The Nervous System and Nervous Tissue

A collection of vocabulary flashcards related to the structure and function of the nervous system and nervous tissue.

Central Nervous System (CNS)

The part of the nervous system composed of the brain and spinal cord.

Peripheral Nervous System (PNS)

The part of the nervous system outside the CNS, including all nerves and ganglia.

Neuron

A nerve cell that transmits electrical signals in the nervous system.

Glial Cell

Supportive cells in the nervous system that maintain homeostasis, form myelin, and provide support and protection for neurons.

Gray Matter

Regions in the nervous system rich in neuronal cell bodies and dendrites, giving it a gray appearance.

White Matter

Regions in the nervous system rich in myelinated axons, making it appear lighter in color.

Action Potential

A rapid change in membrane potential that propagates along the axon and transmits electrical signals.

Resting Membrane Potential

The baseline voltage across the cell membrane when a neuron is not transmitting signals, typically around -70 mV.

Sodium-Potassium Pump

A transmembrane protein that moves sodium ions out of the cell and potassium ions into the cell to maintain resting membrane potential.

Dendrite

The branching process of a neuron that receives signals from other cells and transmits them to the soma.

Axon

A long, slender projection of a neuron that conducts electrical impulses away from the cell body.

Synapse

The junction where a neuron communicates with another cell, such as another neuron or muscle cell.

Neurotransmitter

Chemical messengers released by neurons that transmit signals across a synapse.

Graded Potential

A temporary change in the membrane potential in response to a stimulus, which can be depolarizing or hyperpolarizing.

Excitatory Postsynaptic Potential (EPSP)

A graded potential that makes a postsynaptic neuron more likely to generate an action potential.

Inhibitory Postsynaptic Potential (IPSP)

A graded potential that makes a postsynaptic neuron less likely to generate an action potential.

Somatic Nervous System (SNS)

The division of the PNS that controls voluntary movements and transmits sensory information.

Autonomic Nervous System (ANS)

The division of the PNS that controls involuntary bodily functions, including heart rate and digestion.

Parasympathetic Nervous System

A branch of the autonomic nervous system responsible for promoting the 'rest and digest' responses in the body. It conserves energy by slowing heart rate, increasing gastrointestinal activity, and promoting relaxation.

Sympathetic Nervous System

Another branch of the autonomic nervous system that prepares the body for 'fight or flight' responses. It increases heart rate, redirects blood flow to muscles, and enhances alertness in response to perceived threats or stress.

Autonomic Nervous System

A division of the peripheral nervous system that controls involuntary bodily functions, consisting of the parasympathetic and sympathetic nervous systems. It regulates processes such as heart rate, digestion, and respiratory rate.

Rest and Digest

A physiological state stimulated by the parasympathetic nervous system, characterized by decreased heart rate, increased digestion, and energy conservation.

Fight or Flight

A physiological response triggered by the sympathetic nervous system, preparing the body to confront or flee from perceived danger, marked by increased heart rate, release of adrenaline, and heightened alertness.

Preganglionic Neurons

Neurons that originate in the central nervous system and project to autonomic ganglia, where they synapse with postganglionic neurons. They are part of both sympathetic and parasympathetic nervous systems.

Postganglionic Neurons

Neurons that originate in autonomic ganglia and extend to target organs. They receive signals from preganglionic neurons and are responsible for carrying out autonomic functions, influencing heart rate, digestion, and glandular secretions.

Cholinergic Neurons

Neurons that release acetylcholine as their neurotransmitter. Most preganglionic neurons of both the sympathetic and parasympathetic systems are cholinergic, as well as postganglionic neurons of the parasympathetic system.

Adrenergic Neurons

Neurons that release norepinephrine as their neurotransmitter. Most postganglionic neurons of the sympathetic nervous system are adrenergic, which help mediate the fight or flight response.

Characteristics of the Parasympathetic Division

Promotes relaxation, energy conservation, and maintenance of bodily functions. It slows the heart rate, increases digestive activities, and facilitates restorative processes in the body.

Characteristics of the Sympathetic Division

Prepares the body for action during stress or danger. It increases heart rate, dilates airways, and inhibits digestive functions to allocate energy to essential functions for 'fight or flight' responses.

Neurotransmitters of the Parasympathetic Division

Primarily uses acetylcholine as its neurotransmitter at both preganglionic and postganglionic synapses, facilitating a calming effect on target organs.

Neurotransmitters of the Sympathetic Division

Mainly utilizes norepinephrine at postganglionic synapses, which amplifies the body's alertness and readiness for emergency responses, alongside the use of acetylcholine at cholinergic sympathetic fibers (e.g., sweat glands).

Location of Preganglionic Neurons in the Parasympathetic Division

Originate in the brainstem and sacral spinal cord, targeting ganglia that are close to or within the organs they innervate.

Location of Preganglionic Neurons in the Sympathetic Division

Originate in the thoracic and lumbar regions of the spinal cord, with ganglia situated close to the spinal cord forming the sympathetic chain.