Lecture 8 Nervous System

Flashcards for reviewing vocabulary related to the nervous system from Lecture 8.

Sensory Input

Information gathered by sensory receptors about internal and external changes

Integration

To process and interpret sensory input and decide if action is needed

Motor Output

A response to integrated stimuli; the response activates muscles or glands.

Central Nervous System (CNS)

Brain and spinal cord; integrative and control centers.

Peripheral Nervous System (PNS)

Cranial nerves and spinal nerves; communication lines between the CNS and the rest of the body.

Afferent

Sensory division of PNS; conducts impulses from receptors to the CNS.

Somatic

Conscious senses related to the body.

Autonomic

Visceral organs and involuntary functions.

Efferent

Motor division of PNS; conducts impulses from the CNS to effectors (muscles and glands).

Sympathetic

Division of the autonomic nervous system that mobilizes body systems during activity.

Parasympathetic

Division of the autonomic nervous system that conserves energy and promotes housekeeping functions during rest.

Neurons

Nerve cells which generate and conduct electric signals.

Glia

Cells that modulate neuron activity and provide support. Includes Macroglia and Microglia.

Macroglia

Modulate neuron activity and provide support.

Microglia

Small phagocytic cells; major immune defense mechanism in the nervous system.

Oligodendrocytes

Glial cells in the CNS.

Astrocytes

Glial cells in the CNS that contribute to the blood–brain barrier.

Schwann cells

Glia called schwann cells wrap the axons of other nerves.

Blood-brain barrier

Protects the brain from toxic substances in the blood.

Glymphatic System

Interstitial fluid enters the brain through the perivascular spaces between arteries and astrocytes; fluid leaves through perivascular spaces of the veins, taking metabolic waste products with it.

Myelination

Oligodendrocytes (in CNS) and Schwann cells (in PNS) wrap around neuron axons, forming concentric layers of insulating cell membrane.

Dendrites

Bring information to the cell body of a neuron.

Axon

Carries information away from the cell body of a neuron.

Axon terminals

At the tip of the axon.

Action potential (AP)

A sudden, rapid reversal in the voltage across a portion of the cell membrane.

Sodium-potassium pump

Moves Na+ to the outside and K+ to the inside; requires energy; establishes concentration gradients.

Electrochemical gradient

The combination of concentration gradient and voltage difference that affects ion movement.

Voltage-gated channels

Respond to change in voltage across membrane.

Chemically-gated channels

Depend on specific molecules that bind or alter the channel protein.

Mechanically-gated channels

Respond to force applied to membrane.

Depolarization

When the inside of a neuron becomes less negative.

Hyperpolarization

The membrane potential becomes even more negative.

Graded membrane potentials

Changes from resting potential proportional to the stimulus magnitude.

Axon hillock

The location where voltage-gated Na+ channels are concentrated.

Threshold

When the membrane is depolarized about 5 to 10 mV above resting potential; a large number of sodium channels open and an action potential is generated.

Refractory period

After an impulse has passed, each successive portion of the axon is unable to conduct an impulse.

Nodes of Ranvier

Regularly spaced gaps in the myelin along an axon.

Saltatory conduction

Action potentials appear to jump from node to node.

Synapse

Axon terminals come extremely close to the membrane of a target cell.

Neurotransmitter

Chemicals which diffuse to receptors on the postsynaptic cell; binding to the postsynaptic cell may excite or inhibit it.

Neuromuscular junctions

Chemical synapses between motor neurons and skeletal muscle cells.

Acetylcholine (ACh)

The neurotransmitter at neuromuscular junctions.

AChRs

Receptors on the motor end plate; gated channels that allow Na+ and K+ to flow through; synapses between motor neurons and muscle cells are excitatory, always causing depolarization.

Spatial summation

Adds up messages at different synaptic sites.

Temporal summation

Adds up potentials generated at the same site in a rapid sequence.

Acetylcholinesterase (AChE)

Enzyme that destroys ACh, clearing it from the synaptic cleft.

Glutamate

Main excitatory neurotransmitter in the brain.

Glycine

Inhibitory neurotransmitter in the brain.

γ-aminobutyric acid (GABA)

Inhibitory neurotransmitter in the brain.

Monoamines

Neurotransmitters such as dopamine, norepinephrine, and serotonin.

Telencephalization

In vertebrate evolution, the telencephalon increases in size and complexity.

Nucleus (CNS)

An anatomically distinct group of CNS neurons.

Ganglion (PNS)

An anatomically distinct group of PNS neurons.

Reticular activating system

The core of the brainstem; activity in these complicated sensory pathways can promote wakefulness.

Thalamus

Communicates sensory information to the cerebral cortex.

Hypothalamus

Regulates many homeostatic functions.

Limbic system

Responsible for instincts, long-term memory formation, drives such as hunger and thirst, sexual behavior, and emotions.

Amygdala

Involved in fear and fear memory.

Hippocampus

Transfers short-term memory to long-term memory.

Association cortex

Areas that integrate or associate sensory information or memories; higher-order information processing.

Agnosias

Inability to identify objects due to damage in the temporal lobe of the cerebral cortex.

Parietal lobe

Primary somatosensory cortex; receives touch and pressure information from the thalamus.

Insular cortex

Receives a great variety of afferent information; integrates physiological information from all over the body to create a sensation of how the body “feels.”

Nerve Net

A simple nervous system found in cnidarians with little or no integration or processing of signals.

Gray matter

Rich in neural cell bodies.

White matter

Contains myelinated axons.

Sensory receptor cells (sensors or receptors)

Transduce physical and chemical stimuli into neural signals.

Photosensitivity

Sensitivity to light.

Opsins

Photoreceptor molecules in animals; proteins with functional groups called 11-cis-retinal.

Rhodopsin

The most common opsin; gives humans sensitivity to low levels of light, but not color.

Rod cells

Highly light-sensitive and perceive shades of gray in dim light.

Cone cells

Function at high light levels; responsible for high-acuity color vision.