Hormones Flashcards
Organs in the endocrine system
Hypothalamus & pituitary Thyroid & parathyroid Adrenals Islets of Langerhans Ovaries and testes Placenta Digestive system
Hormone functions
-homeostasis
-regulate growth and development
-sexual maturation, sexual rhythms and reproduction
-regulate energy production
-adapt/adjust to stress/emergency situations
=promote/inhibit production/release of other hormones
hormones composed of amino acid residues, water soluble, and have a short half life
Polypeptide hormones
Function of polypeptide hormones
Interact with target receptors, trigger second messengers to complete specific action of the hormone
derived from amino acids, water soluble, interact with receptors of target cells
amines
half life of polypeptide hormones
<30 minutes
Thyroxine (amine) half life
7-10 days
Catecholamine (amine) half life
<1 minute
Hormones derived from cholesterol cycoperhydrophenathrene ring structure
steroid hormones
steroid hormone characteristics
hydrophobic
- bound reversibly in blood to carrier proteins
- unbound version is active
steroid hormone half life
30-90 minutes
Originate from anterior pituitary gland, specific from another endocrine gland
ex. TSH targets thyroid gland
Tropic hormones
Act on peripheral tissue
exert a feedback effect on the hypothalamus or anterior pitutary gland
ex. growth hormone
direct effector hormones
target receptors
- located on cell membrane/cytoplasm
- binding of hormone to receptor initiates a signal, causing a biological response
defect in target receptor,,,,
- disease
- absence/defect of feedback
ex. goiter formation –> TSH stimulation of thyroid due to decrease in circulating T3 and T4
increase in product causes a decrease in the system
- stabilizes a process
- hormone regulation
negative feedback
increase in product causes increase in activity of system
positive feedbakc
Disorder with a target gland, in presence of normal stimuli
feedback
Primary feedback disorder
Target gland functions normal in the presence of stimuli, abnormal in absence of stimuli
Secondary feedback disorder
Regulation of hormone occurs by controlling rate of _____ rather than rate of _____
synthesis, degredation
Primary control gland of hormones
hypothalamus
hypothalamus role in regulation
releases hormones that stimulate/inhibit secretion of anterior pituitary hormones
- activated by CNS
- emotion or stress to secrete one or more releasing factors
Releases TSH and Prolactin
Thyrotropin Releasing Hormone
Releases LH and FSH
Gonadotropin Releasing Hormone
Releases ACTH
Corticotropin releasing hormone
Releases GH
Growth hormone releasing hormone
Inhibits GH and TSH release
Somatostatin
Inhibits Prolactin release
Prolactin Inhibiting Hormone
Small gland located at the base of the skull
lies within sella turcica
Anterior pitutary
Where hormones which target other endocrine gland are stored
Anterior pituitary
Stores and releases oxytocin and vasopressin (ADH). Releases both tropic and direct effector hormones
Posterior pituitary
Targets gonads, tropic hormone, function in ovulation and testosterone production
Luteinizing hormone
targets gonads, tropic hormone, functions in estrogen synthesis and spermatogenesis
Follicle stimulating hormone
Targets thyroid, tropic hormone, stimulates thyroid hormone production
Thyroid stimulating hormone
Targets adrenal cortex, tropic hormone, stimulates synthesis and secretion of glucocorticoid hormones
Adrenocorticotropin hormone (ACTH)
Targets liver and bone, direct effector hormone, stimulates tissue growth
Growth hormone
Targets breast, direct effector, functions in secretion
Prolactin
also called somatotropin, peptide with direct effector functions
Growth hormone
inhibited by somatostatin, release is stimulated by GHRH
growth hormone
amphibolic
influences both anabolic and catabolic processes
growth hormone and metabolism
- effective transition from a fed state to fasting state
- antagonizes effect of insulin on glucose
- hepatic gluconeogenesis
- enhances protein synthesis
diurnal variation of growth hormone
- secretion in pulse every 2-3 hours
- peaks at onset of sleep
elevated growth hormone
- adenomas on pituitary
- acromegaly
- artherosclerosis, diabetes, arthritis, hypertension
- shortened life expectancy
Decreased growth hormone
- tumors, pituitary abnormalities
- GH replacement therapy possible
Genetic defects with decreased GH
- recessive GHRH gene
- loss of GH gene
- GH insensitivity
- lesions of pituitary or hypothalamus
prolactin is stimulated by
TRH
prolactin is inhibited by
Prolactin inhibiting factor (dopamine)
prolactin elevation symptoms
- tumor
- premenopausal women, menstrual irregularities
- oligospermia/impotence
most common pituitary tumor
prolactinoma
promotes growth and uptake of iodine by thyroid gland.
TSH
under negative feedback control by thyroxine
TSH
TSH and hypothyroidism
serum TSH is elevated due to absence of negative feedback
adrenal steroids
-glucocorticoids (cortisol)
-mineralcorticoids (aldosterone)
androgen (sex hormone precursors)
diurnal variation of ACTH
peak: 6-8 am
lowest: 6-11 pm
stimulates the production of adrenal steroids
ACTH
hypothalamus secreted GNRH which is responsible for secretion of both gonadotropins __ and __
FSH and LG
serves to promote ovulation, formation of corpus luteum, and secretion of progesterone and androgens
Luteinizing hormone
stimulates growth of follicles and development of seminiferous tubules, spermatogenesis
Follicle-stimulating hormone
lactation, stimulates smooth muscle (urine), enhance labor (posterior pituitary hormone)
oxytocin
regulates water excretion in renal tubules (posterior pituititary hormone)
vasopressin(ADH)
_____ osmolality receptors and blood pressure regulate the release of ______
hypothalamus, vasopressin
deficiency of ADH is associated with ______
diabetes insipidus