30 Questions
What is the primary concern of endocrine physiology?
Maintaining various aspects of homeostasis
What is a characteristic of the endocrine system?
It operates as a distributed network
What is the most common type of hormone?
Peptide hormones
What is a characteristic of peptide hormones?
Many are heterodimers with a common α chain
Why does the number of hormones and their diversity increase in higher life forms?
Because of the added challenges in providing for homeostasis
What is a common feature of hormone families?
They have similar structural and functional characteristics
What is the primary function of the steroidogenic acute regulatory protein (StAR)?
Transferring cholesterol from the outer to inner mitochondrial membrane leaflet
What is the primary mechanism of controlling synthesis of amine and steroid hormones?
Regulating the production of key synthetic enzymes and substrate availability
What is the effect of phosphorylation on StAR?
Activation of StAR
What is the first intermediate in the steroid biosynthetic pathway?
Pregnenolone
What is the purpose of processing large polypeptide chains into smaller hormone molecules in peptide hormone synthesis?
To provide a level of genetic economy
Why are hormone precursors typically inactive?
To provide an additional measure of regulatory control
What is the role of extracellular signals in the regulation of steroid biosynthesis?
Activation of protein kinases
What is the role of nuclear receptors in regulating hormone transcription?
To bind to specific regions of peptide hormone genes
What is the characteristic of some hormone secretion?
Pulsatile manner
What is the rate-limiting first step in the synthesis of pregnenolone?
Transfer of cholesterol from the outer to inner mitochondrial membrane leaflet
How does thyroid hormone regulate TSH expression?
By directly suppressing TSH expression via the thyroid hormone receptor
What is the effect of elevated levels of circulating glucose on insulin mRNA?
It stimulates the translation of insulin mRNA
What is the ultimate result of the concerted action of hormones in the body?
Maintenance of homeostasis
What happens to certain hormones when they pass through the pulmonary circulation or the liver?
They are destroyed
Which of the following hormones is NOT a key contributor to homeostasis?
Growth hormone
What type of receptors do hydrophilic hormones, such as peptides and catecholamines, bind to?
Cell surface receptors
What is the effect of hormone binding on the second class of nuclear receptors?
Removal of a co-repressor and recruitment of a co-activator
What is the primary function of Sex hormone–binding globulin (SHBG) in the plasma?
To bind testosterone and 17β-estradiol
What is the primary mechanism of action for hydrophobic hormones?
Binding to nuclear receptors
What is the effect of regulating the expression and secretion of carrier proteins on hormone bioavailability?
It increases the bioavailability of hormones
What is the consequence of altering the levels of binding proteins or displacing hormones bound to them in a pathophysiologic setting?
It may have clinical implications for endocrine homeostasis
What is the role of the anatomic relationship of sites of release and action of hormones in their regulation?
It plays a key role in hormone regulation
What is the function of transcortin in the plasma?
To bind progesterone, cortisol, and other corticosteroids
What is the result of the equilibrium between the SBP-hormone complex and the free hormone in the plasma?
Only the free hormone can diffuse across cell membranes
Test your understanding of endocrine physiology, including the role of hormones in maintaining homeostasis and the unique characteristics of the endocrine system. Learn about the distributed network of glands and circulating messengers, and how they interact with the central nervous system. Review the basics of endocrine regulation with this quiz!
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