Nervous System Organization, Neurons, and Synapses

Flashcards covering the organization of the nervous system, neuron structure and function, types of membrane potentials, and synaptic transmission, based on the provided lecture notes. Flashcards are in FILL_IN_THE_BLANK style.

The 'Big Picture' of the Nervous System involves sensory input, integration, and __.

motor output

Information gathered by sensory receptors about internal and external events is called __.

sensory input

The interpretation of sensory input by the nervous system is known as __.

integration

Activation of effector organs to produce a response is referred to as __.

motor output

The __ consists of the brain and spinal cord, acting as the integration and command center.

Central Nervous System (CNS)

The __ relays information to and from the CNS.

Peripheral Nervous System (PNS)

Neurons that relay information towards the CNS are called __ neurons.

afferent

__ neurons relay sensory information from the skin, skeletal muscles, and joints.

Somatic afferent

__ neurons relay sensory information from internal organs.

Visceral afferent

The __ division of the PNS consists of efferent neurons that relay information from the CNS to effector organs.

Motor (Efferent)

Conscious control of skeletal muscles via somatic motor neurons is part of the __.

Somatic (Voluntary) Nervous System

The __ regulates smooth muscle, cardiac muscle, and glands involuntarily.

Autonomic (involuntary) nervous system (ANS)

The two subdivisions of the Autonomic Nervous System are the sympathetic and __ divisions.

parasympathetic

__ are excitable cells that transmit electrical signals, are long-lived, and amitotic.

Neurons

Cells that protect neuronal function, such as Schwann cells, are called __.

supporting cells

The specialized part of the neurolemma for stimulus reception that conveys electrical signals toward the cell body are the __.

dendrites

The structure that propagates a 'message' away from the cell body and arises from the axon hillock is the __.

axon

__ produce a segmented protein-lipid sheath around most long or large-diameter axons, which functions to protect, nourish, insulate, and increase the speed of nerve impulse transmission.

Schwann cells

Myelin sheath gaps between adjacent Schwann cells, where axon collaterals can emerge, are called __.

Nodes of Ranvier

Dense collections of myelinated fibers are known as __.

white matter

Mostly neuron cell bodies and unmyelinated fibers, characterized by slow information transfer, form __.

gray matter

Neuron cell bodies grouped together in the CNS are called __.

nuclei

Neuron cell bodies grouped together in the PNS are called __.

ganglia

Bundles of axons grouped together in the CNS are called __.

tracts

Bundles of axons grouped together in the PNS are called __.

nerves

Neurons that transmit electrical impulses from sensory receptors toward the CNS are __ neurons.

Sensory (Afferent)

Neurons that carry electrical impulses from the CNS to effectors are __ neurons.

Motor (Efferent)

__ are association neurons that shuttle electrical impulses through CNS pathways; most are entirely within the CNS and unmyelinated.

Interneurons

Neurons relay information by changes in their __.

resting membrane potential

Ion channels that are always open are called __ channels.

leakage (non-gated)

__ channels open with the binding of a specific chemical compound, such as a neurotransmitter.

Chemically gated (ligand-gated)

Channels that open and close in response to changes in membrane potential are known as __ channels.

Voltage-gated

When gated channels are open, ions diffuse quickly across the neurolemma along chemical concentration gradients and __.

electrical gradients

Incoming short-distance signals, usually initiated in dendrites and propagated toward the neuron cell body, are called __.

graded potentials

Long-distance signals along axons that are propagated to other cells are called __.

action potentials

A reduction in membrane potential where the inside of the neuron becomes less negative than the resting potential, increasing the probability of producing a nerve impulse, is called __.

depolarization

The membrane potential at which the electrical 'message' will be propagated along the axon is known as the __.

threshold potential

During the repolarizing phase of an action potential, Na+ channels inactivate and slow voltage-sensitive __ gates open, allowing ions to exit the cell.

K+

When some K+ channels remain open after repolarization, allowing excessive K+ efflux and causing an undershoot of the membrane potential, it is called __.

hyperpolarization

The period during which an action potential ensures an all-or-none event and enforces one-way transmission of nerve impulses is the __.

absolute refractory period

The CNS determines stimulus intensity by the __ of action potentials.

frequency

A junction that mediates information transfer from one neuron to another neuron or to an effector cell is a __.

synapse

The neuron that conducts impulses toward the synapse is the __ neuron.

presynaptic

The neuron that transmits impulses away from the synapse is the __ neuron.

postsynaptic

Chemical messengers used within the nervous system are called __.

neurotransmitters

The fluid-filled space separating the presynaptic and postsynaptic neurons, ensuring unidirectional communication, is the __.

synaptic cleft

When an action potential arrives at the axon terminal of the presynaptic neuron, voltage-gated __ channels open, leading to neurotransmitter release.

Ca2+

Binding of neurotransmitter to postsynaptic receptors that open chemically-gated channels, leading to a local depolarization, results in an __.

excitatory postsynaptic potential (EPSP)

When neurotransmitter binds to postsynaptic receptors that open channels for K+ or Cl–, causing the intracellular compartment to become more negative (hyperpolarize) and reducing the neuron's ability to produce an action potential, it is called an __.

inhibitory postsynaptic potential (IPSP)

One or more presynaptic neurons transmitting impulses in rapid-fire order leads to __.

temporal summation

A postsynaptic neuron being stimulated by numerous presynaptic neurons at the same time results in __.

spatial summation

Neurotransmitter effects are terminated by reuptake through transport proteins, enzymatic degradation, or __.

diffusion away from the synapse

The effect of a neurotransmitter (excitatory or inhibitory) is determined by the __ type of the postsynaptic neuron.

receptor