PGY 206- Exam 3 (Endocrinology)

describe peptide/protein hormones:

• free in plasma

• bind to cell surface receptors

• hydrophilic

• short half-life

• includes insulin, prolactin, and TSH

• do NOT directly bind with DNA

describe catecholamines:

• secreted by neurons/ adrenal medulla

• binding/activating via cell surface GPCRs

• circulate free in the plasma

• hydrophilic

• includes norepinephrine, epinephrine, and dopamine

• short half-life

thyroid hormones:

• T3 and T4

• hydrophobic

• binded, NOT free in plasma

• binds to DNA

• long half-life

• intracellular receptor

steroid hormones:

• aldosterone, cortisol, progesterone, estradiol, DHEA, testosterone, calcitriol

• binded, NOT free

• directly binds to DNA

• intracellular receptor

• long half-life

• hydrophobic

what are the endocrine glands? (5)

• pancreas

• hypothalamic pituitary

• thyroid parathyroids

• adrenals

• male/female gonads

describe endocrine signaling:

• bulk flow through the blood

• when a hormone goes from one organ to another

what happens when there is extra of a hormone? less?

• extra hormone= negative feedback increases to lower the hormone

• less hormone= positive feedback to increase it

what are endocrine axes?

• a regulatory pathway connecting multiple endocrine glands in a sequence

list the endocrine axes:

• stress axis (HPA)

• thyroid axis (HPT)

• growth axis

define secreting:

• making a substance and releasing to the body

• usually via blood

describe stress axis (IN ORDER):

• hypothalamus: CRH

• pituitary gland: ACTH

• adrenal cortex: cortisol

• CRH stimulates the pituitary, ACTH stimulates the adrenal cortex, and cortisol inhibits pituitary and hypothalamus

describe the thyroid axis (IN ORDER):

• hypothalamus: CRH

• pituitary gland: ACTH

• adrenal cortex: cortisol

• CRH stimulates the pituitary gland, ACTH stimulates the adrenal cortex, and cortisol inhibits the hypothalamus and pituitary gland

describe the growth axis (IN ORDER):

• hypothalamus: GHRH

• pituitary: GH

• liver: IGF-1

• CHRH stimulates pituitary, GH stimulates liver, IGF-1 inhibits the hypothalamus and pituitary

what are all of the inhibiting hormones from the endocrine axes?

• HPA: cortisol

• HPT: T3/T4

• Growth: IGF-1

describe anterior pituitary:

• stimulated via portal vessels

• synthesizes FSH, LH, ACTH, TSH, prolactin, endorphins, and GH

describe posterior pituitary:

• neural storage

• neural tissue

• does NOT make hormones

• stores and ships hormones

• release oxytocin and ADH

acromegaly:

• an excessive release of growth hormone

• enlarged hands and facial bones

what hormones increase Ca++?

• PTH

• calcitriol

• low Ca++ causes PTH to increase which causes vitamin D activation, increasing Ca++

describe the adrenal cortex:

• outer part

• steroid hormones

• three parts: zona glomerulosa, zona fasciculata, and zona reticularis

describe each part of the adrenal cortex:

• zona glomerulosa: aldosterone, controls Na+/K+, blood pressure, salt and NOT controlled by ACTH

• zona fasciculata: cortisol, increases blood glucose, stress response, anti-inflammatory

• zona reticularis: sex hormones, develops sexual characteristics

describe the adrenal medulla:

• inner (neural) part

• catechalimines

goiter:

• enlarged thyroid gland

• can be high or low

• can cause weight gain OR loss

• decreases ability to adapt to cold

cushing’s disease:

• too much cortisol

• associated with adrenal cortex

• causes buffalo humps

addison’s disease:

• too little cortisol

• salt craving

• associated with adrenal cortex

grave’s disease:

• antibodies activate TSH receptors

• hyperthyroidism

• causes exophthalmos

sheehan’s disease:

• pituitary damage

• decreased secretion of GH, ACTH, TSH, LH, FSH, prolactin

• causes fatigue, hypotension, and decreased ability to lactate

what does thyroid hormone effect?

• metabolism, growth, nervous system, and heart

what is involved with bone reabsorption?

• vitamin D/PTH

thyroid hormone production steps:

• iodide uptake

• oxidation and organification

• coupling of iodotyrosine

• storage

• release

• T4 converted to T3

calcitonin:

• lowers Ca+ levels

• inhibits bone reabsorption

• secreted from thyroid gland

• high calcium stimulates its release

parathyroid hormone:

• stimulates kidneys to reabsorb Ca++

• stimulates formation of 1,25 vitaminD3

• simulates bone reabsorption

list the cells of the pancreas:

• alpha, beta, delta, PP

describe what alpha and beta cells do:

• alpha: secretes glucagon, increases blood glucose

• beta: secretes insulin, decreases blood glucose

describe what delta and PP cells do:

• delta: secretes somatostatin, which inhibits alpha and beta cells

• PP: secretes pancreatic polypeptide, which regulates digestive enzymes

describe type I and type II diabetes:

• type 1: low insulin, high glucose, destruction of beta cells, ketoacidosis, lower weight

• type 2: insulin resistance, high glucose, weight gain/obesity because insulin receptors are down

how is glucose stored?

• as glycogen in the liver

prohormone (give examples):

• a hormone that can be converted to a more active form

• ex: T4, testosterone, and proinsulin

ADH:

• in hypothalamus

• water soluble, peptide hormone

• FREE

• posterior pituitary

• unaffected by portal vein blockage

TRH:

• in the hypothalamus

• secreted normal during portal vein blockage

ACTH:

• in anterior pituitary

• secreted in response to CRH from hypothalamus

• ACTH production increases with portal vein blockage

DA:

• in hypothalamus

• blockage of portal vein prevents DA from reaching anterior pituitary

angiotensin II:

• vasoconstricts, increases BP

• stimulates aldosterone secretion from the zona glomerulosa

• increases thirst

compare and contrast T3 and T4:

• T3: more potent and shorter half life

• T4: less potent, converted to T3, higher affinity, secreted in larger amounts, and longer half life

• both depend on iodine

what happens if there is no iodine?

• thyroid cannot make enough T3 and T4

• TSH increases

• goiter forms

what happens if PTH deficient?

• fatal because it causes hypoglycemia

how does PTH increase vitamin D-3?

• by stimulating 1-hydroxylase

what does glucagen do?

• stimulates the breakdown of lipids in adipocytes

what does insulin in a healthy individual to a short time after eating? what about glucogen?

• insulin increases a little but glucogen should NOT increase