T1 L3 histology Flashcards
endocrine glands and hormones
ductless
Hormones: organic chems released at specific times in small amounts into tissue fluids/ BVs
Pancreas: has exocrine and endocrine function
endocrine definition
action of hormone on target organ away from secreting cell
autocrine definition
action on self cell
paracrine definition
adjacent cell
neuroendocrine
neural stimulation of endocrine cells to secrete hormones (medulla of adrenal)
structure of endocrine glands
- cuboidal secretory cells w/ lumen at centre, supported by myoepithelial cells
- all have lumen except pituitary and parathyroid
clinical manifestations of endocrine diseases
- hormone overproduction
- hormone underproduction
- tumor/ mass lesion (ass. w/ overproduction of hormones, if non-functional there is a pressure effect)
pituitary gland divisions
- adenohypophysis: anterior lobe
2. neurohypophysis: posterior lobe
anterior pituitary gland (adenohypophysis) cells present in relation to staining patterns
- acidophils: take up acid dyes
- basophils: take up basic dyes
- chromophobe: no staining features
staining method to identify specific hormone secreting cells
Antibody staining against specific hormone (antibodies to GH identify cells secreting GH)
hormones from ant. pituitary, cells responsible and target organ
- GH secreted by somatotroph, targets bones
- prolactin secreted by lactotroph targets breasts
- ACTH secreted by corticotroph targets adrenal gland
- FHS secreted by gonadotroph targets ovaries and testes
- TSH secreted by thydotroph targets thyroid gland
hormones of posterior pituitary (neurohypophysis)
- ADH: facilitates H2O absorption in kidneys, makes more concentrated (lack in diabetes insipidus = increase in vol, decrease in conc)
- oxytocin: contraction of smooth muscle in uterus during birth and myoepithelial cells in breast (feeding)
pituitary adenomas (benign tumors)
arise from anterior lobe
can be functional/ non-functional
-Functional: productive, cause hyperpituitarism
-non-fucntional: pressure effects and hypopituitarism bc space occupying lesion. Space occupying effects of functional/ non-functional adenomas (headache, nausea, vomiting, diplopia, vision impairment)
compression of optic chiasm due to pituitary adenoma
bitemporal hemianopsia
Thyroid gland synthesises:
- T4 (thyroxine)
- T3 (triiodothyroxine)
which stimulate metabolic rate, synthesis of these require iodine
goitre
thyroid enlargement due to lack of iodine, thyroid enlarges to absorb max conc of iodine
normal thyroid gland
- 2 lobes and isthmus
- tissue comprised of follicles w/ variable sized lumina
- lined by cuboidal cells
- follicles stain pink
features of thyroid cells
- v. vascular
- endothelial cells lining capillaries (fenestrated)
- parafollicular cells (C cells/ clear cells) found between follicles
fenestration of endothelial cells lining capillaries
allows passage of hormone into circulation
parafollicular cells, C cells/ clear cells
- found between follicles
- secrete calcitonin which promotes reduction of Ca2+ conc in blood
patholigies of thyroid gland (5)
- Goitre- euthyroid (no symptoms), enlargement of gland
- Graves disease: hyperthyroid
- hashimoto’s disease: Hypothyroid
- adenoma: euthyroid
- cancer: euthyroid
multinodal goitre
- lack of iodine, enlarged thyroid (hyperplasia and hypertrophy)
- increase amount of iodine absorbed
- increase in size overcomes hormonal deficiency and pts are euthyroid (no symptoms)
multinodal goitre compresses trachea
- pt may arrest after successful thyroidectomy due to tracheomalacia
- softening of trachea bc pressure causes a collase and obstruction of airways
graves disease
- autoantibodies stimulate TSH receptors
- diffuse enlargement of thyroid bc hyperplasia of htyroid cells
- INFILTRATIVE OPTHALMOPATHY: accumulation of soft tissue and inflammation behind eye, proptosis (displacement of eye)
- INFILTRATIVE DERMOPATHY: thickening and induration of skin (ant. skin => pretibial myxoedema)
Hashimoto’s Thyroiditis
- Most common cause of hypothyroidism where iodine is readily available
- autoimmune disease: immune system destroys own thyroid tissue
- progressive depletion of thyroid cells by inflammation and replaced by fibrosis
- decrease in T3/4 (hypothyroidism)
- increase in TSH due to loss of negative feedback from T3/T4
steps of hashimoto’s hypothyroidism
- inflammation
- depletion of thyroid cells
- replaced by fibrosis
- decrease in T3/4 , increase in TSH
histology of hashimoto’s disease
- prominent lymphocytic infiltrate
- bc lymphoid tissue destroys thyroid tissue
Tumors: (follicular adenomas)
benign tumor of the thyroid follicular cells
Tumors: carcinomas (4 types)
- papillary (most common, increased risk of lymph metastasis)
- Follicular (metastasis to bone, lung and liver
- medullary: C cells
- anaplastic: older patients, poor prognosis
parafollicular cells/ clear cells/ c cells
- secrete calcitonin
- promotes reduction of Ca2+ conc in blood (decreases risk of tetanic contraction)
- found between follicles
- c cells are origin of medullary carcinoma of thyroid
parathyroid glands
- secrete PTH
- controls levels of Ca2+ in blood
- decreases in Ca2+ conc stimulates PTH secretion
- chief cells w/ no lumen (prominent vascularity)
pathologies of parathyroid glands
all cause hypercalcaemia
- adenoma: involves 1 gland
- hyperplasia: involves 4 glands
adrenal glands
- paired, upper poles of kidneys
- consist of adrenal cortex (derived from mesoderm) and medulla (derived from neural crest cells)
normal colour of adrenal glands
yellow bc rich in lipids
cortex of adrenal gland 3 zones
GFR (the deeper you go the sweeter it gets)
- zona glomerulosa: SALT
- aldosterone for absorption of Na+
- mineralocorticoids - zona fasiculata: SUGAR
- cortisol/ corticosterone
- glucocorticoids (+ some sex hormone) - zona reticularis: SEX
- 17 ketosteroids
- sex hormones (testosterone)
pathology of adrenal gland
adrenocortical hyperactivity
due to hyperplasia, adenoma or cancer (rare)
- CUSHING’S SYNDROME (excess cortisol)
- CONN’S SYNDROME (excess aldosterone)
- ADRENOGENITALSYNDROME (excess androgens)
pathology of adrenal gland: adrenocortical insufficiency
addison’s disease
adrenal cortex adenoma
- non-functional
- incidental findings on abdo imaging
- functional adenomas: CUSHINGS (cortisol excess) CONN’S (aldosterone excess)
compact cells
- secrete adrenaline and NA
- fight or flight response/ intense emotional reaction
- result in vasoconstriction, ^ HR, ^ BGL (defense to stress)
phaechomocytoma
tumor or adrenal medulla
- 10% tumor- 10% familial, 10% extraadrenal, 10% bilateral, 10% malignant, 10% childhood
- due to high levels of catecholamines
- precipitous ^ BP, tachycardia
- sweating, tremor, sense of apprehension
complications of BP as a result of phaechomocytoma
- congestive cardiac failiure
- ischaemic heart disease
- arrhythmias
- CVA
