Endocrine Flashcards

1
Q

Endocrine System:

Structure

A
  • Derived from neural ectoderm
    • strong association with vascular and neural tissue
  • Endocrine organs include:
    • pituitary gland
    • Thyroid gland
    • Parathyroid gland
    • Adrenal gland
    • Gonads
    • Endocrine pancrease
    • Chemoreceptors organs
    • Pineal gland
    • Adipose tissue
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2
Q

Endocrine System:

Funciton

A
  • Maintenance of homestasis:
    • Hormones are the mediators of homeostasis
      • polypeptides
      • Steroids
      • Catecholamines and iodothyronines
    • Feedback systems regulate most hormone concentrations
      • hypothalamus - pituitary - target tissue axis
    • Some hormones respond to plasma concentrations of various products of nervous stimuli
      • thyroid C-cells, Parathyroid cheif cells, adrenal medulla
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3
Q

Endocrine System:

Dysfunction:

Increased Function

A
  • Primary Hyperfunction
    • increased hormones secretion by an abnormal gland
  • Secondary Hyperfunction
    • increased hormone secretion by a normal endocrine gland that is excessively stimulated
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4
Q

Endocrine System:

Dysfunction:

Decreased Function

A
  • Primary hypofunction
    • decreased hormone secretion by an abnormal gland
  • Secondary hypofunction:
    • decreased hormone secretion by a normal endocrine gland that is inadequately stimulated
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5
Q

Endocrine System:

Patterns of Disease

A
  • Metabolic processes are altered with any endocrine abnormality
  • Neoplasia is the most common pathology pattern
  • Cell adaptation is fairly common, atrophy, hyperplasia
  • Immunopathology (autoimmunity) is relatively common as a pattern of endocrine disease
  • Developmental, cell injury, vascular distrubances and inflammation are less common patterns associated with endocrine disease
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6
Q

Endocrine System:

Causes of Disease

A
  • Genetic alterations are important as predisposing factors for neoplasia, immunopathologic and developmental endocrine diseases
  • Nutritional factors can have significant impact of hormone-regulated homeostasis
  • Infectious, chemical and physical insults are less common causes of endocrine disease
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7
Q

Pituitary Gland

A
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8
Q

Pituitary Gland

Structure:

Anterior Lobe

A
  • Pars Distalis:
    • acidophils
      • GH and LTH
    • Basophils:
      • Lh, FSH, TSH
    • Chromophobes
      • ATCH, MSH
  • Pars Intermedia
    • melanotrophs
  • Pars Tuberalis
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9
Q

Pituitary Gland:

Structure:

Posterior Lobe

A
  • Hypothalamic Neurosecretory neurons
    • paraventricular and supraoptic nuclei
      • ADH, Oxytocin
    • Infundibular stalk
    • Pars Nervosa
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10
Q

Adenohypophysis:

Growth Hormone

A

Regulates growth and metabolism

Somatotropin

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11
Q

Adenohypophysis:

Luteotropic Hormone

A

Stimulates progesterone secretion

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12
Q

Adenohypophysis:

Luteinizing Hormone

A

Stimulates estrogen secretion

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13
Q

Adenohypophysis

Follicle Stimulating Hormone

A

Stimulates ovarian follicle growth and spermatogenesis

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14
Q

Adenohypophysis:

Thyroid Stimulating Hormone

A

Thyrotrophin, TSH

Stimulates thyroid hormone secretion

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15
Q

Adenohypophysis

Adrenocorticotrophic Hormone

A

Stimulates glucocorticoid secretion

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16
Q

Adenohypophysis

Melanocyte Stimulating Hormone

A

Stimulates melanocytes

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17
Q

Neurohypophysis:

Antidiuretic hormone

A

regulates water excretion

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18
Q

Neurohypophysis

Oxytocin

A

Stimulates smooth muscle contraction

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19
Q

Pituitary Gland:

Dysfunction

Increased Hormone Activity

A

Functional neoplasia

Increased stimulation hy hypothalamus

AnteHormone-like substances

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20
Q

Pituitary Gland:

Dysfunction:

Decreased Hormone Activity

A

Destructive lesions

Non-Responsive target cells

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21
Q

Pituitary Gland

Pathogenesis

Neoplasia

A

functional or non-functional

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22
Q

Pituitary Gland

Pathogenesis

Cell Adaptation

A

Hyperplasia and atrophy

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23
Q

Pituitary Gland

Dysfunction

Developmental Anomalies

A

Aplasia, hypoplasia, cysts

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24
Q

Pituitary Gland

Dysfunction

Immunopathology

A

Autoimmunity

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25
Q

Pituitary Gland

Dysfunction

Inflammation

A

Uncommon

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26
Q

Pituitary Gland

Dysfunction

Metabolic

A

All hormonal dysfunctions will result in metabolic alterations

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27
Q

Pituitary Gland

Causes

A
  • Genetic Injury
    • inherited or acquired
  • Infectious Agents
    • Uncommon
  • Nutritional
  • Chemical
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28
Q

Chromophobe adenoma in dogs

Functional adenoma

A
  • Neoplastic chormophobes are unregulated and produce large amounts of ACTH
  • Excessive ACTH causes diffuse adrenocortical hyperplasia
    • hyperadrenocorticism (Cushing Disease)
  • Approximately 80-90% of cases of canine hyperadrenocorticism are dut to pituitary neoplasia
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29
Q

Chromophobe adenoma in dogs:

Most common pituitary tumor of dogs

A
  • Increased frequency in Boston Terriers, Beagles, Boxers, Dachshunds, and Miniature Poodles
  • May arise from hyperplasitc nodules that mutae and become clonal
  • Microadenoma
    • more likely to be functional and produce excess ACTH
  • Macroadenoma
    • Less likely to be functional, and act as space-occupying mass
      • Hypopituitarism or hypothalamic compression
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30
Q

pars intermedia ademona

A
  • Pars intermedia is the second most common location for chromophobe adenoma in dogs
    • These can be functional or compressive, just like those of the pars distalis
      • compressive = hypoptiutarism or diabetes insipidus due to pressure of the hypothalamus or destructiono f the neurohypophysis
  • Pars intermedia dysfunction is the most common endocrine abnormality of horses
    • Most common in older horses
    • Possibly due to age-related oxidative injury of dopaminergic neurons
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31
Q

Pituitary Pars Intermedia Dysfunction in Horses

A
  • Decreased dopamine production results in increased activity of melanotrophs
    • melanotrophs produce proopiomelanocortin (POMC)
    • POMC > ACTH > a-MSH > B-endorphin + corticotrophin-like intermediate peptide
  • Signs include increased hair growth (Hypertrichosis/hirsutism) increaed adipose tissue deposition, weight loss
  • Pituitary lesions ranges from diffuse hyperplasia to micro/macro adenoma
  • Hirsutism may be due to increased POMC activity or hypothalamic compression
    • compression can interfere with thermoregulation and appetite centers
  • Melanotrophs are regulated by dopaminergic-pituitary-adrenal axis
    • adrenal glands are usually normal
32
Q

Somatotroph Adenoma

A
  • Arise from somatotrophs (Acidophils)
    • uncommon, mainly cats, dogs, sheep
    • Functional adenoma in cats
      • increased production of insulin-like growth factor 1 by the liver
        • growth of soft tissue and bone
        • Insulin-resistant diabetes mellitus (Type 2)
    • Non-functional adenoma can cause panhypopituitarism and hypothalamic compression
  • Basophil ademona
    • Rare
33
Q

Pituitary Cysts

A
  • Mainly in brachycephalic dogs
  • Abnormal Development in or around the pituitary gland
    • craniopharyngeal duct cyst
    • Pharyngeal hypophyseal cyst
    • Orapharyngeal ectoderm cyst
  • These can compress and damage surrounding sturcutes
34
Q

Pituitary Cysts:

Major Types:

Craniopharyngeal duct cysts

A

Diabetes insipidus, pituitary hypofunction

35
Q

Pituitary Cysts:

Major types:

Pharyngeal Hypophyseal cysts

A

Respiratory distress

36
Q

Pituitary cysts:

Major types:

Oropharyngeal ectoderm cysts

A

Panhypopituitarism

Junenile hypopituitarism in German Shepherds

37
Q

Pituitary Dwarfism

A
  • Failure of Rathkes pouch ectoderm to differentiate into the adenohypophysis
  • Autosomal Recessive in german shepherds
    • also occurs in spitz, toy pinschers, and karelian bead dogs
    • Generally normal until 2 months of age
  • Manifestations due to decreased growth hormone
    • decreased insulin-like growth factor 1
    • Decreased growth (retain infantile characteristics)
    • Retention of puppy hair progressing to alopecia
38
Q

Craniopharyngioma

A
  • Neoplastic Remnants of Rathkes pouch oropharyngeal ectoderm
    • young dogs, rare
    • Hypothalamic destruction and decreased hypothalamic trophic hormones
39
Q

Non-functional Adenoma

A
  • Dogs, cats, and others
  • These can arise from any cell, but often of chromophobe origin
  • Hypopituitarism with endocrine gland atrophy and hypofunction
40
Q

Pituitary Gland Inflammation

A
  • Pituitary Abcesses
    • most common in cattle
      • secondary to nasal septal infections
    • Acts as a space occupying lesion
      • Blindness, depression, drooling, tongue prolapse
        • these signs can mimic rabies
41
Q

Neurohypophysis Disease:

Pituitary Diabetes Insipidus

A
  • Destruction of the neurohypophysis or supraoptic nuclei of hte hypothalamus
    • decreased ADH production or release
      • polyuria, polydipsia, dilute urine
    • Decreased oxytocin
42
Q

Neurohypophysis Disease:

Nephrogenic Diabetes Insipidus

A

Primary renal disease ADH is normal

43
Q

Adrenal Gland:

Structure:

Cortex

Zona Glomerulosa

A

Mineralocorticoids

44
Q

Adrenal Gland

Structure

Cortex

Zona fasciculata

A

Glucocorticoids

45
Q

Adrenal Gland

Structure

Cortex

Zona reticularis

A

Sex steroids

46
Q

Adrenal Gland

Structure

Medulla

A

Catecholamines

47
Q

Adrenal Gland:

Function:

Mineralicorticoids

A
  • Aldosterone
    • regulates blood pressure
    • Promotes sodium retention and potassium excretion by renal tubules
      • increaes intracellular fluid volume and regulates extracellular fluid volume
48
Q

Adrenal Gland

Function

Glucocorticoids

A
  • Cortisol and Corticosterones
    • Gluconeogenesis, protein and fat catabolism, suppressive for inflammation and immunity
49
Q

Adrenal Gland

Function

Sex Steroids

A

Progesterone, estrogen, and androgens

50
Q

Adrenal Gland

Function

Catecholamines

A

Epinephrine and norepinephrine

51
Q

Adrenal Gland

Function

Regulation of Adrenal Function

A
  • Pituitary hormones
    • ACTH
  • Renin-angiotensin system
    • renin cleaves angiotensinogen
    • Angiotensin 1 and 2 contracts vascular smooth muscle and stimulates aldosterone secretion
  • Neural Controls
    • catecholamine secretion
52
Q

Adrenal Gland:

Dysfunction:

Hyperfunction

A
  • Primary or secondary adrenal involvement
  • Polyuria, polydipsia, increased appetite, weakness, alopecia, increased infection
  • Cushings Disease
53
Q

Adrenal Gland:

Dysfunction:

Hypofunction (Hypoadrenocorticism)

A

Primary or secondary adrenal involvement

Anorexia, weight loss, GI disturbances, Dehydration

Addisons Disease

54
Q

Adrenal Gland:

Dysfunction:

Hypofunction (Hypoadrenocorticism)

A

Primary or secondary adrenal involvement

Anorexia, weight loss, GI disturbances, Dehydration

Addisons Disease

55
Q

Adrenal Gland:

Pathogenesis:

Metabolic

A

Adrenal dysfunction will result in metabolic alterations

56
Q

Adrenal Gland:

Pathogenesis:

Neoplasia

A

Functional or non-functional

57
Q

Adrenal Gland:

Pathogenesis:

Cell Alteration and Injury

A

Secondary hyperplasia is common secondary to pituitary diesease

Secondary atrophy due to hypopituitarism

58
Q

Adrenal Gland:

Pathogenesis:

Developmental Anomalies

A

Aplasia

Hypoplasia

Cysts

59
Q

Adrenal Gland:

Pathogenesis:

Immunopoathology

A

Autoimmunity

60
Q

Adrenal Gland:

Causes

A
  • Genetic Predisposition:
    • pituitary neoplasia causing adrenal hyperplasia
  • Chemical:
    • exogenous administration of glucocorticosteroids
61
Q

Adrenal Cortical Neoplasia

A
  • Adrenal coritcal adenoma or carcinoma
    • most arise from zona fasciculata
    • Adenomas are more common than carcinomas
  • Can be multiple or single, unilateral or bilateral
    • contralateral adrenal gland atrophy occurs with functional unilateral neoplasms
62
Q

Adrenal Cortical Neoplasia:

Functional Neoplasia

A
  • Polyuria and polydipsia
  • Increased appetite
  • Muscle atrophy and weakness
  • Alopecia
  • Increased incidence of infections
63
Q

Hyperadrenocorticism

A

Clinical syndrome characterized by increased cortisol/glucocorticosteroid

64
Q

Hyperadrenocorticism:

Functions of Glucocorticosteroids

A

Gluconeogenesis

Lipogenesis

Protein catabolic

Anti-inflammatory

Immunosuppressive

Inhibition of fibroplasia

65
Q

Hyperadrenocorticism:

Cause

A

Most often due to ACTH-secreting pituitary adenoma

Less often due to adrenal cortical adenoma or carcinoma

66
Q

Hyperadrenocorticism:

Lesions

A

Hepatic lipidosis and glycogenosis

Epidernal and adnexal atrophy

Systemic mineralization

Lymphoid tissue depetion

67
Q

Adrenal Gland Hypoplasia:

A
  • Diffuse adreanal coritcal hyperplasia
    • common in dogs
    • Occurs secondary to functional chromophobe adenoma of hte pituitary gland
      • excessive and unregulated secretion of ACTH
    • Hyperadrenocorticism isthe results
      • signs and lesions are the same as those of hyperadrenocorticism caused ny primary adrenal neoplasia
68
Q

Adrenal Cortical Nodular Hyperplasia

A

common age-related change in dogs, cats, and horses

Some of these are functional

Some are non-functional and of minimal to no clinical significance

69
Q

Adrenal Medulary neoplasia:

Pheochromocytoma

A

Arise in chromaffin cells of the medulla

Most common in dogs and cattle

70
Q

Adrenal medullary neoplasia:

Ganglioneuroma and neuroblastoma

A

uncommon

Neuroectoderm origin

71
Q

Pheochromocytoma

A
  • Most are non-functional
    • functional neoplasia results in systemic hypertension due to norepinephrine secretion
  • They can be benign or malignant
    • malignant neoplasms often invade the greater vessels
      • 50% metastasize in dogs
72
Q

Adrenal Gland abnormal development:

Adrenal hypoplasia or agenesis

A

Rare conditions in dogs

Total agenesis is fatal

Hypoplasia resutls in variable degrees of hypoadreocorticism

73
Q

Adrenal Gland Atrophy

A
  • Diffuse adrenal cortical atrophy
    • most common in dogs on long-term glucocorticosteroid therapy
    • Exogenous glucocorticosteroids result in inhibition of adrenal cortical function and subsequent atrophy
74
Q

Adrenal Gland Atrophy:

Idiopathic adrenal cortical atrophy

A
  • Uncommon condition of dogs and cats
  • Immune-mediated damage and atrophy of hte adrenal cortex
    • may also result from destruation of non-functional neoplasia of the pituitary gland
      • Signs usually occur only after 90% of the cortex is destroyed or atrophied
  • Results in hypoadrenocorticism
    • anorexia and weight loss
    • Diarrhea and dehydration
75
Q

Adrenal Gland Destruction:

A
  • A wide variety of porcesses periodically affect the adrenal gland
    • this is mainly due to the rich vascular network at the cortico-medullary junciton
  • Examples include:
    • thrombosis due to DIC
    • Adrenalitis due to infections embolis
    • Metastatic neiplasia
76
Q

Hypoadrenocorticism

A
  • Clinical syndrome characterized by decreased adrenocortical homrones
    • Addisons Disease
  • Mainly affects the Zona glomerulosa
    • immune-mediated most common in portuguese water dogs, bearded collies, standard poodles
    • Hypoaldosteronism
      • hypoantremia and hyperkalemai
      • Decreased cortisal is also present