Endocrine Flashcards
Endocrine System:
Structure
- 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
Endocrine System:
Funciton
- 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
- Hormones are the mediators of homeostasis
Endocrine System:
Dysfunction:
Increased Function
- Primary Hyperfunction
- increased hormones secretion by an abnormal gland
- Secondary Hyperfunction
- increased hormone secretion by a normal endocrine gland that is excessively stimulated
Endocrine System:
Dysfunction:
Decreased Function
- Primary hypofunction
- decreased hormone secretion by an abnormal gland
- Secondary hypofunction:
- decreased hormone secretion by a normal endocrine gland that is inadequately stimulated
Endocrine System:
Patterns of Disease
- 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
Endocrine System:
Causes of Disease
- 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
Pituitary Gland
Pituitary Gland
Structure:
Anterior Lobe
-
Pars Distalis:
- acidophils
- GH and LTH
- Basophils:
- Lh, FSH, TSH
- Chromophobes
- ATCH, MSH
- acidophils
-
Pars Intermedia
- melanotrophs
- Pars Tuberalis
Pituitary Gland:
Structure:
Posterior Lobe
- Hypothalamic Neurosecretory neurons
- paraventricular and supraoptic nuclei
- ADH, Oxytocin
- Infundibular stalk
- Pars Nervosa
- paraventricular and supraoptic nuclei
Adenohypophysis:
Growth Hormone
Regulates growth and metabolism
Somatotropin
Adenohypophysis:
Luteotropic Hormone
Stimulates progesterone secretion
Adenohypophysis:
Luteinizing Hormone
Stimulates estrogen secretion
Adenohypophysis
Follicle Stimulating Hormone
Stimulates ovarian follicle growth and spermatogenesis
Adenohypophysis:
Thyroid Stimulating Hormone
Thyrotrophin, TSH
Stimulates thyroid hormone secretion
Adenohypophysis
Adrenocorticotrophic Hormone
Stimulates glucocorticoid secretion
Adenohypophysis
Melanocyte Stimulating Hormone
Stimulates melanocytes
Neurohypophysis:
Antidiuretic hormone
regulates water excretion
Neurohypophysis
Oxytocin
Stimulates smooth muscle contraction
Pituitary Gland:
Dysfunction
Increased Hormone Activity
Functional neoplasia
Increased stimulation hy hypothalamus
AnteHormone-like substances
Pituitary Gland:
Dysfunction:
Decreased Hormone Activity
Destructive lesions
Non-Responsive target cells
Pituitary Gland
Pathogenesis
Neoplasia
functional or non-functional
Pituitary Gland
Pathogenesis
Cell Adaptation
Hyperplasia and atrophy
Pituitary Gland
Dysfunction
Developmental Anomalies
Aplasia, hypoplasia, cysts
Pituitary Gland
Dysfunction
Immunopathology
Autoimmunity
Pituitary Gland
Dysfunction
Inflammation
Uncommon
Pituitary Gland
Dysfunction
Metabolic
All hormonal dysfunctions will result in metabolic alterations
Pituitary Gland
Causes
- Genetic Injury
- inherited or acquired
- Infectious Agents
- Uncommon
- Nutritional
- Chemical
Chromophobe adenoma in dogs
Functional adenoma
- 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
Chromophobe adenoma in dogs:
Most common pituitary tumor of dogs
- 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
- Less likely to be functional, and act as space-occupying mass
pars intermedia ademona
- 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
- These can be functional or compressive, just like those of the pars distalis
- 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