Exam 3 Flashcards
Calcitonin
- regulates calcium levels in blood in response to HIGH calcium levels in blood
- released from the parafollicular cells in the thyroid gland
Parathyroid hormone
- regulates calcium levels in the blood in response to LOW calcium levels
- hypofunction leads to hypocalcemia
Hypoparathyroidism symptoms
- hyperphosphatemia
- hypocalcemia -> positive Chvosteks (tetany)
- neuromusclar irritability/ hyperexcitability
- bronchospasm
- laryngospasm
- seizures
- cardiac arrythmia -> leads to prolonged QT interval
- impaired cardiac function -> decreased excitation-contraction coupling
Hyperparathyroidism symptoms
- hypercalcemia -> excess bone resorption
- hypercalcemia symptoms ->
- muscle weakness
- kidney stones from high calcium accumulation
- vomiting and constipation
- polyuria -> kidney loses urine concentrating abilities
- dehydration from vomiting and polyuria
- depressed nervous system and mental state
- mental depression due to decreased perfusion to brain due to low BV
- hypertension due to increased cardiac output from inc SV due to high calcium entry-> calcium release coupling occurring
Parathyroid biological functions
in bones:
PTH binds to osteoblasts -> release osteoclast activating factors OAFs -> lead to bone resoprtion, releasing phosphate ions and calcium ions into the blood
in kidneys:
- PTH stimulates calcium reabsorption to increased blood calcium
- PTH stimulates phosphate excretion to prevent formation of calcium phosphate crystals
- activates 1 alpha dehydroxylasse which converted vitamin D in 1,25 (OH), 2 Vit D which allows for calcium reab from the small intestine
Hypoparathyroidism causes
- thyroidectomy
- damaged parathyroid gland
- PTH gene mutation
- inhibition of PTH release due to chronic hypomagnesemia
Pseudohypoparathyroidism causes
- genetic disorder with dysfunctional PTH receptors -> PTH is present but goes undetected
Synergy
the total effect is greater than the sum of all of the individual effects of the hormones
3 Hormone chemical structures
Biogenic amine hormone
peptide/protein/glycoprotein hormone
steroid hormone
Biogenic amine hormone
derived from the amino acid Tyrosine (polar)
- L-dopa, dopamine, norepinephrine, epinephrine
Peptide/ protein/glycoprotein
derived from chain of amino acids (polar)
- oxytocin, insulin, follicle stimulating hormone
Steroid hormone
derived from cholestrol (nonpolar)
- testosterone
Locations for receptors
- membrane/ cell surface -> bind polar hormones that can not enter
- cytoplasm or nucleus -> bind nonpolar hormones that can enter the cell
Permissiveness
- hormone binds it’s own receptors but in doing so it’s biological action increases the release of another hormone or the expression of receptors for that hormone, thereby increasing the other hormones effect
Cooperativity
- hormones work together on the same target tissue to achieve the desired biological effect
Posterior Pituitary
- connected to neurosecretory centers in hypothalamus via the hypothalemic- hypophyseal tract
- receives oxytocin and ADH via axonal transport
- stores and releases these two hormones into the body
Anterior pituitary
- connected to neurosecretory centers in the hypothalamus via hypothalemic- hypophyseal portal system
- receives CRH, TRH, GHRH, GRIH, PHH, PIH, GnRH
- these hormones act on the endocrine cells (target tissues) to release stimulating hormones which then are sent out into the body
CRH
corticotropin releasing hormone -> activates corticotrophs to release ACTH adrenocorticotropic hormone to send to the kidney
TRH
thrytropin releasing hormone -> activates thyrotrophs to release TSH thyroid stimulating hormone in the thyroid gland
HPT axis
hypothalamus TRH -> pituitary TSH -> thyroid gland T3 and T4 -> tissues -> negative feedback to hypothalamus and pituitary if T3 or T4 are high levels
HPA axis
hypothalamus CRH -> pituitary ACTH ( can also do negative feedback loop) -> zona fesiculata
in the adrenal gland cortisol -> negative feed back loop
Iodine
thryoid can pick up 3 to 4 iodide atoms as it is synthesized making T3 or T4
Stimulatory factors for thyroid release
- TRH
- TSH
- exposure to the cold