Integration in Living Organisms – Nervous & Endocrine Systems

A set of 100 vocabulary flashcards covering system integration, nervous and endocrine structures, sensory reception, neural pathways, muscle contraction, and hormonal control mechanisms.

System integration

The coordinated functioning of multiple body systems so that their combined activity supports the needs of the whole organism.

Living system

A group of interacting biological components (cells, tissues, organs) that performs a specific vital function within an organism.

Cell–cell communication

The processes by which cells send and receive signals—chemical or electrical—to coordinate activity.

Hormone

A chemical messenger released by an endocrine gland into the blood that alters the activity of specific target organs.

Endocrine system

The collection of hormone-secreting glands that regulates long-term body processes via the bloodstream.

Reproductive system

The organ system responsible for producing gametes and enabling sexual reproduction; a common hormonal target.

Hierarchy of organisation

The structural levels in multicellular organisms: cells → tissues → organs → organ systems → organism.

Specialised cell

A cell adapted to perform a particular function within a tissue, e.g. epithelial or muscle cell.

Tissue

A group of similar specialised cells working together to carry out one function.

Epithelial tissue

Layers of epithelial cells that line organs; in the small intestine they absorb digested food.

Muscle tissue

Bundles of muscle cells that contract to produce movement.

Organ

A structure made of several tissue types performing a specific, complex function.

Heart

A muscular organ composed of cardiac muscle, vessels and connective tissue that pumps blood.

Organ system

A group of organs that cooperate to carry out major body functions, such as circulation or digestion.

Emergent property

A new ability that appears when simple components interact, summed up as 'the whole is greater than the sum of its parts.'

Reductionist approach

Studying biology by isolating and analysing individual components like single cells.

Systems approach

Studying biology by examining how different parts interact within a whole organism.

Nervous system

A rapid communication network using electrical impulses to sense, process and respond to stimuli.

Central nervous system (CNS)

The brain and spinal cord, which integrate incoming information and issue commands.

Peripheral nervous system (PNS)

The nerves outside the CNS that connect it with the rest of the body.

Electrical impulse

A travelling action potential along a neurone transmitting information.

Neurone

A nerve cell specialised to generate and conduct electrical impulses.

Nerve

A bundle of axons (neurones) wrapped together, carrying impulses to or from the CNS.

Endocrine gland

A ductless gland that secretes hormones directly into the bloodstream.

Secretion

The release of substances, such as hormones, from a glandular cell.

Target organ

A tissue whose cells possess receptors that bind a particular hormone and initiate a response.

Receptor (cell-surface)

A protein on the plasma membrane that specifically binds a signalling molecule like a hormone.

Complementary binding

The specific fit between a receptor and its hormone, enabling signal recognition.

Long-lived hormonal effect

A sustained physiological change that persists as long as a hormone remains bound to its receptor.

Brain

The main organ of the CNS composed of billions of neurones that processes and coordinates information.

Cerebral cortex

The highly folded outer layer of the cerebrum responsible for higher functions like memory and consciousness.

Cerebellum

A brain region beneath the cortex that coordinates balance and fine muscle movements.

Brainstem

The part of the brain connecting to the spinal cord; it relays signals and controls vital reflexes.

Medulla oblongata

A section of the brainstem that regulates unconscious activities such as heartbeat and breathing.

Pituitary gland

An endocrine gland at the brain’s base that secretes hormones like FSH and LH.

Hypothalamus

A brain region that regulates homeostasis and controls the pituitary gland via releasing hormones.

Photoreceptor

A light-sensitive cell in the retina that initiates vision.

Chemoreceptor

A sensory receptor that detects chemical stimuli, e.g. taste buds.

Thermoreceptor

A sensory receptor that detects temperature changes.

Mechanoreceptor

A receptor sensitive to mechanical stimuli such as sound vibrations or touch.

Osmoreceptor

A receptor in the hypothalamus or carotid artery that senses blood water potential.

Baroreceptor

A pressure receptor in blood vessels that detects stretch and blood pressure changes.

Proprioceptor

A receptor in muscles or joints providing information about body position and movement.

Spinal cord

A CNS structure conveying impulses between brain and body and mediating reflexes.

White matter

Regions of the spinal cord containing myelinated axons carrying signals to and from the brain.

Grey matter

Spinal cord tissue containing neurone cell bodies and synapses involved in reflex integration.

Reflex arc

The neural pathway that mediates an automatic reflex from receptor to effector without conscious brain involvement.

Sensory neurone

A nerve cell that transmits impulses from receptors to the CNS.

Relay neurone

An interneurone within the CNS that connects sensory and motor neurones in reflex pathways.

Motor neurone

A nerve cell that carries impulses from the CNS to effectors such as muscles.

Action potential

A rapid, temporary change in membrane potential that propagates along a neurone.

Depolarisation

The loss of the resting membrane potential when sodium ions enter a cell, initiating an action potential.

Neuromuscular junction

The synapse between a motor neurone terminal and a muscle fibre.

Acetylcholine (ACh)

The neurotransmitter released at neuromuscular junctions to stimulate muscle contraction.

Sarcolemma

The plasma membrane of a muscle fibre cell.

T-tubule

An invagination of the sarcolemma that conducts action potentials into the muscle interior.

Sarcoplasmic reticulum

Modified endoplasmic reticulum in muscle cells that stores and releases calcium ions.

Calcium ions (muscle contraction role)

Ions that bind troponin, initiating sliding of actin and myosin filaments.

Troponin

A regulatory protein on actin filaments that binds calcium to move tropomyosin.

Tropomyosin

A protein that blocks myosin-binding sites on actin until moved by troponin.

Sliding filament model

The explanation of muscle contraction based on actin and myosin filaments sliding past each other.

Myelin sheath

A multilayered lipid covering around some axons that increases impulse speed.

Schwann cell

A glial cell that produces a segment of myelin around a peripheral neurone.

Myelinated neurone

A neurone whose axon is wrapped in myelin, allowing saltatory conduction.

Fight-or-flight response

The body’s rapid physiological reaction to stress, preparing for action.

Epinephrine (adrenaline)

A hormone from the adrenal medulla that triggers the fight-or-flight response.

Adrenal medulla

The inner region of the adrenal gland that secretes epinephrine.

Sinoatrial node (SAN)

The heart’s natural pacemaker whose rate is increased by epinephrine.

Cardiovascular control centre

A medulla region that regulates heart rate via autonomic nerves.

Vasoconstriction

Narrowing of blood vessels, diverting blood away from less vital organs during stress.

Reflex

An automatic, rapid response to a stimulus that protects the body.

Nociceptor

A pain receptor that detects harmful stimuli like extreme heat or sharp objects.

Papilla (tongue)

A small projection on the tongue surface housing multiple taste buds.

Taste bud

A cluster of chemoreceptor cells on the tongue that detects dissolved chemicals.

Receptor potential

The graded depolarisation generated in a receptor cell by a stimulus.

Voltage-gated channel

A membrane protein that opens or closes in response to changes in membrane potential.

Neurotransmitter

A chemical released by neurones to transmit signals across synapses.

Synapse

The junction between two neurones where neurotransmitters convey impulses.

End-plate

Another term for the neuromuscular junction’s postsynaptic region on a muscle fibre.

Muscle fibre

A single, elongated muscle cell capable of contraction.

Circadian rhythm

A roughly 24-hour biological cycle regulating physiology and behaviour.

Melatonin

A pineal hormone that helps regulate circadian rhythms and sleep patterns.

Pineal gland

A small endocrine gland in the brain that secretes melatonin, acting as a biological clock.

Diurnal behaviour

Activity pattern in which an organism is mainly active during daylight hours.

Homeostasis

The maintenance of a stable internal environment despite external changes.

Hypothalamic control

Regulation of body functions through hormones and autonomic signals originating from the hypothalamus.

Osmoregulation

The homeostatic control of water balance and solute concentration in the blood.

Antidiuretic hormone (ADH)

A posterior pituitary hormone that increases water reabsorption in kidneys.

Oxytocin

A posterior pituitary hormone that stimulates uterine contractions and milk ejection.

Appetite regulation

Hypothalamic control of hunger and satiety via hormonal and neural signals.

Endocrine clock

The pineal gland’s role in timing hormonal secretion to daily light–dark cycles.

Endocrine calendar

Adjustment of melatonin release pattern to seasonal changes in day length.

Autonomic nervous system

The part of the PNS that controls involuntary actions of organs and glands.

Sympathetic nervous system

The autonomic division that prepares the body for stress or activity.

Adrenal gland

An endocrine gland above each kidney consisting of cortex and medulla; secretes steroid hormones and epinephrine.

Posterior pituitary

The pituitary lobe that stores and releases ADH and oxytocin made by the hypothalamus.

Anterior pituitary

The pituitary lobe that synthesises and secretes hormones such as FSH, LH, and growth hormone.

Integration centre

A CNS region, such as the spinal cord, that processes sensory input and initiates motor output.

Motor cortex

A region of the cerebral cortex that initiates voluntary muscle movements.

Balance

The ability to maintain body posture and equilibrium, coordinated mainly by the cerebellum.