VET 375 > Adaptive Tissue Responses > Flashcards

Adaptive Tissue Responses Flashcards

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1
Q

The sentence above outlines the mechanism of
which type of adaptive tissue response?
“Loss of or decreased stimulus OR insufficient
nutrition > decreased protein synthesis, increased
protein degradation +/- autophagy > decreased
cell size and number”

A

Atrophy

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2
Q

Provide an example of Physiological, compensatory, endocrine driven hyperplasia

A

Mammary gland hyperplasia during pregnancy and lactation

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3
Q

Provide an example of Inappropriate, endocrine driven hyperplasia

A

Prostatic hyperplasia in aged dogs

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4
Q

Provide an example of disuse atrophy

A

Muscle atrophy in a painful limb due to osteoarthritis

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5
Q

Provide an example of concentric hypertrophy

A

Left ventricular hypertrophy due to subaortic stenosis

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6
Q
  1. Which is part of the mechanism of
    metaplasia?
    A. Stimulus (i.e. increased workload, hormone) >
    growth factor production
    B. Reprogramming of local stem cells
    C. Mechanical stretch receptors
    D. Increased number of organelles within the
    cytoplasm
A

B. Reprogramming of local stem cells

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7
Q

Pulmonic stenosis
(narrowing at the outflow
into the pulmonary artery)

Which of following is the
most likely pattern of
hypertrophy in the heart?
a. Right ventricular
concentric hypertrophy
b. Left ventricular
concentric hypertrophy
c. Right ventricular
eccentric hypertrophy
d. Left ventricular eccentric
hypertrophy

A

Right ventricular concentric hypertrophy
Outflow obstruction → RV pressure overload → increased workload for the RV to force blood through the
narrower outflow tract → right ventricular concentric hypertrophy

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8
Q

Lymphoid Nodular
Hyperplasia in the spleen of
a dog.

Which of following is a
potential sequelae?
a. Haemorrhage
b. Thrombosis
c. Pulmonary oedema
d. Hepatic atrophy

A

The most correct answer here is haemorrhage. These nodules can get very large and sometimes they may
spontaneously rupture or they may rupture secondary to minor trauma.

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9
Q

A histology report describes: Markedly increased epithelial
thickness within the oral mucosa with the epithelium
approximately 20 cells thick compared to 3 cells in the normal oral
mucosa. The epithelial cells are well-differentiated with normal
maturation and progression and no atypia.

Question: What is the correct interpretation?
A. Dysplasia
B. Hyperplasia
C. Hypertrophy
D. Atrophy

A

Hyperplasia

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10
Q
A

No, not definitively. But, in both images not only is the mucosa yellow but it’s also pale, especially in the
cat, so it’s likely these patients are also anaemic.

You could determine whether the bilirubin was conjugated, unconjugated or mixed – this would help
you narrow it down considerably. Or you could consider the history and other clinical and laboratory findings to help you work out which is most likely.

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11
Q

Which pigment do you think is in the macrophages vs. the neurons?

A. Haemosiderin
B. Ceroid/Lipofuscin

A

The top image is haemosiderin in macrophages.

The second image is lipofuscin in neurons. Note: Neurons are not phagocytic cells so they are
unlikely to contain haemosiderin. But, neurons are a permanent cell so they are likely to accumulate a wear and
tear pigment like lipofuscin over their lifetime.

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12
Q

This tissue is lung from a dog

A

The colour suggests that a pigment has been added to this tissue – black or dark brown pigments we could
consider include carbon (anthracosis) or melanin.

This case it is anthracosis – the
histological images shows some of the pigment in the alveolar walls.

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13
Q

Is this melanosis or melanoma?

A

Melanoma
-discrete nodules that vary in colour

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14
Q

Is this melanosis or melanoma?

A

The image on the left the lesions are flat; melanosis.

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15
Q

What diagnosis is most likely?
A. glycogenosis
B. lipidosis
C.amyloidosis
D. Icterus

A

Hepatic lipidosis

On the cytology image you can see a hepatocytes with multiple clear
vacuoles in the cytoplasm and this is typical of hepatic lipidosis. The special stain we use for lipid is Oil Red O.

The reason for the zonal pattern is because the liver is arranged into triads; the blood enters the liver in the portal regions,
trickles through the sinusoids and leaves via the central veins.

Depending on the cause, often lipid deposition will occur
more in the hepatocytes around the central veins because those hepatocytes are getting the less well oxygenated blood
and are more prone to hypoxic injury and other stressors. Patterns often follow the microanatomy of an organ and can
give us clues to the pathogenesis.

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16
Q

What are adaptations in tissue responses?

A

Reversible functional and structural responses to changes in physiologic states and some pathologic stimuli

Adaptations allow the cell to survive and continue to function.

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17
Q

List the types of adaptations that allow cells to continue functioning.

A
  • Atrophy
  • Hypertrophy
  • Hyperplasia
  • Metaplasia
  • Dysplasia
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18
Q

What defines labile cells?

A

Cells that are continuously dividing, such as those in epithelial surfaces and bone marrow.

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19
Q

What are quiescent/stable cells?

A

Cells in G0 that retain the ability to proliferate on demand, like hepatocytes and renal parenchyma.

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20
Q

What are permanent terminally differentiated cells?

A

Cells that do not divide, such as cardiac myocytes and neurons.

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21
Q

What is atrophy?

A

Reduction in the size of an organ or tissue due to a decrease in cell size.

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22
Q

What mechanisms lead to atrophy?

A
  • Loss of or decreased stimulus
  • Insufficient nutrition
  • Decreased protein synthesis
  • Increased protein degradation
  • Autophagy
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23
Q

What are physiological causes of atrophy?

A
  • Disuse
  • Loss of endocrine stimulation
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24
Q

What are pathological causes of atrophy?

A
  • Disuse
  • Denervation
  • Diminished blood supply
  • Inadequate nutrition
  • Pressure
  • Cachexia
  • Endocrine disease
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25
What is the microscopic appearance of atrophy?
Decreased cell size and number.
26
What is the macroscopic appearance of atrophy?
Reduced size and weight of an organ or tissue.
27
How does muscle atrophy occur due to denervation?
Loss of stimulation leads to atrophy of muscles, such as unilateral atrophy of laryngeal muscles.
28
What is hypertrophy?
Increase in cell size due to increased production of cellular proteins.
29
What mechanisms lead to hypertrophy?
* Stressor sensed by cell membrane sensors * Intracellular signal transduction * Gene transcription * Increased protein synthesis * Increased numbers of organelles
30
What are physiological causes of hypertrophy?
* Increased workload (e.g., weightlifters) * Hormonal factors (e.g., pregnancy)
31
What are pathological causes of hypertrophy?
Increased workload due to heart disease.
32
What is the microscopic appearance of hypertrophy?
Larger cells.
33
What is the macroscopic appearance of hypertrophy?
Increase in size and weight of the organ or tissue.
34
What is hyperplasia?
Increase in the number of cells in an organ or tissue in response to a stimulus.
35
What mechanisms lead to hyperplasia?
* Stimulus leads to growth factor production * Proliferation of mature cells or stem cell activation and differentiation
36
What are physiological causes of hyperplasia?
Hormonal stimulation, such as in mammary tissue and bone marrow.
37
What are pathological causes of hyperplasia?
* Increased workload * Hormonal changes * Infectious agents * Chronic irritation/inflammation
38
What is metaplasia?
Reversible change in which one differentiated cell type is replaced by another cell type.
39
What triggers metaplasia?
Chronic irritation, nutrient deficiencies, hormonal stimulation, or idiopathic causes.
40
What is dysplasia?
Abnormal formation of a tissue characterized by an increase in poorly differentiated or immature cells.
41
What are the differences between hyperplasia and neoplasia?
* Hyperplasia: controlled growth, regresses if stimulus is removed * Neoplasia: uncontrolled proliferation due to genetic aberrations
42
What is eccentric hypertrophy?
Hypertrophy due to volume overload resulting in a thinned wall and increased chamber size.
43
What is concentric hypertrophy?
Hypertrophy due to pressure overload resulting in a thickened wall and smaller chamber size.
44
What is the main cause of hypertrophic cardiomyopathy in cats?
Ventricular myocardial hypertrophy inherited as an autosomal dominant trait.
45
What is the role of atrial natriuretic factor in cardiac hypertrophy?
It decreases blood volume and pressure, reducing hemodynamic load.
46
What is the effect of chronic irritation on epithelial cells?
It can lead to metaplasia, such as replacement of ciliated columnar epithelium by squamous epithelium.
47
Fill in the blank: Atrophy is due to a decrease in _______.
[cell size]
48
True or False: Hyperplasia can occur in cardiac myocytes.
False
49
What is the mechanism of intracellular accumulation of endogenous normal substances?
Inadequate removal of a normal endogenous substance secondary to defects in mechanisms of packaging and transport or overwhelming of these mechanisms ## Footnote Examples include Lipidosis and Glycogenosis.
50
What is the mechanism of intracellular accumulation of endogenous abnormal substances?
Accumulation of an abnormal endogenous substance due to genetic or acquired defects in its folding, packaging, transport, or secretion ## Footnote Example: Amyloid.
51
What is the mechanism of intracellular accumulation of exogenous substances?
Deposition and accumulation of an abnormal exogenous substance because the cell cannot process or transport it ## Footnote Examples include Carbon and Silica.
52
What conditions can lead to intracellular lipid accumulation in the liver?
1. Excessive FFA Delivery 2. Diabetes Mellitus / Insulin Resistance 3. Hepatocellular Injury 4. Idiopathic Lipidosis 5. Hyperlipaemia ## Footnote Each of these factors disrupts normal lipid metabolism.
53
What is the microscopic appearance of lipidosis?
Clear vacuoles within cells ## Footnote This appearance is due to lipid accumulation.
54
What is the macroscopic appearance of lipidosis?
Enlarged, swollen, pale liver ## Footnote The liver appears shiny or greasy.
55
What is glycogenosis?
Accumulation of excess glycogen primarily in the liver and skeletal muscle ## Footnote It can lead to hepatic rupture and hemorrhage.
56
What is the microscopic appearance of glycogenosis?
Hazy vacuoles within cells ## Footnote Glycogen is clear or negatively staining.
57
What is the primary organ affected by glycogenosis?
Liver ## Footnote Glycogen is stored primarily in the liver and skeletal muscle.
58
What is amyloidosis?
Accumulation of abnormal proteins in tissues ## Footnote Major affected tissues are the liver and kidney.
59
What is the microscopic appearance of amyloidosis?
Eosinophilic, extracellular, hyaline matrix in the extracellular space between cells ## Footnote Congo red stain is used for identification.
60
What are the forms of amyloidosis?
1. Primary (AL amyloid) 2. Secondary (AA protein) 3. Hereditary forms 4. Idiopathic ## Footnote Each form has different underlying causes.
61
What is gout?
Deposition of sodium urate crystals in tissue ## Footnote It can cause acute inflammatory responses in joints.
62
What is the microscopic appearance of gout?
Urate crystals are acicular, surrounded by neutrophils and macrophages ## Footnote This is characteristic of the inflammatory response.
63
What is melanin?
Pigment responsible for the color of hair, skin, and iris ## Footnote Synthesized by melanocytes derived from the neural crest.
64
What is melanosis?
Melanin accumulation in unusual sites ## Footnote Example: Menigeal Melanosis in sheep.
65
What differentiates melanoma from melanosis?
Melanoma is a neoplastic proliferation of melanocytes, while melanosis is a non-pathological deposition of melanin ## Footnote Melanoma appears as a raised, pigmented mass.
66
What causes acquired hyperpigmentation?
Typically post-inflammatory changes due to irritation or other factors ## Footnote Factors include UV radiation, viral infections, and endocrinopathies.
67
What factors influence skin pigmentation?
1. Melanocyte activity 2. Type of melanin produced 3. Distribution of melanocytes ## Footnote Skin pigmentation is not primarily determined by the number of melanocytes.
68
What is the mechanism of anthracosis?
Deposition of carbon dust or soot in the lungs ## Footnote It is associated with chronic exposure to air pollution.
69
What is the primary determinant of skin pigmentation?
Melanocyte activity, type of melanin produced, distribution of melanocytes ## Footnote Melanocyte types include eumelanin and pheomelanin.
70
What is anthracosis?
Deposition and accumulation of carbon in tissues due to inhalation ## Footnote It primarily affects the lungs and bronchial lymph nodes.
71
What is the most common exogenous pigment associated with anthracosis?
Carbon (coal dust) ## Footnote Carbon is a prevalent air pollutant in urban areas.
72
What is the microscopic appearance of anthracosis?
Fine, black/crystalline material within macrophages ## Footnote This occurs around airways and in lymph node sinuses.
73
Define hematogenous pigments.
Pigments derived from erythrocytes, including hemoglobin, hematins, hemosiderin, hematoidin, bilirubin, biliverdin, and porphyrins ## Footnote These pigments are related to blood components.
74
What is the role of hemoglobin in the blood?
Carries O2 in the blood ## Footnote Hemoglobin gives blood its red or bluish color.
75
What causes the brown granular pigment hematoidin to appear?
Breakdown of hemoglobin in macrophages ## Footnote This occurs during the body's normal processes.
76
What is the pathogenesis of hyperbilirubinemia?
Breakdown of hemoglobin leads to unconjugated bilirubin, which is conjugated in the liver and excreted ## Footnote Excess bilirubin causes tissues to stain bright yellow (jaundice).
77
What is lipofuscin?
A yellow-brown lipoprotein that accumulates in long-lived postmitotic cells ## Footnote It is known as a 'wear and tear' pigment of aging.
78
What distinguishes ceroid from lipofuscin?
Ceroid accumulates in disease states, while lipofuscin is more associated with aging ## Footnote Ceroid can be seen in conditions like vitamin E deficiency.
79
What is the primary cause of chronic musculoadipose atrophy in a dog?
Chronic malnutrition ## Footnote This can result from inadequate nutrient provision or malabsorption.
80
What pathological process is indicated by a severely enlarged prostate gland in a dog?
Chronic prostatic hyperplasia ## Footnote This condition can also be referred to as prostatomegaly.
81
What is the morphological diagnosis for severe left ventricular hypertrophy in a cat?
Severe, diffuse, chronic myocardial hypertrophy ## Footnote This condition can lead to feline aortic thromboembolism (FATE).
82
What are the three pathways of jaundice?
* Pre-hepatic Jaundice * Hepatic Jaundice * Post-hepatic Jaundice ## Footnote Each pathway involves different mechanisms of bilirubin accumulation.
83
What is the likely cause of squamous metaplasia in the chicken oesophagus?
Vitamin A deficiency (Hypovitaminosis A) ## Footnote This deficiency impairs epithelial differentiation and mucus secretion.
84
What is the appearance of tissues affected by pulmonary hemosiderosis?
Brown granular pigment in macrophages, giving organs a brown tinge ## Footnote This can occur in conditions such as chronic passive congestion.
85
Describe the gross changes in a lesion on the caudal elbow of a dog.
Roughly oval, well-circumscribed, nodular/plaque-like, black lesion ## Footnote This is likely due to chronic irritation, leading to hyperplasia and hyperpigmentation.
86
What abnormality is expected in histological analysis of a dog with chronic malnutrition?
Increased layers of normal keratinocytes with increased pigmentation ## Footnote These changes indicate chronic irritation and adaptation.
87
What is immune mediated haemolytic anaemia?
A type of haemolytic anaemia caused by the immune system attacking red blood cells ## Footnote This condition can lead to elevated levels of unconjugated bilirubin in the blood, causing jaundice.
88
What is hepatic jaundice?
A condition characterized by impaired uptake, conjugation, or excretion of bilirubin in the liver, resulting in accumulation of both unconjugated and conjugated bilirubin in the blood ## Footnote Causes include viral hepatitis, immune mediated hepatitis, and drug-induced liver injury.
89
What causes post-hepatic jaundice?
Obstruction of the bile ducts preventing bile flow from the liver to the intestine, leading to accumulation of conjugated bilirubin in the blood ## Footnote Examples include gallstones, tumors, or strictures.
90
What is the appearance of renal cortex affected by amyloidosis?
Diffusely discolored tan/yellow/orange with a firm, smooth texture ## Footnote Differential diagnoses include inflammation, neoplasia, or acellular substance deposition.
91
What does necrosis look like in the renal medulla?
Foci of yellowish-green discoloration on the medullary crest, with bright discoloration around the edges ## Footnote This is indicative of tissue death in that area.
92
What is the MDx for severe chronic renal amyloidosis in a dog?
Severe, chronic, diffuse and bilateral renal amyloidosis with acute multifocal medullary crest necrosis ## Footnote MDx stands for Morphologic Diagnosis.
93
What is the most common cause of amyloidosis?
Reactive/secondary (AA) amyloid occurring secondary to chronic inflammation ## Footnote Other organs such as liver and spleen may also be affected.
94
What are the types of amyloidosis?
1. Primary amyloidosis 2. Endocrine/inherited amyloidosis 3. Secondary (reactive) amyloidosis 4. Prion-associated amyloidosis ## Footnote Each type is associated with different underlying conditions.
95
How would the kidneys palpate in a living animal with amyloidosis?
Enlarged but regular, not nodular ## Footnote They may become painful if necrosis occurs.
96
What contributes to lesions in the renal medulla?
Ischemic injury due to low oxygen tension, vascular compromise from amyloid deposition, and dehydration ## Footnote NSAID toxicity can also manifest in this location.
97
Describe the gross lesions of chronic skin lesions on a dog.
Extensive, patchy thinning and loss of hair coat with black discolored skin and regions of mottled redness ## Footnote This can indicate alopecia and hyperpigmentation.
98
What pathological processes can cause hair loss in dogs?
1. Inflammation/destruction of hair follicles 2. Atrophy of hair follicles 3. Necrosis of hair follicles 4. Hair follicles never formed ## Footnote Each of these processes can lead to different types of alopecia.
99
What is the mechanism behind allergic skin disease in dogs?
Hypersensitivity to environmental allergens causes histamine release, leading to skin damage and chronic inflammation ## Footnote This results in hair loss and hyperpigmentation.
100
What is the appearance of a liver affected by hepatic lipidosis?
Diffusely pale yellow with rounded margins and a shiny surface ## Footnote This may indicate accumulation of lipids within liver cells.
101
What cytological findings are expected in lipidosis?
Hepatocytes containing large, clear vacuoles ## Footnote This is indicative of lipid accumulation in liver cells.
102
What are possible causes of hepatic lipidosis?
1. Negative energy balance 2. Diabetes mellitus 3. Obesity ## Footnote These conditions can lead to fat accumulation in the liver.
103
What is the significance of amyloidosis in veterinary medicine?
It is associated with various inherited, neoplastic, and inflammatory disorders characterized by extracellular protein deposition ## Footnote There are multiple forms of amyloid depending on the inciting cause.
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