Chapter 12 Study Guide Flashcards

Flashcards covering anatomical and functional divisions of the nervous system, neuron structures, neuroglia types, membrane potentials, and synaptic transmission based on Textbook Chapter 12 material.

Afferent division of the PNS

Brings sensory information to the CNS from receptors in peripheral tissue and organs.

Efferent division of the PNS

Carries motor commands from the CNS to muscle, glands, and adipose tissue.

Special sensory receptors

Monitor smell, taste, vision, balance, and hearing.

Visceral sensory receptors

Monitor internal organs.

Somatic sensory receptors

Monitor skeletal muscles, joints, and skin surface.

Somatic nervous system (SNS) effector

Skeletal muscle.

Autonomic nervous system (ANS) effectors

Smooth muscle, cardiac muscle, glands, and adipose tissue.

Central Nervous System (CNS)

Consists of the brain and spinal cord.

Peripheral Nervous System (PNS)

Includes all the nervous tissue outside of the CNS and the ENS.

Nerve fibers

Bundles of axons that carry sensory information and motor commands in the PNS.

Nerves

Bundles of axons with associated blood vessels and connective tissues.

Soma

The cell body, which contains a large, round nucleus with a prominent nucleolus.

Axolemma

The plasma membrane of the axon, which surrounds the axoplasm.

Perikaryon

The cytoplasm surrounding the nucleus containing organelles that provide energy and synthesize organic materials.

Axoplasm

The cytoplasm of the axon, containing neurofibrils, neurotubes, small vesicles, lysosomes, mitochondria, and enzymes.

Nissl bodies

The ribosomes, golgi apparatus, rough endoplasmic reticulum, and mitochondria of the perikaryon; they give a gray color to neuron cell bodies.

Telodendria

The series of fine extensions at the end of the main trunk and any collaterals of an axon.

Dendrites

Slender processes that extend and branch out from the cell body, playing a key role in intercellular communication.

Axon terminals

Structures that play a communicating role with another cell.

What is the signficance of nerons not having centroileis

Lack centrolies, which permanently blocks them from undergoing cell division.

Anterograde axoplasmic transport

The flow of materials from the cell body to the axon terminal, carried by kinesin.

Retrograde axoplasmic transport

The flow of substances from the axon terminal toward the cell body, carried by dynein.

Anaxonic neurons

Small neurons with numerous dendrites but no obvious axons, located in the brain and special sense organs.

Bipolar neurons

Small, rare neurons with one dendrite and one axon with the cell body between them; they relay information in special sense organs.

Unipolar neurons

Neurons where the dendrites and axon are continuous and the cell body lies off to one side; they carry sensations from peripheral receptors to the CNS.

Multipolar neurons

Neurons with two or more dendrites and a single axon; they are the most common in the CNS and include motor neurons controlling skeletal muscles.

Sensory neurons

Unipolar neurons forming the afferent division of the PNS; their cell bodies are located in peripheral sensory ganglia.

Motor neurons

Neurons forming the efferent divisions of the PNS that carry instructions from the CNS to peripheral effectors.

Interneurons

Located between sensory and motor neurons, primarily within the brain and spinal cord; they function in integration and coordination.

Astrocytes

CNS neuroglia that maintain the blood-brain barrier, regulate ion concentration, and form scar tissue after injury.

Ependymal cells

CNS neuroglia that line ventricles and the central canal, assisting in producing and monitoring cerebrospinal fluid (CSF).

Oligodendrocytes

CNS neuroglia that myelinate CNS axons and provide a structural framework.

Microglia

CNS neuroglia that remove cell debris, wastes, and pathogens through phagocytosis.

Satellite cells

PNS neuroglia that surround neuron cell bodies in ganglia and regulate levels of $O_2$, $CO_2$, nutrients, and neurotransmitters.

Schwann cells

PNS neuroglia that surround all axons in the PNS, responsible for myelination and repair processes.

Myelin

Serves as electrical insulation and increases the speed at which an action potential travels along the axon.

Internodes

The fairly large areas of the axon that are wrapped in myelin.

Nodes of Ranvier

The small gaps of a few micrometers that separate adjacent internodes.

White matter

Regions of the CNS dominated by myelinated axons, appearing glossy white due to lipids.

Gray matter

Areas containing neuron cell bodies, dendrites, and unmyelinated axons.

Wallerian degeneration

The process where the axon distal to an injury site degenerates and macrophages clean up the debris.

Leak channels

Passive channels that are always open.

Sodium-potassium pump

An active exchange pump powered by ATP that exchanges $3$ intracellular sodium ions for $2$ extracellular potassium ions.

Resting membrane potential

The potential of a neuron at rest, which is $-70\,mV$.

Chemically gated ion channels

Channels that open or close when they bind specific chemicals or ligands.

Voltage-gated ion channels

Channels that open or close in response to changes in the membrane potential.

Mechanically gated ion channels

Channels that open or close in response to physical distortion of the membrane surface.

Graded potential

Changes in the membrane potential that cannot spread far from the site of stimulation.

Depolarization

Any shift from the resting membrane potential toward a less negative potential.

Repolarization

The process of restoring the normal resting membrane potential after depolarization.

Hyperpolarization

An increase in the negativity of the resting membrane potential caused by the loss of positive ions.

Action potential

An all-or-nothing electrical event initiated by a graded potential that affects an entire excitable membrane.

Threshold

The membrane potential at which an action potential begins, typically between $-60\,mV$ and $-55\,mV$.

Refractory period

The time between the initiation of an action potential and the restoration of the resting membrane potential during which the membrane does not respond normally.

Saltatory propagation

The rapid carrying of action potentials along a myelinated axon where the signal jumps between nodes.

Type A fibers

The largest myelinated axons that carry action potentials at speeds up to $120\,m/s$.

Type C fibers

Unmyelinated axons with slow propagation speeds.

Neuromuscular junction

A synapse between a neuron and a skeletal muscle cell.

Neuroglandular junction

A junction at which a neuron controls or regulates the activity of a secretory gland cell.

Cholinergic synapses

Synapses that release the neurotransmitter Acetylcholine (ACh).

Acetylcholinesterase

The enzyme that breaks down Acetylcholine into choline and acetate.

Neuropeptides

A class of neurotransmitters that acts as neuromodulators to adjust the sensitivity of other neurons.

Excitatory postsynaptic potential (EPSP)

A graded depolarization caused by the arrival of a neurotransmitter at the postsynaptic membrane.

Inhibitory postsynaptic potential (IPSP)

A graded hyperpolarization of the postsynaptic membrane.

Temporal summation

The addition of stimuli occurring in rapid succession at a single synapse.

Spatial summation

The cumulative effect on membrane potential from simultaneous stimuli applied at different locations.

What are the four classes of neurotransmitters

1. Biogenic amines

2. Amino acids

3. Neuropeptides

4. Dissolved gases

 What ion enters the axon terminal triggering the release of ACh?

Calcium

What molecule are realsed at a chemical snyase

neuttransmitter

Two factors that affect potential propagation speed

1. Myelin

2. Diameter of the axon

The presence of what substance on an axon determines whether r continuous or salutatory propagation of actin potential occurs

Myelin

Step 1. of the generation of an action potential

Depolarization to threshold

Step 2. of the generation of an action potential

Activation of voltage-gated sodium ion channels and rapid depolarization 

Step 3. of the generation of an action potential

Inactivation of voltage gated soidum ion channels and activation of voltage gates potassium ions channel being reploarization

Step 4 of the generation of an action potential

Closing of voltage-gated potassium ion channels and the restoration of the normal resting membrane potential. During this period, the membrane will not return to the resting membrane potential

What is the threshold of an axon in mV

between -60mV and 55mV

What is the membrane potential of the neuron in millivolts

-70mV

When a neuron is at rest, do potassium ions enter or leave the cell through leak channels

Potassium ions leave the cell

When neurons are at rest, do sodium ions enter or leave the cell through leak channels

sodium ions enter the cell through leak channels

Why is the repair of damaged PNS neurons more likely than the repair of CNS neurons

Limited regeneration can occur in the CNS, but the situation is more complicated because many more axons are likely to be involved.

Why is white matter whiter in color

The lipids in the myelin

What are the neuralgia located in the PNS

1. Satellite cells

2. Schwann cells

List the Neuroglia located in the CNA

1. Astrocytes

2. Ependymal cells

3. Oligodendrocytes

4. Microglia

List the three groups of recpetors

1. Special sensory receptors

2. Visual sensory receptors

3. Somatic sensory receptors