Name and describe the fourstructural categories of

neurons

1. multipolar: multiple nerve processesextend directly from the cell body;typically many dendrites and oneaxon.

2. bipolar: two nerve cell processesextend directly from the cell body;one dendrite/one axon

3. unipolar: single short cell processextends directly from the cell andlooks like T as a result of fusion oftwo processes into one long axon

4. anaxonic: nerve cell processes areonly dendrites; no axon present.

Describe the distribution ofpumps and channels in the

plasma membrane of aneuron.

entire plasma membrane of aneuron: Na+ leak channels, K+ leakchannels, and Na+/K+ .

establish/maintainresting membranepotential.

receptive segment: includesdendrites and cell body; chemicallygated (cation, K+ Na+ channelspresent)Initial segment: composed of axonhillock; voltage-gated channels(Na+, K+)Conductive segment: length of axonand its branches; voltage-gatedchannels (Na+, K+)Transmissive segment: includessynaptic knobs; voltage-gatedCa2+channel, Ca2+ pump

Explain how the restingmembrane potential of a

neuron is maintained.

RMP is chiefly a consequence of plasmamembrane permeability to ions. It is primarilyestablished by leak channels (K + and Na +)

and maintained by the activity of Na +/K +pumps located in the plasma membrane.Potassium diffusion is the most importantfactor, K + movement is dependent on itselectrochemical gradient. K+ movement is

facilitated by its chemical concentrationgradient but opposed by the electrical

gradient.

depolarization: inside of a cellbecomes more positive than theRMP. occurs when Na+ moves intothe neuron via open gated

Compare depolarization andhyperpolarization.

channels.hyperpolarization: inside of a cellbecomes more negative than theRMP. Results in gated K+ channelsallowing positively charged K+ tomove out of the neuron, permittingCl- to move into the neuron.

Explain what a gradedpotential is and where it would

occur in the neuron.

(local potentials) occur in the receptivesegment of the neuron (dendrites and cell

bodies) and are due to the opening ofchemically gated channels. Voltage changecan either be positive or negative. Amount ofvoltage change is relatively small. Intensity

decreases with distance.

Explain how EPSP's andIPSP's are generated

IPSPs (inhibatory neurotransmittor) binds toK+ or Cl- channels and causes them to openwhich makes the cell hyperpolarize (inside

more negative). EPSPs (excitatory) cause aslight depolarization (inside more positive) by

opening up Na+ channels

Compare/contrast spatial andtemporal summation

1. Spatial - occurs when excitatory potentialsfrom many different presynaptic neuronscause the postsynaptic neuron to reach

threshold & fire 2. Temporal - occurs when a single

presynaptic neuron fires many times (tap, tap,tap), causing the postsynaptic neuron to reach

its threshold & fire

Define threshold.Minimum voltage change to

open voltage-gated channels(typically -55 mV)

Describe the formation of an action potential.Describe the polarized, depolarized,

repolarized, and hyperpolarized phases. Explain the roles of voltage gated sodium and

potassium channels at each phase.

An action potential is due to theopening of voltage-gated channelsin response to voltage chain.Propagated along the length of anaxon. The propagation of an actionpotential is called a nerve signal.Depolarization and its propagationinvolves the sequential opening ofvoltage-gated Na+ channels alongthe axon. Occurs when threshold(-55mV) is reached. Na+ enters,polarity goes from negative topositive (-55mV to +30mV)Repolarization and its propagationinvolves the sequential opening ofvoltage-gated K+ channels thatafter the closing of the Na+channels right (depolarization). K+moves out of cell and it becomesnegative (+30 to -70mV)Hyperpolarization: voltage-gated K+open longer than need to be andinside of neuron is more negative

than -70mV. Na+/K+ pumpsreestablish RMP after v.g. K+channels close

Explain the role of calcium inneurotransmitter release.

1. Action potential reaches synaptic knob 2. V.G. calcium channels open, Ca enters and

binds with proteins of synaptic vesicles 3. Synaptic knob vesicles merge with plasma

membrane and neurotransmitters are releasedby exocytosis

4. Neurotransmitters cross synaptic cleft andattach to receptors

Describe two ways in which

neurotransmitters are removed

from the synaptic cleft

1. degradation: chemically inactivated in

synaptic cleft

2. reuptake: reabsorbed by neurotransmitter

protein in membrane of presynaptic neuron.

Recycled by presynaptic neuron once

packaged into another synaptic vesicle for

reuse.

Explain the myelination

process and how it impacts the

transmission of the nerve

impulse

insulates axons and helps with nerve impulse

transmission

1. Schwann cells wrap along portion of axon

2. Cytoplasm and plasma membrane of

Schwann cells form layers around axon and

keep wrapping

3. Overlapping inner layers of Schwann cell

plasma membranes form myelin sheaths

4. Schwann cell cytoplasm and nucleus

pushed to outer area of cell as myelin sheath

is formed

Compare and contrast

continuous and salutatory

conduction. Which is faster

and why?

Continuous conduction occurs on

unmyelinated axons and involves sequential

opening of v.g. Na+ and K+ channels located

within axon p.m.

Salutatory occurs on myelinated. Salutatory is

faster because the action potential leaps

across the myelin sheaths (at neurofibril

nodes). Process repeats till it reaches the

synaptic knobs.

Compare anterograde and

retrograde axonal transport.

anterograde: movement of materials from cell

body to synaptic knobs

retrograde: movement of materials from

synaptic knob to cell body

Neuromodulation

facilitation

a) occurs when greater respons of

postsynaptic neuron

b) may increase amount of neurotransmitter in

synaptic cleft

c) may increase number of receptors on

postsynaptic neurons

Neuromodulationinhibition

a) occurs when less response frompostsynaptic neuron

b) may decrease amount of neurotransmitter c) may decrease number of receptors on

postsynaptic neruon

Compare absolute and relativerefractory periods

Absolute: won't fire again for a while, nomatter the signal. Ensures action potentialmoves along axon in one direction toward

synaptic knobs.

Relative: immediately after absolute. Will fireagain only if there is a STRONG signal

(greater than initial stimulus)

Compare and contrast thethree layers of the meninges

surrounding the brain

pia mater: innermost; thin layer of areolartissue that adheres to brain and follows

contours of brain surface arachnoid mater: middle layer; web of collagen

fibers and elastic fibers dura mater: external, tough, dense irregularconnective tissue composed of two fibrous

layers (strongest layers)

Describe the structure andfunction of the dural sinus and

dural septa

dural sinus: blood-filled layer, rigid walls, novalves, triangular

draws blood from braincycle CSF is added to venoussupply here

dural septa: inward partitions dividing cranialcavity and provide support

four cranial dura septa; falxcerebri is the largest

How/where is CSFformed?

- formed through active transport of ions andsmall molecules and diffusion of water-Formed (in ventricles) at choroid plexus

What is the CSFcirculation pattern?

-CSF is produced by choroid plexus -CSF flows into subarachnoid space via the

median and lateral apertures for the brain andspinal cord

-CSF flows through the subarachnoid space -CSF is absorbed into the superior sagittal

sinus via the arachnoid villi

Structure of bloodbrain barrier

tight junctions seal together endothelial cells,continuous basement membrane, astrocyte

processes cover capillaries.

Where is the blood brainbarrier missing or reduced?

(Three regions)

the choroid plexus, thehypothalamus, and the pineal

gland

Identify the five lobes found ineach hemisphere and describethe general function of each.

frontal: voluntary motor functions, intellectualfunctions

parietal: sensory interpretation oftextures/shapes; understanding speech and

word formation temporal: interpretation and storage of

auditory and smelling sensations;understanding speech

occipital: perception of visual stimuli, eyefocusing, correlating visual images with

previous experiences insula: interpretation of taste; memory

What are the three types ofcerebral white matter tracts

and examples?

1. association tracts- form connections withinsame hemisphere (~arcuate fibers, premotor

area with primary motor cortex) 2. commissural tracts- connect left and right

hemispheres (~corpus callosum) 3. projection tracts- tracts between cerebrumand other part of brain and spinal cord (motoraxons traveling to spinal cord; sensory axons

traveling from spinal cord)

Explain what cerebral lateralization refers to

and compare categorical and representational

hemispheres.

cerebral lateralization: each hemisphere

specialized for certain tasks

categorical hemisphere: left hemisphere;

specialized for language abilities and

sequential/analytical reasoning tasks

representational hemisphere: right

hemisphere; spatial relationships, creative

thinking, pattern perception, musical/artistic

talents

petalias: structural differences between lobes

(right handed ppl tending to have right frontal

petalia and left occipital petalia)

Identify the three regions of the

diencephalon and describe the

function of each

epithalamus: forms roof of third ventricle

pineal gland: secretes

melatonin

habenular nucleus: controls

emotional responses to odors

thalamus: makes up majority of diencephalon.

Plays role in mediating sensation, motor

activites, cortical arousal, learning, and

memory

hypothalamus: extends from optic chiasma to

posterior end of mammillary bodies. Control

center for autonomic nervous system; major

role in maintaining homeostasis through

regulation of body temperature, food intake,

water balance and thirst

Identify the three regions of the

brainstem and describe the

function of each.

midbrain: surrounds cerebral aqueduct,

contains reflex centers for movements

associated with visual and auditory stimuli

substantia nigra: pigmented

area produces dopamine

pons: anterior wall of fourth ventricle;

maintenance of normal breathing rhythm

medulla oblongata: inferior part of brain stem;

cardiac center, vasomotor, and respiratory

center. Vomiting, hiccupping, and swallowing

regulated here

What is the structure and

function of the cerebellum?

- Structure = internal grey matter surrounded

by white matter. Outer cortex of grey matter.

Two hemispheres.-Vermis connects the two

lobes

-Connects to brain stem by cerebellar

peduncles (fibers)

-Processes and interprets impulses from

motor cortex and sensory pathways.

-Coordinates motor activity for smooth

movements; important for balance. and

posture

helps maintain responses to emotions,

Describe the main functions of the limbicsystem and identify the general regions of the

brain involved.

motivation, mood, and pleasure/pain cingulated gyrus: receives input from other

parts of limbic system; associated withsatisfaction hunger/sexual. Enhanced activityduring obsessive compulsive behaviors and

addictive behaviors hippocampus: essential in storing memories

and long-term memory amygdaloid body: involved in emotion,

especially fear; codes memories based onemotion

Describe the components and function of thereticular formation and identify the general

regions of the brain involved.

motor component assists with regulatingmuscle tone, respiration, blood pressure, and

heart rate Reticular Activating System (RAS) processesvisual, auditory, and touch stimuli. Contributes

to general alertness/consciousness

Compare and contrast thethree spaces associated with

the spinal cord meninges.

Epidural space=lies between dura and materand inner walls of the vertebra, epidural

anesthetics introduced here

subdural space=potential space between duramater and arachnoid mater, cerebral spinal

fluid

subarachnoid space= deep arachnoid mater,space filled with cerebrospinal fluid

What are the 5 anatomicalregions of the spinal cord?

1. Cervical Nerves (C1-C8)2. Thoracic Nerves (T1-T12)3. Lumbar Nerves (L1-L5)4. Sacral Nerves (S1-S5) 5. Coccygeal Nerves (1)

What is gray matter? Where isit located within the spinalcord? What about white

mater?

Gray matter is the butterfly shaped area in themiddle of the spinal cord. This is where theneuron cell bodies and unmyelinated axonsare located. White matter is external to graymatter. It's divided into ventral, dorsal, and

lateral columns

Efferent vs afferent Efferent=output (from brain) afferent=input (to brain)

Compare the dorsal and ventral roots and thespinal cord and describe the pathway of

information into and out of the spinal cord.

Each of these 62 spinal nervesdivides as it nears the cord and itsaxons are joined to the cord 2roots: dorsal or ventral.Dorsal:are sensory (afferent)neurons with their cell bodiesgrouped together just outside thecord to form dorsal root ganglia.Many of synaptic terminals are inthe dorsal horns of the spinal graymatter

Ventral: are motor (efferent)neurons with their cell bodiesin the ventral horns. part ofthe somatic NS--> to skeletalmuscles, autonomic NS -->ganglia

Describe the typicalspinal nerve

Each spinal nerve is formed by thecombination of nerve fibers from the dorsal

and ventral roots of the spinal cord.

The dorsal roots carry afferent sensory axons,while the ventral roots carry efferent motor

axons

Compare anterior, posterior,and communicating rami anddescribe the function of each.

anterior: thicker, form somatic nerve plexusesin cervical, lumbar, and sacral regions

posterior: innervate deep muscles of back communicating: contain axons associated with

autonomic nervous system

Compare the gray and whitebranches of the rami

communicantes

white: carry preganglionicsympathetic axons from spinalnerves to sympathetic trunkgray: carry postganglionicsympathetic axons fromsympathetic trunk to the spinalnerve

Describe the structure andfunction of the sympathetic Allows nerve fibers to travel to spinal nerves;

in front of spinal nerves and lateral to vertebral

trunk and identify where it'slocated

column

Compare and contrast the somatic andautonomic neuron organization including theneurotransmitters and receptors involved.

Somatic: one neuron extending from CNS toskeletal muscle, muscle excitation and

contraction Acetylcholine involved.

ANS: two neurons between the CNS andeffector organ; acetylcholine and

norepinephrine excitation or inhibition

Describe the role ofneurotransmitters in dual

innervation

Sympathetic and parasympathetic divisions.Capable of binding acetylcholine and

norepinephrine respectively. Antagonisticeffects (increase in heart rate with sympathetic

stimulation and decrease withparasympathetic stimulation)