C3.1 Integration of Body Systems – Vocabulary Review

These vocabulary flashcards summarize the key terms and definitions from the lecture on C3.1 Integration of Body Systems, covering nervous and endocrine coordination, feedback control, and interactions among body systems.

System integration

The coordinated interaction of cells, tissues, organs and body systems that allows an organism to function as a whole.

Emergent properties

New characteristics that arise from the collective interaction of system components; the whole is greater than the sum of its parts.

Hierarchy of biological organization

The structural levels of a multicellular organism: cells → tissues → organs → organ systems → organism.

Nervous signaling

Rapid electrical communication carried by neurons that produces fast, short-lived responses at specific targets.

Hormonal signaling

Chemical communication via hormones released into the bloodstream that produces slower, longer-lasting, widespread responses.

Transport system

Blood and lymph vessels that move nutrients, gases, wastes, hormones and heat throughout a large multicellular body.

Neuron

A nerve cell specialized to generate and transmit electrical impulses.

Sensory neuron

Neuron that carries information from receptors to the central nervous system.

Motor neuron

Neuron that conveys signals from the CNS to effectors such as muscles or glands.

Interneuron

Neuron located within the CNS that connects sensory and motor pathways and integrates information.

Nerve

A bundle of sensory and/or motor nerve fibres wrapped in protective connective tissue sheaths.

Myelin sheath

Insulating lipid layer around many axons that speeds impulse conduction.

Central nervous system (CNS)

Composed of the brain and spinal cord; the main integration and processing centre.

Peripheral nervous system (PNS)

All nervous tissue outside the CNS, linking it to the rest of the body.

Autonomic nervous system

PNS division that regulates involuntary functions of organs, glands and smooth muscle.

Somatic nervous system

PNS division that controls voluntary movements of skeletal muscles and relays sensory input from skin and sense organs.

Sympathetic nervous system

Autonomic branch that triggers ‘fight-or-flight’ responses, increasing heart rate and mobilising energy.

Parasympathetic nervous system

Autonomic branch that promotes ‘rest-and-digest’ activities, lowering heart rate and conserving energy.

Enteric nervous system

Network of neurons embedded in the gut wall that independently controls digestive tract motility and secretions.

Brain

Central organ that receives sensory input, processes information, stores memories and issues motor commands.

Cerebral hemispheres

Large folded regions responsible for conscious thought, learning, memory and voluntary control of skeletal muscles.

Cerebellum

Brain region that coordinates balance, posture, and the timing of skeletal muscle contractions.

Spinal cord

CNS pathway inside the vertebral column that relays impulses and serves as an integration centre for reflexes.

Reflex arc

The simplest neural pathway producing an involuntary response; includes receptor, sensory neuron, CNS synapse(s), motor neuron and effector.

Monosynaptic reflex

Reflex arc containing only one synapse between the sensory and motor neuron, e.g., the knee-jerk.

Reaction time

Interval between stimulus presentation and appearance of a voluntary response mediated by the brain.

Sensory receptor

Specialized cell or nerve ending that detects specific stimuli such as light, sound, pressure or chemicals.

Baroreceptor

Stretch receptor in aortic, carotid or atrial walls that senses blood pressure changes.

Chemoreceptor

Receptor that detects chemical changes, e.g., blood pH or gas levels, and informs cardiovascular or respiratory centres.

Pacemaker (sinoatrial node)

Cluster of cardiac muscle cells in the right atrium that sets the rhythm of the heartbeat.

Melatonin

Pineal hormone whose night-time secretion promotes sleep and helps set circadian rhythms.

Circadian rhythms

Endogenous 24-hour cycles in physiology and behaviour, regulated chiefly by melatonin.

Suprachiasmatic nuclei (SCN)

Hypothalamic cell clusters that act as the body’s master clock and control melatonin release.

Hypothalamus

Brain region linking nervous and endocrine systems; monitors blood variables and directs pituitary secretions.

Pituitary gland

Endocrine gland inferior to the hypothalamus that releases many hormones under hypothalamic control.

Epinephrine (adrenaline)

Adrenal medulla hormone that prepares the body for vigorous activity by increasing heart rate, blood flow and metabolic rate.

Feedback mechanism

Regulatory loop in which the output of a process influences its own activity.

Negative feedback

Control mechanism that counteracts deviations from a set point, maintaining homeostasis.

Positive feedback

Mechanism that amplifies a change until a specific outcome is achieved (less common in physiology).

Heart rate regulation

Adjustment of sinoatrial node activity via autonomic nerves in response to baro- and chemoreceptor input.

Ventilation rate

Number of breaths per minute, modulated by medullary centres in response to blood CO₂-linked pH changes.

Peristalsis

Wavelike contraction of circular and longitudinal gut muscles that propels food through the digestive tract.

Blood plasma components

Water, ions, plasma proteins, nutrients, gases, hormones and waste products transported in the liquid portion of blood.

Erythrocyte

Red blood cell; transports oxygen (and some CO₂) using haemoglobin.

Leukocyte

White blood cell; involved in defence and immunity.

Platelet

Small blood fragment essential for clot formation.

Homeostasis

Maintenance of a stable internal environment despite external or internal changes.

Stimulus

A detected change in the internal or external environment that can elicit a response.

Effector

Muscle or gland that carries out a response commanded by the nervous or endocrine system.

Response

An organism’s action or physiological change resulting from a stimulus.

Integration centre

Part of the CNS (brain or spinal cord) that processes sensory input and initiates motor output.