Endocrine System and Hormonal Regulation

Vocabulary-style flashcards covering the components, chemical classes, mechanisms, and specific organs/hormones of the human endocrine system based on the lecture transcript.

Hormone

A chemical messenger secreted into the blood that stimulates a response in another tissue or organ.

Target cells

Cells characterized by having specific hormone receptors that allow them to respond to circulating hormones.

Steroids

A chemical class of hormones derived from cholesterol, including hormones like aldosterone, cortisol, and estrogens.

Monoamines

Biogenic amines made from amino acids, such as catecholamines ($dopamine$, $epinephrine$, $norepinephrine$), $melatonin$, and $thyroid hormone$.

Peptides

Hormones consisting of chains of amino acids, ranging from oligopeptides ($3$ to $10$ amino acids) to glycoproteins like $FSH$ and $LH$.

Humoral stimuli

The stimulation of hormone secretion by blood factors such as glucose levels or osmolarity.

Up-regulation

A process where a cell increases its number of receptors, making it more sensitive to a specific hormone.

Enzyme Amplification

A reaction cascade where $1$ hormone molecule triggers the synthesis of many enzyme molecules, allowing a small stimulus to produce a large effect.

Paracrine Secretions

Chemical messengers that diffuse short distances to affect nearby cells rather than traveling through the blood.

Eicosanoids

A family of paracrine secretions derived from a polyunsaturated fatty acid called arachidonic acid.

Leukotrienes

Eicosanoids that mediate allergic and inflammatory responses.

Prostacyclin

An eicosanoid that functions to inhibit blood clotting.

Thromboxanes

Chemicals released by platelets after injury that stimulate blood clotting.

Adenohypophysis

The anterior lobe of the pituitary gland which is regulated by hypothalamic releasing and inhibiting hormones.

Neurohypophysis

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

Thyrotropin-releasing hormone (TRH)

A hypothalamic hormone that promotes the secretion of $TSH$ and $PRL$.

Somatostatin

A hormone that inhibits the secretion of growth hormone ($GH$) and thyroid-stimulating hormone ($TSH$), also found as a paracrine secretion in the pancreas.

Follicle-stimulating hormone (FSH)

An anterior pituitary hormone that stimulates the development of ova/follicles in the ovaries and sperm production in the testes.

Luteinizing hormone (LH)

An anterior pituitary hormone that stimulates ovulation in females and testosterone secretion in males.

Adrenocorticotropic hormone (ACTH)

Also known as corticotropin, it stimulates the adrenal cortex to secrete corticosteroids that regulate metabolism and stress response.

Antidiuretic hormone (ADH)

Also known as vasopressin, it increases renal water retention and reduces urine volume.

Involution

The process of organ shrinkage after puberty, specifically noted in the pineal gland and the thymus.

Calcitonin

Secreted by $C$ cells of the thyroid gland, it lowers blood $Ca^{2+}$ and promotes bone formation, especially in children.

Parathyroid hormone (PTH)

A hormone that increases blood $Ca^{2+}$ by stimulating bone resorption and the synthesis of calcitriol.

Chromaffin cells

Modified neurons in the adrenal medulla that release $epinephrine$ and $norepinephrine$ as part of the sympathetic response.

Aldosterone

A mineralocorticoid produced in the zona glomerulosa of the adrenal cortex that promotes $Na^+$ retention and $K^+$ excretion.

Cortisol

A glucocorticoid from the zona fasciculata that stimulates fat and protein catabolism and gluconeogenesis.

General adaptation syndrome (GAS)

The consistent three-stage body reaction to stress consisting of the alarm reaction, stage of resistance, and stage of exhaustion.

Insulin

Secreted by beta ($\beta$) cells of the pancreatic islets, it stimulates glucose and amino acid uptake and nutrient storage.

Glucagon

Secreted by alpha ($\text{α}$) cells of the pancreatic islets, it stimulates glycogenolysis and fat catabolism.

Atrial natriuretic peptide

A hormone released by the heart in response to high blood pressure that increases renal $Na^+$ and $H_2O$ loss.

Erythropoietin (EPO)

A hormone produced primarily by the kidneys (85 \text{%}) and liver (15 \text{%}) that stimulates the bone marrow to produce red blood cells.