Response - Nervous Communication: Key Terms Flashcards
Central nervous system (CNS)
The brain and spinal cord.
Peripheral nervous system (PNS)
The nerves branching off the brain or spinal cord, allowing the CNS to communicate with the rest of the body.
Neurone
A nerve cell which is adapted to conduct action potentials.
Sensory (or afferent) neurones
Neurones which transmit nerve impulses from receptors towards the CNS.
Motor (or efferent) neurones
Neurones which transmit nerve impulses away from the CNS to an effector.
Relay (or intermediate) neurones
Neurones which transmit impulses between sensory and motor neurones.
Stimulus
A detectable change in the internal or external environment of an organism.
Response
The result of a stimulus on an organism.
Receptor
A cell adapted to detect changes in the environment.
Effector
A cell, tissue, organ or system that responds to stimulation by a nerve impulse resulting in a response.
Reflex arc
The pathway of neurones involved in a reflex.
stimulus - receptor - sensory neurone - relay neurone - motor neurone - effector - response
Somatic nervous system
A division of the motor nervous system which carries nerve impulses to body muscles and is under voluntary control.
Autonomic nervous system
A division of the motor nervous system which carries nerve impulses to glands, smooth and cardiac muscle and is not under voluntary control.
Sympathetic
An autonomic pathway which stimulates effectors and so speeds up an activity.
Parasympathetic
An autonomic pathway which inhibits effectors and so slows down an activity.
Axon
A process extending from a neurone that conducts action potentials away from the cell body.
Dendrons
Extensions of a neurone’s cell body which subdivide into smaller branched fibres, called dendrites, that transmit nerve impulses from other cells to the cell body.
Nerve impulse
A self-propagating wave of electrical disturbance that travels along the surface of an axon membrane.
Sodium potassium pump
A carrier protein which actively transports 2 potassium ions into the axon and 3 sodium ions out of the axon.
Resting potential
A potential difference of -70mV found across the plasma membrane of a neurone that is not conducting an impulse.
Generator potential
Depolarisation of the membrane of s receptor cell as a result of a stimulus.
Threshold value
The minimum level of stimulus needed to trigger an action potential: -55mV
Coordinator
The link between a sensory neurone and motor neurone in the spinal cord
Polarised
Condition used to describe the axon when the inside of an axon is negatively charged relative to the outside
Voltage gated channels
Channels in the axon membrane which change shape
and therefore open or close depending on the voltage across the membrane
Depolarised
Condition used to describe the part of the axon membrane when the inside of the membrane has a positive charge of around +40mV
Hyperpolarisation
When the inside of the axon is more negative relative to the outside than usual
Repolarisation
When the resting potential of -65mV is re-established the axon is described as this
Refractory period
Time after an action potential when it is impossible for a further action potential to be generated
All-or-nothing principle
An action potential is exactly the same size, regardless of the size of the stimulus, providing it reaches the threshold value