5.1 Endocrine

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What is the primary function of second messengers in hormone signaling?

To transport hormones through the bloodstream
To inhibit hormone biosynthesis
To activate hormone receptors (correct)
To synthesize hormones

Which of the following hormone receptors is NOT correctly paired with its activation mechanism?

Ligand-gated ion channel - activation of gene transcription (correct)
Intracellular receptor - binding of hormone to receptor in cytoplasm or nucleus
G-protein coupled receptor - activation of G-protein
Tyrosine kinase receptor - phosphorylation of tyrosine

What is the primary difference between the three main classes of hormones?

Their mechanisms of action
Their modes of intercellular communication
Their classifications of endocrine disorders
Their chemical structure (correct)

What is the result of the inhibition of biosynthesis of eicosanoids?

Reduced inflammation (A) Signup and view all the answers

What is a characteristic of hormones that require carrier proteins in blood?

Low water solubility (C) Signup and view all the answers

What is the duration of action of catecholamines compared to thyroxine or GH?

Seconds for catecholamines, months for thyroxine or GH (C) Signup and view all the answers

What is the purpose of negative feedback mechanisms in hormone secretion?

To prevent overactivity of hormone systems (C) Signup and view all the answers

What is an example of positive feedback in hormone secretion?

Surges of anterior pituitary hormone secretion (A) Signup and view all the answers

Why is a single blood sample less useful than stimulation tests in hormone secretion?

Because hormone secretion is pulsatile and varies with time (A) Signup and view all the answers

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 (A) Signup and view all the answers

What is the primary function of a second messenger in hormone signaling?

To activate or inhibit enzymes involved in metabolic reactions (C) Signup and view all the answers

Where are the receptors for catecholamines, peptide hormones, and eicosanoids typically located?

In the plasma membrane (D) Signup and view all the answers

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 (D) Signup and view all the answers

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 (C) Signup and view all the answers

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 (A) Signup and view all the answers

What is the effect of down-regulation of hormone receptors on the target tissue?

It decreases the number of active receptors. (C) Signup and view all the answers

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. (C) Signup and view all the answers

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. (D) Signup and view all the answers

What is the role of G-proteins in G protein-linked hormone receptors?

They are the link between the first and 2nd messenger. (B) Signup and view all the answers

What is the effect of the activation of receptor tyrosine kinase on the cell?

It initiates cascades of phosphorylation reactions within the cell. (B) Signup and view all the answers

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. (C) Signup and view all the answers

What is the role of inositol triphosphate (IP3) in the phospholipase C system?

It opens Ca++ channels of the ER. (A) Signup and view all the answers

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. (A) Signup and view all the answers

What is the role of cyclic adenosine monophosphate (cAMP) in hormone signaling?

It is a 2nd messenger that exerts intracellular effects. (B) Signup and view all the answers

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 (D) Signup and view all the answers

What is the main difference between the nervous system and the endocrine system?

One uses electrical impulses, and the other uses chemical messengers (D) Signup and view all the answers

Which of the following glands is responsible for the secretion of melatonin?

Pineal gland (C) Signup and view all the answers

What is the term for the release of hormones that stimulate or inhibit the release of other hormones?

Tropic hormones (A) Signup and view all the answers

What is the name of the hormone secreted by the heart that helps regulate blood pressure?

Atrial natriuretic peptide (C) Signup and view all the answers

What is the term for the chemical messengers that are involved in the regulation of immune responses?

Cytokines (C) Signup and view all the answers