Cell Adaptations

Question 1

Cell adaptation

Answer 1

-cell under stress can result in multiple different ways in which they can adapt
>hypertrophy
>atropy
>hyperplasia
>metaplasia

Question 2

Cell Hypertrophy

Answer 2

-increase in the size of cells by increase in cytoplasmic mass (not due to cellular swelling)

Question 3

Organ hypertrophy

Answer 3

-an increase in the size of an organ due to increase in size but not in number of cells

Question 4

When does physiological hypertrophy become pathologic?

Answer 4

-when occurring in the organs

Question 5

Heart physiology

Answer 5

• 3:1 ratio thickness for left side compared to right side
  -Left: T shaped, Right: crescent shaped
  -Right: septomarginal band
  **As heart works harder, it undergoes hypertrophy and the lumen gets smaller, which leads to it needing to work even harder and lumen gets even smaller. Also means that thickness increases and leads to decreased diffusion ability of O2 and CO2

Question 6

Heart with same thickness of both sides

Answer 6

-increase in size of cell because it is muscle (but otherwise would be increase in number of cells)
Options:
1.Neonate
2. Right ventricular hypertrophy

Question 7

Hyperplasia

Answer 7

-Increase in organ size or tissue mass caused by an increase in the number of constituent cells
-only in tissues composed of ells capable of mitotic division
*hyperplasia and hypertrophy often occur together

Question 8

Mechanisms of hyperplasia

Answer 8

-increase local production of growth factors
-increased levels of growth factor receptors
-activation of intracellular signaling pathways
**NET result=cellular proliferation

Question 9

Hormone-induced hyperplasia

Answer 9

-increases the functional capacity of a tissue when needed
Ex. hyperplasia of endometrium and hypertrophy of smooth muscle in pregnant uterus

Question 10

Compensatory hyperplasia

Answer 10

-increases tissue mass after damage or partial loss
>hepatocellular compensatory hyperplasia (liver transplant)
>renal hyperplasia after nephrectomy

Question 11

Bone marrow

Answer 11

-mostly composed of fat/adipose tissue (white) in an adult
-if bone marrow is red, then producing high numbers of RBCs
>animal is anemic and bone marrow is constantly making RBCs of erythroid hyperplasia
>if animal is a neonate, then red bone marrow is considered normal

Question 12

Pathologic hyperplasia

Answer 12

-result of excessive hormonal stimulation, growth factor production, and irritation

Question 13

Examples of pathological hyperplasia

Answer 13

1.cystic endometrial hyperplasia in bitch and pyometria
-hyperplasia occurs normally during heat
-hyperplasia should go away when heat ends, but sometimes it does not and results in cysts within the uterus. Cysts create pockets and poor flushing within the uterus and rsults in increased chance of pyometra
2. prostatic hyperplasia in old intact dogs
3.Lawsonia intracellularis infection
4.Epidermal hyperplasia

Question 14

Thyroid hyperplasia

Answer 14

-goiter
-mostly associated with lack of iodine. Animal does not produce enough iodine, so the thyroid is overstimulated to try and recover iodine (but it cannot so over time thyroid increases in size)
-Ex. lambs

Question 15

Stimulus removal and hyperplasia

Answer 15

-when stimulus is removed, the proliferative response should top
**different than neoplasia (cancer): if you remove the cause, it will not just go away
-Areas in which hyperplasia occurred creates fertile soil in which cancerous proliferation may eventually arise later

Question 16

Cellular Atrophy

Answer 16

-cellular atrophy is shrinkage in the size of the cell

Question 17

Organ atrophy

Answer 17

-the decrease in size of an organ or tissues (after it has achieved normal size) caused by loss of cells or decreased cell size

Question 18

Hypoplasia

Answer 18

-failure of organ to reach its normal size

Question 19

Atrophy types

Answer 19

-Disuse atrophy- ex.arm in a cast
-denervation atrophy-nerve supply going to muscle is damaged (ex. Swinney in horses)
-atrophy due to diminished blood supply-
-pressure atrophy
-nutrition atrophy
-atrophy due to loss or exaggerated endocrine

Question 20

Serous atrophy of fat

Answer 20

-yellow gelatinous bone marrow
>means that the fat reserve in the bone marrow has been used. This is the bodies last reserves and would therefore have no storage of fat

Question 21

Prostate

Answer 21

-normally appears as a walnut
-when hyperplasia occurs, creates long island appearance
>straining to defecate=prostate hypertrophy because prostate is compressing the colon
-Post castration: many tiny islands and shrinking or prostate

Question 22

Mechanisms of atrophy

Answer 22

-phagosomes and lysosomes
-ubiquitin and proteasome pathway
-autophagy and autophagic vacuoles

Question 23

Villus atrophy

Answer 23

-when the villi in the intestines have become shorter due to damaged epithelium
>all villi want to be covered by epithelium

**Common viruses causing this and diarrhea: coronaviruses and rotaviruses destroy cells at tip whereas parvovirus destroy cells at base (which are the proliferative cells needed to cover with epithelium)
»more water into intestines and therefore diarrhea

Question 24

What would an atrophic organ look like and feel like?

Answer 24

-smaller and firmer than normal
-colour change (paler)= due to increase in fibrous connective tissue
-capsule is wrinkly (due to organ not filling out capsule)
-increased/exaggerated blood supply in comparison)

Question 25

Metaplasia

Answer 25

-one tissue undergoes stressor and then it is replaced with another tissue that is similar/related (but not the same)
>if stress removed, will return to normal
**reversible response in which one type of mature differentiated cells is replaced by a different mature differentiated type of the same germ line that is not normal to that location
>may represent an adaptive substitution of cells that are sensitive to stress by a cell type that is better able to withstand adverse environment

Question 26

Metaplasia clinical examples

Answer 26

1.metaplasia of respiratory columnar (cilia) to squamous epithelium
2.deficiency of vitamin A
>squamous metaplasia in esophageal glands in birds (esophagus)
>Squamous metaplasia in the lacrimal duct (Xerophthalmia/dry eye)
>Nyctalopia (night blindness)
3. Sertoli cell tumor induces squamous metaplasia of prostatic epithelium

Question 27

Vitamin A

Answer 27

-needed for differentiation of epithelia

Question 28

Histology of prostate

Answer 28

-Hyperplasia- excess epithelium
-atropy- epithelia wastes away
-metaplasia-glandular tissue replaced with squamous tissue

Question 29

Examples of clinical scenarios similar to metaplasia

Answer 29

-look like a lesion by are not really clinically significant
1.Myosititis ossificans - bone forming within muscle
2.ossifying pachymeningitis- appears in old dogs. Small nodules of bone present within the meninges
3.pulmonary ossification-bone in lungs