Vertebrae Endocrinology Exam 1

Gerald Litwack

Author of the textbook 'Basic Medical Endocrinology,' which provides foundational knowledge in the field of endocrinology.

Diabetes

A condition characterized by high blood sugar levels due to insufficient insulin production or action.

Gigantism

A condition caused by excessive growth hormone, leading to abnormal growth and height.

Dwarfism

A condition resulting from insufficient growth hormone, leading to shorter stature.

Insulin

Lowers blood sugar levels by facilitating glucose uptake in cells.

Glucagon

Raises blood sugar levels by promoting glycogen breakdown in the liver.

Cortisol

Involved in stress response and metabolism regulation.

Thyroid Hormone

Regulates metabolism and energy levels in the body.

Epinephrine

Involved in the fight-or-flight response, increasing heart rate and energy.

Kopec (1917)

Conducted extirpation studies on insects to understand hormonal control by removing the brain and observing effects.

Fukuda (1940)

Performed ligation studies to investigate the role of the prothoracic gland in molting hormone production.

Wigglesworth (1934)

Conducted parabiosis studies to suggest the presence of juvenile hormone in insects.

Hormones

Chemical messengers synthesized and released by endocrine tissues that regulate physiological processes in the body.

Endocrinology

The study of hormones and the endocrine system, focusing on chemical communication and regulation of bodily functions.

Homeostasis

The maintenance of stable internal conditions in the body, such as blood sugar levels, through hormonal regulation.

Biosynthesis

The process by which hormones are synthesized in the body, often regulated by specific pathways.

Transport in Blood

Hormones are transported in the bloodstream, often bound to proteins to prevent loss to kidneys.

Target Tissue Processing

Hormones may undergo conversion (e.g., T4 to T3) at the target tissue level to become active.

Receptor Specificity

Only cells with specific receptors can respond to a hormone, leading to distinct physiological effects.

Ablation Studies

Investigating the effects of removing an endocrine organ to understand its role in hormone regulation.

Replacement Therapy

Injecting hormones or transplanting glands to restore normal physiological function.

Molecular Techniques

Using recombinant DNA technology to study hormone synthesis and receptor function.

HPLC

High-Performance Liquid Chromatography: A technique used to separate and analyze compounds, including hormones, based on their chemical properties.

Microarray Hybridization

A method for studying gene expression changes on a large scale, useful in understanding hormone regulation.

Hormone titer

Concentration of hormone in the blood.

Key binding proteins

CBG (Cortisol Binding Globulin), SBG (Sex Steroid Binding Globulin), TBG (Thyroxin Binding Globulin).

Types of hormones

Peptides, Steroids, Amino Acid derivatives.

Rosalind Yalow (1978)

Awarded the Nobel Prize for her work in developing the radioimmunoassay technique, which revolutionized hormone measurement.

Bioassay

Measures physiological responses to quantify hormone levels using living organisms.

Radioimmunoassay (RIA)

Uses antibodies and radioactively labeled hormones to measure hormone concentrations in samples.

ELISA

Enzyme-linked immunosorbent assay, a non-radioactive method to detect and quantify proteins or hormones using enzyme-linked antibodies.

Standard Curve

A graph that shows the relationship between known concentrations of a substance and the response measured, used to determine the concentration of unknown samples.

Steroid Hormone Action

Steroid hormones enter cells due to their lipid solubility, bind to intracellular receptors, and regulate gene transcription.

Protein Hormone Action

Protein hormones bind to surface receptors, activating second messenger systems like cAMP, leading to cellular responses.

Receptor Regulation

Hormone exposure can lead to upregulation (increased receptors) or downregulation (decreased receptors) affecting hormone sensitivity.

cAMP Pathway

Hormone binding activates GPCR, which activates adenylate cyclase, converting ATP to cAMP, a second messenger that activates protein kinase A (PKA).

IP3/DAG Pathway

Hormone binding activates phospholipase C, which cleaves PIP2 into IP3 and DAG, leading to calcium release and activation of protein kinase C (PKC).

Nuclear Receptor Mechanism

Hormone-receptor complexes translocate to the nucleus, bind to hormone response elements (HREs) on DNA, and regulate gene transcription.

Epinephrine (Adrenaline)

A protein hormone that triggers the fight-or-flight response, acting through GPCRs and cAMP pathways.

G-Protein Coupled Receptors

Mediate responses to hormones like epinephrine and glucagon through second messenger systems.

Receptor Tyrosine Kinases

Activate signaling cascades in response to growth factors, leading to cell growth and differentiation.

Nuclear Receptors

Bind steroid hormones and regulate gene expression in the nucleus.

Hormone response elements (HRE)

Specific DNA sequences where hormone-receptor complexes bind.

cAMP (cyclic adenosine monophosphate)

A key secondary messenger in protein hormone signaling.

Calmodulin

An intracellular calcium receptor that regulates various cellular processes.

Hypothalamus (HTH)

A region of the brain that connects the endocrine and neural systems, located around the third ventricle.

Pituitary Gland

An endocrine gland divided into two major parts: adenohypophysis (anterior lobe) and neurohypophysis (posterior lobe).

Median Eminence (ME)

A neurohemal area where blood portal systems connect the hypothalamus to the pituitary gland.

Dopamine

Inhibits prolactin release.

Norepinephrine (Norepi)

Involved in the regulation of various hormones.

Epinephrine (Epi)

Functions in stress response and regulation of blood pressure.

Serotonin

Affects mood and regulates various physiological functions.

Acetylcholine

Plays a role in neurotransmission and muscle activation.

Hypothalamus

Part of the diencephalon that lies ventral to the thalamus.

Infundibulum

Connects the hypothalamus to the pituitary gland.

Hypothalamic-pituitary portal system

Crucial for hormone signaling between the hypothalamus and anterior pituitary.

Adenohypophysis

The anterior lobe of the pituitary gland, which produces and secretes several hormones.

Neurohypophysis

The posterior lobe of the pituitary gland, which stores and releases hormones produced by the hypothalamus.

Follicle Stimulating Hormone (FSH)

Stimulates the growth of ovarian follicles in females and spermatogenesis in males.

Luteinizing Hormone (LH)

Triggers ovulation and stimulates testosterone production in males.

Thyroid Stimulating Hormone (TSH)

Stimulates the thyroid gland to produce thyroid hormones.

Adrenocorticotropic Hormone (ACTH)

Stimulates the adrenal cortex to produce cortisol.

Growth Hormone (GH)

Promotes growth and cell reproduction.

Prolactin

Stimulates milk production in females.

Somatotropes

Cells in the anterior pituitary that produce Growth Hormone (50% of cells).

Lactotropes

Cells in the anterior pituitary that produce Prolactin (10-20% of cells).

Corticotropes

Cells in the anterior pituitary that produce ACTH (20% of cells).

Thyrotropes

Cells in the anterior pituitary that produce TSH (5% of cells).

Gonadotropes

Cells in the anterior pituitary that produce FSH and LH (5% of cells).

Antidiuretic Hormone (ADH)

Regulates water balance.

Oxytocin

Stimulates uterine contractions and milk ejection.

Rathke's Pouch

An embryonic structure that gives rise to the anterior pituitary.

Sella Turcica

The concavity in the sphenoid bone where the pituitary gland is embedded.

Herring Bodies

Neurosecretory cells in the posterior pituitary that store hormones.

Pro-opiomelanocortin (POMC)

A precursor protein that is cleaved to produce several hormones including ACTH and MSH.

Glycoproteins

Proteins that have carbohydrate groups attached, important for the activity of certain hormones like FSH, LH, and TSH.

Hormonal Specificity

The ability of a hormone to elicit a specific biological response in a target tissue.

Quaternary Structure

Refers to the arrangement of multiple polypeptide chains in a protein, crucial for hormone function.

Evolution of Hormones

Suggests that many pituitary hormones evolved from a common ancestral molecule.

Radioimmunoassay Studies

Used to assess the phylogenetic relationships of hormones by examining the activity of antibodies against different species' hormones.

Prolactin (PRL)

Has diverse functions across different vertebrates, including lactation and osmoregulation.

FSH & LH

Both are glycoproteins involved in gonadal function; FSH is primarily involved in gametogenesis, while LH stimulates steroid secretion.

ACTH & MSH

Both derived from POMC and have roles in the endocrine system; ACTH stimulates adrenal cortex, while MSH primarily affects melanocytes and appetite.

GH & Prolactin

Both are peptide hormones with overlapping amino acid sequences; GH primarily stimulates growth, while PRL has diverse roles depending on the vertebrate species.

ADH (Antidiuretic Hormone)

Also known as arginine vasopressin (AVP) in mammals, it regulates water retention in the kidneys and is involved in blood pressure regulation.

Oxytocin (OT)

A hormone that triggers milk letdown during breastfeeding and induces uterine contractions during childbirth.

Neurophysin

A protein that binds to neurohypophyseal hormones (like ADH and oxytocin) and serves as a chaperone for their transport and storage.

ADH Function

Increases water permeability in kidneys, reducing urine volume.

Oxytocin Function

Induces uterine contractions and milk letdown.

ADH Mechanism of Action

G protein/cAMP signal transduction.

Oxytocin Mechanism of Action

G protein/IP3 signal transduction.

Releasing Hormones

Hormones produced by the hypothalamus that stimulate the release of hormones from the anterior pituitary.

Corticotropin-Releasing Hormone (CRH)

A hormone that regulates the secretion of ACTH from the anterior pituitary.

Thyrotropin-Releasing Hormone (TRH)

Stimulates the secretion of TSH from the anterior pituitary.

Gonadotropin-Releasing Hormone (GnRH)

Stimulates the release of FSH and LH from the anterior pituitary.

CRH Function

Stimulates ACTH release from the anterior pituitary.

TRH Function

Stimulates TSH and prolactin release; involved in metabolism regulation.

GnRH Function

Triggers release of FSH and LH; has pulsatile secretion patterns.

GHRH

Stimulates growth hormone release from the anterior pituitary.

Somatostatin

Inhibits growth hormone release and regulates other hormones.