Yr 9 Science: Homeostasis and the Endocrine System

Vocabulary flashcards covering key terms from the Homeostasis and Endocrine System notes.

Homeostasis

Maintenance of a constant internal environment despite changes in the external environment.

Nervous system

Fast-acting control system that uses electrical impulses via neurons to transmit messages to the brain, spinal cord, and effectors.

Endocrine system

Slow-acting system of glands that release hormones into the bloodstream to coordinate body functions.

Hormone

Chemical messenger produced by glands, transported in blood, delivered to target tissues; can act locally or throughout body; often binds to specific receptors (lock-and-key).

Antidiuretic Hormone (ADH)

Produced by the pituitary gland; regulates water absorption in the kidneys, reducing urine output.

FSH (Follicle Stimulating Hormone)

Produced by pituitary; stimulates development of ovarian follicles and estrogen secretion.

LH (Luteinising Hormone)

Produced by pituitary; triggers ovulation.

GH (Growth Hormone)

Produced by pituitary; promotes growth and development of bones and muscles.

TSH (Thyroid Stimulating Hormone)

Produced by pituitary; stimulates the thyroid to release thyroid hormones.

Thyroxine

Thyroid hormone that regulates the metabolic rate of cells.

Insulin

Produced by beta cells in the pancreas; lowers blood glucose by promoting uptake and storage as glycogen in the liver.

Glucagon

Produced by alpha cells in the pancreas; raises blood glucose by promoting conversion of glycogen to glucose in the liver.

Adrenaline

Hormone from the adrenal gland; triggers fight-or-flight responses increasing heart rate, respiration, and energy availability.

Testosterone

Male sex hormone produced by the testes; promotes male secondary sexual characteristics.

Progesterone

Hormone from the ovaries; thickens uterine lining and helps maintain pregnancy; prevents contractions before birth.

Oestrogen

Female sex hormone produced by the ovaries; develops female secondary sexual characteristics and regulates the menstrual cycle.

Ovaries

Glands that produce eggs and secrete hormones such as estrogen and progesterone.

Exocrine gland

Glands (e.g., salivary, sweat, tear glands) that release substances into ducts; not part of the endocrine system because they don’t release hormones into the bloodstream.

Respiration

Process of energy release from glucose using oxygen: oxygen + glucose → carbon dioxide + water + heat + ATP.

ATP (Adenosine Triphosphate)

Main energy currency of cells; produced during respiration and used to power cellular processes.

Vasodilation

Widening of blood vessels to increase blood flow near the skin and promote heat loss.

Vasoconstriction

Narrowing of blood vessels to reduce heat loss through the skin.

Goose bumps

Hair on the skin stands up to trap a layer of air and reduce heat loss.

Shivering

Involuntary muscle contractions that generate heat to raise body temperature.

Thirst

Sensation prompting fluid intake; helps prevent dehydration and maintains fluid balance.

Hypothalamus

Brain region that monitors temperature and osmolarity and acts as a control center for homeostasis, signaling the pituitary.

Pituitary gland

Master endocrine gland that releases multiple hormones (including ADH) and regulates other glands.

Osmolarity

Total concentration of solute particles in a liter of solution.

Solute

Substance dissolved in a solvent.

Glycogen

Stored glucose in liver and muscle tissue; released as glucose when needed.

Type 1 diabetes

Autoimmune condition where the body does not produce insulin; usually diagnosed in childhood; requires insulin injections.

Type 2 diabetes

Condition where insulin is insufficient or not used effectively; often linked to overweight; managed with diet, exercise, and sometimes medication.

Voluntary response

A response that is consciously controlled (e.g., removing clothing, seeking shade).

Involuntary response

An automatic, non-conscious response (e.g., reflexes such as dodging a flying object, sweating).

Neuron

Nerve cell; basic unit of the nervous system that transmits electrical impulses.

Neuron parts

Dendrites, cell body, axon; transmit electrical signals between neurons and to effectors.

Nervous system characteristics

Fast-acting; uses electrical impulses; neurons act on effectors (muscles/glands).

Endocrine system characteristics

Slow-acting; uses chemical messengers (hormones) in the bloodstream; targets many organs.},{