Bio Bases

Question 1

dichotomous traits

Answer 1

• present in one form or another but never in combination e.g. pea color
• mututally exclusive

Question 2

true breeding lines

Answer 2

• interbred members always produce offspring with the same trait
  
  • brown pea parents produce brown pea children
  • white pea parents produce white pea children
  • has to do with the carried traits, not the expressed trait

Question 3

Mendelian genetics

Answer 3

• Gregor Mendel Augustinian monk from Moravia (Austria) breed pea plants 1850-60’s

Question 4

Dominant trait

Answer 4

• first generation offspring all had brown peas

Question 5

recessive trait

Answer 5

• second generation offspring were 75% brown and 25% white – white was recessive trait
  
  • replicated this with other traits

Question 6

Mendelian genetics Key Points

Answer 6

• dichotomous traits
  
  • present in one form or another but never in combination e.g. pea color
• true breeding lines
  
  • interbred members always produce offspring with the same trait – brown pea parents produce brown pea children- white pea parents produce white pea children.
• first generation offspring all had brown peas
  
  • Dominant trait
• second generation offspring were 75% brown and 25% white
  
  • white was recessive trait
    
    • replicated this with other traits
• Demonstrated that traits not expressed by parents could be passed onto children

Question 7

Dr. Egas Moniz

Answer 7

• Portuguese neurologist attended a conference in 1935 at which he heard 2 presentations
  
  • a chimp who frequently became upset when she made errors on a food reward task did not get upset after bilateral prefrontal lesions
  • a patient who had removal of prefrontal lobes during tumor resection showed no intellectual impairment
• Applied to psychiatric patients after hearing this data
• won a Nobel Prize in Physiology and Medicine 1949 for the development of prefrontal lobotomy
  
  • Follow up of lobotomy shows no sig decline in IQ, but there are other areas they showed substantial impairment. While the psychiatric issues deimished it took their capacity of emotion away. They had flat affect, could have problems of apathy, lack of inituation, poor motivation, many patients could not sustain employment because of EF issues. They needed people to prompt, direct, instruct for everyday activities.
• 40,000 prefrontal lobotomies done in U.S. before being discontinued in the 1960’s and still done in some places today.

Question 8

Phenotype

Answer 8

• organism’s observable traits

Question 9

Genotype

Answer 9

• traits that can be passed on to children thru genetic material

Question 10

genes

Answer 10

• Two kinds of inherited factors for each dichotomous trait
• located on the nucleus in the chromosome of the cell
• Each organism possesses two genes for each of its dichotomous traits
• Occur in matched pairs
• each species has a certain number of chromosomes
• humans have 46 arranged in 23 pairs
• one pair is sex chromosomes
• other 22 pairs which are not sex chromosomes are autosomes

Question 11

alleles

Answer 11

• Two genes that control the same trait
• located at the same locus at each chromosome of a particular pair

Question 12

homozygous

Answer 12

• Identical genes

Question 13

heterozygous

Answer 13

• two different genes
  
  • one dominates the other in the pair in expression of the trait
  • randomly inherits one of the mothers two genes and one of the fathers two genes

Question 14

autosomes

Answer 14

• other 22 pairs which are not sex chromosomes

Question 15

Mendel proposed four ideas

Answer 15

• Two kinds of inherited factors for each dichotomous trait – now referred to as genes.
• Each organism possesses two genes for each of its dichotomous traits
  
  • a. Two genes that control the same trait are called alleles
  • b. Identical genes are homozygous
  • c. two different genes are heterozygous
• one of the genes in a heterozygous pair dominates the other in expression of the trait
• for each trait, a child randomly inherits one of the father’s two genes and one of the mother’s two genes

Question 16

Meiosis

Answer 16

• process of cell division that produces gametes i.e. sperm and egg
  
  • chromosomes divide and one of the pair goes to one gamete andthe other of the pair goes to the other gamete
  • each gamete contains only half the usual number of chromosomes i.e. 23 instead of 46
  • union of sperm and egg combines these two sets of 23 chromosomes to produce 46
  • because each of the 23 pairs is randomly distributed to gametes, there are 223 possibilities or 8,388,608 possible chromosomes combinations. THis is why we see differences in siblings
  • This is where crossing over occurs

Question 17

Genetic reproduction

Answer 17

• Meiosis
  
  • process of cell division that produces gametes i.e. sperm and egg
  • chromosomes divide and one of the pair goes to one gamete andthe other of the pair goes to the other gamete
  • each gamete contains only half the usual number of chromosomes i.e. 23 instead of 46
  • union of sperm and egg combines these two sets of 23 chromosomes to produce 46
  • because each of the 23 pairs is randomly distributed to gametes, there are 223 possibilities or 8,388,608 possible chromosomes combinations
• All cell growth afterward is mitosis
  • set of 46 chromosomes duplicates and when cell divides each new cell receives a full compliment of 46 cells
• Linkage
  
  • traits that are controlled by genes on same chromosome have a higher probability of being inherited together
  • e.g. Down’s syndrome and facial features
  • However, linkage is not absolute. The probability 2 genes on the same chromosome will be inherited together ranges from almost 1.0 to .5 or chance. How can this be?
  • Linkage is the observation that traits that are controlled by genes of the same chromosome code for are are involved in controlling different traits. When you have 2 genes on the same chromosome that have the same traits, they will be inherited as a package and occur together in a high probability. Traits controlled by genes in separate chromosomes do not happen together in the same . The chromosome comes as a package, so the same traits come together.
• Cross-over
  
  • during early stages of meiosis, chromosomes overlap or crossover one another and break apart at the points of contact, exchanging sections of chromosome.
    • as result parents rarely pass on intact chromosomal clusters of genes to children.
    • Each gamete contains chromosomes that are unique spliced together combinations of chromosomes inherited from your father and mother
    • Degree of linkage between two genes is determined by how close together they are on the chromosome
    • Crossover rarely occurs between adjacent genes and frequently between genes at opposite ends of chromosome

Question 18

mitosis

Answer 18

• cell growth after meiosis
• set of 46 chromosomes duplicates and when cell divides each new cell receives a full compliment of 46 cells

Question 19

Linkage

Answer 19

• traits that are controlled by genes on same chromosome have a higher probability of being inherited together
  
  • e.g. Down’s syndrome and facial features
  • However, linkage is not absolute. The probability 2 genes on the same chromosome will be inherited together ranges from almost 1.0 to .5 or chance. How can this be?
  • sex linked traits only occur in males

Question 20

Cross-over

Answer 20

• during early stages of meiosis, chromosomes overlap or crossover one another and break apart at the points of contact, exchanging sections of chromosome.
  
  • as result parents rarely pass on intact chromosomal clusters of genes to children.
  • Each gamete contains chromosomes that are unique spliced together combinations of chromosomes inherited from your father and mother
  • Degree of linkage between two genes is determined by how close together they are on the chromosome
  • Crossover rarely occurs between adjacent genes and frequently between genes at opposite ends of chromosome

Question 21

Sex related genes

Answer 21

• Only exception to matched pairs of chromosomes is the pair that determine gender.
• two different types X and Y
• X and Y look different and carry different genes
• two X’s for females; X and Y for males
• traits influenced by genes on sex chromosome are called sex-linked traits
• almost all sex-linked traits are controlled by X chromosome because Y is small and carries few genes other than those determining male sex development
• traits controlled by genes on the X chromosome occur in one sex more often than the other
• dominant traits occur more often in females than males because they have twice the chance of inheriting the dominant gene
• recessive sex-linked traits occur more in males because if they inherit the trait on X, there is nothing to over-ride it on Y and they express the trait, whereas in females they will express it only if they inherit two recessive genes
• color blindness is recessive sex-linked trait and is rare in women

Question 22

sex-linked traits

Answer 22

• traits influenced by genes on sex chromosome

Question 23

deoxyribonucleic acid (DNA)

Answer 23

• Each chromosome is composed of double stranded molecule

Question 24

each strand composed of sequence of nucleotide bases attached in chain

Answer 24

• adenine (a goes with t)
• thymine (t goes with s)
• guanine (g goes with c)
• cytosine (c goes with g)

Question 25

Replication

Answer 25

• in mitosis and other processes
  
  • the helix unravels and loose nucleotides are attracted to the unpaired strands and form two identical chromosomes
• errors sometimes occur and result in mutations

Question 26

Structural genes

Answer 26

• most prevalent – contain information necessary for synthesis of proteins.

Question 27

Proteins

Answer 27

• are long chains of amino acids that control physiological activities of cells and are important components of their structure

Question 28

Enhancer or promoter

Answer 28

• Sections of DNA that control structural genes and whether or not they initiate synthesis of protein
• If protein is synthesized the gene is expressed
  
  • no protein synthesis, gene is not expressed.
• Control of gene expression is important because it determines how a cell will develop and how it will function once it is mature
• Enhancers are like switches: they can be turned on, off, up or down

Question 29

Transcription factors

Answer 29

• Proteins that bind to DNA and regulate genetic expression
• Many of these binding proteins that influence enhancers are influenced by signals received from the cell as it responds to the environment
• thus providing the mechanism for interaction of the environment and genes to influence development

Question 30

Expression of a gene

Answer 30

• operator gene initiates process
• DNA for the section of structural gene unravels
• exposed DNA attracts messenger RNA which forms a strand until reaching another operator gene that signals the end of the structural gene
  
  • mRNA same as DNA except it has uracil instead of thymine
• mRNA then goes to a ribosome in the cytoplasm of the cell
• ribosome moves along the mRNA and transcribes the genetic code
• each group of 3 consecutive nucleotides is called a codon
• codon instructs the ribosome which of 20 amino acids to add to the protein it is constructing
• as ribosome reads mRNA it attracts transfer RNA attached to an amino acid
• ribosome reads codon after codon and adds amino acid after amino acid until it reaches another operator gene that signals the end of the structural gene
  
  • the completed protein is then released into the cytoplasm
• This process is very accurate but there can be mutations if it codes for a different protein

Question 31

Human Genome Project

Answer 31

• Procedure:
  
  • enzymes split chromosomes
  • clone to have unlimited supply
  • exposed to chemical markers that uniquely label specific loci - not nucleotide bases – but loci which are composed of hundreds/thousands of nucleotide bases
  • placed in a jell
  • jell forced through a very small tube
  • as going through end of tube exposed to a special light
  • chemical markers show up differently and are recorded in a computer
  • patterns of markers were examined to identify identical sequences which were overlapping portions of the chromosome
  • loci have been identified
    
    • now attempting to identify sequence of nucleotide bases for each
• Findings of HGP
  
  • The human genome contains 3.1647 billion chemical nucleotide bases (A, C, T, and G).
  • The average gene consists of 3000 bases, but sizes vary greatly, with the largest known human gene being dystrophin at 2.4 million bases.
  • The total number of genes is estimated at 20,000, much lower than previous estimates of 80,000 to 140,000 that had been based on extrapolations from gene-rich areas as opposed to a composite of gene-rich 2% of genes code for proteins – i.e. structural genes
  • Almost all (99.9%) nucleotide bases are exactly the same in all people.
  • The functions are unknown for over 50% of discovered genes.
  • Scientists have identified about 1.4 million locations where single-base DNA differences occur in humans called Single Nucleotide Polymorphism (SNPs). This information promises to revolutionize the processes of finding chromosomal locations for disease-associated sequences
• New understandings: Epigenetic factors that influence genetic expression
  
  • Pseudogenes
    
    • Structural genes make up about 2% of human genome
    • Rest are pseudogenes previously thought to be inactive
    • Now known to exert control over structural genes…e.g. may bind to and block mRNA
  • Alternative splicing
    
    • Strands of mRNA are broken apart and pieces are spliced to new segments
    • As a result a single gene can code for more than one protein
    • Particularly prevalent in neural tissue
  • microRNA’s control DNA
    
    • influence enhancers and mRNA
    • influence brain development and synaptic function
    • disruption associated with neurodegenerative disorders
  • monoallelic expression
    
    • exception to dominant allele is expressed
    • epigenetic mechanisms (presently unknown) inactivate one allele and the other is expressed
    • happens particularly in the nervous system
• Now clear that genetic influences include
  
  • Not only structural genes
  • Interaction of many structural genes
  • Influence of epigenetic factors
  • Developmental timing of expression of particular genes in specific brain structures

Question 32

Genetic breeding

Answer 32

• Overall idea: Genetics create a risk or advantage. They convey a context and expression is based on the environment context.
• Bright and dull maze rats (1934)
• after 8 generations virtually no overlap in the number of errors made in learning maze
• cross fostering to control for parents teaching offspring
• since this finding many traits have been selectively breed in lab animals including
• Behavioral trait used as criteria for selective breeding is not the behavioral trait influenced by the genes segregated by the breeding
  
  • Subsequent research found the bright rats learned maze better not because they were more intelligent but because they were less fearful
• However, environment/experience influenced expression of this trait
  
  • Dull rats worse than bright rats only if raised in impoverished environment

Question 33

Genetic influences on human behavior

Answer 33

• Genetic control and influence of normal behavior is complex
  
  • it takes many genes functioning normally to produce normal behavior, but abnormality can often be caused by dysfunction of a single gene
• Down syndrome
• Huntington’s disease
  
  • Causes issues in the basal ganglia. Autozomal dominant gene disorder
• Alzheimer’s
  
  • APIE*E4 associated.
  • If you have APOE E4 you have an increased risk of Alzheimer’s.
  • (2/3 of people with gene have AZH)
  • (1/3 of people with AZH do NOT have this gene)
• Serotonin transporter gene
• Otosclerosis – hearing impairment
• Multiple exostoses – benign bone tumors
• Neurofibromatosis – tumors of nervous system and skin
• Cystic fibrosis – abnormal transport chloride and sodium effecting lungs most critically
• Duchenne muscular dystrophy
  
  • recessive X-linked abnormality
  • effects primarily boys
  • muscle degeneration and death with average life expectancy of 25
• Fragile X
  
  • most common form of inherited intellectual disability in boys
  • can occur in girls but more common in boys
  • portion of X chromosome is repeated
  • codes for a protein critical for brain development

Question 34

Genetic control and influence of normal behavior is complex

Answer 34

• it takes many genes functioning normally to produce normal behavior, but abnormality can often be caused by dysfunction of a single gene

Question 35

Otosclerosis

Answer 35

• hearing impairment

Question 36

Multiple exostoses

Answer 36

• benign bone tumors

Question 37

Neurofibromatosis

Answer 37

• tumors of nervous system and skin

Question 38

Cystic fibrosis

Answer 38

• abnormal transport chloride and sodium effecting lungs most critically

Question 39

Duchenne muscular dystrophy

Answer 39

• recessive X-linked abnormality
• effects primarily boys
• muscle degeneration and death with average life expectancy of 25

Question 40

Fragile X

Answer 40

• most common form of inherited intellectual disability in boys
• can occur in girls but more common in boys
• portion of X chromosome is repeated
• codes for a protein critical for brain development

Question 41

Nature or nurture; genetics vs. experience

Answer 41

• Formulating the question in terms of either – or is too simplistic and does not reflect reality
  
  • Breast feeding and IQ – news paper article
  • maze bright and dull rats reared in impoverished and enriched environments.
  • Other studies show enriched environment results in thicker cortices
  • Head Start
    
    • the above suggest early experience can at least partially offset genetic disadvantage
  • an individual’s behavior is result of the interaction of genetics and experience
• However, it does make sense to ask what portion of the difference between individuals on a certain trait is due to genetics vs. experience
• to study the contribution of genetics to the differences between individuals, individuals with varying degrees of genetic similarity are studied
  
  • Twin studies
    
    • Identical vs. fraternal
    • Raised together vs. adopted
    • Concordant vs. discordant for the trait of interest
  • Minnesota twin study
• I.Q. correlated .80 for identical twins raised together and .75 for those raised apart
• Schizophrenia 4 times higher in mono twins than di twins
• These results indicate that differences between individuals’ I.Q. and expression of schizophrenia has a genetic influence
• heritability estimate
  
  • the estimate of the proportion of variability occurring in a particular trait in a particular study that resulted from the genetic variation in that study:
  • .7 for I.Q. in the twin studies
  • heritability estimate
    
    • tells us about the contribution of genetic differences to phenotypic differences among subjects – i.e. in the population
    • h.e. says nothing about the relative contribution of genetics and experience to the development of an individual
• interactive influence of genes and environment
  
  • discussed earlier that environmental events directly influence DNA binding proteins that control regulator genes and determine if structural genes are expressed
  • gene expression also influences the type of environmental stimulation person seeks and is exposed to
    
    • e.g. an aggressive person seeks out contact and/or extreme sports
    • people also tend to select social partners that have similar genetics to their own
  • when a particular gene encourages a developing individual to select experiences that increase the behavioral effects of that gene
  • cycle of genetics and environmental experiences influencing and determining each other
  • Although raised apart, twins in MN study grew up in culturally and economically similar environments
  • Recent research shows the correlation of iq in twins:
    
    • Near 0 in low SES
    • Near 1.0 in high SES

Question 42

heritability estimate

Answer 42

• the estimate of the proportion of variability occurring in a particular trait in a particular study that resulted from the genetic variation in that study:
  
  • .7 for I.Q. in the twin studies
• tells us about the contribution of genetic differences to phenotypic differences among subjects – i.e. in the population
• h.e. says nothing about the relative contribution of genetics and experience to the development of an individual

Question 43

Soma

Answer 43

• contains the nucleus and much of machinery that operates cell
• this is the headquarters
• this is the cell body
• involved in biological processes

Question 44

Dendrites

Answer 44

• receive information from other neurons
• can grow and form new connections
• where synapses occur

Question 45

Axon

Answer 45

• collaterals – telodendria
• can grow and form new connections
• a nerve is composed of many axons surrounded by a tough, elastic connective membrane
• can often split into different pieces

Question 46

Axon hillock

Answer 46

• where action potential originates.
• Location where the initiation of a nerve impulse occurs
• Between the axon and the soma

Question 47

Terminal button

Answer 47

• secretes transmitter substance or nt
• forms synapse with dendrites, soma or axons of other neurons
• points of connection between this neuron and other neurons
• allows neurons to communicate with each other

Question 48

Neuron internal components

Answer 48

• Membrane
• Nucleus
• Nucleolus
• Ribosome
• Mitochondria
• Endoplasmic reticulum
• Glia
• Microtubules / filaments

Question 49

Membrane

Answer 49

• NEURON INTERNAL COMPONENT
• double layer of lipid molecules
• embedded in membrane are a variety of protein molecules that perform various functions
  
  • detect and pass on information about substances outside cell
  • control access to inside of cell allowing in some things and barring others
  • active transport of material into and out of cell

Question 50

Ribosome

Answer 50

• neuron internal components
• in cytoplasm “decodes” mRNA for formation of proteins used in the neuron

Question 51

Nucleolus

Answer 51

• neuron internal components
• produces ribosomes

Question 52

Nucleus

Answer 52

• Nueron internal component
• contains chromosomes and nucleolus

Question 53

Endoplasmic reticulum

Answer 53

• neuron internal component
• system of tubes for storage and transport of material within cell and important for protein synthesis
• Rough
  • contains ribosomes that produce proteins which are transported out of cell or used in the membrane
• Smooth
  
  • channels for transport and storage of molecules

Question 54

Endoplasmic Reticulum Rough

Answer 54

• contains ribosomes that produce proteins which are transported out of cell or used in the membrane

Question 55

Endoplasmic Reticulum Smooth

Answer 55

• channels for transport and storage of molecules

Question 56

Mitochondria

Answer 56

• neuron internal component
• converts glucose to ATP and stores CA. Contain different DNA (only from mother) than other cells

Question 57

Golgi Apparatus

Answer 57

• packages proteins including neurotransmitters into vesicles
  produces lysosomes which break down substances no longer needed by the neuron

Question 58

Microtubules / filaments

Answer 58

• transport substances between cell body and distal cell / terminal button

Question 59

Support cells

Answer 59

• Glia
• Astrocytes
• Oligodendrocytes
• Microglia
• Schwann cells

Question 60

Glia

Answer 60

• “glue”
• neurons have high rate of metabolism but cannot store energy
• therefore, they must be supplied by glial cells with a constant source of nutrients (glucose) and oxygen and will die within minutes if this is interrupted
• provide physical support, control nutrient flow, and are involved in phagocytosis (what holds the brain together)
• types of glial cells are:
  
  • astrocytes
  • oligodendrocytes
  • micoglia
  • schwann cells

Question 61

Astrocytes

Answer 61

• Provide physical support, remove debris, and transport nutrients to neurons
• one astrocyte cell will have connections with many neurons
• provide structure or matrix that holds neurons in place
• surround synapses so neurotransmitter are not dispersed beyond synapse (to contain neurotransmitters)
• Phagocytosis -digests dead neurons
• forms scar tissue in area left from phagocytosis
  produce some chemicals needed by neurons
  absorb and release substances to keep concentration levels around neuron at critical levels
  aid in energy use efficiency.
• Break down glucose received from capillaries into lactate used by neuron for energy
• Glucose is transported into and changes glucose into clackogen that can be used as fuel.

Question 62

phagocytosis

Answer 62

• Cells engulf and digest other cells or debris caused by cellular degeneration
• Done by microglia and astrocyte

Question 63

Oligodendrocytes

Answer 63

• Provide physical support and form the myelin sheath around axons in the brain
• form myelin sheath CNS which insulated axons
• Nodes of Ranvier: bare portion of axon
• A single oligo. will provide myelin for multiple axons

Question 64

Microglia

Answer 64

• phagocytosis
• immune function for brain
  
  • inflammatory response to damage
  • destruction of pathological cells

Question 65

Schwann cells

Answer 65

• The “oligodendendrocytes of the PNS”
• Form myelin for Peripheral nervous system axons. Wraps around one axon.
• When a neuron is damaged fagocytosis will occur for the damaged part and the Schwann cells will start forming a tube and the survivied part will grow parts and find its way in the tube and grow and will result in recovery.
• In the brain this does not happen, there is no meaningful repair like this.

Question 66

Blood-brain barrier

Answer 66

• Capillaries in body have permeable walls allowing for free movement of most substances between plasma and extra cellular fluid
• In CNS capillary walls are not permeable for most part and substances are actively transported between capillary and neuron
• BBB allows for control of delicate balance of substances in neuron extra cellular fluid necessary for brain to function normally and exclude toxins or chemicals that would interfere with neuron function
• BBB not as strong throughout brain e.g. in area that controls vomiting
• Function to keep toxins and poisons etc that can damage the brain away. Also, substances in the brain need to be very controlled and at the right concentration levels.
• Not uniform through the brain, the area postrema is nonexistent there
• Nutrition is absorbed from food and then enters blood, oxygen enters lungs, then enters blood.In the third stage you have the glucose and oxygen moving across, moving from the blood in the brain, across the small cappilaries into the tissue. Then what you want to get rid of permeates what you take away. In the brain these are not permeable. Glucose and oxygen don’t flow freely through these walls.

Question 67

Electrical potentials

Answer 67

• Inside of axon has –70 mV charge relative to the outside called resting potential or membrane potential
• Positively charged electrical stimulation on inside of axon depolarizes membrane – i.e. “takes away some of the charge difference” across the membrane
• Sub-threshold and threshold stimulation
• action potential with threshold stimulation
• to understand what makes an action potential occur must first understand what maintains resting potential

Question 68

resting potential or membrane potential

Answer 68

-70mV charge is produced by a balance between difusion and electrostatic forces

Question 69

depolarizes

Answer 69

• “takes away some of the charge difference” across the membrane
• This occurs during an action potential

Question 70

Membrane or resting potential in depth

Answer 70

• Difference in voltage between the inside and outside of the axon membrane
• Electrostatic Force
• intra and extracellular fluid contain different ions
• membrane potential (-70mV charge) is produced by a balance between diffusion and electrostatic forces
• Ions in and outside of the neuron:
• NA+ ions are high in concentration outside of the cell, while K+ ions are in high concentration inside the cell.
• The ratio of the positive charge on the outside to the negative charge on the inside.

Question 71

Diffusion (concentration) force

Answer 71

• resting potentional
• molecules go from areas of high concentration to low until they are evenly distributed throughout the medium

Question 72

Electrostatic force (or pressure)

Answer 72

• resting potential
• substances which, when dissolved in water, split apart into two particles each with an opposing electrical charge are electrolytes
• charged particles are ions
• like charged particles repel and opposite charged particles attract
• particles will distribute themselves in a medium until the charged particles are evenly distributed

Question 73

electrolytes

Answer 73

• substances which, when dissolved in water, split apart into two particles each with an opposing electrical charge

Question 74

ions

Answer 74

• charged particles
• The repel like charged particles, and attract opposite charged particles

Question 75

Ions in and outside of the neuron

Answer 75

• organic ions
  
  • negatively charged (A-) present only on inside of neuron. Membrane is impermeable to it so it stays inside neuron and contributes to negative charge on internal surface of membrane.
• Potassium
  
  • positively charged ion (K+) highly concentrated inside neuron. Diffusion force tends to push K+ out of cell, but since outside of membrane is positively charged, electrostatic force pushes it in. The balance of these forces results in greatest concentration of K+ inside
• Chloride
  
  • negatively charged ion (Cl-) highly concentrated outside neuron. Diffusion force pushes it into the neuron, but since the internal membrane is negatively charged electrostatic force pushes it out. The balance of these forces results in greatest concentration of Cl- outside
• Sodium
  
  • positively charged ion (Na+) highly concentrated outside neuron. Diffusion force pushes it into neuron. Because the internal membrane is negatively charged electrostatic force attracts it into the neuron
• high concentration of Na+ outside neuron is maintained by two factors:
  
  • membrane is not very permeable to Na+ so only a small amount is able to “leak” into the neuron
  • protein molecules in the membrane called “sodium-potassium transporters” (pump) remove the Na+ that leaks in and the K+ that leaks out
  • sodium-potassium transporters are made up of proteins that actively transport these ions
  • Na+ - K+ pumps consume ~ 40% of neurons energy

Question 76

organic ions

Answer 76

• negatively charged (A-) present only on inside of neuron. Membrane is impermeable to it so it stays inside neuron and contributes to negative charge on internal surface of membrane

Question 77

Potassium ion

Answer 77

• positively charged ion (K+) highly concentrated inside neuron. Diffusion force tends to push K+ out of cell, but since outside of membrane is positively charged, electrostatic force pushes it in. The balance of these forces results in greatest concentration of K+ inside

Question 78

Chloride ion

Answer 78

• negatively charged ion (Cl-) highly concentrated outside neuron. Diffusion force pushes it into the neuron, but since the internal membrane is negatively charged electrostatic force pushes it out. The balance of these forces results in greatest concentration of Cl- outside

Question 79

Sodium ion

Answer 79

• positively charged ion (Na+) highly concentrated outside neuron. Diffusion force pushes it into neuron. Because the internal membrane is negatively charged electrostatic force attracts it into the neuron

Question 80

high concentration of Na+ outside neuron is maintained by two factors

Answer 80

• membrane is not very permeable to Na+ so only a small amount is able to “leak” into the neuron
• protein molecules in the membrane called “sodium-potassium transporters” (pump) remove the Na+ that leaks in and the K+ that leaks out
  
  • sodium-potassium transporters are made up of proteins that actively transport these ions
  • Na+ - K+ pumps consume ~ 40% of neurons energy

Question 81

Action Potential

Answer 81

• A stereotyped change in membrane potential
  
  • If the RMP moves past the threshold, membrane potential quickly moves up to +40 mV and then returns to resting
  • This is caused by NA+ coming in and causing a spike, then K+ going out, the downsizing of the spike
• Neuron membrane also contains ion channels (pores) that can open and allow ions (Na+ and K+) to enter and leave neuron
• membrane contains billions of channels that can admit billions of Na+ ions
• When threshold of excitation is reached on the membrane
  
  • opening of channels is triggered by depolarization of membrane potential (i.e. immediately adjacent membrane charge changing to negative. Thus they are called voltage dependent ion channels).
  • Diffusion and electrostatic forces propel Na+ into neuron.
  • Influx of Na+ causes rapid change of membrane potential (charge) from –70 mV to 40 mV
• K+ ion channels are less sensitive than Na+, require more depolarization (change in membrane charge) to open, and open after Na+ channels.
• At peak of action potential (i.e membrane charge reaches 40 mV) Na+ channels become refractory, i.e. are blocked, and no more Na+ can enter until membrane resting potential is restored
• K+ channels are open. Because of influx of Na+, inside of membrane is positively charged and immediate outside of membrane is negatively charged. K+ is driven out of the neuron by diffusion and attracted out by electrostatic forces. This causes the membrane potential to begin returning to normal. As this happens K+ channels are closed
• Na+ channels reset so another depolarization can cause them to open again
• Accumulation of K+ outside causes the membrane to “overshoot” and become hyperpolarized, i.e. charge goes below –70 mV. K+ diffuses away and membrane returns to –70 mV
• Na+ - K+ transporters eventually remove Na+ from neuron and retrieve K+
• Changes Na+ and K+ concentrations, and in membrane charge take place just at the area immediately inside and outside the membrane and not throughout the neuron. Influx of Na+ is small relative to the overall concentration of Na+ in the neuron
• Na+ - K+ transporters are not that essential in restoring Na+ and K+ levels after action potential. The small amount of these ions that cross the membrane is small relative to the overall concentration in the neuron and is “hardly noticeable”. Transporters are most important on a long-term basis to prevent the slight amount of Na+ that leaks into the neuron (because of the slight permeability of the membrane to Na+) from causing too high a concentration in the neuron that would prevent it from functioning

Question 82

synaptic vesicles

Answer 82

• small sv contain neurotransmitter
• are produced in the soma and transported to button by microtubules or recycled in the button

Question 83

transmitter substances

Answer 83

• Chemicals produced by the body that communicate between neurons i.e. across synapses

Question 84

neurotransmitters

Answer 84

• released by terminal button and detected by receptors on membrane of neuron across synaptic cleft

Question 85

neuromodulators

Answer 85

• released by terminal buttons in greater quantities and are more widely dispersed influencing many neurons in an area of the brain

Question 86

hormones

Answer 86

• most produced by endocrine glands, but some produced by cells in stomach, intestines, kidney and brain. Released into extracellular space and dispersed by blood stream.
  
  • Neurons that have receptors for hormones are target cells. Hormones affect the functioning of the cells that have the receptors

Question 87

target cells

Answer 87

• Neurons that have receptors for hormones are target cells. Hormones affect the functioning of the cells that have the receptors

Question 88

Peptides

Answer 88

• Insulin and pituitary hormones
• Stimulate metabotropic receptors in membrane
• Second messenger travels to nucleus and influences activity of cell

Question 89

Steroids - lipid

Answer 89

• sex hormones and those secreted by the adrenal cortex i.e. adrenalin
• pass through membranes to nucleus where it binds with receptor. When activated, the receptor influences protein production
• Steroid receptors have recently been discovered in terminal buttons and post-synaptic membranes

Question 90

Anatomical directions of the brain

Answer 90

• neuroaxis
  
  • imaginary line drawn through the spinal rode up to the front of the brain
    
    • animals: gator on flat plane
    • humans: 90 degree turn at junction of spinal cord and the brain. This changes the terms.
• Superior/Dorsal: toward the back or top (or in humans to the back because of the 90 degree turn)
• Inferior/Ventral:toward the bottom or “belly
• Anterior/Rostral: toward the head, front
• posterior or caudal: toward the tail, back
• medial: toward the middle of the body, away from the side
• lateral: toward the side of the body, away from the middle
• ipsilateral: same side of the brain
• contralateral: opposite side of the brain
• afferent: sensory pathways – all of those neural pathways that goes to sensory receptors
  
  • take information into the brain
• efferent: motor pathways – our pathways that control some sort of response –
  
  • take information out of the brain

Question 91

Brain slices

Answer 91

• transverse / frontal / coronal: If you slice the brain from top to bottom like a slice of bread, view from front
• horizontal: Horizontal cut, lookat at brain fron the top
• sagittal: Cut from front to back down the middle, looking at the exact middle.

Question 92

Divisions

Answer 92

1.Central NS

• brain and spinal cord
• anything that is inside of a bone

2.Peripheral NS

• cranial nerves, spinal nerves and peripheral ganglia
• anything outside of a bone
• Efferent- PNS nerves project to target organs and to muscles
• Afferent- PNS nerve carry sensory information to the brain

Question 93

Central NS

Answer 93

• brain and spinal cord

Question 94

PNS

Answer 94

• cranial nerves, spinal nerves and peripheral ganglia

Question 95

Vascular system- Blood supply

Answer 95

• Brain- major consumer of body’s energy
  
  • Receives 20% of blood volume
• Continuously receives this amount even though blood flow to other parts of the body varies depending on need and activities of other systems
• cannot store fuel (glucose) and requires O2 to extract glucose
• thus brain requires continuous blood flow to function normally and suffers permanent damage after approximately 5 minutes without blood (i.e. O2 and glucose)
• The brain starts dysfunctioning within seconds after cutoff
• Circle of Willis: brain gets blood from 2 sources.
  
  • Posterior comes from basal artery

Question 96

Meninges

Answer 96

tough protective membrane surrounding brain and spinal cord

• Dura mater – outer, thicker and tougher, most elastic
• Arachnoid – middle layer
  
  • Overlies the arachnoid space
  • CSF in arachnoid layer
• Subarachnoid Space- between arachnoid and pia.
  
  • Contains cerebrospinal fluid
• Pia mater – inner, soft
  
  • contains smaller surface blood vessels
  • overlies every detail of outer brain

Meningitis is a viral or bacterial infection of the meninges.

Meninges are Durable Architecture Protecting SoftStuff

Question 97

Meninges (In depth)

Answer 97

1. Dura mater – outer, thicker and tougher
2. Arachnoid – middle layer
3. Pia mater – inner, soft
   * contains smaller surface blood vessels
4. subarachnoid space between arachnoid and pia. Contains cerebrospinal fluid

Question 98

Dura mater

Answer 98

• part of meninges
• outer, thicker and tougher

Question 99

Arachnoid

Answer 99

• part of meninges
• middle layer

Question 100

Pia mater

Answer 100

• part of meninges
• inner, soft
  
  • contains smaller surface blood vessels

Question 101

subarachnoid

Answer 101

• part of meninges
• space between arachnoid and pia. Contains cerebrospinal fluid

Question 102

Cerebrospinal fluid

Answer 102

• brain is soft, jelly like and delicate; it weighs 1400 g or ~ 3 lbs. Therefore requires protection from shock and trauma
• brain floats in CSF which reduces weight to ~ 80 g or ~ 3 ozs. and helps protect it from shock
• bran ventricles can expand when brain cells are lost
  
  • Cerebrospinal fluid (CSF) produced by choroid plexus of each ventrical
• Contained within four brain ventricles

Question 103

Ventricular system

Answer 103

• brain is soft, jelly like and delicate; it weighs 1400 g or ~ 3 lbs. Therefore requires protection from shock and trauma
• 4 ventricles
• Contains CSF
• access point for drug studies

Question 104

Describe the ventrical system

Answer 104

• 2 Lateral (mirror images of each other) flows into
• interventricular foramina (of Monro) flows into
• 3rd flows into
• cerebral aqueduct flows into
• 4th flows into
• subarachnoid space around brain and spinal cord to superior aspect of brain where it drains into superior sagittal sinus and into veinous system
• 2 Late I Faced 3 CAlifornians 4 State Senate

Question 105

choroid plexus

Answer 105

• continuously extracts csf from blood. Resembles blood plasma. CSF half life is 3 hrs.
• Part of all 4 ventricles

Question 106

Central Nervous System

Answer 106

• Cortex
• Limbic system
• Basal ganglia
• Thalamus
• Hypothalamus
• Tectum
• Tegmentum
• Cerebellum
• Pons
• Medulla
• Spinal cord

Question 107

Cortex & Major components

Answer 107

Forms outer surface of the cerebral hemispheres

Convoluted by grooves:

• Gyrus: bulges in the cortex (outside of cortex that we see from the outside)
• Sulci: Small grooves (2/3 of the cortex)
• Fissures: Large deep grooves
  
  • 3 major fissues: longitudinal, 2 lateral. These are the boundaries of the 4 lobes of the brain.

Gyrus, Sulci, and Fissures allow for 3 times greater surface area.

Gray matter: outside, made of cell bodies

White matter: deeper, made of axons

Question 108

sulci / fissure

Answer 108

• in cortex
• allow for 3 X’s greater surface area
• 2/3 of cortex is in sulci
• Sulci: Small grooves (2/3 of the cortex)
• Fissures: Large deep grooves
  
  • 3 major fissues: longitudinal, 2 lateral. These are the boundaries of the 4 lobes of the brain

Question 109

lobes

Answer 109

• Cortex is divided into 4 lobes
  
  • frontal- front part, executive functioning
  • temporal- bottom, near temples, hearing
  • parietal- top, sensory, somatosensory, hearing
  • occipital- back, eyes, sight
    *

Question 110

posterior part of brain

Answer 110

• in cortex
• mediates sensory processing
  
  • contralateral representation
    
    • primary visual cortex
    • primary auditory cortex
    • primary somatosensory cortex

Question 111

anterior part of brain

Answer 111

• in cortex
• planning and executing behavior
• premotor area- controls patterns of movementand transmits input to primary motor area
• prefrontal area- planning, regulation, strategy formulation, execution of action
  
  • contralateral control
    
    • primary motor cortex

Question 112

central sulcus

Answer 112

• in cortex
• dividing demarcation between frontal and parietal / motor and sensory

Question 113

Posterior association areas

Answer 113

• in cortex
• posterior – perceiving, learning
• each primary sensory area sends info to adjacent sensory association areas where perception takes place and memories are stored
• multi-modal cortex receives input from multiple sensory areas / modalities

Question 114

Anterior association areas

Answer 114

• in cortex
• anterior – planning and executing behavior
• premotor area – controls patterns of movement and transmits input to primary motor area
• prefrontal area – planning, regulation, strategy formation, execution of action

Question 115

Lateralization of function

Answer 115

• in cortex
• R and L sides do not process info in the same way and do not process the same aspects of information
  
  • L hemisphere: analysis of information, serial processing of and controlling events in sequence. Language
  • R hemisphere: synthesis, integrating elements into a whole, visual- perceptual processing

Question 116

corpus callosum

Answer 116

• in cortex
• a commissure - connects corresponding parts of L and R hemis
  
  • Despite lateralized functions, we perceive experience as seamless, unaware of unique processing of each hemisphere
• The only thing connecting the left and right hemisphere!

Question 117

Neocortex vs. limbic cortex

Answer 117

• cingulate gyrus

Question 118

Limbic system

Answer 118

Motivation, learning, memory

• cingulated cortex: does a lot depends on how anterior or posterior you are. Anterior is in motivation, personality, pain perception, activation of hypnosis areas. As you move to the back it gets more cognitive
• hippocampus: involved in learning and memory
  
  • hippocampus and adjacent areas critical for forming new memories and learning
• amygdala: emotion
  
  • amygdala important for mediating some aspects of emotional functioning
• Mamilliary Bodies
  
  • Fornix is a fiber bundle that interconnects the hippocampus with the mammiliary bodies

Question 119

Basal ganglia

Answer 119

• collection of subcortical nuclei that lie just under the anterior aspect of the lateral ventricles
• important for regulation of motor function and caudate for cognitive functioning

Made up of:

• Caudate nucleus: motor and cognitive function
• putamen
• globus pallidus

Parkinsins is caused by dysfunction in the basal ganglia

Huntingtons is caused by deterioration of the basal ganglia

Question 120

Thalamus

Answer 120

1. two symmetrical lobes: R and L
2. most neural input to cortex goes through thalamus
   * specific areas – nuclei - of thalamus project to specific areas of cortex
3. sensory input first goes to thalamus which projects to sensory

area

4. areas of brain that regulate movement (motor) (e.g. basal ganglia) project to thalamus which projects to motor cortex
5. All senses except for smell go to a specific nucleous in the thalamus

Question 121

Hypothalamus

Answer 121

• controls autonomic ns and endocrine system
• pituitary attached to hypo
• most of endocrine system is controlled by hypo hormones

Question 122

anterior pituitary

Answer 122

• hypo hormones secreted into blood vessels that connect to a.p. which causes a.p. to secrete hormones which in most cases cause other endocrine glands to secrete hormones e.g. gonadotropin from a.p. causes release of gonadotropic hormones involved in reproduction

Question 123

posterior pituitary

Answer 123

• axons of hypo terminate in p.p. and release hormones which enter blood stream and produce effects e.g. p.p. releases vasopressin which regulates kidney output

Question 124

Tectum

Answer 124

1. superior colliculus
   * visual orienting / head turning
2. inferior colliculus
   * auditory processing

Question 125

superior colliculus

Answer 125

• visual orienting / head turning
• Part of the tectum

Question 126

inferior colliculus

Answer 126

• auditory processing
• Part of the tectum

Question 127

Tegmentum

Answer 127

• reticular formation – over 90 nuclei with diffuse network of neuron interconnections with complex dendritic and axonal processes
• receives sensory input and projects to cortex, thalamus and spinal cord
• plays role in arousal, sleep, muscle tone, movement
• Periaqueductal gray
  
  • nuclei involved in control of movement
  • nuclei involved in inhibition of pain perception
• Substantia nigra
  
  • involved in motor control
  • project to caudate and putamen
  • Parkinson’s

Question 128

reticular formation

Answer 128

• over 90 nuclei with diffuse network of neuron interconnections with complex dendritic and axonal processes
  
  • receives sensory input and projects to cortex, thalamus and spinal cord
  • plays role in arousal, sleep, muscle tone, movement

Question 129

Periaqueductal gray

Answer 129

• nuclei involved in control of movement
• nuclei involved in inhibition of pain perception

Question 130

Substantia nigra

Answer 130

• involved in motor control
• project to caudate and putamen
• Parkinson’s

Question 131

Cerebellum

Answer 131

• Receives visual, auditory, vestibular and somatosensory input as well as information about muscle movement
• Integrates this info and exerts a smoothing and coordinating effect on movement
• Especially important for rapid, sequenced movements

Question 132

Pons

Answer 132

• Nuclei involved in control of sleep and arousal
• Nucleus that relays info from cortex to cerebellum

Question 133

Medulla

Answer 133

• reticular formation
• nuclei involved in control of cardiovascular, respiration and muscle tone
• Starts at base of skill and transitions into the spinal cord

Question 134

Spinal cord

Answer 134

• primary functions
  
  • transmission of information from brain to control motor movements and body functions
  • transmission of sensory information from sense receptors to brain
  • control of reflexes
• Vertebrae
• Spinal Nerve

Question 135

Vertebrae

Answer 135

• cervical
• thoracic
• lumbar
• sacral
• coccygeal
• cauda equina

Question 136

spinal nerve

Answer 136

• small bundles of fibers emerge from dorsal and ventral surface of s.c.
• groups of nerves fuse together and become the dorsal and ventral roots
• dorsal and ventral roots join to become spinal nerves

Question 137

Peripheral Nervous System - Somatic

Answer 137

• comprised by nerves that control muscle action and that carry sensory information back to the CNS
• involved in transmitting sensory and motor information to and from brain
• Spinal nerves
• Cranial nerves

Question 138

Spinal nerves (PNS Somatic)

Answer 138

• Cell bodies of afferent neurons - axons transmitting sensory info from somatosensory receptors to spinal cord - are located outside CNS in dorsal root ganglion (except visual) and enter spinal cord thru dorsal root
• Cell bodies of efferent neurons – axons transmitting info from brain to muscles and glands – are located in the gray matter of spinal cord and exit spinal cord thru ventral root

Question 139

Cranial nerves (PNS Somatic)

Answer 139

• 12 pair of nerves – R & L – exit brain on ventral surface of brain
• Control motor and sensory functions of head and neck except #10 Vegas nerve which innervates visceral organs

Question 140

Peripheral NS – Autonomic

Answer 140

• Autonomic ns controls vegetative – largely involuntary - functions of body
• smooth muscle of blood vessels, lens of eye, gut, bladder, cardiac muscle, gland secretion
• Sympathetic and parasympathetic – most organs have both and they have opposite effects, they are yin and yang
  
  • Sympathetic
  • Parasympathetic

Question 141

Autonomic Nervous System

Answer 141

• controls vegetative – largely involuntary - functions of body
• Smooth muscle of blood vessels, lens of eye, gut, bladder
• Cardiac muscle
• Glands
• Sympathetic and parasympathetic – most organs have both and they have opposite effects, they are yin and yang

Question 142

Sympathetic

Answer 142

• PNS
• mediates increased and rapid energy use by:
  
  • increasing blood flow to skeletal muscles
  • stimulates release of epinephrine which causes increased heart rate and increased blood sugar level
  • sweat glands
  • exit s.c. from thoracic and lumbar levels
  • most synapse in the sympathetic ganglion outside s.c.
  • most preganglionic neurons secrete Ach; postganglionic secrete norepinephrine
  • winds you up, flight or fight

Question 143

Parasympathetic

Answer 143

• PNS
• mediates processes responsible for storage of energy
  
  • salivation
  • gastric and intestinal motility
  • secretion of digestive juices
  • increased blood flow to gastrointestinal system
  • exit s.c. from cervical and sacral levels
  • neurons secrete Ach
  • rest and digest
• Sensory affarent, Moror efferent
• Leaves from cranial and sacral nerves
  *

Question 144

Neurotransmitter production

Answer 144

• Presynaptic Drug Actions
• Presynaptic autoreceptors regulate the amount of NT released from the axon terminal.
  
  • nt precursor can be administered, increasing the amount of nt produced and serving as agonist
  • drug can inactivate an enzyme used to make a nt and serve as antagonist

Question 145

Neurotransmitter storage

Answer 145

• storage is accomplished by the same transporter molecules that reuptake nt from synaptic cleft into terminal button
  
  • these transporter proteins are in the membrane of synaptic vesicles and “pump” nt into the vesicle
  • some drugs can block the transporter protein and the vesicles are empty when they dock and are released

Question 146

Neurotransmitter release

Answer 146

• Some drugs prevent release by deactivating the protein that cause docked vesicles to fuse with presynaptic membrane
• Other drugs have opposite effect and by binding with these proteins (as Ca+ would) and cause release of nt

Question 147

Receptors

Answer 147

• some drugs bind to post synaptic receptors just like nt’s do
  
  • they can cause the opening of ion channels – direct agonist
  • they can occupy the binding sites preventing nt from binding and not cause ion channels to open – direct antagonist
• some receptors have multiple sites to which different ligands can bind: some for nt’s, others for hormones or other neuromodulators
  
  • drug can bind to one of these alternative sites – called non-competitive binding:
  • prevents ion channels from opening – indirect antagonist
  • facilitates ion channels opening – indirect agonist
• drugs can bind to autoreceptors in presynaptic membrane
  
  • activate autoreceptors – antagonist
  • block autoreceptors – agonist

Question 148

indirect antagonist

Answer 148

• prevents ion channels from opening

Question 149

indirect agonist

Answer 149

• facilitates ion channels opening

Question 150

antagonist

Answer 150

• activate autoreceptors

Question 151

agonist

Answer 151

• block autoreceptors

Question 152

Reuptake and enzyme deactivation

Answer 152

• neurotransmitter is inactivated by protein that binds to it and returns it to terminal button
  
  • drug can bind to the reuptake protein and block its action
• neurotransmitter can be broken down by an enzyme
  
  • drug can inactivate the enzyme

Question 153

synaptic communication in brain is accomplished by 2 Neurotransmitters

Answer 153

Both are amino acids that act as neurotransmitters

• Glutamate
  
  • Excitory
• GABA
  
  • Inhibitory
• “there are probably no neurons in the brain that do not receive excitatory input from glutamate secreting terminal buttons and inhibitory input from neurons that secrete GABA” (or glycine in the brain stem)
• With the exception of pain, all sensory organs transmit information to the brain through axons whose terminals release glutamate (pain is a peptide)
• Most local circuits in the brain involve balance between these excitatory and inhibitory influences and is responsible for most of the information transmitted from place to place in the brain

Question 154

Neurotransmitters: Information processing networks in the brain other than Glutamate and GABA

Answer 154

• the role of these other nt’s is to modulate and regulate the information transmission of the glutamate / GABA circuits
• release of nt’s other than glutamate or GABA activates or inhibits circuits of neurons that are involved in particular brain functions

Question 155

Acetylcholine

Answer 155

• primary nt secreted by efferent neurons in CNS
• primary action in the brain is facilitation
• causes motor actions
• Ach axons and terminal buttons distributed widely throughout brain
• 3 Ach systems that have received most research (in rats):
  
  • dorsolateral pons – involved in eliciting most of the characteristics of REM sleep
  • basal forebrain – general activation of cortex and facilitation of learning , especially perceptual learning
  • medial septum – regulate electrical rhythms of hippocampus, important in formation of certain kinds of memories
• not possible to do the tissue destruction in humans necessary to trace nt pathways, but assumed to be similar to rat, although not certain
• Ach is deactivated in post-synaptic receptor by
  
  • enzyme AchE – acetate and choline
  • choline is taken up into pre-synaptic button
• myasthenia gravis
• 2 types of Ach receptors
  
  • nicotinic – ionotropic (thus rapid firing) – neuromuscular junctions, some in CNS
  • muscarinic – metabotropic (slower firing) – predominate in CNS
• Drugs:
  
  • botulinum toxin – blocks protein that causes fusion of nt vesicle with pre-synaptic membrane
  • black widow venom – binds with protein and causes release of Ach
  • curare – blocks nicotinic receptors and produces paralysis, used in “poison darts” and in surgery
  • Acetylcholinesterase inhibitor - Aricept

Question 156

3 Ach systems that have received most research

Answer 156

• dorsolateral pons – involved in eliciting most of the characteristics of REM sleep
• basal forebrain – general activation of cortex and facilitation of learning , especially perceptual learning
• medial septum – regulate electrical rhythms of hippocampus, important in formation of certain kinds of memories, deteriorates during alzheimers

Question 157

Ach is deactivated in post-synaptic receptor by

Answer 157

• enzyme AchE – acetate and choline
• choline is taken up into pre-synaptic button

Question 158

2 types of Ach receptors

Answer 158

• nicotinic – found in skeletal muscle. ionotropic (thus rapid firing) – neuromuscular junctions, some in CNS
• muscarinic – receptors found in heart are smooth muscles metabotropic (slower firing) – predominate in CNS

Question 159

Ach Drugs

Answer 159

• botulinum toxin: blocks protein that causes fusion of nt vesicle with pre-synaptic membrane. Can cause paralysis (antagonist effect)
• black widow venom – binds with protein and causes release of Ach (agonist effect)
• curare – blocks nicotinic receptors and produces paralysis, used in “poison darts” and in surgery. antagonist
• Acetylcholinesterase inhibitor – Aricept is used to treat alzeimers, keeps ACH open longer and slows down progression of alzheimers

Question 160

Monoamines

Answer 160

The monoamine transmitters share a common structure and form a family of neurotransmitters. Divided into the two following groups:

• Catecholamines include dopamine (DA), norepinephrine (NE), and epinephrine (EPI)
  
  • EPI does not seem to be part of a lot of processes
  • Catecholamines will usually refer to DA and NE
• Indolamines
  
  • Include serotonin (5-HT)

The cell bodies of monoamine neurons are located in the brainstem and give rise to axon terminals that are distributed widely throughout the brain

Question 161

catecholamines

Answer 161

• dopamine, epinephrine and norepinephrine

Question 162

Dopamine & systems

Answer 162

• has excitatory and inhibitory influences depending on post synaptic receptor
• appears to be involved in learning, attention, movement, planning, and reinforcing effects of drugs
• production:
  
  • tyrosine – essential amino acid, must be obtained from diet
  • L-dopa
  • Dopamine
  • Norepinephrine
• Tegmentum: headquarters of neurotransmitters

Used by several neural systems. Three important DA systems:

nigrostriatal

• projects from the substantia nigra to the caudate nucleus and putamen
• involved in control of movement

mesolimbic

• cell bodies in ventral tegmental area
• project from ventral tegmental area to limbic system: nucleus accumbens (imcluding nucleus accumbens, amygdald, and hippomapus; important in the reinforcing effects of substance use)
• Limbic areas: amygdala and hippocampus (important for learning & memory)

mesocortical

• ventral tegmental area
• project from ventral tegmental area to frontal cortex
• important for judgment, planning, strategy formation for problem-solving and working memory

Question 163

Parkinson’s

Answer 163

• dopamine does not cross bbb
• treated with L-dopa: Parkinsins is due to not enough dopamine in the basal ganglia. Dopamine will not pass the blood-brain barrier so you cannot just give it to people. L-dopa will cross the blood-brain barrier, which is why it is given to people with parkinsins.

Question 164

nigrostriatal

Answer 164

• a.cell bodies in substantia nigra
• b.project to neostriatum, i.e. caudate and putamen, part of basal ganglia
• c.involved in control of movement

Question 165

mesolimbic

Answer 165

a. cell bodies in ventral tegmental area
b. project to limbic system: nucleus accumbens (important in the reinforcing effects of substance use)
c. amygdala and hippocampus (important for learning & memory)

Question 166

mesocortical

Answer 166

a. ventral tegmental area
b. project to prefrontal area
c. important for judgment, planning, strategy formation for problem-solving and working memory

Question 167

Norepinephrine

Answer 167

• adrenalin and epinephrine are the same thing
  
  • adrenalin is hormone produced by the adrenal cortex
  • epinephrine also is nt in brain, but “not very important”
• norepinephrine and noradrenalin are same thing
• cell bodies of neurons that secrete ne are located in several nuclei in the pons and medulla and one in the thalamus
  
  • locus coeruleus in pons is “most important”- involved in vigilance and attentiveness to environment
• almost every region of the brain receives input from ne neurons
• synaptic effects are excitatory and inhibitory
• in general, behavioral effects of ne are excitatory
  
  • increases vigilance & attentiveness to the environment
• receptors also in organs of body and are responsible for the effects of catecholamines when they act as hormones

Question 168

Serotonin (5-HT)

Answer 168

• (5-HT)
• Mostly located in the gut (98%) with only 2% of serotonin cells in the brain
• behavioral effects are complex
  
  • regulation of mood
  • control of eating, sleep, dreaming, arousal
  • regulation of pain
• tryptophan is precursor
• cell bodies of neurons that secrete are in raphe nulei in mid brain, pons and medulla
• “most important”
  
  • dorsal raphe – projects to cortex, basal ganglia
  • median raphe – cortex, dentate gyrus of hippocampal formation
• at least 9 different types of 5-HT receptors
• Drugs:
  
  • Prozac
  • Paxil
  • Zoloft
  • Fenfluramine – diet control
  • LSD
  • MDMA (ecstasy)

Question 169

Glutamate or glutamic acid

Answer 169

• amino acid (remember aa used to make proteins)
• principal excitatory nt in brain
• 4 types of receptors
  
  • NMDA – (slide) at this receptor there are at least 6 different binding sites which must work in concert to produce changes in the synapse important for learning and memory formation
  • Controls the CA++ channels
• PCP acts at glutamate synapses

Question 170

GABA – gamma-aminobutyric acid

Answer 170

• inhibitory neurotransmitter; induces IPSPs
• widespread distribution in brain
• without inhibitory synapses brain would become unstable
  
  • neurons would excite neighbors who would excite their neighbors eventually exciting the original neuron
  • eventually most neurons of the brain would be firing uncontrollably
  • this is what a seizure is – epilepsy
• at least 5 different binding sites at GABA synapses
  
  • GABA
  • Benzodiazepine (etoh likely binds here)
  • Barbiturates
  • Steroid
• etoh, benzo and barbs all are agonists producing relaxation and sedation
• it is not known if the brain produces a ligand that is an agonist that naturally produces this same effect
• brain does produce an antagonist, the behavioral effects of which are fear, anxiety, tension
  
  • this possibly serves a protective function in times of danger
• A naturally produces agonist ligand has not been identified. There are a lot of manmade ones!
• There are body produdced antagonists to these sites. The effect of an antagonist would be (if you are antagonizing an inhibitory site) diminishes the inhibitory effects and causes emotional escalation.
• GABA and glutamate work in concert. Glutamine is excitatory and GABA inhibits it. The keep a balance so that glutamine does not just fire all of your neurons to fire.

Question 171

Peptides

Answer 171

• made of amino acids joined together
• Are neuromodulators (released from end of terminal button and around it and they diffuse out around the area of the brain and have an effect on neurons they do not have a direct connection with)
• released from all parts of the terminal button, not just the active zone
  
  • only a small amount goes into synaptic cleft
  • the rest affects other receptors in the area
• most appear to be neuromodulators, some act as nt’s
• endogenous opioids are peptides
  
  • opiates are synthetic opioids; heroin, morphine, demerol, codeine, percodan,
  • naloxone is an antagonist that blocks the effects of opiates and is used to treat o.d. of heroin

Question 172

Lipids

Answer 172

• another type of neurotransmitter
• substances derived from lipids act as nt
• Endocannabinoid (CB) receptors
  
  • these types of receptor sites are where marijuana has its effects
  • THC used to treat nausea associated with chemotherapy in children without the psychoactive effects
• CB receptors concentrated in: frontal cortex, anterior cingulate, basal ganglia, cerebellum, hypothalamus, hippocampus

4. Very low levels of CB receptors in brain stem, thus low toxicity of THC
5. CB receptor found on terminal buttons of

• Glutamte
• GABA
• ACh
• Norepinephrine
• Serotonin
• Dopamine

Question 173

Soluble Gases

Answer 173

• Can diffuse widely to exert actions on distant cells
• Nitric oxide does not bind to the receptor site. Enters cell by diffucion and activates an enzyme that produces cyclic GMP (a second messenger) within adjoining cells

Question 174

Animal Research Ethics

Answer 174

• Humane treatment
  
  • 50 X’s more animals are killed by Humane Society because of abandonment than in research
• Worthwhile research

Physiological psychologists study animals to learn of the relation between physiology and behavior

• Animal research must be humane and worthwhile
• Animal studies are justified on the basis of
  
  • Minimized pain and discomfort
  • The value of the information gained from the research
• Progress in developing vaccines
• Progress in preventing cell death immediately after a stroke
  
  • The importance of science for understanding ourselves and animals

Question 175

Ablation / lesion in animals

Answer 175

• involves the destruction of brain tissue followed by an assessment of subsequent changes in behavior sham surgeries as controls
  
  • Include:
  • Electrolytic lesions/Radio Frequency lesions
  • Excitotoxic lesions (kainic acid)
  • Neurochemical lesions (6-OHDA)
  • Aspiration
  • Knife cuts
• Distinction between functions and behaviors
• Brain lesion studies are complicated by the fact that all regions of the brain are interconnected
• Stereotaxic surgery
• stereotaxic instrument holds the head in a fixed position
  
  • The instrument has an arm that can move in 3 dimensions
  • The surgeon can thus position an electrode or other device within a particular sub-cortical structure
• Stereotaxic atlas provides a series of drawings of brain structures
  
  • Each page is a section of brain relative to a landmark on the skull (such as bregma)
• Histology techniques used to verify lesion location within brain.
  
  • Perfuse (to remove blood from brain)
    
    • Remove brain
  • Fix brain in formalin to solidify tissue and to prevent autolysis
    
    • Slice brain into thin sections (10-80 microns thick)
  • Use stains to highlight selective neural elements
    
    • Myelin (Weil stain)
    • Cell body (cresyl violet: Nissl substance in cytoplasm)
    • Membrane (Golgi stain)
• Microscopes
  
  • Electron
  • Confocal laser – can also image living tissue
• Tracing efferent and afferent projections of a brain area
  
  • Tracing efferent connections is done using anterograde labels that are taken up by the cell bodies and transported to axons
    
    • “Forward: toward axons from cell bodies”
    • Inject the lectin PHA-L into a nucleus, wait several days, process brain tissue.
    • Immunocytochemistry uses a radioactive antibody to PHA-L in order to identify cells containing PHA-L
  • Tracing afferent connections is done using retrograde labeling
    
    • “Backwards: from axons to cell bodies”
    • e.g. fluorogold is a retrograde tracer

Question 176

Verification of lesions in patients

Answer 176

• CT scan – tomography (CT) uses an x-ray beam to scan the brain from all angles, these scans are then summarized in an image of the skull and brain (in a horizontal plane)
• MRI – magnetic field makes hydrogen atoms spin or reorient. Radio waves are then passed through brain tissue and measured, resulting information is combined to form an image of tissue.
• MRI DTI – measures the migration of water molecules along / across axons
  *

Question 177

Recording neural (electrical) activity in the brain

Answer 177

• microelectrodes
  
  • can record the activity of a single neuron
• macroelectrodes
  
  • EEG

Question 178

Recording electrical activity by magnetic fields

Answer 178

• Magnetoencephalopathy
  
  • measures magnetic fields of electrical impulses
  • the new EEG

Question 179

Recording metabolic / synaptic activity

Answer 179

• measure FOS protein which is produced when neuron is active
• PET scan
• fMRI
  
  • has better spatial and temporal resolution than PET

Question 180

Stimulation of the brain

Answer 180

• electrical
  
  • animals
  • seizure patients - Penfield
• chemical
  
  • usually amino acids
• TMS

Question 181

Genetic Research

Answer 181

• concordance rates of disorders in mono and dizygotic twins
• adoption studies
  
  • compare concordance rates of disorders of people adopted at early age with bio and adopted parents
• targeted mutations or knockout genes
  
  • defective gene produced in the laboratory inserted in mice
  • gene controls the production of a particular protein or some enzyme necessary for its production
  • subsequent behavioral impairments are associated with the protein

Question 182

Physiological Psychology

Answer 182

• Effects of manmade substances on systems and behavior

Question 183

Neuropsychology

Answer 183

• Cognitive and psychological effects of brain damage
• Application of cognitive neuroscience
• Clinical application
• Diagnose brain and person to find treatment

Question 184

Psychophysiology

Answer 184

• Measuring brain processes
  
  • Observable feedback (EEG)
  • Relationship between physiological response

Question 185

Cognitive Neuroscience

Answer 185

• Brain basis for cognitive and emotional behavior
  
  • Pet scan/fMRI
  • Correlate increase activation in the brain with a particular area of interest

Question 186

5 Specialties of Biopsychology:

• Physiological Psychology
• Psychopharmacology
• Neuropsychology
• Psychophysiology
• Cognitive Neuroscience

Answer 186

Physiological Psychology

• direct manipulation of brain in animal research; focuses more on theory rather than immediate practical application.
• Started with animals. They damaged parts of the brain and then saw how that changed behaviors. How the brain mediates different levels of functioning. Our more detailed knowledge came from this

Psychopharmacology

• Manipulation of neural systems and behavior with drugs; animals and humans
• effect of substances on brain functioning and behavior

Neuropsychology

• Clinical application of this application. Diagnose brain and then diagnose person and find treatment
• cognitive & psychological effects of brain damage in human patients
• Application of cognitive neuroscience

Psychophysiology

• Measuring brain process that we are normally are not aware of and that we do not directly control. Turn into observable representation. With the person observing the representation of measurement they learn to alter and gain control of the processes that feedback is measuring. Ex: EEG, blood pressuree, etc. measure
• relationship between physiological activity and psychological processes in humans (EEG)

Cognitive Neuroscience

• brain basis for cognitive activity (PET Scan, fMRI)
• Both techniques allow for measurement of brain activity and functioning. The basic paradigm in this area is to correlate increase activation of certain areas of the brain with a particular area of interest. Which show activation and then modiate the capacity or condition.

Question 187

Interactive influence of genes and enviornment

Answer 187

• discussed earlier that environmental events directly influence DNA binding proteins that control regulator genes and determine if structural genes are expressed
• gene expression also influences the type of environmental stimulation person seeks and is exposed to
  
  • e.g. an aggressive person seeks out contact and/or extreme sports
• people also tend to select social partners that have similar genetics to their own
• when a particular gene encourages a developing individual to select experiences that increase the behavioral effects of that gene
• cycle of genetics and environmental experiences influencing and determining each other
• Although raised apart, twins in MN study grew up in culturally and economically similar environments
• Recent research shows the correlation of iq in twins:
  
  • Near 0 in low SES
  • Near 1.0 in high SES
    *

Question 188

Neuron Parts

Answer 188

Soma – cell body

• contains the nucleus and much of machinery that operates cell
• headquarters of the cell, involved in biological processes

Dendrites

• receive information from other neurons
• can grow and form new connections
• where synapses occur

Axon

• collaterals – telodendria
• can grow and form new connections
• a nerve is composed of many axons surrounded by a tough, elastic connective membrane
• Can often split into different pieces

Question 189

Two ways of classifying a neuron

Answer 189

1. Number of axon processes

• Multipolar Neurons: one axon, many dendritic branches
• Bipolar Neurons: one axon, one dendritic tree
• Unipolar neurons: one stalk that splits into two branches. Soma is in between the two branches

  2. Function

• Motor neurons: Carry messages to muscles (project effective information out of the brain)
• Sensory Neurons: Neurons carry messages toward the brain (Input element)
• Interneurons: connect neurons (everything in between; do all perciefing, integrating, remembering, planning, feeling )

Question 190

Electrochemical conduction overview

Answer 190

• Nerve cells are specialized for communication (neurons conduct ELECTROCHEMICAL signals)
• Dendrites receive chemical message from adjoining cells
• Chemical messengers activate receptors on the dendritic membrane
• Receptor activation opens ion channels, which can alter membrane potential
• Action potential can result, and is propagated down the membrane
• Action potential causes release of transmitter from axon terminals

Question 191

sodium-potassium transporter

Answer 191

• Moves Na+ out and K+ in.
• Helps maintain the Increased K+ on the outside and inside.
• This process consumer 40% of the energy of neurons

Question 192

Depolarization

Answer 192

when the membrane potential becomes more positively charged

Question 193

Polarization

Answer 193

When the membrane potential becomes more negatively charged

Question 194

Hyperpolarization

Answer 194

When the action potential goes into resting and becomes even more negatively charged beyond the membrane potential.

Question 195

Conduction of an Action Potential

Answer 195

“All or none” principle

• Action potential either occurs or not
• Membrane potential either passes threshold or does not.
• Once initiated, action potential conducted all the way down axon to end
• Remains the same size without increase or decrease in size of charge
• You don’t have a small action potential or a big action potential
• These are related to sensory imput such that sensory imput can vary and these variations have to do with the speed of the event.
• When axon splits, AP of same size (i.e. does not diminish) is conducted down both axons
• Variations in intensity of sensory stimulus or motor response results from change in rate of neuron firing i.e. faster firing = greater intensity

Question 196

Passive Conduction of depolarization

Answer 196

• Sub-threshold depolarization (electrical impulse) produces a disturbance in the neuron membrane (change in electrical charge) that becomes smaller as it moves away from the point of stimulation
• This type of conduction is passive, i.e. without changes in membrane permeability
• axon is acting like an electrical cable
• In myelinated axons, action potentials occur at Nodes of Ranvier where membranes are not myelinated and are conducted passively in myelinated areas
• This conserves energy because none is used for passive conduction and is faster because passive is faster than active conduction

Question 197

Synapse & Presynaptic and Postsynamtic Membranes

Answer 197

• The physical gap between pre-and post-symaptic membrame
• Presynaptic membrane is typically an axon
• Postsynaptic membrane can be:
  
  • A dendryte (axodendritic synapse)
  • A cell body (axosomatic synapse)
  • Another axon (axoaxonic synapse)

Question 198

Ligand

Answer 198

any substance that attaches to a binding site e.g. poisons, drugs etc.

Question 199

In what three places can a synapse occur

Answer 199

• Dendrites - axodendritic
• Soma - axosomatic
• Axon - axoaxonic

Question 200

Primary structures of a synapse

Answer 200

Question 201

Release of Neurotransmitter

Answer 201

• vesicles are “docked” on release zone of pre synaptic membrane on protein sites
  
  • Release zone contains voltage sensitive Ca++ channels
  • The arrival of an action potential at the axon and terminal buttons depolarize and open open voltage-dependent CA++ channels (CA++ in highest concentration outside of a neuron)
• CA++ ions flow into the axon
  
  • Ca+ enters neuron by diffusion and electrostatic forces and binds with the protein sites where vesicles are docked causing the proteins to move apart creating a fusion pore in the membranes through which nt is released
  • Ca+ transporters in membrane later remove Ca+ (similar to Na+ transporters)
• Vesicle membrane fuses with terminal button membrane
  
  • Tb membrane “pinches off” at the junction of the axon and tb, migrate to and fuse with the cisternae which produces new vesicles –takes from few seconds to few minutes OR “kiss and run”
• CA++ ions change the structure of the proteins that bind the vesticles to the presynaptic membrane
• A fusion pore is opened, which results in the merging of the vesicular and presynaptic membranes
• The vesticles release their contents into the synapse
• Released transmitter then diffuses across the cleft to interact with postsynaptic membrane receptors.

Question 202

Activation of Post Synaptic Receptors

Answer 202

Neurotransmitter binds to post synaptic receptor site and causes neurotransmitter dependent (postsynaptic) ion channels to open changing the membrane potential (i.e. electrical charge).

• Ions flow through the membrane, producing either depolarization or hypolarization
• The resulting postsynaptic potential depends on which ion channel is opened.
• Ion channels opened by direct or indirect method:
  
  • Direct – (Ionotropic receptor) - ion channel has neurotransmitter binding site. When neurotransmitter attaches to binding site, channel opens.
  • Indirect – or (Metabotropic receptor) – nt receptor activates G protein. Part of G protein called alpha subunit breaks off:
• attaches to binding site on ion channel and it opens or activates an enzyme in the membrane which causes production of chemical in cytoplasm called second messenger. Sm causes ion channels to open and also causes biochemical and structural changes in nucleus and other parts of cell, including affecting gene expression.

Question 203

Post-synaptic Potentials

Answer 203

• Conducted down the neuron membrane
• The type of affect neurotransmitterhas on post synaptic membrane is determined by the type of ion channels it opens:
• Excitory post synaptic potential (depolarization)
  
  • Caused by opening of NA+ ion channels and NA+ entering the neuron
• Inhibitory post synaptic potential (polarization)
  
  • Caused by opening of CL- ion channels
  • K+ leaves the neuron and produces inhibitory post synaptic potential (hyperpolarization)
• CL-
  
  • if neuron is at rest diffusion and electrostatic forces are balanced and there is no CL- movement and thus has no affect
  • If neuron is firing, the outside of membrane will be negative and electrostatic force will cause Cl- to enter neuron and it will “neutralize” the EPSP by returning the membrane to resting potential and slow the rate of firing
• Ca+ EPSP
  
  • causes release of ts in terminal button
  • binds with and activates enzymes that are involved in biochemical and structural changes in neurons important for processes such as learning

Question 204

Termination of Post-synaptic potentials

Answer 204

Accomplished in two ways

• Reuptake:
  
  • the neurotransmitter molecule is transported back into the cytoplasm of the presynaptic membrane
  • Most common form of neurotransmitter deactivation
  • The NT molecule can be reused
• Enzymatic deactivation:
  • an enzyme destroys the neurotransmitter molecule
  • Ach is deactivated by enzyme present in cleft called acetylcholinesterase which divides Ach into constituent molecules
  • It is destroyed

Question 205

Neural Integration

Answer 205

• Activity of a neuron is determined by the combined effects of all the excitatory and inhibitory influences on the neuron
  
  • conducted by passive cable properties
  • temporal (if it happens enough over a period of time)
  • spatial summation (if there are enough in a given space)
• If summation reaches threshold, action potential will initiate at axon hillock
• Inhibitory and excitatory effects on a neuron do not equal inhibitory and excitatory effects on behavior
• If a neuron’s function is to inhibit a behavior, the effect of a inhibitory synaptic connection on that neuron is to decrease the inhibition of the behavior and increase the behavior
• IPSP’s counteract EPSPs; action potential is not triggered
• If the EPSP is very strong then the IPSP will just slow down the process
• Terman summation: if excitatory connection and the terminal button is firing rapidly enough that the postsynaptic effects

Question 206

Autoreceptors

Answer 206

• Receptors in the terminal button of the neuron that are sensitive to the neurotransmitter the neuron releases. Activation causes decrease in neurotransmitter production in and release from the neuron. If autoreceptors are not activated neurotransmitter production and release in not inhibited and increases.
• This function regulates the amount of neurotransmitter
• Involved in Negative feedback loop

Question 207

Negative feedback loop

Answer 207

• neurotransmitters – released by terminal button and detected by receptors on membrane of neuron across synaptic cleft. Only affect the neuron across the way.
• neuromodulators – released by terminal buttons in greater quantities and are more widely dispersed influencing many neurons in an area of the brain. Bind to and have effects on neurons they do not have direct connect with.
• hormones – Also transmitter substances!! Any tissues that have a hormone receptor will be affected by it. most produced by endocrine glands, but some produced by cells in stomach, intestines, kidney and brain. Sometimes hormones are released and are treated as a neurotransmitter. Other times they are in the nucleous of the cell and has different kind of actions on the functioning on the neuron. Released into extracellular space and dispersed by blood stream.
  
  • Neurons that have receptors for hormones are target cells. Hormones affect the functioning of the cells that have the receptors

Question 208

Primary Somatosensory Cortex

Answer 208

• Multimodal
• Region of the anterior parietal lobe whose primary input is from the somatosensory system, receives information from senses
• Sits side by side to primary motor cortex

Question 209

Primary Motor Cortex

Answer 209

• Region of the posterior frontal lobe that contains neuros that control movements of skeletal muscles
• Control of movement
• Sits side by side to primary somatosensory cortex

Question 210

Sensory association Cortex

Answer 210

• Gets information from each primary sensory area of the cortex.
• Analyze information perceived form the primary sensory cortex; perception takes place here, and memories are stored here

Question 211

Diencephalon

Answer 211

Consists of Thalamus and Hypothalamus

Question 212

Mesencephalon

Answer 212

(midbrain)

Made up of two parts

• Tectum: dorsal portion of midbrain
• Tegmentum: Located under the tectum

Question 213

Metencephalon

Answer 213

Made up of:

• Pons
  
  • bump on the brainstem
  • Headquarters for neurotransmitter systems. Involved ind reaming, REM, control of sleep and arousal
  • Relay station or pathway in and out of the cerebellum
  • Core of reticular functioning
• Cerebellum
  
  • Motor control as a principle area, also involved in postural tone, rapidly executed movements that require precise movements

Question 214

Myelencephalon

Answer 214

Consists of Medulla oblongata

Question 215

Nerve

Answer 215

Collection of axons outside the CNS

Question 216

Tract

Answer 216

collection of axons inside the CNS

Question 217

Nucleus

Answer 217

collection of cell bodies inside the CNS

Question 218

Ganglion

Answer 218

collection of fell bodies outside the CNS

Question 219

Types of drugs and place where they have their action

Answer 219

Most drugs have their site of action at the synapse

• Agonists- activates
• Antagonists-does not activate

Question 220

Competitive vs. Non competitive binding

Answer 220

Competitive: binding of a drug to a site on a receptor; does interfere with the binding site for the principal ligand

Non-competitive: binding of a drug to a site on a receptor; does not interfere with the binding site for the principal ligand

Question 221

Types of Dopamine Receptors

Answer 221

• Receptors are not all the same. There are different classes. At the synapses there are other types of receptors. Those associated non-dopamine receptors will vary from one dopamine pathway to another.
  
  • D1 – exclusively post-synaptically
  • D2 – pre and post synaptic

Question 222

Neuromodulators

Answer 222

• other networks of neurotransmitters that alter the action of networks of neurons that transmit information using either glutamate or GABA
  
  • Project pathways to these glutamate and GABA processing networks.

Question 223

Drug-Dopamine Interactions

Answer 223

• amphetamine, cocaine, Ritalin – blocks reuptake and causes the transporters to run in reverse so dopamine and norepinephrine are released
• Chlorpromazine blocks D2 receptors
• production of dopamine regulated by enzyme MAO (monoamine oxidase) in the presynaptic membrane where it destroys excess dopamine. It also does this to norepinephiphine.
  
  • MAO inhibitors old antidepressants
  • MAO also deactivates amines in food; rise in BP occurs with accumulation of amines, which is a downside
• sxs. of schizophrenia are reduced by dopamine antagonist drugs
• chlorpromazine (Thorazine) à D2 receptors
• There are risks with dopamine agonists (parkinsins) and antagonists (psychoatic conditions)
• :agonists (treat parkinsins)- side effects can cause delusions and hallucinations etc
• antagonists (treat psychoatic conditions)

Question 224

Norepinephrine

Answer 224

• adrenalin and epinephrine are the same thing
  
  • adrenalin is hormone produced by the adrenal cortex
  • epinephrine also is neurotransmitter in brain, but “not very important”
• norepinephrine = noradrenalin =noradrenergic
• cell bodies of neurons that secrete norepinephrine are located in several nuclei in the pons and medulla and one in the thalamus
  
  • locus coeruleus in pons is “most important”- involved in vigilance and attentiveness to environment
• almost every region of the brain receives input from ne neurons
• synaptic effects are excitatory and inhibitory
• in general, behavioral effects of norepinephrine are excitatory
• increases vigilance & attentiveness to the environment
• receptors also in organs of body and are responsible for the effects of catecholamines when they act as hormones