Endocrine System and Pineal Gland (Sherwood 9e)

Vocabulary flashcards covering key endocrine concepts, glands, hormones, feedback mechanisms, pituitary hormones, hypothalamus, and circadian regulators.

Tropic hormones

Hormones whose primary function is to regulate secretion of another endocrine gland.

Endocrine glands

Ductless glands that secrete hormones into the bloodstream to regulate body functions.

Central endocrine system

The hypothalamus and pituitary (anterior and posterior) as the main regulatory axis of the endocrine system.

Hypothalamus

Homeostatic control center that links the nervous and endocrine systems; contains nuclei that control different functions.

Posterior pituitary

Stores and releases oxytocin and vasopressin (ADH); hormones are synthesized in hypothalamic neurons and released from the posterior pituitary.

Anterior pituitary

true endocrine gland that secretes six classic hormones; regulated by hypothalamic releasing hormones via a portal system.

Oxytocin

Posterior pituitary hormone that stimulates uterine contractions and lactation; also involved in bonding; nicknamed the 'Love Hormone.'

Antidiuretic hormone (ADH)/vasopressin

Posterior pituitary hormone that acts on kidneys to conserve water, increasing blood volume and pressure and reducing urine output.

Prolactin

Anterior pituitary hormone that stimulates mammary gland development and milk production; has metabolic actions as well.

Growth hormone (GH)

Hormone that promotes growth; acts directly on some tissues and indirectly by stimulating IGF-I; secreted by somatotropes.

Thyroid-stimulating hormone (TSH)

Anterior pituitary hormone that stimulates the thyroid gland to release thyroid hormones (T3 and T4).

Adrenocorticotropic hormone (ACTH)

Anterior pituitary hormone that stimulates the adrenal cortex to secrete cortisol.

Gonadotropins (LH & FSH)

LH and FSH stimulate the gonads to secrete sex hormones and to produce gametes (ova and sperm).

Gonadotropes

Cell type in the anterior pituitary that secretes LH and FSH.

Lactotropes

Pituitary cells that synthesize and secrete prolactin.

Hypophysiotropic hormones

Releasing and inhibiting hormones produced by hypothalamic neurons that regulate anterior pituitary hormone secretion.

Hypothalamic–pituitary portal system

Specialized blood vessels that transport hypothalamic releasing hormones to the anterior pituitary.

CRH (corticotropin-releasing hormone)

Hypothalamic releasing hormone that stimulates ACTH secretion from the anterior pituitary.

Cortisol

Steroid hormone from the adrenal cortex involved in stress responses; exerts negative feedback on the hypothalamus and pituitary.

Insulin-like growth factors (IGF-I and IGF-II)

Mediators of GH's growth-promoting effects; IGF-I drives growth of soft tissues via hypertrophy and hyperplasia.

IGF-I

Major mediator of GH's growth-promoting effects; stimulates cell growth and division.

IGF-II

Insulin-like growth factor involved in growth and development.

Epiphyseal plate

Growth plate in long bones where GH/IGF promote lengthwise growth; activity declines with maturity.

Dwarfism

GH deficiency in childhood; can be due to pituitary or hypothalamic dysfunction.

Gigantism

Excess GH secretion before epiphyseal plates close, leading to excessive height.

Acromegaly

Excess GH secretion after growth plates close, causing enlargement of bones and tissues.

Pineal gland

Gland in the brain that secretes melatonin and helps regulate circadian rhythms.

Melatonin

Hormone of darkness; helps regulate circadian rhythms and sleep; secretion rises in darkness.

Suprachiasmatic nucleus (SCN)

Master biological clock in the hypothalamus that coordinates circadian rhythms.

CLOCK and BMAL-1

Clock proteins that drive circadian gene expression and rhythm generation.

Melanopsin

Photopigment in certain retinal ganglion cells that detects light and helps entrain circadian rhythms.

Circadian rhythms

Endogenous ~24-hour cycles that synchronize physiological processes with the light–dark cycle.

Hypothalamus to posterior pituitary connection

Neural pathway that directly links hypothalamic neurons to the posterior pituitary for hormone release.

Hypothalamic neurosecretory neurons

Neurons that produce releasing/inhibiting hormones and transport them to the pituitary via the portal system or posterior pituitary.