pathology

• What is autocrine signalling?

  Cells act on their own secreted factors
• What is paracrine signalling?

  Cells respond to nearby cell factors
• What is endocrine signalling?

  Cells respond to distant cell factors
• How can hormone signals generate activation events in target cells?

  1. Bind to ion channel receptors.
  2. Attach to G-protein coupled receptors.
  3. Act on enzyme-linked receptors.
• What do many hormones act on to generate signals?

  Cell surface receptors
• What is a common second messenger in hormone signaling?

  Cyclic AMP
• What happens when enzymes are phosphorylated?

  They turn from inactive to active form
• How do some hormones bypass cell surface receptors?

  They are soluble and cross lipid membranes
• What hormones do steroids bind to?

  Cytoplasmic receptors
• What does thyroid hormone do upon entering the nucleus?

  It binds to nuclear receptors and switches genes on
• What are the 8 endocrine organs?

  1. Hypothalamus
  2. Pituitary gland
  3. Thyroid gland
  4. Parathyroid glands
  5. Adrenal glands
  6. Pancreas
  7. Ovaries (female)
  8. Testes (male)
• What is secondary endocrine disease?

  End organ is normal but lacks signals
• What is primary endocrine disease?

  Hormone deficiency due to end organ pathology
• What feedback occurs in the HPA axis?

  • CRH from hypothalamus stimulates ACTH production.
  • ACTH stimulates cortisol production from adrenal gland.
  • Negative feedback from ACTH and cortisol regulates the axis.
• What are common causes of endocrine pathology?

  • Developmental/inherited
  • Inflammatory
  • Trauma
  • Infection
  • Immune-mediated
  • Degenerative
  • Nutritional deficiencies
  • Metabolic disturbances
  • Toxin/iatrogenic
  • Neoplastic
• What is the anatomy of the hypothalamus and pituitary gland?

  • Located at the base of the brain
  • Divided into anterior pituitary lobe, pars intermedia, posterior pituitary lobe
• What is pituitary dwarfism?

  Developmental anomaly with growth hormone deficiency
• What hormones does the pituitary gland secrete?

  • Anterior pituitary: GH, TSH, ACTH, FSH, LH, Prolactin
  • Pars intermedia: MSH
  • Posterior pituitary: ADH, Oxytocin
• How does pituitary neoplasia typically present?

  Often as benign adenomas or space-occupying lesions
• What do non-secretory tumors cause?

  Local growth effects rather than systemic effects
• What can compression of the hypothalamus lead to?

  Central diabetes insipidus due to ADH deficiency
• How does a pituitary adenoma present in dogs?

  Excess ACTH leading to Cushing’s syndrome
• How does a pituitary adenoma present in cats?

  Overproduction of growth hormone causing acromegaly
• How does a pituitary adenoma present in horses?

  Causes pituitary pars intermedia dysfunction (PPID)
• What are the clinical signs of a pituitary adenoma in horses?

  • Behavioural changes
  • Somnolence
  • Ravenous appetite
  • Hyperthermia
  • Cushing’s syndrome
  • Metabolic syndrome/laminitis
  • Thick matted coat (hirsutism)
• What hormone does the thyroid gland respond to?

  TSH from the pituitary gland
• What hormones does the thyroid gland produce?

  Thyroxine (T4) and triiodothyronine (T3)
• What immune-mediated disease affects the thyroid?

  Hypothyroidism/lymphocytic thyroiditis
• What degenerative disease affects the thyroid?

  Goitre/iodine deficiency
• What neoplastic disease can affect the thyroid?

  Primary tumour leading to hyperthyroidism
• What is hypothyroidism/lymphocytic thyroiditis?

  Immune-mediated destruction of thyroid tissue
• What are 4 clinical signs of hypothyroidism/lymphocytic thyroiditis?

  Lethargy, alopecia, hyperpigmentation, scurfy coat
• What is adenomatous nodular hyperplasia in cats?

  Palpable mass leading to hyperthyroidism
• What causes adenomatous nodular hyperplasia in cats?

  Mutations in TSHR or goitrogens exposure
• What are 3 potential goitrogens in cats?

  1. Heavy metals/biphenyls
  2. Bisphenol A
  3. Polybrominated diphenyl ethers (PBDEs)
• What is a true goitre?

  Non-inflammatory enlargement of the thyroid gland
• What causes a true goitre?

  Iodine deficiency leading to thyroid hyperplasia
• What are 3 types of thyroid gland neoplasia?

  1. Thyroid adenoma (benign)
  2. Thyroid carcinoma (malignant)
  3. Thyroid C cell neoplasia
• What is thyroid C cell neoplasia?

  Transition from adenoma to carcinoma in bulls
• What hormone(s) do the parathyroid glands secrete?

  Chief cells produce parathyroid hormone (PTH)