NERVOUS SYSTEM

Cerebrospinal fluid (CSF)

A clear fluid circulating around the CNS that provides protection, support and transport.

Protective function of CSF

Absorbs shock and cushions the brain and spinal cord against physical damage.

Support function of CSF

Suspends the brain within the cranium, allowing it to effectively float and reducing pressure on nervous tissue.

Transport function of CSF

Transports nutrients to the CNS and removes wastes before returning to the circulatory system.

Cerebrum

The largest region of the brain, containing sensory, motor and association areas.

Cerebral cortex

A highly folded outer layer of grey matter in the cerebrum containing a large proportion of CNS neurons.

Cerebral white matter

Myelinated nerve fibres extending through the cerebrum.

Basal ganglia

Regions of grey matter located deep within the cerebrum.

Sensory areas of cerebrum

Areas that receive and process nerve impulses from sensory receptors.

Motor areas of cerebrum

Areas that send nerve impulses to muscles, particularly for voluntary movement.

Association areas of cerebrum

Areas involved in intellectual and emotional processes.

Corpus callosum

A bundle of nerve fibres connecting the left and right cerebral hemispheres and allowing communication between them.

Cerebellum

A brain region involved in posture, balance and fine coordination of voluntary muscle movements.

Cerebellum sensory input

The cerebellum receives information from the inner ear and stretch receptors in muscles to assist balance and coordination.

Hypothalamus

A brain region that maintains homeostasis and coordinates functions including body temperature, heart rate, blood pressure and endocrine activity.

Medulla oblongata

The lowest region of the brainstem that automatically regulates heartbeat, breathing and blood vessel diameter.

Cardiac centre

A region of the medulla oblongata that regulates the rate and force of the heartbeat.

Respiratory centre

A region of the medulla oblongata that controls the rate and depth of breathing.

Vasomotor centre

A region of the medulla oblongata that regulates blood vessel diameter.

Spinal cord

The part of the CNS extending from the base of the skull down through the vertebral canal.

White matter of spinal cord

Myelinated nerve fibres located towards the outside of the spinal cord.

Grey matter of spinal cord

Unmyelinated fibres and neuron cell bodies located towards the centre of the spinal cord.

Dorsal root ganglion

A region containing the cell bodies of sensory neurons entering the spinal cord.

Cranial nerves

Twelve pairs of nerves connected to the brain that may be sensory, motor or mixed.

Spinal nerves

Thirty-one pairs of mixed nerves connected to the spinal cord containing both sensory and motor fibres.

Mixed nerve

A nerve containing both sensory and motor neurons.

Afferent division of PNS

The division of the PNS that carries sensory information towards the CNS.

Somatic sensory division

Carries sensory impulses from the skin and muscles towards the CNS.

Visceral sensory division

Carries sensory impulses from internal organs towards the CNS.

Efferent division of PNS

The division of the PNS that carries motor information away from the CNS.

Somatic nervous system

The efferent division carrying impulses from the CNS to skeletal muscles and involved predominantly in voluntary responses.

Autonomic nervous system

The efferent division carrying impulses from the CNS to cardiac muscle, smooth muscle and glands, primarily maintaining homeostasis.

Somatic nervous system effector

Skeletal muscle.

Autonomic nervous system effectors

Cardiac muscle, smooth muscle and glands.

Somatic efferent pathway

One continuous nerve fibre carries information from the CNS to the effector.

Autonomic efferent pathway

Two nerve fibres carry information from the CNS to the effector with a synapse in an autonomic ganglion.

Autonomic ganglion

A collection of neuron cell bodies where the preganglionic and postganglionic neurons of an autonomic pathway synapse.

Preganglionic neuron

The first neuron in an autonomic pathway, travelling from the CNS to an autonomic ganglion.

Postganglionic neuron

The second neuron in an autonomic pathway, travelling from the autonomic ganglion to the target organ.

Sympathetic nervous system

The autonomic division responsible for the fight-or-flight response and preparing the body for increased physical activity.

Parasympathetic nervous system

The autonomic division responsible for maintaining basal conditions and promoting rest-and-digest functions.

Fight-or-flight response

The sympathetic response that increases oxygen and glucose supply to tissues required for increased physical activity while inhibiting less essential processes such as digestion.

Rest-and-digest response

The parasympathetic response that promotes functions associated with resting conditions, including digestion and energy storage.

Sympathetic effect on heart

Increases the rate and strength of heart contractions.

Parasympathetic effect on heart

Decreases the rate and strength of heart contractions.

Sympathetic effect on lungs

Dilates the bronchioles to increase airflow.

Parasympathetic effect on lungs

Constricts the bronchioles.

Sympathetic effect on stomach

Decreases movement and digestive activity.

Parasympathetic effect on stomach

Increases movement and digestive activity.

Sympathetic effect on liver

Increases glycogen breakdown and releases glucose into the blood.

Parasympathetic effect on liver

Increases glucose uptake and storage as glycogen.

Sympathetic effect on pupil

Dilates the pupil.

Parasympathetic effect on pupil

Constricts the pupil.

Sympathetic effect on salivary glands

Decreases saliva secretion.

Parasympathetic effect on salivary glands

Increases saliva secretion.

Sympathetic ganglia

Ganglia located close to the spinal cord that allow rapid and widespread activation of the fight-or-flight response.

Sympathetic pathway structure

Short preganglionic neurons synapse in ganglia near the spinal cord with relatively long postganglionic neurons.

Why sympathetic responses can be widespread

One preganglionic neuron can communicate with multiple postganglionic neurons, allowing simultaneous activation of multiple organs.

Parasympathetic ganglia

Ganglia located close to or within target organs, allowing precise and localised responses.

Parasympathetic pathway structure

Long preganglionic neurons travel close to the target organ and synapse with very short postganglionic neurons.

Alzheimer's disease

A progressive neurodegenerative form of dementia affecting memory, thinking, social and behavioural skills and eventually the ability to perform simple tasks.

Physiological cause of Alzheimer's disease

A build-up of beta-amyloid plaques and tau tangles on or within nerve cells causes neurons to lose function.

Beta-amyloid plaque

A protein deposit associated with loss of neuronal function in Alzheimer's disease.

Tau tangle

An abnormal accumulation of tau protein within neurons associated with Alzheimer's disease.

Parkinson's disease

A progressive neurodegenerative disease affecting movement controlled by the nervous system.

Symptoms of Parkinson's disease

Tremors that may progress to slowed movement, muscle stiffness and loss of automatic movements such as blinking.

Physiological cause of Parkinson's disease

Loss of dopamine-producing nerve cells, possibly associated with the accumulation of Lewy bodies.

Dopamine

A neurotransmitter produced by neurons that are progressively lost in Parkinson's disease.

Lewy body

An abnormal protein accumulation associated with loss of dopamine-producing neurons in Parkinson's disease.

Cell replacement therapy

The transplantation of human cells, potentially including stem cells, to replace or repair damaged cells or tissues.

Cell replacement therapy for Alzheimer's disease

Using stem cells to replace neurons affected by plaques or tangles with healthy neuronal cells.

Cell replacement therapy for Parkinson's disease

Using stem cells to replace damaged dopamine-producing cells with healthy functioning cells.

Receptor

A structure that detects changes in the body's internal or external environment.

Stimulus

A detectable change in the internal or external environment.

Thermoreceptor

A receptor that detects changes in temperature.

External thermoreceptor

A thermoreceptor in the skin that detects temperature outside the body and sends this information to the brain.

Internal thermoreceptor

A thermoreceptor in the hypothalamus that detects the temperature of blood flowing through the brain.

Osmoreceptor

A receptor located in the hypothalamus that detects changes in the osmotic pressure of blood.

Osmotic pressure

The concentration of dissolved substances in blood plasma; a higher solute concentration produces greater osmotic pressure.

Chemoreceptor

A receptor stimulated by chemicals, including receptors involved in smell, taste and monitoring blood chemistry.

Blood chemoreceptor

A receptor in blood vessels that detects changes in blood pH and oxygen or carbon dioxide levels.

Touch receptor

A receptor mainly found in the skin that detects touch, pressure or vibration.

Touch receptor sensitivity

The sensitivity of an area to touch depends on the concentration of touch receptors present.

Pain receptor (nociceptor)

A receptor stimulated by tissue damage, poor blood flow or excessive stimulation such as heat or chemicals.

Nociceptor

Another name for a pain receptor.

Pain receptor adaptation

Pain receptors do not adapt, allowing pain to continue while tissue damage remains.

Neuron

A specialised cell that transmits nerve impulses.

Cell body

The region of a neuron containing the nucleus and organelles that controls cell functioning.

Dendrite

A short extension of a neuron that carries nerve impulses towards the cell body.

Axon

A usually single, long extension of a neuron that carries nerve impulses away from the cell body.

Axon terminal

The branched ending of an axon involved in transmitting information to another cell.

Myelin sheath

A fatty layer surrounding some axons that insulates and protects the axon and increases the speed of nerve impulse transmission.

Schwann cell

A cell that forms the myelin sheath around axons in the peripheral nervous system.

Neurilemma

The outer layer of a Schwann cell that assists in repairing damaged nerve fibres.

Node of Ranvier

A gap between sections of myelin sheath along an axon.

White matter

Nervous tissue containing many long, myelinated axons.

Grey matter

Nervous tissue containing more cell bodies and short or unmyelinated fibres.

Synapse

The junction between two neurons, usually between the axon terminal of one neuron and the dendrite of another.

Sensory neuron

A neuron that carries nerve impulses from receptors or sense organs towards the central nervous system.

Afferent neuron

Another name for a sensory neuron; carries information towards the CNS.