A&P II — Chapter 16A: Endocrine System Flashcards

A set of vocabulary flashcards covering the major concepts, glands, and hormones of the Endocrine System as detailed in the Chapter 16A teacher notes.

Endocrine System

A body system that uses hormones released into the bloodstream to send slower, longer-lasting messages for controlling processes like reproduction, growth, and metabolism.

Hormones

Chemical messengers that travel through the blood to reach distant target cells.

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream; examples include the pituitary, thyroid, parathyroid, adrenal, and pineal glands.

Exocrine Glands

Glands that use ducts to carry secretions to a membrane surface; examples include sweat and saliva glands.

Pancreas

A gland that is special because it possesses both endocrine and exocrine functions.

Target Cell

A specific cell that responds to a hormone because it possesses the correct receptors for that hormone.

Water-soluble Hormones

Mainly amino-acid-based hormones that cannot enter the cell and must bind to membrane receptors, typically using a G-protein/cyclic AMP second messenger system.

Lipid-soluble Hormones

Steroid hormones and thyroid hormones that can enter the target cell, bind to intracellular receptors, and interact with DNA to trigger protein synthesis.

Thyroid Hormone

An amino-acid-derived hormone that acts as an 'oddball' because it behaves like a lipid-soluble hormone rather than a water-soluble one.

Negative Feedback

A regulatory mechanism where the body's response returns a system toward its normal range (e.g., blood glucose or calcium regulation).

Humoral Stimulus

A hormone release triggered by changing levels of ions or nutrients in the blood, such as low blood $Ca^{2+}$ levels triggering Parathyroid Hormone (PTH).

Neural Stimulus

A hormone release triggered by nerve fibers, such as the sympathetic nervous system stimulating the adrenal medulla to release epinephrine.

Hormonal Stimulus

A release of hormones in response to hormones produced by other endocrine organs, such as the hypothalamus-pituitary axis.

Up-regulation

An increase in the number of receptors on a cell in response to low hormone levels.

Down-regulation

A decrease in the number of receptors on a cell in response to high hormone levels.

Permissiveness

A hormone relationship where one hormone needs another hormone to be present in order to exert its full effect.

Synergism

A hormone relationship where two hormones produce similar effects, and their combined effect is amplified (e.g., glucagon and epinephrine).

Antagonism

A hormone relationship where two hormones produce opposite effects to maintain balance, such as insulin lowering and glucagon raising blood glucose.

Posterior Pituitary

The neural tissue lobe of the pituitary that acts as a 'warehouse' to store and release ADH and oxytocin made by the hypothalamus.

Anterior Pituitary

The glandular tissue lobe of the pituitary that produces and releases six major hormones: GH, TSH, ACTH, FSH, LH, and PRL.

Oxytocin

A hormone stored in the posterior pituitary that stimulates uterine contractions during childbirth and milk ejection; it operates on a positive feedback loop.

Positive Feedback

A mechanism that increases the intensity of a response until an event is completed, such as in childbirth.

Antidiuretic Hormone (ADH)

Also called vasopressin, this hormone causes the kidneys to reabsorb more water, resulting in less urine production and helping to maintain blood pressure.

Diabetes Insipidus

A disorder caused by a deficiency of ADH, leading to excessive urination and a risk of dehydration (described as 'Dry Inside').

SIADH (Syndrome of Inappropriate ADH Secretion)

A disorder caused by too much ADH, leading to excessive water retention, disorientation, and sodium concerns (described as 'Soaked Inside').

Tropic Hormones

Hormones that stimulate other endocrine glands to release their hormones; examples include TSH, ACTH, FSH, and LH.

Growth Hormone (GH)

Also known as somatotropin, it targets bone and skeletal muscle to promote cell division, protein synthesis, and fuel availability for growth.

Gigantism

A condition caused by excessive GH production in children while bones are still able to lengthen.

Acromegaly

A condition caused by excessive GH production in adults, resulting in thicker/wider bones in the hands, feet, and face because longitudinal growth has stopped.

Pituitary Dwarfism

A condition caused by a deficiency of growth hormone in children, resulting in short stature.

TSH (Thyroid-stimulating hormone)

An anterior pituitary hormone that stimulates the thyroid gland to release thyroid hormones.

ACTH (Adrenocorticotropic hormone)

An anterior pituitary hormone that stimulates the adrenal cortex, often associated with stress and daily rhythms.

FSH (Follicle-stimulating hormone)

A hormone that stimulates the production of gametes (eggs in females, sperm in males).

LH (Luteinizing hormone)

A hormone that promotes the production of gonadal hormones, such as estrogen and progesterone in females (associated with ovulation) and testosterone in males.

Prolactin (PRL)

An anterior pituitary hormone responsible for the production of milk.