Histo - Endocrine Organs II

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What is Grave's Disease?

hyperthyroidism: thyroid stimulating immunoglobins stimulate thyroid in addition to TSH = continuous stimulation of thyroid occurs

What are the thryoid stimulating immunoglobins and what do they bind to?

antibodies against TSH receptor (IgG)

These antibodies bind to ( ) receptors and elevate levels of ( ). This in turn increases synthesis and secretion of ( ).

TSH receptors, cAMP, T3/T4

What physical changes occur in thyroid gland with Grave's?

hypertrophy/hyperplasia = hyperthyroidism and goiter (enlarged thyroid)

What is exopthalamus?

bulging eyes = sign of Graves's disease

What happens with dietary deficiency of iodine?

hypothyroidism = cannot synthesize thyroid hormone

Why does diffuse enlargement of the thyroid (goiter) result?

no synthesis of T3/T4 due to lack of iodine = no negative feedback to anterior pituatary to inhibit release of TSH

What is Hashimoto's thyroiditis?

inflammation of the thyroid gland causing hypothyroidism

What else can cause hypothyroidism?

thyroidectomy (obviously)

How is hypothyroidism treated pharmacologically?

give T4 orally

What do parafollicular (C-cells) secrete?

calcitonin

Where do they arise from?

neural crest cells

What does calcitonin do?

binds to osteoclasts = prevents release of calcium from bone into blood

Does calcitonin have to be given after thyroidectomy? Why?

no: calcitonin has no major effect on blood calcium levels

If you see tumor cells surrounded by extracellular deposition of amyloid in thyroid what is it?

C-cell carcinoma-thyroid medullary carcinoma

What does parathyroid hormone do?

produces parathormone to regulate calcium plasma levels

What do pricipal/chief cells of parathyroid do?

monitor calcium and release PTH

How does PTH stimulate release of calcium from bone?

binds to osteoblasts which in turn stimulate osteoclasts to reabsorb bone and mobilize calcium and phosphate

What does PTH do in renal?

-prevents calcium excretion and promotes phosphate excretion
-upregulates 1-hydroxylase
-also increases calcium absorption in GI tract

Primary hyperparathyroidism?

excess PTH from parathyroid adenoma or chief cell hyperplasia

What are the symptoms?

-stones: urinary tract stones
-bones: demineralized bones
-groans: pain from stones, fractured bones, and constipation (decreased neuronal excitation)

What are the four layers of adrenal gland and what is the mnemonic?

4 S's: salt, sugar, sex, sympathetic
-z.glomerulosa: mineralcorticoids
-z. fasciculta: glucocorticoids
-z. reticularis: androgens
-medulla: norepinephrine and epinephrine

What does z. glomerulosa secrete?

mineralocorticoids: mainly aldosterone

What does z. fasciculta secrete?

glucocorticoids

What z. reticularis?

androgens

Medulla?

norepinephrine and epinephrine

What is aldosterone produced by? Influence?

z. glomerulosa: angiotensin-II

What distinguishes z. fasciculata?

-more cytoplasma and abundant lipid droplets
-cells arranged in parallel plates seperated by capillaries

What does z. fasciculata release and under what influence?

cortisol: under influence of ACTH (exerts negative feedback on ACTH)

What is cortisol needed for?

-normal carb metabolism and maintanence of blood sugar
-stress adaptation
-maintenance of blood pressure

What do z. reticularis cells secrete? Influene?

androstenedione and DHEA: some influence from ACTH

What is order of cortisol regulation?

CRH to ACTH to Cortisol

When are androstenedione important?

in females (only androgens) but not in males

what happens if there is excess androgens during fetal development?

virilzation in females (enlarged clitoris, fusion of labioscrotal folds)

excess androgens in adulthood?

hirsuitism/acne

Decreased androgens?

loss of pubic and axillary hair, decreased libido

What happens to androgens in cushing's?

elevated because ACTH is increased

Addison's?

destruction of adrenal cortex (tuberculosis, autoimmune)

What is lost in addisons?

all adrenal steroids are effected - mineralcorticoids, glucocorticoids and androgens

Adrenal cortical failure can also occur secondary to failure of ( ) secretion. In this case, ( ) are not effected as they are under influence of ( ).

ACTH: mineralocorticoids, RAAS

Cushing's?

-ACTH-secreting adenoma
-excess of ACTH in blood

What is elevated?

ACTH drives cortisol and androgen synthesis/release

What does ACTH do?

drives cortisol and androgen synthesis/release

Besides a tumor, what else can cause cushings?

pharmacological administration of glucocorticoids: in this ACTH will be negatively inhibited by doses of cortisol

Key symptoms cushing's?

buffalo hump, moon face, fat distribution, hypertension, hyperglycemia

What is conn's syndrome?

adenoma of glomerulosa cells = hyperaldosteronemia

What can cause hyperaldosteronemia?

adenoma of glomerulosa cells = XS aldosterone produced

What are pheochromocytes?

modified post-ganglionic sympathetic nerves

when do pheochromocytes stain yellow-brown?

with chromic salts (chromaffin cells)

What activates medullary cells?

sympathetic nerves: fight or flight

What are pheochromocytomas?

tumors of suprarenal medulla: excess catecholamines produced

What do delta cells of pancreas release?

somatostatin: inhibits insulin and glucagon secretion

What permits rapid flow of ions and molecules between pancreatic cells?

gap junctions

What type of capillaries are found in the islet of langerhans?

fenestrated

Which type of diabetes is insulin deficient? Why?

Type I: beta cells of pancreas are destroyed

Which type is insulin resistant diabetes mellitus?

type II: target tissue do not respond to insulin

What are the two cell types of the pineal gland?

pinealocytes and neuroglial cells

What do the secretory granules of pinealocytes contain?

melatonin and serotonin

Melatonin induces rhythmic changes in hypothalamus, adenophysis and gonads in response to ( ).

changes in light received by retina

what is corpora arenacea (pineal sand)?

concentric accretions of calcium and magnesium phosphate in pineal gland

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