is and what causes it.

Answer 10

Metaplasia is a reversible change in which one adult cell type is replaced by another adult cell type. This occurs in response to stress because the new cell type is more able to withstand the stress. There is stem cell reprogramming and not just a phenotypic change of already differentiated cells.

Question 11

What is dysplasia?

Answer 11

If the insult causing metaplasia presists, the metaplastic population begins to grow and mature in an increasingly disordered manner. This is still reversible if the insult is removed but can develop into a neoplasm if it is not.

Question 12

Out of the following, which are considered to be premalignant:

• Atrophy
• Hyperplasia
• Metaplasia
• Dysplasia

Answer 12

Dysplasia

Question 13

What are the primary factors that lead to cellular aging?

Answer 13

Question 14

What is the arrow pointing to in this image?

Answer 14

Lipofuscin accumulations in aging cells

Question 15

What has happened to this tissue?

Answer 15

Hypertrophy

Question 16

What is this a photo of?

Answer 16

Squamous metaplasia of the respiratory epithelium

Question 17

What is this an example of?

Answer 17

Hypertrophy

Question 18

What is happening with the tissue here?

Answer 18

Hyperplasia

Question 19

What is happening in this image?

Answer 19

Atrophy

Question 20

What is this a photo of?

Answer 20

Columnar metaplasia of the esophagus

Question 21

What is the purpose of inflammation?

Answer 21

• Removal of the injurious agent and necrotic tissue through a series of vascular and cellular changes
• Setting the base for the tissue healing and repair process
• Setting the bases of the long lived, more specific, adaptive immune response

Question 22

What are the major drawbacks of inflammation?

Answer 22

• Inflammatory reaction may cause or exacerbate tissue injury
• Can cause pain
• Can fail to resolve leading to complication (e.g. - abscess)
• Can occur at inapropriate times (e.g. - allergic reactions and autoimmunity)

Question 23

List the general sequence of events to inflammation

Answer 23

1. The offending agent, which is located in extravascular tissues, is recognized by host cells and molecules
2. Leukocytes and plasma proteins are recruited from the circulation to the site
3. The leukocytes and plasma proteins become activated and work together to destroy and eliminate the offending agent
4. The above reaction is terminated
5. The damaged tissue is repaired

Question 24

What basic information do we need to know about acute inflammation.

Answer 24

• It is the initial rapid response to tissue injury
• It develops within minutes to hours
• It lasts for several hours or days
• Characterized by the presnece of exudate
• Predominant leukocyte is the neutrophil

Question 25

What basic information do we need to know about Chronic inflammation?

Answer 25

• It develops slowly and is of longer duration
• It is associated with more tissue destruction
• Its predominant leukocytes are lymphocytes and macrophages

Question 26

What are the cardinal signs of inflammation?

Answer 26

• Heat (calor)
• Redness (rubor)
• Swelling
• Pain (dolor)
• Loss of function

Question 27

How does the body recognize microbes and damaged cells?

Answer 27

• Cellular receptors (most notably toll-like receptors) recognize microbes
• Upon introduction to the body, some microbes can be coated by antibodies (IgG), complement proteins (C3), and collectins (opsonization) which can be recognized by leukocytes, leading to the release of cytokines and initiation of the inflammatory process
• Certain circulating proteins like mannose-binding lectin and collectins can recognize microbial sugars or proteins and then activate the complement system
• All cells have cytosolic receptors that recognize a diverse set of molecules that are only liberated or altered when the cell is damaged. Once stimulated, these receptors activate a multiprotein cytosolic complex called the inflammasome, which induces the production of cytokines