The node of Ranvier is a periodic gap on the axon of certain neurons, that plays a key role in speeding the transmission of a nerve impulse along the neuron. Myelin sheath is concentric layers of lipids separated by protein layers providing high-resistance, low-capacitance electrical insulation.
The node of Ranvier ensures that rather than having the impulse travel the whole length of the axon, it jumps from one node of Ranvier to another through a process called saltatory conduction.
The Node of Ranvier regenerates the impulse ensuring the signal remains constant. The correct answer to the question is false since the regeneration of the signal occurs.
Revision
NEURON
- a specialized impulse- conducting cell that is the functional unit of the nervous system, consisting of the cell body and its processes, the axon and dendrites. 2. a nerve cell; the basic building block of the nervous system. (receive, process, transmit)
DENDRITE
- the branching process of a neuron that conducts impulses towards the cell. 2. The bushy, branching extensions of a neuron that receive messages and conduct impulses toward the cell body.
AXON
- the appendage of the neuron that transmits impulses away from the cell body. 2. the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands.
MYELIN SHEATH
- a layer of fatty tissue segmentally encasing the fibers of many neurons; enables vastly greater transmission speed of neural impulses as the impulse hops from one node to the next.
SENSORY/MOTOR NEURONS
- neurons that carry incoming info from the sensory receptors to the brain and spinal cord. B. neurons that carry outgoing info from the brain and spinal cord to the muscles and glands.
ACTION POTENTIAL
- a neural impulse; a brief electrical charge that travels down an axon.
THRESHOLD
1. the level of stimulation required to trigger a neural impulse
SYNAPSE
- the junction between the axon tip of the sending neuron and the dendrite or cell body of the receiving neuron. The tiny gap at this junction is called the synaptic gap or synaptic cleft. (some reduce nerve impulses)
NEUROTRANSMITTER
- chemical messengers that cross the synaptic gaps between neurons. When released by the sending neuron, neurotransmitters travel across the synapse and bind to receptor sites on the receiving neuron, thereby influencing whether that neuron will generate a neural impulse.
ALL-OR-NONE PRINCIPAL
- the neuron either fires or doesn’t 2. Something happens or doesn’t (go big or go home)
NERVOUS SYSTEM
- the body’s speedy, electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous system.
CENTRAL NERVOUS SYSTEM
1. CNS- the brain and spinal cord
PERIPHERAL NERVOUS SYSTEM
1. PNS- the sensory and motor neurons that connect the central nervous system (CNS) to the rest of the body
SOMATIC NERVOUS SYSTEM
1. the division of the peripheral nervous system that controls the body’s skeletal muscles. Also called the skeletal nervous system.
AUTONOMIC NERVOUS SYSTEM
- the part of the peripheral nervous system that controls the glands and the muscles of the internal organs (such as the heart). Its sympathetic division arouses, its parasympathetic division calms.
SYMPATHETIC NERVOUS SYSTEM
- the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
PARASYMPATHETIC NERVOUS SYSTEM
- the division of the autonomic nervous system that calms the body, conserving its energy
ENDOCRINE SYSTEM
- the body’s “slow” chemical communication system; a set of gland that secrete hormones into the bloodstream.
