Nervous System, Endocrine System & Plant Hormones – Vocabulary

Vocabulary flashcards covering key terms and definitions from the notes on the nervous system, brain anatomy, endocrine glands and hormones, and plant hormones and movements.

Nervous System

The body's fast, electrochemical control system consisting of the brain, spinal cord, and all nerves.

Central Nervous System (CNS)

The body's processing centre, comprising the brain and spinal cord.

Peripheral Nervous System (PNS)

Nerves that connect the CNS to the rest of the body, including cranial and spinal nerves.

Neuron

Nerve cell that transmits information via electrical impulses.

Dendrite

Branch of a neuron that receives signals and conducts them to the cell body.

Axon

Long nerve fibre conducting impulses away from the cell body to other neurons or effectors.

Synapse

Junction between neurons where impulses pass via chemical signals.

Receptor

Specialized tips of nerve cells in sense organs that detect environmental stimuli.

Sense organs

Organs containing receptors (e.g., eyes, ears, nose, tongue, skin) that detect stimuli.

Reflex Action

Quick, involuntary response to a stimulus mediated by reflex pathways.

Receptor → Sensory Neuron → Brain → Motor Neuron → Effector

Typical reflex pathway for a reflex action.

Voluntary Action

Action controlled by the brain (cerebrum).

Involuntary Action

Action controlled by the mid and hindbrain; occurs without conscious control.

Brain

Main coordinating centre that receives, interprets information and sends instructions to effectors.

Forebrain

Largest brain region; involved in higher thinking; contains the cerebrum.

Midbrain

Part of the brain noted as the main thinking/processing region in the notes.

Hindbrain

Part of the brain including the cerebellum and medulla; coordinates involuntary actions and respiration.

Cerebrum

Largest part of the forebrain; associated with thought, voluntary actions, and sensory processing.

Hypothalamus

Brain region that helps regulate body functions and controls the pituitary gland.

Pituitary Gland

Master gland at the base of the brain that secretes hormones regulating other glands and growth.

Pons

Part of the hindbrain involved in regulation of respiration and facial movements.

Medulla Oblongata

Lower brainstem; controls involuntary actions such as BP, vomiting, salivation.

Cerebellum

Part of the hindbrain that coordinates balance and precise movements.

Spinal Cord

Long bundle of nerve tissue within the vertebral column; conducts impulses between brain and body.

Meninges

Three protective membranes surrounding the brain.

Cerebrospinal Fluid (CSF)

Fluid that cushions the brain and spinal cord; acts as a shock absorber.

Nervous Tissue

Tissue that conducts nerve impulses.

Endocrine System

System of ductless glands that secrete hormones into the bloodstream for chemical signaling.

Hormone

Chemical messenger secreted by endocrine glands into the bloodstream.

Endocrine Glands

Ductless glands that secrete hormones directly into the bloodstream.

Pituitary Gland (Master Gland)

Gland at the base of the brain that secretes growth hormone and regulates other glands.

Thyroid Gland

Gland in the throat that secretes thyronine and regulates metabolism.

Adrenal Gland

Gland above the kidneys; secretes adrenaline during emergencies, increasing BP and heart rate.

Pancreas

Gland near the stomach with endocrine (insulin/glucagon) and exocrine functions; regulates blood sugar.

Insulin

Hormone that lowers blood glucose levels.

Glucagon

Hormone that raises blood glucose levels.

Diabetes Mellitus

Disorder caused by deficiency of insulin leading to high blood sugar.

Testes

Male gonads; secrete testosterone; produce sperm and drive secondary sexual characteristics.

Ovaries

Female gonads; secrete estrogen and progesterone; produce eggs and drive secondary sexual characteristics.

Feedback Mechanism

Regulatory system where hormone levels are kept in precise quantities and timing by influencing other substances.

Phytohormones

Plant hormones that regulate growth and development.

Nastic Movement

Plant movement that is independent of stimulus direction; non-directional.

Tropic Movement

Growth movement of a plant organ in response to an external stimulus; directional.

Phototropism

Growth movement toward or away from light (toward light is positive phototropism).

Geotropism (Gravitropism)

Growth response to gravity.

Chemotropism

Growth response to chemicals.

Hydrotropism

Growth response to water.

Thigmotropism

Growth response to touch.

Auxins

Plant hormones produced at shoot tips; promote cell elongation, apical dominance, and tropisms.

Gibberellin

Plant hormone that promotes stem elongation and can overcome genetic dwarfism.

Cytokinins

Plant hormones that promote cell division, delay aging, and influence germination, flowering, and fruit development.

Abscisic Acid

Stress hormone that inhibits growth and causes seed dormancy and leaf senescence.

Ethylene

Gaseous plant hormone that promotes fruit ripening and leaf senescence/abscission.