Organic Chemistry Solomon and Fryhle: Ch2 Representative Carbon Compounds

POLAR, NON-POLAR MOLECULES

• Non-polar covalent bonds have no difference in electronegativity between bonded atoms ie. No charge separation. 
• Ex. H2, Cl2, O2, N2….
• Polar covalent bonds have a difference in electronegativity between atoms in which the center of the positive charge and the negative charge coincide, so no  net dipole moment is created.
• The overall polarity is the sum of all the dipole vectors.

PHYICAL PROPERTIES AND MOLECULAR STRUCTURE

• The physical properties include melting point, boiling points, density, dipole moment, and solubility.
• Intermolecular forces (van der waals) - these are forces that act between molecules that give them the ability to exist in liquid and solid states even though they are non-polar.
• Dipole - a movement resulting in a non-uniform distribution of bonding electrons. This will cause the molecules to orient themselves so that the positive end of one molecule is directed toward the negative end of another. 
• This is also apparent in Cis (same) and Trans (opp) alkenes which have different physical properties.

 

• Hydrogen bonds - a very strong dipole-dipole bond that occurs between a hydrogen and a small, or strongly electronegative atom (O,N, or F) and other non bonding electron pairs. These are stronger than dipole bonds but weaker than covalent bonds.
• Dispersion forces - (London force) this is a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles. This is the force that causes non-polar substances to change from liquid to solids when the temp is lowered significantly.
• Symmetry - molecules that are symmetrical tend to have abnormally high melting points due to the compactness of the molecule.
• Solubility - a solvent will only be soluble in its solute if the molecules of the solute are able to overcome the intermolecular forces that are holding the solvent in its solid state.     
• Polar compounds - these are soluble only by water and a few other solutes, they do so by hydrating or solvating the ions.
• Like dissolves like
• Some alkyl groups are miscible in water though, namely methanol and ethanol due to their short carbon chains. Since they are more like water than an alkane they will dissolve in water, but if there is a long carbon chained alcohol it will not dissolve in water because its carbon chain makes it more like an alkyl than an alcohol.
• 1-3carbons are soluble in water
• 4-5 carbon chains are borderline
• 6 or more carbons are not soluble in water.
• Changes from order to disorder are favorable, but changes from disorder to order are not favorable.  

CARBON-CARBON BONDS

• Carbon has a unique bonding ability with other atoms (H, O, N, S, and halogens)
• Carbon compounds have a very large number of possible compounds that allow for a great deal of complexity and many many isomers.

HYDROCARBONS

• These molecules contain only carbon and hydrogen
• Alkanes - single carbon-carbon bonds
• Ethane (also called acetylene)

 

• Alkenes - have at least one carbon-carbon double bond (planer in shape)

 

• Alkynes - have at leave one carbon-carbon triple bond ( this will have a linear shape)

 

• Aromatic hydrocarbons - (benzene rings)  these are sp2 hybridized

 

FUNCTIONAL GROUPS

• This is where most of the chemical reactions will take place.  
• Alkyl halides - compounds in which a halogen atom replaces a hydrogen atom of an alkane (halo alkanes). These can be divided into groups depending on the number of carbons that its attached carbon is attached to ( 1°, 2°, 3°)

• Alcohols - (methanol/ethanol) have the structural form CH3OH, characterized by its hydroxyl (OH) group attached to an sp3 carbon.

• Ethers- these have the general formula of R-O-R or R-O-R' (where R' may be an alkyl or phenyl group different from R). These can be thought of as water where the hydrogen atoms have been replaced by alkyl groups. One way we name these is by naming the attached alkyl groups (diethyl ether)

• Amines - can be thought of as derivatives of ammonia (NH3). This is classified depending on the number of carbon (organic groups) that are attached to the nitrogen.  This is also an sp3 hybridization.

• Carbonyl group - a group in which a carbon is double bonded to an oxygen.

• Ketone - this is a carbonyl group that is bonded to two carbon atoms (RCOR or RCOR') has a trigonal planer arrangement.

• Aldehydes - a carbonyl group that is bonded to one hydrogen and one carbon atom ( RCHO or HCHO) has a trigonal planer arrangement. 

• The following groups of carboxylic acids, esters, and amides can be inter converted using chemical reactions that will be covered later.
• Carboxylic acids - a carbonyl and hydroxyl group combined with the general formula of RCO2H or RCOOH. Examples of these are formic acid, acetic acid, and benzoic acid.

 

• Esters - have the general formula RCO2R' or RCOOR', where a carbonyl  group is bonded to an alkoxyl group.

 

•  Esters can be made from a carboxylic acid and an alcohol through the acid catalyzed loss of a molecule of water, which the OH of the acid will react with the Hydrogen of the alcohol. This will then allow for the remaining portion of the alcohol to attach to the remaining portion of the acid.
• Amides - a carbonyl group is bonded to a nitrogen atom bearing hydrogen and/or alkyl groups with the general formula RCONH2 or RCONHR'.

 

COMMON ORGANIC TERMINOLOGY

• Alkyl groups "R-"
• The dash show attachment to the rest of the molecule.
• IUPAC names

• Methyl is one carbons, ethyl has 2 carbons, and propyl has 3 carbons… isopropyl groups have 3 carbons that are not in a chain. Each lower group can derived from the groups above it.
• When a carbon ring is attached to some other groups, it is called a phenyl. The phenyl group and its CH2 group attaching it to the rest of the molecule makes up the benzyl group.

• Sub-classification of Sp3 carbons atoms
• 1°, 2°, 3° alkyl halides
• Primary carbons are bonded to one other carbon
• Secondary carbons are bonded to two other carbons
• Tertiary carbons are bonded to three other carbons
• Quaternary carbons are bonded to four other carbons
• Classification of alkyl halides (-X)  and alcohols (-OH)
• Can either be primary, secondary, or tertiary
• The degree here is determined by how many carbons are attached to the carbon that the halide or alcohol is bonded to
• Classification of Amines
• Primary, secondary, or tertiary possibilities
• This is dependent on how many carbons the Nitrogen is bonded to, meaning this focuses on the nitrogen and not the carbon as the center atom.

CURVED ARROWS

• A curved arrow is used to show the movement of electrons in a Lewis Structure 
• The arrow needs to starts where the electron was originally (either a bond or lone pair) then ends where the electron is being moved to.

 

• Do not move an atom from a positively charged atom, and do not go from an atom to a lone pair ( this would suggest that the atom moved.
• Homolysis - the bond is evenly broken, this produces fragments with unpaired electrons called radicals.

 

• Heterolysis - the bond is not evenly broken, one will get both electrons while the other will get none ( this will depend on electronegativity, where the bond is polarized) this will form charged fragments or ions.

• Making bonds
• Coordinate covalent bonds - where one atom brings two electrons to the bond while the other brings none; it doesn’t matter where the electrons are coming from just that they are there.

 

• An arrow can also be used to show electron flow during a chemical reaction.
• Curved arrows can also help depict resonance structures.

IR SPECTRA

• This is used to identify functional groups, which will absorb at different frequencies, showing the IR spectra
• When a bond absorbs IR, it will stretch or bend changing the average amplitude of the bond but not the frequency of the vibration. This absorption is due to how strong the bond is and the size of the atoms.
• The frequency is equal to the IR absorption. A stronger bond will absorb more energy, as will a lighter atom.  

 

Organic Chemistry Solomon and Fryhel: Ch1 Carbon Compounds and Chemical Bonding

• Atomic Orbitals
• Electron probability density - the square of a wave for a particular x,y,z location expresses the probability of finding an electron there.
• Orbitals - a place where finding an electron is high
• Atomic orbital - plots of wave functions in three dimension, this is where we get the shapes for the S, P, and D orbitals.
• Molecular orbital - shows the region in space where one or two electrons of a molecule are likely to be found.
• Energy levels
• As we get further away from the nucleus of an atom, the electrons gain energy. Ie 1s has less energy than 2s and even less energy than 2p. But each electron in an electron pair have the same amount of energy.
• Aufbau Principle - orbitals will fill lowest energy to highest energy
• Pauli exclusion principle - a max of two electrons can be places in each orbital as long as the electrons spin in opposite directions.
• Hund's rule - when it comes to degenerate orbitals, we fill each orbital with one electron first then go back and add the second electron to each orbital. This allows the electrons to be further apart is they can ( two negatives will repel)
• Chemical bonding.
• Ionic bonding - (electrovalent) electrons are taken from one atom and given to another.
• This occurs due to the attractive force between two oppositely charged ions.
• Covalent bonding - two atoms will share an electron.
• This occurs when two atoms with similar electronegativity interact and end up sharing an electron, this is the most common and ALL molecules are formed by covalent bonds.
• Electronegativity is an atoms ability to attract electrons.

 

• Octet rule - the tendency of an atom to try to achieve 8 electrons in its valence shell
• There are exceptions too this rule. All elements in the third period and beyond have "d" orbital and can make more than the normal 4 bonds (ie 8 electrons) these are usually P, S, CL
• And some highly reactive molecules or ions may have less than 8 electrons.

• Lewis structure
• Lewis structures show the connection between atoms in a molecule or ion using only the valence electrons of the atom involved.
• Main group elements have the same number of valence electrons as their group number on the periodic table.
• Each atom will attempt to obtain eight electrons
• Hydrogen wants to have 2 valence electrons, meaning it will be like helium and can make one covalent bond.
• Isomers - different substances that share the same molecular formula (the atomic connectivity is different) these molecules will have different physical and chemical properties.

• Formal charge - the number of valence electrons minus half of the number of shared electron minus the number of unpaired electrons.
• F=Z-(1/2)s-u
• The sum of all the charges in a molecule or ion will equal the overall charge of the ion or molecule.
• Resonance  = the state attributed to certain molecules having a structure that con not adequately be represented by a single structure or formula, but is a composite of two or more structures of higher energy. (only the electrons are moving around)
• None of the structures are an accurate depiction of the molecule or ion, and will be better represented by a hybrid structure.

 

• It is important to understand that a single barred arrow is sign for resonance and that the double barred arrow is the sign for equilibrium.
• The energy of the resonance hybrid is lower than the energy of any contributing structure; but if the resonance structures are equivalent, then its energy is large.  (the more stable a contributing factor is by itself, the greater its contribution to the hybrid.
• Stability of structures in resonance.
• The more covalent bonds the more stable
• Charge separation decreases stability  (Ϩ+ and Ϩ-)
• Structures that have an octet are more stable.
• Molecular orbitals
• Molecular orbitals are formed when atomic orbitals combine, the number of molecular orbitals always equals the number of atomic orbital that combined, and they will combine either in or out of phase.

 

• Bonding molecular orbital occurs when the two orbitals are in the same phase
• Anti-bonding molecular orbitals occur when the two orbitals are of an opposite phase. This state occurs when the molecule in the ground state absorbs a photon of light of the proper energy level.
• Bond length - the inter-nuclear distance between the two atoms.
• Heisenberg theory of uncertainty - there is no way to know the position AND momentum of an electron at a given time.
• There are four types of atomic orbitals

 

• S orbitals
• Each S orbital can hold two electrons
• S block elements, elements that have an S orbital as their valence group, include group 1 (alkali metals) and group 2 (alkaline earth metals)
• P orbitals
• There are three p orbitals
• P block elements , elements in groups 13-18, all have a fully filled S orbital and a full or partially full P orbital.
• D orbitals
• There are 5 D orbitals with a possible 10 electrons
• D block elements are in groups 3-12 on the periodic table (transition metals)
• F orbitals
• There are 7 F orbital with a possible 14 electrons
• F block elements are in the lanthanide and actinide families at the very bottom of the periodic table
• These orbitals combine to form molecules

• HYBRIDIZATION
• Hybridization - the concept of "mixing" atomic orbitals into new hybrid orbitals that are more suitable for the pairing of electrons to form chemical bonds in valence bond theory.
• Percent S and percent P character.
• The amount of s- and p- character in a molecular orbital relates to the amount of energy and stability of the bond or orbital. This is important in carbocations.
• p- orbitals have more energy and stability than s-orbitals.
• To find the % s or p divide the number of s or p orbitals by the total number of orbitals.
• Sp3 hybridization
• This is the simplest of the three carbon hybridizations, where one s-orbital combines with three p-orbitals

 

•  ex. Methane - the hydrogen's s-orbital overlaps with one of the carbons half filled sp3 orbitals forming a covalent bond. 
• This bond is also an example of a single bond or sigma σ, which is cylindrically symmetrical allowing for a lot of movement.
• The 2 cylinders will overlap, this will allow for rotation without changing the overall shape of the.
• Sp2 hybridization

 

• Uses two p-orbitals and  one s-orbital to hybridize, when this happens three sp2 orbitals and one p orbital is left un-hybridized which tends to lead to a double bond with the sp2 hybridized carbon, oxygen, or nitrogen. Resulting in one π bond and one σ bond.
• The p2 orbitals are responsible for the π bond
• This type of bond is more ridged than the sp3 bond but is still partially cylindrically symmetrical. The σ bond is more stable than the π bond and must be formed first, in a reaction the π bond will be the first to break.
• Sp hybridization

 

• One s-orbital and one p-orbital combine to for 2sp orbitals, this bond is responsible for the extremely inflexible triple bond.
• This will form either one triple bond with a similarly hybridized carbon, nitrogen, or oxygen… or it can form two double bonds.
• MOLECULAR GEOMETRY (VSEPR Theory)

 

 

Play Therapy: The Art of The Relationship: Ch2 The Meaning of Play

• Play is intrinsically complete, does not depend on external reward, and assimilates the world to match the child's concepts…"play is the way children learn what no one can teach them it is the way they explore and orient themselves to the actual world of space and time, of things, animals, structures, and people. By engaging in the process of play, children learn to live in our symbolic world of meanings and values, at the same time exploring and experimenting and learning in their own individual ways." - Frank (1982)
• Analyzing play is a way for us to see how the child sees the world and their place in the world.
• Play can help bridge the gap between concrete experience and abstract thought.
• A major function of play is the changing of what may be unmanageable in reality to manageable situations through symbolic representation, which provides children with opportunities for learning to cope by engaging in self-directed exploration.
• This can be seen by observing the effects of 911 on children and adults. Adults would talk about their experience and feelings on the subject at length, while children would not verbalize their emotions, thoughts, or concerns. Rather they would build towers and crash airplanes into them, or at walls, then scolded the toy aircraft.
• For children to "play out" their experiences and feelings is the most natural dynamic and self-healing process in which they can engage.
• It is the therapists responsibility to go to a child's level and communicate with children through the medium which they are comfortable.
• "the toys implement the process because they are definitely the child's medium of expression… his free play is an expression of what he wants to do… when he plays freely and without direction, he is expressing a period of independent thought and action… he is releasing the feelings and attitudes that have been pushing to get out into the open". (Axline, 1969)
• Children's feelings are often inaccessible at a verbal level.
• The child's world is a world of concretes and must be approached as such if contact is to be made with the child.
• "the most normal and competent child encounters what seem like insurmountable problems in living. But by playing them out, in the way he chooses, he may become able to cope with them in a step-by-step process. He often does so in symbolic ways that are hard for even him to understand, as he is reacting to inner processes whose origin may be buried deep in his unconscious. This may result in play that makes little sense to us are the moment or may even seem ill advised, since we do not know the purposes it serves or how it will end. When there is no immediate danger, it is usually best to approve of the child's play without interfering, just because he is so engrossed in it. Efforts to assist him in his struggles, while well intentioned, may divert him from seeking, and eventually finding, the solution that will serve him best." - bettelheim (1987)
• Play is a voluntary, intrinsically motivated activity involving flexibility of choice in determining how an item is used. No extrinsic goal exists. The processes of play is enjoyed, and the end product is less important. Play involves the child's physical, mental, and emotional self in creative expression and can involve social interaction.
• Thus when the child plays, one can say that the total child is present.
• "play therapy is defined as a dynamic interpersonal relationship between a child and a therapist trained in play therapy procedures who provides selective play materials and facilitates the development of a safe relationship for the child to fully express and explore self through play, the child's natural medium of communication, for optimal growth and development."
• The dynamics of expression and vehicle for communication are different for children, but the expression (fear, satisfaction, anger, happiness, frustration, contentment) are similar to those of adults.
• Even though many children may have the vocabulary, they do not have the rich background of experience and associations which would render these words meaningful condensates of emotional experiences in terms of their potential usefulness in therapy.
• Children's play is meaningful and significant to them, for through their play they extend themselves into areas they have difficulty entering verbally
• Play is the child's symbolic language of self-expression and can reveal
• What the child has experienced
• Reactions to what was experienced
• Feelings about what was experienced
• What the child wishes, wants, or needs
• The child's perception of self.
• Play is the child's way of working out balance and control in their lives for, as children play, they are in control of the happenings in play, although it may not be possible to actually be in control of the life experience represented in the play. It is the sense or feeling of control, rather than actual control, that is essential to children's emotional development and positive mental health.
• The therapist is allowed to experience and participate in the emotional lives of children rather than reliving situational happenings. Because children thrust their total beings into their play, expressions and feelings are experienced by children as being specific, concrete, and current, thus allowing the therapist to respond to their present activities, statements, feelings, and emotions rather than to past circumstances.

Stages in the play therapy process.

• Stages in the play therapy process are the result of shared interactions between the therapist and the child, experienced in the non-evaluative, freeing environment of the playroom, facilitated by the genuine caring for and prizing of the child as communicated by the total person of the therapist. In this unique living relationships, in which the unique nature and individuality of the child are accepted and appreciated, the child experiences permission to expand the horizons of themselves in keeping with the degree of acceptance inwardly felt and communicated by the therapist.
• Moustakas' (1955)
1. Defuse negative feelings, expressed everywhere in the child's play.
2. Ambivalent feelings, generally anxious or hostile.
3. Direct negative feelings, expressed towards parents, siblings, and others, or in a specific forms of regression
4. Ambivalent feelings, positive and negative, toward parents, siblings, and others.
5. Clear, distinct, separate, usually realistic positive and negative attitudes, with positive attitudes predominating in the child's play.
• The disturbed child's attitudes-whether anger, anxiety, or other negative attitudes- all follow this process and play therapy progresses. … the interpersonal relationship allows the child to express and explore the various levels of the emotional process and thus to achieve emotional maturity and growth.
• Hendricks (1971)
• 1-4 sessions: at thi8s stage, children expressed curiosity; engaged in exploratory, noncommittal, and creative play; made simple descriptive and informative comments; and exhibited both happiness and anxiety
• 5-8 sessions: here the children continued exploratory, noncommittal, and creative play. Generalized aggressive play increased, expressions of happiness and anxiety continued, and spontaneous reactions were evident.
• 9-12 sessions: exploratory, noncommittal, and aggressive play decreased; relationship play increased; creative play and happiness were predominant; nonverbal checking with the therapist increased; and more information about family and self was given.
• 13-16 sessions: creative and relationship play predominated; specific aggressive play increased; and expressions of happiness, bewilderment, disgust, and disbelief increased.
• 17-20 sessions: dramatic and role play predominated, specific aggressive statements continued, and increased relationship building with the therapist occurred. Expression of happiness was the predominate emotion, and children continued to offer information about self and family.
• 21-24 sessions: relationship play and dramatic and role play predominated, and incidental play increased.

Play of adjusted and maladjusted children.

• The initial reactions of maladjusted children are cautious and deliberate. Adjusted children are free and spontaneous in their play.
• Adjusted children will examine the whole play setting and use a large variety of play materials, in contrast to maladjusted children, who use a few toys and play in a small area. Maladjusted children often want to be told what to do and what not to do. Adjusted children use various strategies to discover their responsibilities and limitations in the therapeutic relationship.
• When bothered or annoyed, adjusted children use a concrete way to bring out their problem. Maladjusted children are more likely to express their feelings symbolically with paints, clay, sand, or water. Maladjusted children often are aggressive and want to destroy the play materials and some times the therapist. Aggression also is seen in the adjusted children, but it is clearly expressed  without massive destruction, and responsibility is accepted for the expression. Adjusted children are not so serious and intense in their feelings about themselves, the therapist, or their play as are maladjusted children.
• The difference between well-adjusted and maladjusted children lies not primarily in the type of negative attitudes they demonstrate, but rather in the quantity and intensity of such attitudes.
• Maladjusted- less focus and direction.
• Aggressive children presented frequent play disruptions, conflicted play, self-disclosing statements, high levels of fantasy play, and aggressive behavior towards the therapist and toys.
• Withdrawn boys- identified by their regression in response to anxiety, bizarre play, rejection of the therapist's intervention, and dysphoric content in play.
• Well- adjusted children- less emotional discomforts, less social inadequacy, and less fantasy play.
• Withdrawn girls- could not be differentiated from well adjusted girls.
• " maladjusted children expressed significantly more disphoric feelings, conflictual themes, play disruptions, and negative self-disclosing statements than did adjusted children. Maladjusted children also spent a larger portion of their playtime feeling angry, sad, fearful, unhappy, and anxious than did the adjusted children. Maladjusted children talked and played out their problems and conflicts during more of the play session than did adjusted children. No significant differences existed between adjusted and maladjusted children in the area of social inadequacy play of the use of fantasy play.
•  the therapist is cautioned about unrestrained inferences as to the meaning of child's play. Neither the toys the child uses nor the manner in which the child plays with the toys is an absolute indication of an emotional problem area. Environmental factors, recent happenings, and economic depravation may be structuring factors.

Neuroscience: Exploring the Brain: Ch2 Neurons and Glia

• THE NEURON DOCTRINE
• There are two main types of brain cells; neurons and glia. The ratio of these cells are about 1:10.
• Neurons sense changes in the environment, communicate these changes to other neurons, and command the body's responses to these changes.
• Glial cells contribute to the brain function mainly by insulating, supporting, and nourishing neighboring neurons.
• The ability to examine the cells of the brain depended on the use of formaldehyde to fix the cells in place without distorting the structure, and the development of the microtome to slice the brain thin enough for it to be studied under a microscope. Stains, like the Nissl (crystal violet) and the Golgi stain, allowed us to study cells.
• The Nissl stain stains the nuclei of the cells as well as the clumps of material surrounding the nuclei (Nissl bodies). This stain allows us to distinguish between glial cells and neurons, as only the nuclei of the neurons will be stained. It also gives us the ability to study the arrangement of the cells (cytoarchitecture) in different parts of the brain.
• The study of cytoarchitecture led to the discovery that the brain is made up of many specialized regions.
• The Golgi stain is done by soaking the brain tissue is a silver chromate solution, which will stain a small amount of the neurons in their entirety showing that the neuron is made up a central cell area (soma) and a neurites (axons, and dendrites)
• Cajal used the Golgi stain to work out the circuitry of many regions of the brain and proposed that the neurites of different cells are fused together to form a continuous network, and that the brain is a continuation of cell theory ( the individual cell is the elementary functional unit of all animal tissue).
• Neuron doctrine is the idea that neurons adhere to the cell theory.

 

 

 

• THE PROTOTYPICAL NEURON
• THE SOMA  
• This is the body of the neuron, measuring about 20 nanometers in diameter, and filled with a watery fluid called cytosol, which is a salty potassium rich solution that is separated from the outside by the neuronal membrane. Within the cytosol, there are several organelles.
• Contains all the organelles that a normal cell would have.
• THE NEURONAL MEMBRANE
• this serves as a  5nm barrier to enclose the cytoplasm inside the neuron and to exclude certain substances that float in the fluid. It is studded with proteins and protein pumps that have the ability to regulate what can enter and leave the cell. The composition of the proteins depends on whether it is a soma, dendrite, or the axon.
• THE CYTOSKELETON
• this is the internal structuring of the cell and is composed of microtubules, microfilaments, and neurofilaments.  
• Microtubules- about 20 nm in diameter and run longitudinally down neurites. It consists of a hollow tube that is composed of smaller strands made of tubulin that are braided like a rope around the center. These can be regulated by the cell using proteins like Microtubule-associated proteins (MAPs) which help anchor the microtubules to one another and to other parts of the neuron. Changes in the axonal MAPs (tau) are associated with the dementia in Alzheimer's.
• Microfilaments- only 5nm in diameter and are particularly numerous in the neurites and are composed of two thin braided strands of the polymers of the protein actin. These are closely associated with the membrane and form a spider web like mesh of support for the cell.
• Neurofilaments- about 10 nm in diameter and exist in all cells of the body as intermediate filaments, and are organized like sausage links.

 

 

 

• THE AXON
• these are found only in neurons and are specialized for the transfer of information over distances in the nervous system.
• No rough ER extends into the axon, and there are few , if any, free ribosomes. And the protein composition of the axon membrane is different from the soma membrane.
• These different proteins mean that there is no protein synthesis and allows it to send information over long distances.
• The axon begins with the axon hillock, which tapers to form the initial segment of the axon.
• Axon collaterals- this is where the axon branches out, and will occasionally return to communicate with the same cell (recurrent collaterals).
• Axon proper- the middle part of the axon
• Axon terminal- also called the terminal bouton, and is where the axon comes into contact with other neurons or cells to pass information on to them through a point called a synapse.
• The cytoplasm of the axon terminal differs from the axon in several ways
• The microtubules do no extend into the terminal.
• The terminal contains synaptic vesicles.
• The inside surface of the membrane that faces the synapse has a particularly dense covering of proteins.
• It has mitochondria, indicating a high energy demand.

 

• SYNAPSE
• The synapse is composed of two sides, the presynaptic and postsynaptic. These indicate the direction of information flow. The presynaptic side tends to consist of an axon terminal, and the postsynaptic side may be a dendrite or a soma, with a space referred to as the synaptic cleft in between.
• At most of the synapses the electrical signal is changed into a chemical signals, called neurotransmitters, that can cross the synaptic cleft. This transmitter is stored in and released from the synaptic vesicles in the terminal.
• Axoplasmic transport- this is the movement of materials from the soma down the axon to the terminal by being connected to microtubule "tracks" by Kinesin. This transport is powered by ATP.
• The transport in the direction of soma to bouton is referred to as anterograde transport, and any transportation in the opposite direction would be referred to as retrograde transport (this uses dynein instead of kinesin).
• DENDRITES
• Dendrites function as antennas for the neuron, collectively forming the dendritic tree, and are covered in specialized protein molecules called receptors that can detect the neurotransmitters in the synaptic clef.
• Some dendrites are covered in dendritic spines, a specialized structure that receive some types of synaptic inputs. They are believed to isolate various chemical reactions that are triggered in some synaptic activation, and is sensitive to the type and amount of synaptic activity.

 

• CLASSIFYING NEURONS
• NUMBER OF NEURITES
• Unipolar- has only a single neurite.
• Bipolar- if there are two neurites.
• Multipolar- if there are three or more neurites. Most cells in the brain fall under this category. 
• NUMBER OF DENDRITES
• There are many different types of neurons based on dendrites, many specific to certain areas of the brain, but we will focus on only the main classes.
• Stellate cells- more star shaped dendritic trees.
• Pyramidal cells - pyramid shaped trees.
• These can then further be classified as either spiny or aspinous.
• TYPE OF CONECTIONS
• Primary sensory neurons- are neurons that have neurites in the sensory surfaces of the body, like the skin or other sensory organs.
• Motor neurons - are neurons that have axons that form synapses with the muscles and command movements.
• Interneurons- only form connections with other neurons. This is the most common of this category.
• AXON LENGTH
• Golgi type I - neurons that have axons that extend from one side of the brain to the other.
• Golgi type II - these only have axons that are short and tend to not extend past the vicinity of the soma.
• NEUROTRANSMITTER
• A way to chemically classify neurons by the neurotransmitter that they use. These collections of cells that use the same neurotransmitter makeup the brain's neurotransmitter systems.

 

• GLIA
• ASTROCYTES
• The purpose of these glial cells is to fill the space in between neurons, they may influence whether a neurite can grow or retract, and help to regulate the chemical content of the extracellular space.  Not only do these have the ability to uptake extra neurotransmitters from the synaptic clef, but they also have the ability to respond to these chemicals and can trigger electrical and biochemical events in the glial cells.
• MYELINATING GLIA
• Oligodendroglia and Schwann cells, are another type of glial cell that are responsible for forming the myelin sheath that helps promote the electrical charge that is passing though the axon of the neurons.
• The Oligodendroglia cells form the myelin sheath in only the central nervous system.
• Schwann cells form the sheath for the peripheral nervous system. (outside the skull and vertebral column) 
• The openings in between the segments of the myelin sheath are called the nodes of Ranvier.
• OTHER NON-NEURONAL CELLS
• Ependymal cells- these provide the lining of the ventricles with in the brain, as well as helping to direct cell migration during brain development.
• Microglia - these function as phagocytes in the brain, removing debris left by dead or degenerating neurons and glial cells.