Def - the conductive cells of the nervous system that form the circuitry that processes sensory input and controls behavior

-Human nervous system contains about 100 billion neurons

-Most Behaviors are produced by groups of hundreds or thousands of neurons

-They continuously change their shape

(grow and shrink)

-Most neurons are with you for life and are never replaced

Language of Neurons

-Each neuron receives thousands of excitatory and inhibitory signals every second

-Neurons sum these signals and respond accordingly by becoming active or not

-From simple "yes or no" language of neurons emerges enormous possibilities for behavior

Neural Connections

-The appearance of eeach neuron tells us something about the connections it must make

Ex: In general, neurons with large cell bodies have extensions that are very long; neurons with small cell bodies have short extensions

Synapse- gap between one neuron and another neuron that is usally between an end foot of the axon of one neuron and a dendritic spine of another neuron

Basic Structure

1) Cell Body or Soma

-core region 

2) Dendrites (Greek for "tree")

-branching extensions that collect info from other cells

-Dendritic Spines are many small protrusions that further increase surface area

-Surface area is important because a larger one can collect more info from other cells

3) Axon (Greek for "axle")

-Main "root" that carries messages to other neurons

-Axon Hillock is where the axon begins at one end of the cell body at an expansion

Axon Collaterals- Branch of an axon

Separate Info: 

Terminal Button is a knob at the tip of an axon that conveys info to other neurons

Order of Info Processing

1) Dendrite

2) Cell Body

3) Axon

4) End Foot

What are the Three Main Types of Neurons?

1) Sensory Neurons

-Designed to bring info into the brain from sensory receptors

-Simplest neurons structurally

-Ex: Bipolar neurons transmit sensroy info from retina's light receptors to the neurons that carry info into the visual centers of the brain.

Ex 2: Somatosensory neurons transmit sensory info from body to spinal cord 

Interneurons

- called association cells b/c they link sensory and motor neurons

-Branch extensively to better collect info from many sources

Motor Neurons

-Send signals from the brain and spinal cord to muscles

Def- (Gree for "glue) are support cells of the nervous system

-They do not transmit info themselves but help neurons carry out this task, binding them together and providing support, nutrients, and protection

-Constantly replace themselves as opposed to neurons

1) Ependymal Glial Cells

-Small, ovoid; secrete cerebrospinal fluid that fill ventricles in the brain

-Located on the walls of the ventricles in the cavities inside the brain

-Hydrocephalus- condition where the CSF is blocked causing a build up of pressure in the brain and swelling, can result in retardation

2) Astroglia (astrocytes) Glial Cells

-Star shaped, symmetrical; nutrititive and support function

-Enhance brain activity

-Form scars to protect damaged brain tissue

-Blood-Brain Barrier- astrocytes play a role in a protective partition between blood vessels and the brain

3) Microglia Glial Cells

-Originate in the blood as offshoot of immune system

-Phagocytosis -an immune process that scavenges debris (ex dead cells)

-Also supplies growth factors which help to repair damage

4) Oligodendroglia Cell

-Glial cell in the CENTRAL NERVOUS SYSTEM that myelinates axons

Myelin- Glial coating that surrounds axons

5) Schwann Cell

-Glial cell in the PERIPHERAL NERVOUS SYSTEM that myelinates axons

Paralysis - loss of sensation and movement due to nervous sytem injury

PNS - Microglia and Schwann cells help repair neurons

 CNS - if repair does not take place, regrowth may even be inhibited (oligodendroglia)

Def- naturally occurring substances that can not be broken down into other substances

1) Oxygen

2) Carbon

3) Hydrogen

Def- smallest quantity of an element that retains the property of that element

1) Nucleus

2) Neutrons (usually same number as protons)

3) Protons

4) Electrons

Def Atoms held together by shared electrons

-Opposite charges at opposite ends (Ex H20)

- Important function of neurons, major product of cells

-Important in organelles and enzymes, allowing cells to bind to surrounding environment

1. Organelles - internal parts of a cell
2. Cell Membrane - separates cell from its surroundings and allows it to regulate what enters and leaves
3. Extracellular Fluid- composed mainly of water with dissolved salts and other chemicals
4. Intracellular Fluid- Fluid in which the cell's internal structures are suspended
5. Nuclear Membrane- ,e,brane surrounding nucleus
6. ER- folded layers of membrane where proteins are assembled
7. Golgi Bodies- Membranous structure that packages protein molecules for transport
8. Microfilaments- threadlike fibers making up much of the cell's "skeleton"
9. lysosomes - sacs containing enzymes that break down wastes
10. Mitochondria- the ells power plant that supply its energy needs

-Separates intracellular and extracellular fluid

-Regulates movement of substances into and out of the cell: most cannot pass (oxygen can)

(Proteins embedded within membrane allow substances in and out of cell)

-Made up of Phospholipids

Hydrophilic Head- phosphorous (attracts water)

Hydrophobic Tail- lipids (fat molecules that repel water)

Important Note -  The nucleus is the site of gene transcription

Genes

-segments of DNA that encode the synthesis of particular proteins

-Sequences of nucleotides determine which amino acids are to be joined to form the particular protein

Chromosomes- Double Helix like structures that hold an organism's entire DNA (Dexoribonucleic acid) sequence

-Human somatic cells have 23 pairs

-One copy from mother and one from father

-Autosomes- Pairs 1-22

-Sex Chromosomes: Pair 23 (XX or XY)

-Y chromosome does not carry much genetic info, males are as a result affected more by genetic abnormalities as opposed to female because X chromosomes carry more genetic info and if X is fault, Y does not have enough info to often prevent issues

-Four Nucleotide bases that contain the genes

1) Adenine

2) Thymine

3) Guanine

4) Cytosine

A generally binds with T and G tends to bind with C

Aminom Acids- the constituent molecules of proteins. Their type is determined by the particular order spelled out by nucleotide bases

1) Transcription- Early phase of protein synthesis in which the DNA strands unwind and a complementary strand of messenger RNA is created

2) One strand of the gene serves as a template for transcribing a molecule of mRNA

3) Translation - Later phase in which the mRNA travels from nucleus to the ER. mRNA is translated into a particular sequence of amino acids to form a protein

4) As a ribosome moves along the mRNA, it translates the bases into a specific amino acid chain, which forms a protein

Simply Put- DNA --> mRNA --> Protein

-Amino acids are linked together chemically by a special peptide bond

-Series of amino acids called a polypeptide chain (meaning many peptides)

-Related to protein but not the same

-Polypeptide Chains form a pleated sheet or a helix. the ultimate three-dimensional shape is determined by the sequence of amino acids in its primary structure

-Proteins are dynamic structures that can change shape, are complex structures that change when shape can create passageways through the middle of protein

1. Proteins formed in the ER enter the Golgi bodies, where they are wrapped in a membrane and given a shipping address
2. Each protein package is attached to a motor molecule and moves along a microtubule to its destination
3. A protein ma be incorporated into the membrane
4. Remain within the cell to act as an enzyme
5. Or be excreted from the cell by exocytosis

Channels

-Ions can cross a cell membrane through the appropriately shaped channels

-Different-sized channels in different proteins allow the passages of different substances

Gated Channel

-Changes shape to allow the passage of substances when gates are opened and prevent passage when one or both gates are closed

-Unequal charges can affect whether a gate is open/closed

Pump

-A pump transporter changes shape to carry substances across a cell membrane

Def- field of study directed toward understanding how genes produce proteins

-Genome size and chromosome number seem unrelated to an organism's complexity

-You can't estimate an organisms complexity based on base pairs

-We can make more proteins than genes because we have genes that can make many diff types

mRNA can be edited, proteins can be edited/cleaved by enzymes

-Proteins can combine to form new proteins

Allele- 

-alternate form of a gene

-A gene pair contains two alleles which may be the same or differ from each parent

2 types:

1) Homozygous- having two identical alleles for a traid

2) Heterozygous- having two different alleles for the same trait

Wild-Type Allele- a nucleotide sequence that is most common in population

Mutation- a less frequently occuring nucleotide sequence

Dominant Allele- the member of the gene pair that is routinely expressed phenotypically

Recessive Allele- the member of the gene pair that is routinely unexpressed phenotypically

*this suggests that some alleles are more dominant than others, explaining whether phenotypically they are un/expressed*

Complete Dominance- Only the dominant allele's trait is expressed in the phenotype

Incomplete Dominance- the phenotypic expression of the dominant allele's trait is only partial

Codominance- The traits of both alleles of a gene pair are expressed completely in the phenotype

Genotype - the full set of all the genes that an organism possesses

Phenotype - the appearance of an organism that results from the interaction of genes with one another and with the environment

*Having identical genes does not mean that those genes will be identically expressed. Even if we knew everything about the structure and function of our own genes, predicting how much of our behavior is due to genotype would be impossible because so much of our behavior is phenotypical*

-Hereditary disease characterized by chorea (ceaseless, involuntary, jerk movements) and progressive dementia ending in death

-Gene is dominant

-Genetic disorders involve abberations in part of a chromosome (or entire chromosome) rather than a single deective allele

-Downs Syndrome- chromosomal abnormality resulting in mental retarding and other abnormalities, usually caused by an extra copy of chromosome 21 (trisomy)

Genetic Engineering

-Adding or removing genes from a genome or modification of a gene

- Can be done through selective breeding, cloning and maintaining spontaneous mutations

Chimeric Animals- have genes from two diff species

Knockout Technology- used to inactivate a gene so that it is not expressed

-Potential application to human genetic disorders 

Transgenic animal- product of the genetic engineering procedure of take a gene from one species and introducing it into the genome of another species