Endocrine System and Hormones

Flashcards covering the key concepts of the endocrine system, hormones, and their functions.

Endocrine Signaling

Hormones released into the bloodstream act on distant target cells.

Paracrine Signaling

Signals act on neighboring cells (local effects).

Autocrine Signaling

A cell targets itself.

Neuroendocrine Signaling

Neurohormones released by neurons enter the bloodstream.

Synaptic Signaling

Neurotransmitters act across a synapse.

Pheromones

Signals released into the environment to influence other individuals of the same species.

Hypothalamus

Regulates the pituitary; secretes releasing hormones (e.g. GnRH).

Pituitary Gland

Anterior produces FSH, LH, TSH, ACTH, GH, prolactin; Posterior produces ADH, oxytocin

Thyroid Gland

Produces T3 and T4 (metabolism), calcitonin (calcium regulation).

Parathyroid Glands

Produce PTH (raises blood calcium).

Adrenal Medulla

Releases epinephrine, norepinephrine (short-term stress).

Adrenal Cortex

Releases cortisol, aldosterone (long-term stress, mineral balance).

Pancreas (Islets of Langerhans)

Insulin (lowers blood sugar), glucagon (raises blood sugar).

Gonads (Testes/Ovaries)

Produce testosterone, estradiol, progesterone.

Pineal Gland

Melatonin (circadian rhythms).

Peptide/Protein Hormones

Water-soluble, bind surface receptors (e.g., insulin, FSH).

Steroid Hormones

Lipid-soluble, bind intracellular receptors (e.g., cortisol, estradiol).

Amine Hormones

Derived from amino acids (e.g., epinephrine from tyrosine, melatonin from tryptophan).

Ecdysone

Hormone in insects that promotes molting.

Juvenile Hormone

Hormone in insects that inhibits metamorphosis.

Thyroid Hormones (T3/T4)

Drive metamorphosis in amphibians (e.g., tadpole to frog).

Epinephrine/Norepinephrine: Short-Term Stress

Triggered by the sympathetic nervous system; Released by the adrenal medulla.

Cortisol: Long-Term Stress

Hypothalamus → CRH → Pituitary → ACTH → Adrenal cortex → Cortisol; Effects: increased glucose, suppressed immune response, protein/fat breakdown.

Insulin and Glucagon

Regulate blood glucose levels.

ADH

Promotes water retention in kidneys.

Aldosterone

Regulates salt and water balance.

PTH and Calcitonin

Regulate calcium homeostasis.

Thyroid Hormones

Regulate basal metabolic rate.

Endocrine Disruptors

Sources: Plastics, pesticides, industrial chemicals; Effects: Mimic/block hormone actions; linked to reproductive issues, cancers, developmental problems.