Endocrine System and Homeostasis Flashcards

This set of flashcards covers vocabulary terms related to the endocrine system glands, hormones, disorders, and the principles of homeostasis and negative feedback based on the Curro Krugersdorp High School Term 1 2025 notes.

Endocrine System

A system that controls responses that are not that fast but are long-lasting and reflect the body’s internal environments, made up of glands that produce hormones.

Nervous System

A system made up of nerves that co-ordinates very quick responses to external stimuli using nerve impulses.

Exocrine Glands

Glands that do not secrete hormones but instead secrete their substances into ducts rather than the bloodstream (e.g., salivary glands).

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream through capillaries.

Hormone

Organic chemical messengers consisting of proteins and fats that travel in the bloodstream to tissues or organs to affect processes like growth, metabolism, and reproduction.

ADH (Antidiuretic Hormone)

A hormone secreted by the Hypothalamus that controls osmoregulation by making collecting ducts and distal convoluted tubes more permeable for water reabsorption.

GH (Growth Hormone)

Secreted by the Pituitary gland to control the growth, repair, and replacement of cells in bones and other tissues.

TSH (Thyroid Stimulating Hormone)

Secreted by the Pituitary gland to stimulate the thyroid gland to secrete thyroxin.

FSH (Follicle Stimulating Hormone)

Secreted by the Pituitary gland to stimulate the development of follicles in the ovaries.

LH (Leutenising Hormone)

Secreted by the Pituitary gland to stimulate ovulation and the development of the corpus luteum.

Prolactin

A hormone produced by the Pituitary gland that stimulates mammary glands to produce milk.

Thyroxin

A hormone secreted by the thyroid gland that controls the basic metabolic rate (cell respiration) and affects the heart and nervous system.

Adrenaline

Secreted by the adrenal gland to increase heartbeat, blood pressure, breathing rate, and the conversion of glycogen to glucose for a flight-or-fight response.

Aldosterone

A hormone secreted by the adrenal gland that regulates salt concentration by increasing the reabsorption of Sodium ions in the renal tubules.

Islets of Langerhans

The specific clusters of cells in the pancreas that secrete the hormones insulin and glucagon.

Glucagon

A hormone that stimulates the conversion of glycogen to glucose in the liver to increase blood glucose levels.

Insulin

A hormone that stimulates the conversion of glucose to glycogen to reduce blood glucose levels.

Oestrogen

A female hormone secreted by the ovaries that stimulates puberty and promotes thickening of the endometrium.

Progesterone

Secreted by the ovaries to promote thickening of the endometrium and maintain pregnancy.

Testosterone

A male hormone secreted by the testes that stimulates the maturation of sperm cells and puberty.

Type 1 Diabetes

A condition that occurs when the pancreas is unable to produce enough insulin, requiring insulin therapy and usually developing at a young age.

Type 2 Diabetes

A condition occurring due to insulin resistance where the body does not respond well to insulin, often manageable with lifestyle changes.

Gigantism

A disorder caused by the hypersecretion of GH in children, resulting in a body height of $7$ to $8$ feet.

Acromegaly

A condition caused by hyperactivity of the pituitary gland in adults, characterized by enlarged hands, feet, and overgrowth of the jaws.

Dwarfism

A condition characterized by stunted growth caused by the hypo-activity of the pituitary gland in a child.

Cretinism

A disease in infants with stunted growth, low IQ, and a ‘pigeons chest’, caused by hyposecretion of thyroxine.

Myxoedema (Gull's Disease)

A condition in adults caused by hyposecretion of thyroxine, characterized by a swollen face and hands due to albuminous myxomatous tissue deposition.

Goitre

A swelling in the neck caused by an enlarged thyroid gland, often due to an iodine deficiency.

Hashimoto's Disease

An auto-immune disease where the immune system destroys the thyroid gland when thyroxine levels start to decrease.

Exophthalmic goitre

A condition caused by hypersecretion of thyroxine, characterized by high BMR, high body temperature, and oedema behind the eyes.

Homeostasis

The maintenance of a constant internal environment (e.g., temperature, glucose, water) in the body or a cell.

Body Fluid

The internal environment of the body composed of blood plasma, tissue fluid between cells, and the cytoplasm inside cells.

Negative Feedback Mechanism

A homeostatic control where the detection of a deviation results in a reaction that counteracts the change to return the factor to normal.

Receptors

Components in a negative feedback system that detect changes in the normal level of a specific factor and transmit information to the control center.

Effectors

Organs (like glands or muscles) that implement reactions to correct deviations detected by receptors, returning levels to normal.