Fundamentals of Biology I - Hormonal Control and Regulation

Flashcards covering key vocabulary terms related to hormonal control and regulation.

Hormones

Natural chemical messengers that modify or control specific physiological processes; effective in minute concentrations and interact with environmental and internal signals.

Auxin

A plant hormone responsible for cell elongation and growth; promotes cell elongation, controls phototropism and gravitropism, maintains apical dominance, and stimulates root formation.

Phototropism

A response to light where auxin builds up on the shaded side of the stem, causing the stem to bend toward the light.

Gravitropism

A response to gravity where auxin builds up on the side where gravity is, inhibiting cell elongation in roots and causing them to bend downward.

Gibberellin

A plant hormone that stimulates stem elongation and bolting, breaks seed dormancy by promoting germination, and promotes flowering and fruit development.

Cytokinin

A plant hormone that promotes cell division and shoot formation, delays leaf aging (senescence), and counters auxin to promote branching.

Abscisic Acid (ABA)

A plant hormone responsible for stress responses and developmental regulation; induces stomatal closure to conserve water, maintains seed dormancy, and triggers stress response pathways during drought or cold.

Ethylene

A plant hormone involved in ripening, aging, and stress responses; promotes fruit ripening and induces leaf and flower abscission, speeds up senescence (aging).

Brassinosteroids

A class of steroid hormones that play a key role in plant growth, development, and stress tolerance; stimulates cell elongation and division, promotes xylem differentiation, and increases resistance to heat, cold, and pathogens.

Neurohormones

Secreted by specialized neurosecretory cells.

Ecdysone

A key hormone in arthropods that controls molting and metamorphosis.

Juvenile Hormone (JH)

A key hormone in arthropods that maintains larval stages.

Prothoracicotropic Hormone (PTTH)

A key hormone in arthropods that signals the release of ecdysone and regulates development, reproduction, and metamorphosis.

Endocrine System

A network of ductless glands that release hormones into the bloodstream, working with the nervous system to maintain homeostasis.

Exocrine Glands

Glands that have ducts and secrete enzymes, sweat, or oil onto body surfaces or cavities.

Endocrine Glands

Ductless glands that secrete hormones into the bloodstream.

Hypothalamus

Acts as the master regulator of the endocrine system, releasing hormones that stimulate or inhibit pituitary gland hormone release.

Pituitary Gland

Located at the base of the brain and connected to the hypothalamus; the anterior lobe synthesizes endocrine hormones, and the posterior lobe stores hormones synthesized by the hypothalamus. Often called the master gland.

Tropic Hormones

Hormones that regulate the function of endocrine cells or glands (e.g., TSH, FSH, LH, ACTH).

Non-Tropic Hormones

Hormones that target non-endocrine tissues (e.g., Prolactin, MSH).

Thyroid Gland

Located in the front of the neck below the larynx; controls metabolism, energy production, and calcium levels.

Parathyroid Gland

Four small glands behind the thyroid that regulate calcium and phosphate levels in the blood.

Adrenal Gland

Located on top of each kidney and consists of the adrenal medulla (inner portion) and adrenal cortex (outer portion).

Pancreas

Located behind the stomach and plays a vital role in glucose regulation, releasing hormones like insulin and glucagon.

Pineal Gland

Located deep in the center of the brain; light/dark cycles control the release of melatonin, which relates to biological rhythms associated with reproduction.

Gonads

Reproductive organs (ovaries and testes) that regulate menstrual cycle, fertility, secondary sex characteristics, and sperm production.

Thymus

Located behind the sternum and in front of the heart; where T-cells (T-lymphocytes) mature for adaptive immunity.