Control and Coordination (Chapter 6)

Vocabulary flashcards covering nervous and endocrine systems, brain regions, reflexes, plant hormones, and tropisms.

Receptor

A sensory cell or nerve ending that detects a stimulus (e.g., gustatory or olfactory receptors) and initiates a nervous impulse.

Neuron

A nerve cell; the basic unit of nervous tissue that transmits electrical impulses.

Dendrite

The part of a neuron that receives impulses from other neurons.

Axon

The long fiber of a neuron that conducts impulses away from the cell body.

Synapse

The gap between neurons where impulses are transmitted by chemicals.

Neuromuscular junction

The synapse between a motor neuron and a muscle cell.

Central nervous system (CNS)

Brain and spinal cord; the main coordinating center for processing information.

Peripheral nervous system (PNS)

Nerves outside the CNS connecting it to limbs and organs.

Spinal cord

Nerve bundle within the backbone; forms reflex arcs and transmits signals to and from the brain.

Brain

Main coordinating center; consists of forebrain, midbrain, and hindbrain.

Forebrain

Front brain region responsible for thinking and processing sensory inputs.

Midbrain

Middle brain region involved in processing and relaying information.

Hindbrain

Posterior brain region controlling involuntary actions and balance.

Cerebellum

Part of the hindbrain; coordinates precision of movements and balance.

Medulla

Part of the hindbrain; controls involuntary actions like breathing and heart rate.

Hypothalamus

Brain region linking nervous and endocrine systems; regulates hunger, thirst, and hormone release.

Pituitary gland

Master endocrine gland; secretes growth hormone and other hormones; regulated by hypothalamus.

Adrenal glands

Glands that secrete adrenaline into the bloodstream in stress.

Adrenaline

Hormone increasing heart rate, blood flow to muscles, and breathing in emergencies.

Thyroxine (thyroxin)

Thyroid hormone regulating metabolism; synthesis requires iodine.

Thyroid gland

Gland in the neck that produces thyroxine.

Growth hormone

Pituitary hormone that stimulates growth in all body organs.

Insulin

Pancreatic hormone that regulates blood glucose levels.

Iodised salt

Table salt fortified with iodine to support thyroid hormone production.

Goitre

Swelling of the neck due to iodine deficiency affecting the thyroid.

Negative feedback

Regulatory mechanism where increased hormone levels reduce further secretion.

Endocrine system

System of glands that use hormones for chemical coordination.

Plant hormone

Chemical signals (e.g., auxin, gibberellins, cytokinins, abscisic acid) guiding growth and responses.

Auxin

Shoot-tip hormone causing cell elongation on the shaded side, bending toward light.

Gibberellins

Plant hormones that promote stem growth and seed germination.

Cytokinins

Plant hormones that promote cell division and growth in rapidly dividing areas.

Abscisic acid

Plant hormone that inhibits growth and helps cope with stress (e.g., wilting).

Tropism

Direction-based growth response of a plant toward or away from a stimulus.

Phototropism

Growth toward light (shoots) or away from light (roots).

Geotropism (gravitropism)

Growth response to gravity; shoots grow upward, roots downward.

Hydrotropism

Growth toward moisture or water sources.

Chemotropism

Growth toward chemical stimuli.

Mimosa pudica (sensitive plant)

Plant that folds its leaves rapidly in response to touch; not growth-based.

Reflex action

Automatic, involuntary response to a stimulus without conscious thought.

Reflex arc

Neural pathway in the spinal cord enabling a quick reflex action.

Involuntary action

Movements not under conscious control, often regulated by brainstem.

Voluntary action

Movements initiated by conscious decision and controlled by the brain.

Nervous tissue

Tissue made of neurons that transmits electrical impulses.

Hormone

Chemical signal released by endocrine glands into blood to act on distant targets.

Endocrine gland

Glands that secrete hormones, such as pituitary, thyroid, pancreas, and adrenal.

Releasing hormone

Hypothalamic hormones that stimulate the pituitary to release other hormones.

Feedback mechanism

Regulatory loop adjusting hormone release based on current conditions.