30 Questions
What is the primary function of second messengers in hormone signaling?
To activate hormone receptors
Which of the following hormone receptors is NOT correctly paired with its activation mechanism?
Ligand-gated ion channel - activation of gene transcription
What is the primary difference between the three main classes of hormones?
Their chemical structure
What is the result of the inhibition of biosynthesis of eicosanoids?
Reduced inflammation
What is a characteristic of hormones that require carrier proteins in blood?
Low water solubility
What is the duration of action of catecholamines compared to thyroxine or GH?
Seconds for catecholamines, months for thyroxine or GH
What is the purpose of negative feedback mechanisms in hormone secretion?
To prevent overactivity of hormone systems
What is an example of positive feedback in hormone secretion?
Surges of anterior pituitary hormone secretion
Why is a single blood sample less useful than stimulation tests in hormone secretion?
Because hormone secretion is pulsatile and varies with time
What is a necessary condition for a cell to respond to a particular hormone?
The presence of a specific receptor for that hormone on the cell surface
What is the primary function of a second messenger in hormone signaling?
To activate or inhibit enzymes involved in metabolic reactions
Where are the receptors for catecholamines, peptide hormones, and eicosanoids typically located?
In the plasma membrane
What is the effect of steroid hormones on target cells?
They directly affect target cells' metabolic activity or structure by altering the rate of DNA transcription
What is the role of hormone binding in the plasma membrane?
It gives rise to a second messenger that acts as an enzyme activator, inhibitor, or cofactor
What is the final outcome of the binding of a hormone to its receptor in the cell cytoplasm or nucleus?
The alteration of the rate of DNA transcription
What is the effect of down-regulation of hormone receptors on the target tissue?
It decreases the number of active receptors.
Which of the following is a characteristic of ion channel-linked receptors?
They usually cause opening or closing of a channel for K+, Ca++, etc.
What is the effect of the hormone-receptor complex on gene transcription in intracellular hormone receptors?
It alters the rate of DNA transcription and pattern of protein synthesis.
What is the role of G-proteins in G protein-linked hormone receptors?
They are the link between the first and 2nd messenger.
What is the effect of the activation of receptor tyrosine kinase on the cell?
It initiates cascades of phosphorylation reactions within the cell.
What is the effect of the activation of phospholipase C on the plasma membrane?
It breaks down the plasma membrane phospholipid PIP2 to DAG and IP3.
What is the role of inositol triphosphate (IP3) in the phospholipase C system?
It opens Ca++ channels of the ER.
What is the effect of the binding of hormone to its receptor on the activity of adenylyl cyclase?
It increases the activity of adenylyl cyclase.
What is the role of cyclic adenosine monophosphate (cAMP) in hormone signaling?
It is a 2nd messenger that exerts intracellular effects.
What is the primary goal of the endocrine system and the nervous system?
To maintain homeostasis by coordinating activities of cells, tissues, organs, and systems
What is the main difference between the nervous system and the endocrine system?
One uses electrical impulses, and the other uses chemical messengers
Which of the following glands is responsible for the secretion of melatonin?
Pineal gland
What is the term for the release of hormones that stimulate or inhibit the release of other hormones?
Tropic hormones
What is the name of the hormone secreted by the heart that helps regulate blood pressure?
Atrial natriuretic peptide
What is the term for the chemical messengers that are involved in the regulation of immune responses?
Cytokines
Test your knowledge on the introduction to endocrinology, covering the coordination of body functions, chemical structure and synthesis of hormones, and mechanisms of hormone actions. Learn about the similarities between the nervous and endocrine systems, major endocrine glands, and their hormones.
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