30 Questions
What is the main function of hormones?
Facilitate intercellular communication within an organism
How do hormones typically travel to exert their effects?
By entering the systemic circulation
In addition to systemic circulation, where else can hormones exert their effects?
On adjacent cells (paracrine action)
Where are hormones primarily present in terms of concentration in the extracellular fluid?
Femto- to nanomolar range
How can hormones be classified?
By chemical composition, solubility properties, location of receptors, and nature of signal for hormonal action
Which substance is NOT listed under hormones synthesized from cholesterol?
$1,25(OH)_2-D_3$
What is the role of second messengers in hormone signaling?
Second messengers transmit the hormone signal from the cell surface to intracellular metabolic processes
Which type of hormones bind to receptors on the plasma membrane?
Polypeptide/protein hormones and catecholamines
How do lipophilic hormones (steroid, retinoid, thyroid) interact with the cell?
They directly provide the signal by interacting with intracellular receptors
How are hormones derived from cholesterol synthesized?
In final form and secreted immediately
How are catecholamines synthesized?
In final form and stored in the producing cells
What are the two different parts of the adrenal gland?
Cortex and medulla
What is the major product of the adrenal medulla?
Epinephrine
Where is most of the norepinephrine present in organs innervated by sympathetic nerves made?
In situ (about 80% of the total)
How many sequential steps are required for the conversion of tyrosine to epinephrine?
4
Which enzyme is responsible for the N-methylation step in the conversion of norepinephrine to epinephrine?
Phenylethanolamine-N-methyltransferase (PNMT)
What is the role of iodine in the synthesis of T3 and T4 hormones?
Iodine is required for the bioactivity of T3 and T4 hormones.
Where are T3 and T4 hormones stored before being released into the circulation?
In the colloid of the thyroid gland
What is the most potent natural mineralocorticoid in humans?
Aldosterone
What is the primary function of cortisol, the most potent natural glucocorticoid in humans?
Stimulates gluconeogenesis and inhibits the immune response
Which of the following is NOT involved in the stimulation of aldosterone secretion?
Estrogen
What is the primary plasma binding protein for glucocorticoids like cortisol?
Corticosteroid-binding globulin (CBG) or transcortin
Which of the following statements about steroidogenesis is correct?
It involves the repeated shuttling of substrates in and out of the mitochondria
Which of the following statements about gonadal steroid transport is correct?
Estrogens are bound to sex hormone-binding globulin (SHBG) or testosterone-estrogen-binding globulin (TEBG)
Which protein binds most of the circulating thyroid hormones in the blood?
Thyroxine-binding globulin (TBG)
What is the ratio of iodide in the thyroid to iodide in the serum called?
T:S ratio
What percentage of the iodide in thyroglobulin exists in the inactive precursors, monoiodotyrosine (MIT) and diiodotyrosine (DIT)?
70%
Where does the coupling of two DIT molecules to form T4 or an MIT and DIT to form T3 occur?
In the thyroid gland
What is the major site of T3 synthesis?
Peripheral tissues
Which step or process in thyroid hormone synthesis has inherited enzyme deficiencies that can cause congenital goiter and often result in hypothyroidism?
All of the above
This quiz covers the general structure and properties of hormones, including how they are synthesized, transported, and their role in intercellular communication between organs. Topics include the nervous system, endocrine system, and the definition of hormones.
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