Endocrine System Review Guide

Flashcards covering all textbook, MIRA, and lecture topics outlined in the Endocrine System Review Guide.

Hormone

A chemical messenger produced by endocrine glands that travels through the bloodstream to regulate target tissue or organ activity.

Target organ/tissue

A specific organ or tissue containing matching receptors designed to respond to a particular hormone.

Lock and key system

The specific fitting mechanism where a hormone acts as a key that fits precisely into a matching receptor site on or inside a target cell.

TEXTBOOK/MIRA topics

Basic review topics that students are required to look up independently using an online textbook or MIRA (AI) resource.

LECTURE topics

Tougher endocrine concepts that are directly covered in class by the instructor.

Adenohypophysis

The anterior pituitary gland, responsible for synthesizing and secreting seven major hormones.

Neurohypophysis

The posterior pituitary gland, which stores and releases two hormones produced by neurosecretory cells in the hypothalamus.

Hypophyseal Portal System

A specialized vascular connection that delivers hypothalamic releasing and inhibiting hormones directly to the anterior pituitary gland.

Free hormones

Unbound hormones circulating in the plasma that are biologically active and free to diffuse out of blood vessels to bind to receptors.

Protein bound hormones

Hormones attached to carrier proteins in the bloodstream, serving as a circulating reserve and extending hormone half-life.

Amplification

The process where a single hormone binding to a target cell receptor triggers a cascade mechanism, producing a large magnitude response.

Down regulation

The process by which target cells decrease their number of receptors in response to elevated hormone levels, reducing cellular sensitivity.

Up regulation

The process by which target cells increase their number of receptors in response to deficient hormone levels, increasing cellular sensitivity.

Endocrine reflexes

Reflex mechanisms regulating hormone secretion triggered by humoral, neural, or hormonal stimuli.

Releasing hormones

Hypothalamic hormones that stimulate the synthesis and secretion of specific anterior pituitary hormones.

Inhibiting hormones

Hypothalamic hormones that suppress the synthesis and secretion of specific anterior pituitary hormones.

Neurosecretory cells

Specialized neurons located in the hypothalamus that produce and secrete hormones into blood vessels.

Follicular cells

Cells of the thyroid gland responsible for producing thyroid hormones, including thyroxine ($T_4$) and triiodothyronine ($T_3$).

Parafollicular cells

Cells of the thyroid gland that produce calcitonin to help regulate blood calcium levels.

Zona glomerulosa

The outermost layer of the adrenal cortex, responsible for secreting mineralocorticoid hormones.

Zona fasciculata

The middle region of the adrenal cortex, responsible for secreting glucocorticoid hormones.

Zona reticularis

The innermost layer of the adrenal cortex, responsible for secreting gonadocorticoids or adrenal androgens.

Adrenal medulla

The inner core of the adrenal gland, responsible for secreting catecholamine hormones including epinephrine and norepinephrine.

Type I Diabetes Mellitus

A metabolic disorder characterized by an absolute deficiency of insulin resulting from autoimmune destruction of pancreatic islet cells.

Type II Diabetes Mellitus

A metabolic disorder characterized by target cell receptor insensitivity to insulin and potential secondary islet cell burnout.

Islet cell burnout

The functional exhaustion and eventual loss of pancreatic islet beta cells caused by long-term hypersecretion of insulin in Type II Diabetes Mellitus.

Negative feedback

A homeostatic regulatory loop in which rising levels of a target hormone inhibit the release of upstream stimulating hormones.