Anatomy and Physiology of the Endocrine System Flashcards
(29 cards)
What hormone does somatostatin inhibit when it is released from the hypothalamus?
growth hormone release from the pituitary
Give an example of a prolactin inhibiting hormone
dopamine, inhibits PRL secretion from the pituitary
What are some characteristics of hypothalamic releasing hormones?
pulsatile secretion, act on specific membrane receptors, transduce signals via second messengers, stimulate release of pituitary hormones, induce hyperplasia and hypertrophy of target cells, regulates its own receptor
What is the other name for the posterior pituitary?
neurohypophysis
What two hormones are secreted by the posterior pituitary?
ADH/vasopressin
oxytocin
What seven hormones are secreted by anterior pituitary?
TSH, ACTH, FSH, LH, GH, prolactin, MSH
What are ‘tropic’ hormones?
hormones that regulate the function of other hormones
What cell type of the anterior pituitary produces ACTH?
corticotroph
What is the most abundant cell type in the anterior pituitary?
somatotroph (40-50%)
What is the least abundant cell type in the anterior pituitary?
thyrotroph (3-5%)
What is the clinical effects of a lack of ACTH?
loss of pigmentation, hypoadrenalism
What is the clinical effect of a lack of ADH?
diabetes insipidus
What is the clinical effect of a lack of FSH?
infertility
What happens in the cell when TSH binds to thyroid specific cell surface receptors?
stimulates adenylate cyclase to produce cAMP
this increases metabolic activity that is required to synthesise Thyroglobulin (Tg) and generate peroxide
TSH stimulates both I- uptake and iodination of tyrosine residues on Tg
Which thyroid hormone is biologically more active?
T3 is more active than T4 but has a shorter half life
What is the predominant thyroid circulating hormone?
T4
What are the most common causes of hypothyroidism?
primary thyroid failure due to autoimmune diseases (Hashimoto thyroiditis)
idiopathic causes
ablative therapy
iodine deficiency
What is a myxoedema coma?
end stage of untreated or insufficiently treated hypothyroidism
What lab results indicate primary hypothyroidism?
free T4 low and TSH high
What is euthyroid sick syndrome?
low T3, normal or low TSH, normal free T4
What biochemical laboratory findings can suggest Addison’s disease?
low serum Na level
high serum K level
What are some clinical features of hyperthyroidism?
excessive sweating, tremor, palpitations, fatigue, increased anxiety, irregular periods
What is the most common etiology of hyperthyroidism?
Graves disease
What is the most common symptom of pheochromocytoma?
hypertension
classical triad: pain(headache), perspiration, palpitations
