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PSYCH 255 > Chapter 3 - Cells, Genes & Behavior > Flashcards

Chapter 3 - Cells, Genes & Behavior Flashcards

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1
Q

Neurons

A

functional units in NS that enable us to receive info, process & act on it

  • nerve cells
  • 80 billion
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2
Q

Glial Cells

A

Neuroglia or Glia

non-neuronal cells that provide multiple support functions

  • 100 billion
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3
Q

Nervous System is made up of? (2)

A

Neurons & Glia

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4
Q

Neurons communicate via?

A

Electrochemical signals

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5
Q

Nucleus

  • (2) definitions
A

1) structure within cell body containing chromosomes
* house genetic material
2) cluster of similar cells that form functional grouping
* functionally related & densely packed

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6
Q

Properties of Neurons (3)

A
  • continously changing (plasticity)
    • ​making new & losing old connections
  • behavior produced by groups of neurons
  • most have longevity
    • ​not continuously replaced
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7
Q

Most Neurons have longevity

  • (2) exceptions
A

2 regions:

  • Hippocampus
  • Olfactory bulb
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8
Q

Neurons: Basic Structure

  • (3) main parts
A

1) Dendrites
2) Soma (cell body)
3) Axon

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9
Q

1) Dendrites

  • define
  • (3) characteristics
  • part(s)
A

branching extensions of neuronal membrane

  • Unmyelinated (few exceptions - somatosensory)
  • # per neuron varies
  • gathers input (afferent part of neuron)

→ Dendritic Spines

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10
Q

Dendrites are usually unmyelinated

  • Exception?
A

Somatosensory Neurons

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11
Q

1) Dendrites → Dendritic Spines

  • function
  • location of?
A

membranous protrusions from dendrite that typically recieve input from single synapse of axon (usual point of contact)

  • increase SA
  • where most synapses are found
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12
Q

2) Soma (Cell Body)

  • contains?
  • functions? (2)
  • (2) additional points
A

contains nucleus → genetic material (DNA)

  • cellular functions (i.e. protein synthesis)
  • processes input → integrates (excitatory & inhibitory)
    →​to determine whether or not to fire
  • can have synapses
  • connects to axon via axon hillock
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13
Q

Axon Hillock

A

specialized part of soma that connects to axon

  • last site** in soma where **membrane potentials propogated** from **synaptic inputs** are **summated** before being **transmitted** to **axon
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14
Q

3) Axon ​

→ define

→ (3)

→ components (3)

A

long, slender projection of neuron that carries msgs to other neurons

  • 1 per neuron
  • usually myelinated
    • occurs with maturation
  • sends output (carries info to other cells)

→ Axon Collaterals
→ Nodes of Ranvier
→ Terminal Boutons (Axon Terminals)

​

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15
Q

Axon → Axon Collaterals

A

branches of axon

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16
Q

3) Axon → Nodes of Ranvier

A

gaps between myelin sheaths (uninsulated)

  • regenerates AP sent down axon
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17
Q

3) Axon → myelin sheath

  • forms when?
  • functions (2)
A

Myelination occurs with maturation

  • protects
  • speeds up communication
    • allows saltatory (jumping) propogation of AP
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18
Q

Nerve

A

bundle of axons in PNS

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19
Q

Tract

A

bundle of axons in CNS

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20
Q

3) Axon

→ Terminal Boutons (Axon Terminals)

A

distal terminal branches of axon that convey info to other cells

  • site where electrical message converted to chemical & sent to next cell
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21
Q

Synapse (Synaptic Cleft)

A

‘almost connection’ usually between terminal bouton of presynaptic neuron & dendritic spines of postsynaptic neuron

  • site of information-transfer

→ permits passing of electrical/chemical signal to another neuron

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22
Q

Types of Neurons (3)

A

different types of neurons are specialized for different types of functions

1) Sensory
2) Interneuron
3) Motor

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23
Q

Types of Neurons (3)

1) Sensory

  • axon
  • cell body (soma)
A

recieves input from sensory receptors & sends to CNS

→ PNS

  • axon projects from periphery (dendrites in PNS) to CNS via dorsal root
  • cell body in dorsal root ganglion OR sensory cranial nerve ganglia
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24
Q

Sensory Neurons → Somatosensory Neurons

  • dendrites
  • axon
  • soma
A

brings sensory info from body into spinal cord

  • few myelinated dendrites (in PNS) connect directly to axon, which projects into CNS
  • soma off to side in dorsal root ganglia (PNS)
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25
Q

Types of Neurons (3)

2) Interneuron

A

integrates info from sensory neurons & conveys to motor neurons

link sensory & motor neural activity in CNS

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26
Q

Types of Neurons (3)

3) Motor

  • cell body
  • axon
A

sends output from CNS to effector organs

→ PNS (lower motor neurons)

  • soma & dendrites in CNS (spinal cord & brainstem)
  • axon projects into PNS forming spinal/cranial nerves → innervate effector organs
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27
Q

Motor Neurons → Upper vs. Lower

A

Upper → entirely in CNS & carry motor info to lower MN

Lower → project from spinal cord & innervate effector organs

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28
Q

Specialization of Neurons is reflected in their ___?

A

Structure, which reflects function

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29
Q

Specialization of Neurons is Reflected in Structure

  • (3)
A

1) # of dendrites
2) Size of Soma
3) length of axon

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30
Q

Types of Neurons → Sensory Neurons

  • ​structure
  • function
A
  • bring info to CNS
    • ex) somatosensory
  • few dendrites
    • innervate small region to allow greater distinction of touch on different parts of body

Unipolar or Bipolar

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31
Q

Types of Neurons → Interneurons

  • function
  • structure
  • examples (2)
A

link sensory & motor activity within CNS

axons branch into numerous collaterals

Examples:

  • Pyramidal → throughout cortex
  • Purkinje → in cerebellum
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32
Q

Interneurons → Pyramidal Cell

A

pyramid-shaped body

long axon

2 sets of dendrites projecting from apex & sides

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33
Q

Interneurons → Purkinje cells

A

extremely branched & fan-shaped dendrites

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34
Q

Types of Neurons → Motor Neurons

  • function
  • structure
A

send signals from CNS to muscle

axons project from spinal cord/brain forming spinal/cranial nerves

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35
Q

Glia

  • provide support to neurons through? (5)
A

Insulation

Nutrients

Structural Support

Aid in Neuron Repair

Waste Removal

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36
Q

Glia

  • Unlike neuron’s characteristic of longevity…
A

Glia are continuously being replaced

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37
Q

Types of Glia (4)

A

1) Ependymal Cells
2) Astroglia/Astrocytes
3) Microglia
4) Oligodendroglia & Schwann Cells

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38
Q

Types of Glia (4)

1) Ependymal Cells

  • location
  • function
A

found on ventricle walls (within choroid plexus)

produce & secrete CSF

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39
Q

Types of Glia

1) Ependymal Cells
* Hydrocephalus

A

blockage of CSF (leads to hydrocephalus) → accumulation causing ↑ intracranial pressure

  • obstruction in
    • interventricular foramen, cerebral aqueduct or 4th ventricle → non-communicating
    • subarachnoid space due to prior bleeding or meningitis → communicating

treatment → 1 end of shunt (tube) inserted into blocked ventricle & other into vein, allowing CSF to drain into blood stream

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40
Q

Types of Glia

2) Astroglia/Astrocytes

  • functions (5)
A

star-shaped cells

  • structural support for CNS
    • holds onto BV & neurons
  • nutrient & waste bridge between BV & neurons
  • part of blood-brain barrier
    • feet hold endothelial cells closely
      • allow certain substances across
  • stimulate BV dilation → enhance brain activity
  • Form scar to seal damage
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41
Q

Types of Glia

2) Astrocytes/Astroglia

  • Scar formation to seal damage
    • pros/cons
A

In acute damage phase → beneficial - seals off damaged area

  • prevents cascade events from affecting other neurons (further microbial infections/spread of cellular damage)

In long-term → harmful

  • scar tissue prevents regrowth & new connections
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42
Q

Blood-Brain Barrier (BBB)

  • definition
  • formed by?
  • function
A

highly selective permeable membrane seperating blood from brain’s ECF in CNS

  • formed by endothelial cells connected by tight junctions
    • encircled by astrocyte feet
      • provide biochemical support
  • protect brain from substances in blood
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43
Q

Types of Glia

3) Microglia

A

originate in blood

  • monitor health of brain tissue → immune system role
    • provide growth factors to repair damaged neurons
    • phagocytosis - engulf foreign tissue & dead cells

→ drawn to damaged area

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44
Q

Types of Glia → 3) Microglia

  • PHAGOCYTOSIS
A

p[rocess of engulfing foreign tissue & dead cells

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45
Q

Types of Glia

4) Oligodendroglia & Schwann Cells

A

support & insulate axons

form myelin sheath (glial coating surrounding & insulating axon)

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46
Q

Myelin Sheath

A

glial coating surrounding & insulating axon

  • keeps info localized & distinct
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47
Q

Types of Glia → Oligodendroglia

  • function
  • axonal regeneration?
A

provide myelin sheath in CNS

  • Branches form segments of myelin on adjacent axons
  • axons do NOT regenerate in CNS
    • prevents by creating hostile, non-permissive growth environment
48
Q

Types of Glia → Schwann Cells

A

provide myelin sheath in PNS

  • facilitate regeneration of axons in PNS
49
Q

Multiple Sclerosis

A

NS disorder resulting from loss of/damage to myelin in CNS

  • cognitive & motor effects
  • since myelin can’t be regenerated in CNS*
50
Q

Neuron Repair in PNS →via Schwann Cells

  • (4)
A

14 - 35 days

i) peripheral axon cut → dies
ii) Schwann cells shrink & then divide, forming glial cells along axon’s former path (secrete chemical signal)
iii) Neuron sprouts axons (proximal segment - attached to cell body) → 1 finds Schwann-cell path & becomes new axon
* distal segment degenerates
iv) Schwann cells envelop new axon to form myelin

51
Q

Regeneration in CNS

  • Why don’t cells regenerate in CNS? (2)
A

Glial environment in CNS prevents regrowth

Astrocyte scars form (chemical & physical) barrier blocking regrowth

Oligodendroglia do NOT form path & release chemical that repels regrowing axons

52
Q

Attempts at Regenerating Neurons (3)

A
  1. Placement of Tubes across Injured Area
  2. Insertion of Immature Glial Cells
  3. Use of Chemicals to Stimulate Axon Growth
53
Q

Attempts to Regenerate Neurons

1) Placement of Tubes across Injured Area

A

to provide path for axons

54
Q

Parts of Cell Body (10)

A

1) Nucleus
2) Nuclear Membrane
3) Endoplasmic Reticulum (ER)
4) Mitochondria
5) ICF
6) Microtubules
7) Cell membrane
8) Lysosomes
9) Microfilaments
10) Golgi Bodies

55
Q

Soma

1) Nucleus

A

contains genetic material (xsomes & genes)

56
Q

Soma

2) Nuclear Membrane

A

double-layered membrane surrounding nucleus

protective barrier

57
Q

Soma

3) Endoplasmic Reticulum (ER)

A

folded extension of nuclear membrane

  • involved in protein & lipid synthesis

→ Smooth

→ Rough

58
Q

Soma → Endoplasmic Reticulum

Smooth ER

A

lacks ribosomes

functions in lipid & carbohydrate metabolism & drug detoxification

59
Q

Soma → Endoplasmic Reticulum

Rough ER

A

studded with ribosomes

site of protein synthesis

60
Q

Soma

4) Mitochondria

A

double-membraned organelle that provides cellular energy (ATP)

  • gathers, stores & releases energy
61
Q

Soma

6) Microtubules

A

component of cytoskeleton

structural support & pathway for synaptic vesicles

62
Q

Soma

7) Cell membrane

A

protective barrier surrounding entire neuron that seperates intracellular & extracellular components

63
Q

Soma

8) Lysosomes

A

organelle enclosing degradative enzymes

  • clean up waste within cell
64
Q

Soma

9) Microfilaments

A

component of cytoskeleton

  • actin filaments (thinnest)
  • provide structural support
    • cell motility
65
Q

Soma

10) Golgi Bodies

A

membranous organelle

  • packages proteins in vesicles (to protect from degradation) for transport to destination
66
Q

Cell membrane → Structure

A

phospholipid bilayer that seperates ICF & ECF → critical for neural functioning & protection

  • embedded proteins control passage of substances
  • Interior: hydrophobic non-polar lipid tails
  • Exterior: hydrophillic polar phosphate heads
67
Q

Cell membrane regulates?

A
  • movement of substances in/out of cell
  • [ions] & [water]
68
Q

Storage of Genetic Materal

  • location?
A

nucleus

69
Q

Genes

A

segment of DNA that encode synthesis of particular proteins

  • contained within chromosomes
70
Q

Chromosomes

  • # in human somatic cell
A

double-helix structurse that hold entire DNA sequence

  • 23 pairs (46 total)
71
Q

Deoxyribonucleic Acid (DNA)

  • made up of?
A

sequence of nucleotides bases

  • Adenine (A)
  • Thymine (T)
  • Guanine (G)
  • Cytosine (C)
72
Q

Gene Transcription

  • location
  • process
A

occurs in nucleus

  • gene segment of DNA uncoils
    • 1 strand serves as template → attracts free-floating nucleotides
    • thymine replaced by uracil
  • complementary mRNA strand formed
    • leaves nucleus
73
Q

Translation

  • process
A

mRNA carries genetic code out of nucleus to ER

  • comes into contact with ribosomes, which move along mRNA strand
  • tRNA drop off AAs encoded by consecutive sequence of 3 nucleotide bases, forming polypeptide chain
    • forms protein
74
Q

Translation

  • codon
A

sequence of 3 bases that encodes for particular AA

75
Q

Protein vs. Polypeptide

A

protein = folded-up polypeptide chain

76
Q

Proteins → Packaging & Shipping

  • functions (4)
A

proteins

→ have various functions

  • cell structures, enzymes, hormones, neurotransmitters

→ packaged in golgi bodies & shipped to destination along microtubules

77
Q

Protein Destinations (3)

A

1) Incorporated into membrane
2) Remain within cell as enzyme
3) Excreted via exocytosis

78
Q

Proteins Embedded in Cell Membrane

  • ability?
    • occurs when?
A

ability to change shape

  • occurs in response to changes in:
    • chemicals
    • voltage
    • touch/stretch (stimuli)
79
Q

Types of Proteins in Cell Membrane (3)

A

1) Channel
2) Gated Channel
3) Pump

80
Q

Types of Proteins in Cell Membrane

1) Channel

A

opening in protein embedded in cell membrane that allows passage of certain ions

81
Q

Types of Proteins in Cell Membrane

2) Gated Channel

A

protein embedded in membrane that allows passage of substances through on certain occasions

  • gates open/close in response to trigger
82
Q

Types of Proteins in Cell Membrane

3) Pump

A

protein embedded in membrane that actively transports substances across

83
Q

Genes do not _____ cause behavior

A

Genes do not directly cause behavior

84
Q

Genes code for proteins, but other factors influence protein production (4)

A

1) Gene pairs → 1 expressed, other may not be
2) Enzymes change mRNA in nucleus
3) Enzymes break-down proteins to make more
4) Proteins merge to create different proteins

85
Q

Behavioral Variation

  • flow chart
A

Genetic Variation

→ Different proteins

→ Different cell function

→ Behavioral variation

86
Q

Abnormal Behavior

  • ​flow chart
A

Abnormal genes

→ defective proteins

→ impaired cell function

→ abnormal behavior

87
Q

Autosomes

A

NON-sex-determining xsome

pairs 1-22

88
Q

Sex Chromosomes

A

pair 23 of human somatic cells

89
Q

Alleles

A

alternate forms of a gene

→ gene pair contains 2 alleles

  • pairs of xsomes → pairs of genes
90
Q

Homozygous

A

having 2 identical alleles for a trait

  • code for same protein
91
Q

Heterozygous

A

having 2 different alleles for a trait

92
Q

wild-type allele

A

most common nucleotide sequence in a population

  • encodes most common phenotype
93
Q

Mutation

A

alteration of allele that yields a different version

less frequently occuring sequence of nucleotides

94
Q

Heterozygous Alleles → Dominant Allele

A

member of gene pair that is routinely expressed as a trait

95
Q

Heterozygous Alleles → Recessive Allele

A

member of gene pair that is routinely unexpressed

96
Q

Phenotype

A

physical & behavioral traits expressed by organism

  • depends upon genotype
97
Q

Genotype

A

genetic makeup of organism (genes), which influences phenotype (determines specific characteristics)

  • can refer to 2 alleles of particular gene
98
Q

Codominance

A

traits of both alleles are expressed completely

99
Q

Examples of Codominance (2)

A

AB blood

Calico cats (only female)

  • X chromosome has color gene
100
Q

Allele Disorders (2)

A

1) Tay-Sachs Disease
2) Huntington’s Chorea

101
Q

Tay-Sachs Disease

  • caused by?
  • results in?
A

caused by recessive allele on xsome 15

  • causes defective HexA enzyme that fails to break down lipids in brain
    • lipids accumulate in neurons
  • results in retardation, physical changes (atypical growth) & death by ~ age 5
102
Q

Tay-Sachs Disease

→ Normal Carrier x Normal

  • possible outcomes & probability for offspring?
A

Normal carrier → 50%

Normal → 50%

103
Q

Tay-Sachs Disease

→ Normal Carrier x Normal Carrier

  • possible outcomes & probability for offspring?
A

Tay-Sachs → 25%

Normal → 25%

Normal Carrier → 50%

104
Q

Huntingtons Chorea

  • ​caused by?
  • results in? when?
A

caused by dominant allele

  • due to ↑ in # of CAG repeats on xsome 4
    • ​> 40
  • presents middle age (earlier if ↑ repeats)
  • results in motor & cognitive disturbances
105
Q

Huntington’s Chorea

→ Normal Carrier x Normal

  • possible outcomes & probability for offspring?
A

Huntingtons → 50%

Normal → 50%

106
Q

Huntington’s Chorea

→ Carrier x Carrier (will have if live long enough)

possible outcomes & probability for offspring?

A

Huntingtons → 75%

Normal → 25%

107
Q

Relationship between Genotype & Phenotype

A

1 Genotype can produce many phenotypes

108
Q

Phenotype is affected by? (2)

A

Gene Expression

Environment

109
Q

Phenotypic Plasticity

A

capacity of one genotype to be expressed as more than one phenotype when exposed to different environments

  • even cloned animals have different phenotypes despite identical genotype
110
Q

Down Syndrome

A

chromosomal abnormality resulting in mental retardation & other abnormalities

caused by extra #21 xsome

111
Q

Epigenetics

A

differences in gene expression related to environment & experience

112
Q

Epigenetics

  • How can environmental factors affect protein production? (3)
A

1) Histone Modification
2) DNA Modification
3) mRNA Modification

113
Q

1) Histone Modification

A

genes may be:

  • exposed via acetylation
  • prevented from being exposed via methylation

… of tails of histones

which affects transcription

114
Q

2) DNA Modification

A

DNA transcription into mRNA enabled/blocked

  • methyl (CH3) groups bind to CG base pairs to block transcription
115
Q

3) mRNA Modification

A

mRNA translation may be enabled/blocked

  • binding of ncRNA to mRNA prevents translation

PSYCH 255 (7 decks)

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