Fundamentals of the Nervous System and Nervous Tissue

Flashcards covering the fundamentals of the nervous system and nervous tissue.

Sensory Input

Detects changes inside and outside the body

Integration

Processes sensory input and decides what should be done at each moment

Motor Output

Dictates a response by activating effector organs (muscles and glands)

Central Nervous System (CNS)

Brain and Spinal Cord; integration and command center

Peripheral Nervous System (PNS)

Nervous system outside of the brain and spinal cord

Afferent (Sensory) Division

Conveys impulses to the CNS from sensory receptors

Somatic Sensory Fibers

Sensory fibers conveying impulses from skin, skeletal muscles and joints

Visceral Sensory Fibers

Sensory fibers conveying impulses from the visceral organs

Efferent (Motor) Division

Transmits impulses from the CNS to effector organs (muscles and glands)

Somatic Nervous System

Voluntary nervous system; Conducts impulses from the CNS to skeletal muscles

Autonomic Nervous System

Involuntary nervous system; Regulates smooth muscle, cardiac muscle, and glands

Neuroglia

Supportive cells of the nervous system (also called glial cells)

Astrocytes

Neuroglia of the CNS; most abundant glial cell; support and brace neurons; help form the Blood Brain Barrier; control the chemical environment around neurons

Microglia

Neuroglia of the CNS; defensive cells (macrophages) that engulf microbes and dead neurons

Ependymal Cells

Neuroglia of the CNS; line the central cavities of the brain and spinal cord; help circulate cerebrospinal fluid (CSF)

Oligodendrocytes

Neuroglia of the CNS; produce myelin sheaths that insulate nerve fibers

Satellite Cells

Neuroglia of the PNS; surround neuron cell bodies

Schwann Cells

Neuroglia of the PNS; surround nerve fibers and form myelin sheaths

Neurons

Excitable cells that transmit electrical signals

Cell Body

The biosynthetic center of the neuron; contains the nucleus and most organelles

Dendrites

Branchlike extensions of the neuron that receive signals from other neurons

Axons

A single extension of the neuron that transmits signals to other neurons or effector cells

Myelin Sheaths

Whitish, fatty covering around axons that protect and insulate the axon and increase the speed of nerve impulse transmission

Multipolar Neurons

Neurons with three or more processes (one axon and multiple dendrites)

Bipolar Neurons

Neurons with two processes (one axon and one dendrite)

Unipolar Neurons

Neurons with a single process extending from the cell body

Sensory (afferent) Neurons

Transmit impulses from sensory receptors to the CNS

Motor (efferent) Neurons

Carry impulses from the CNS to effectors (muscles or glands)

Interneurons

Lie between sensory and motor neurons; integrate sensory input and motor output:

Voltage

Measure of potential energy generated by separated charge

Potential Difference

Voltage measured between two points

Resistance

Hinderance to charge flow (provided by the plasma membrane)

Resting Membrane Potential (RMP)

Potential difference across the membrane of a resting cell

Factors that generate RMP

Generated by differences in ionic makeup of ICF and ECF and differential permeability of the plasma membrane

Electrochemical Gradient

The combined effect of concentration and electrical gradients on ion movement

Concentration Gradient

Ions move from areas of high concentration to areas of low concentration

Electrical Gradient

Ions move toward an area of opposite electrical charge

Depolarization

A reduction in membrane potential (less negative)

Hyperpolarization

An increase in membrane potential (more negative)

Repolarization

The return of the membrane potential to its resting state

Graded Potentials

Short-lived, localized changes in membrane potential that can be either depolarizing or hyperpolarizing.

Action Potential

A brief reversal of membrane potential with a total amplitude of about 100 mV

Threshold

The membrane potential at which the outward current is equal to the inward current

Propagation

Allows the action potential to be transmitted from the origin down the entire axon length

Refractory Period

The period after initiation of an action potential when neuron is not able to respond to another stimulus

Conduction Velocity

Velocity at which an action potential propagates along an axon

Multiple Sclerosis

Autoimmune disease in which the myelin sheaths of the CNS are destroyed

Synapse

A junction that mediates information transfer from one neuron to the next or from a neuron to an effector cell

Chemical Synapse

Synapses that use neurotransmitters to transmit information

Electrical Synapse

Synapses that use gap junctions to directly transmit electrical signals

Excitatory Synapse

A synapse where neurotransmitter binding depolarizes the postsynaptic membrane

Excitatory Postsynaptic Potential (EPSP)

A local depolarization of the postsynaptic membrane that brings the neuron closer to AP threshold

Inhibitory Synapse

A synapse where neurotransmitter binding hyperpolarizes the postsynaptic membrane

Inhibitory Postsynaptic Potential (IPSP)

A local hyperpolarization of the postsynaptic membrane that drives the neuron away from AP threshold

Neurotransmitters

Chemicals that transmit signals across a synapse

Acetylcholine

A neurotransmitter derived from acetic acid and choline

Biogenic Amines

Neurotransmitters that include catecholamines (dopamine, norepinephrine, epinephrine) and indolamines (serotonin, histamine)

Amino Acids

Examples include glutamate, aspartate, glycine, and GABA

Peptides

Examples include substance P and endorphins

Purines

Examples include ATP and adenosine

Gases

Examples include nitric oxide (NO) and carbon monoxide (CO)

Lipids

Examples include endocannabinoids

Channel Linked Receptors

Receptors where ligand binding directly opens an ion channel

G-Protein Linked Receptors

Receptors where ligand binding activates a G protein, which in turn activates or deactivates an enzyme that generates a second messenger