Natriuresis
/ˌneɪtri jʊˈriːsɪs/
The excretion of sodium in the urine; although this is normal, it can be promoted by certain hormones.
Negative Feedback
/ˈnɛɡətɪv ˈfiːdbæk/
A regulatory mechanism in which a stimulus causes a response that opposite or reduces the original stimulus.
Nephron
/ˈnɛfrɒn/
The functional unit of the kidney, responsible for removing waste and reabsorbing substances from the blood.
Nerve
/nɜːrv/
A whitish fiber or bundle of fibers that transmits impulses of sensation to the brain or spinal cord, and impulses from these to the muscles and organs.
Neuroglia
/nʊˈrɒɡliə/
Non-neuronal cells in the central nervous system and the peripheral nervous system that do not produce electrical impulses but provide support and protection for neurons.
Neuromuscular Junction
/ˌnjʊəroʊˈmʌskjʊlə ˈdʒʌŋkʃən/
A chemical synapse formed by the contact between a motor neuron and a muscle fiber.
Neuron
/ˈnjʊərɒn/
A specialized cell transmitting nerve impulses; a nerve cell.
Neurotransmitter
/ˌnjʊəroʊtrænzˈmɪtər/
A chemical substance released at the end of a nerve fiber by the arrival of a nerve impulse.
Neutrophil
/ˈnjuːtrəfɪl/
A type of white blood cell that is the first to arrive at the site of an infection to ingest microorganisms.
Nociceptor
/ˌnoʊsɪˈsɛptər/
A sensory receptor for painful stimuli.
Nodes of Ranvier
/ˌnoʊdz əv ˈrɒnvieɪ/
Gaps in the myelin sheath of a nerve, between adjacent Schwann cells, where the axon membrane is exposed.
Norepinephrine
/ˌnɔːrˌɛpɪˈnɛfrɪn/
A hormone and neurotransmitter involved in the fight-or-flight response, increasing heart rate and blood pressure.
Nucleus
/ˈnjuːkliəs/
A dense organelle present in most eukaryotic cells, typically a single rounded structure bounded by a double membrane, containing the genetic material.