WEEK 1 STUDY GUIDE: Basic Concepts in Endocrinology

Comprehensive fill-in-the-blank practice cards covering receptors, signaling pathways, hormonal integration, and pituitary organization based on Week 1 lecture modules.

Receptors are high-affinity __________ that distinguish a ligand, bind it at low concentration, change conformation, and initiate biochemical events.

glycoproteins

The __________ and the target cell’s machinery—not the hormone alone—determine the cellular response.

receptor

Hormones that are unable to readily cross the plasma membrane typically bind to __________ receptors.

cell-surface

In a resting GPCR, the heterotrimeric G protein contains $\alpha$, $\beta$, and $\gamma$ subunits; the $\alpha$ subunit specifically holds __________.

GDP

During GPCR desensitization, kinases phosphorylate intracellular loops, which leads to uncoupling from $G_{\alpha}$ and the binding of __________.

$\beta$-arrestin

The common pathway involving adenylyl cyclase and cAMP primarily leads to the activation of __________.

PKA

In the $DAG/IP_3$ pathway, phospholipase C (PLC) cleaves $PIP_2$ specifically into DAG and __________.

$$IP_3$$

The JAK/STAT pathway involves receptor dimerization, JAK phosphorylation, and the recruitment of STAT, which eventually enters the __________ to activate gene transcription.

nucleus

__________ feedback occurs when a consequence of secretion strengthens the drive for more secretion, ending with a terminating event like birth.

Positive

__________ is an anticipatory signal that prepares for an impending demand, such as GI hormones stimulating insulin before absorbed glucose enters the blood.

Feed-forward

When complementary pathways produce a combined effect greater than the algebraic sum, the result is called synergy or __________.

potentiation

__________ occurs when one hormone must be present for another response to occur but does not initiate that response alone.

Permissiveness

On a dose-response curve, an increase in sensitivity is indicated by a __________ shift, which results in a lower $EC_{50}$.

left

The maximum response, or $E_{max}$, on a dose-response curve is a measure of the system's __________.

capacity

__________ receptors allow a maximum response to occur before all receptors are occupied, thereby increasing sensitivity.

Spare

The integration mechanism called __________ provides reliability and fine-tuning by having more than one route achieve the same endpoint.

redundancy

The pituitary gland consists of two parts: the neural posterior lobe and the glandular anterior lobe, also known as the __________.

adenohypophysis

Hypothalamic signals reach the anterior lobe of the pituitary through the __________ portal vessels.

hypothalamo-hypophyseal

Oxytocin and vasopressin (AVP/ADH) are __________ that differ by only two amino acids.

nonapeptides

Posterior pituitary hormones are synthesized in the hypothalamic cell bodies but are stored and released from __________.

nerve terminals

TSH, FSH, and LH are all members of the glycoprotein family and share an identical __________ subunit.

$$\alpha$$

__________ is a single gene product that can be cleaved into ACTH, MSH peptides, lipotropins, and $\beta$-endorphin by tissue-specific convertases.

POMC

Unlike most other anterior pituitary hormones, __________ is normally under strong tonic inhibition by dopamine.

prolactin

Hypothalamic __________ is also known as Somatostatin (SRIF), which acts to decrease GH secretion.

Growth Hormone Inhibiting Hormone

__________ negative feedback occurs when target-gland hormones inhibit the secretion of both the pituitary and the hypothalamus.

Long-loop

In the GH axis, __________ decreases somatotrope sensitivity to GHRH and increases hypothalamic somatostatin.

$$IGF-1$$

Both oxytocin and vasopressin have very short circulating half-lives of approximately __________ minutes.

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