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MCAT > Bio: Ch 1, 4 > Flashcards

Bio: Ch 1, 4 Flashcards

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1
Q

cell theory

A
  1. all living things are composed of cells
  2. cell is basic functional unit of life
  3. cells arise only from preexisting cells
  4. cells carry genetic info in the form of DNA
    1. this genetic material is passed on from parent to daughter cell
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2
Q

why are viruses not considered living things?

A
  • acellular
  • cannot reproduce without the assistance of a host cell
  • may use RNA as their genetic material
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3
Q

eukaryotes

A

have membrane-bound organelles, a nucleus, and may for multicellular organisms

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4
Q

prokaryotic cells

A

do not have a nucleus

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5
Q

membranes of eukaryotic cells

A

phospholipid bilayer, which organize to form hydrophilic interior and exterior surfaces with a hydrophobic core

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6
Q

cytosol

A

suspends the organelles and allows diffusion of molecules throughout the cell

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7
Q

nucleus

A

contains DNA organized into chromosomes

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8
Q

nuclear membrane/envelop

A

double membrane that contains nuclear pores

double membrane maintains a nuclear environment separate and distinct from the cytoplasm

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9
Q

nuclear pores

A

in nuclear membrane

allow selective two way exchange of material between the cytoplasm and the nucleus

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10
Q

genes

A

coding regions in DNA

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11
Q

histones

A

orgnaizing proteins that linear DNA is wound around

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12
Q

nucleolus

A

subsection of the nucleus in which ribosomal RNA is synthesized

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13
Q

mitochondria structure

A
  • two layers
    • outer membrane
    • inner membrane that is folded into critae
  • intermembrane space
  • matrix
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14
Q

outer membrane of mitochondria

A

barrier between cytosol and inner environment of the mitochondrion

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15
Q

inner membrane of mitochondria

A
  • arranged into infoldings called cristae
  • contains the molecules and enzymes of the ETC
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16
Q

cristae

A

infoldings in inner membrane of mitochondria

increase the surface area available for ETC enzymes

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17
Q

intermembrane space

A

space between inner and outermembranes of mitochondria

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18
Q

matrix

A

space inside the inner membrane of mitochondria

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19
Q

how are mitochondria different from other parts of the cell?

A
  • semi autonomous
  • contain some of their own genes
  • can replicate independently of the nucleus via binary fission
  • can trigger apoptosis by releasing mitochondrial enzymes into the cytoplasm
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20
Q

cytoplasmic or extranuclear inheritance

A

transmission of genetic material independent of the nucleus

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21
Q

apoptosis

A

programmed cell death

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22
Q

lysosomes

A

contain hydrolytic enzymes that can break down substances ingested by endocytosis and cellular waste products -> when these enzymes are released, autolysis of the cell can occur

often work in conjunction with endosomes

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23
Q

endosomes

A

transport, package, and sort cell material traveling to and from the membrane

can transport materials to the trans-golgi, cell membrane, or to the lysosomal pathway for degradation

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24
Q

autolysis

A

released enzymes lead to the degradation of cellular components -> apoptosis

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25
Q

endoplasmic reticulum

A

series of interconnected membranes

continuous with the nuclear envelope

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26
Q

rough ER

A

contains ribosomes, which permit translation of proteins destined for secretion

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27
Q

smooth ER

A

lipid synthesis and detoxification of certain drugs and poisons

transports proteins from rough ER to golgi apparatus

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28
Q

golgi apparatus

A

stacked membrane bound sacs in which the cellular products can be modified, packaged, and directed to specific cellular locations

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29
Q

perixisomes

A

contain hydrogen peroxide

can break down very long chain fatty acids via beta-oxidation

participate in phospholipid synthesis and pentose phosphate pathway

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30
Q

cytoskeleton

A

provides stability and rigidity to the overall structure of the cell, while also providing transport pathways for molecules within the cell

includes: microfilaments, microtubules, intermediate filaments

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31
Q

microfilaments

A

solid polymerized rods of actin

  • provide structural protection for the cell
  • can cause muscle contraction through interactions with myosin
  • help for the cleavage furrow during cytokinesis in mitosis
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32
Q

cytokinesis

A

division of materials between daughter cells

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33
Q

microtubules

A

hollow polymers of tubulin proteins

  • create pathways for motor proteins like kinesin and dynein to carry vesicles
  • contribute to structure of cilia and flagella
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34
Q

cilia

A

composed of microtubules

projections from a cell that are primarily involved in the movement of materials along the surface of the cell

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35
Q

flagella

A

composed of microtubules

involved in the movement of the cell itself

long whip like structures that can be used for propulsion

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36
Q

cilia and flagella structure

A
  • 9+2 structure
    • 9 pairs of microtubules in center
    • 2 central microtubules
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37
Q

centrioles

A

found in centrosome

organizing centers for microtubules

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38
Q

centriole structure

A

9 triplets of microtubules with a hollow center

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39
Q

centrioles during mitosis

A
  • centrioles migrate to opposite poles of dividing cell and organize the mitotic spindle
  • microtubules emanating from the centrioles attach to chromosomes via kinetochores and exert force on the sister chromatids, pulling them apart
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40
Q

intermediate filaments

A
  • cell to cell adhesion and maintenance of integrity of cytoskeleton
  • help anchor organelles
  • ex: keratin, desmin
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41
Q

types of tissues:

A
  1. epithelial
  2. connective
  3. muscle
  4. nervous
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42
Q

epithelial tissue

A

cover the body and line its cavities, protecting against pathogen invasion and disccation

some epithelial cell absorb or secrete substances or participate in sensation

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43
Q

parenchyma

A

functional parts of the organ

made up of epithelial cells

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44
Q

epithelial cells

A

may be polarized, with one side facing a lumen or the outside world, and the other side facing blood vessels and structural cells

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45
Q

simple epithelia

A

one layer of epithelial cells

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46
Q

stratified epithelia

A

multiple layers of epithelial cells

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47
Q

pseudostratified epithelia

A

appear to have multiple layers due to differences in cell heigh but are actually one layer

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48
Q

cuboidal cells

A

cube shaped

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49
Q

columnar cells

A

long and narrow shaped

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50
Q

squamous cells

A

flat and scale like

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51
Q

connective tissue

A

support the body and provide a framework for epithelial cells

  • in most organs, they form the stroma by secreting materials to form an extracellular matrix
  • bone, cartilage, tendons, ligaments, adipose tissue, blood
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52
Q

prokaryotes

A
  • do not contain membrane bound orgganelles
  • contain genetic material in nucleiod region
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53
Q

nucleoid region

A

area of prokaryotes that carry a single circular molecule of DNA

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54
Q

overarching domains into which all life is classified:

A

archaea, bacteria, eukarya

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55
Q

which of the overarching domains of life include prokaryotes?

A

archaea and bacteria

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56
Q

archaea

A
  • single celled organisms
  • often extremophiles - live in harsh environments and often use chemical sources of energy rather than light
  • similarities to eukaryotes and bacteria
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57
Q

extremophiles

A

live in harsh environments (high temp, high salinity, no light

use chemical sources of energy (chemosynthesis) instead of light (photosynthesis)

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58
Q

archaea

similarities to eukaryotes

A
  • start translation with methionine
  • similar RNA polymerases
  • histones
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59
Q

archaea

similarities to bacteria

A
  • single circular chromosome
  • divide by binary fission or budding
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60
Q

bacteria

A
  • all contain cell membrane, cytoplasm
  • some have flagella or fimbriae
  • have many similar structures to eukaryotes
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61
Q

mutualistic symbiotes

A

both humans and bacteria benefit from relationship

ex: bacteria in human gut

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62
Q

bacteria shapes:

A

cocci, bacilli, spirilli

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63
Q

cocci

A

spherical bacteria

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64
Q

bacilli

A

rod shaped baacteria

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65
Q

spirilli

A

spiral shaped bacteria

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66
Q

bacteria can be classified by metabolic processes:

A

obligate anaerobes, obligate aerobes, facultative anaerobes, aerotolerant anaerobes

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67
Q

obligate aerobes

A

require oxygen for metabolism

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68
Q

obligate anaerobes

A

cannot survive in oxygen containing environments

only carry out anaerobic metabolism

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69
Q

facultative anaerobes

A

can survive in environments with or without oxygen

will toggle between metabolic processes based on environment

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70
Q

aerotolerant anaerobes

A

can survive in oxygen containing envrionment

can only carry out anaerobic metabolism

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71
Q

prokaryote cell structure

A
  • cell wall and cell membrane of bacteria for envelope
    • control movement of solutes in and out of cell
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72
Q

gram positive bacteria

A
  • purple cell wall
  • thin cell wall composed of peptidoglycan and an outer membrane containing phospholipids and lipopolysaccharides
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73
Q

gram negative bacteria

A
  • pink-red cell wall
  • thick cell wall composed of peptidoglycan and lipoteichoic acid
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74
Q

peptidogylcan

A

polymeric substance made from amino acids and sugars

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75
Q

periplasmic space

A

separates the cell wall from the cell membrane in bacteria

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76
Q

chemotaxis

A

ability of a cell to detect chemicla stimuli and move toward or away from them

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77
Q

bacterial flagella

A

can have one, two, or many

generate propulsion to move the bacterium toward food or away from immune cells

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78
Q

prokaryotic flagellum structure

A
  • composed of a filament, basal body, and a hook
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79
Q

filament

A

part of flagella

hollow, helical structure composed of flagellin

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80
Q

basal body

A

part of flagella

complex structure that anchors the flagellum to te cytoplasmic membrane

motor of the flagellum

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81
Q

hook

A

part of flagella

connects the filament and the basal body so that, as the basal body rotates, it exerts torque on the filament, which thereby spins and propels the bacterium forward

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82
Q

plasmids

A

smaller circular strictures that contain DNA acquired from external sources

can contain extrachromosomal material, antibiotic resistance genes, virulence factors

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83
Q

prokaryotic vs eukaryotic ribosomes

A

prokaryotic ribosomes are smaller

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84
Q

how do the structures of eukaryotic and prokaryotic flagella differ?

A

eukaryotic - contain microtubules made of tubulin, organized in 9+2

prokaryotic - made of flagellin, consist of filament, basal body, hook

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85
Q

binary fission

A

chromosome replicates while cell grows in size, until the cell wall begins to grow inward along the midline of the cell and divides it into two identical daughter cells

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86
Q

virulence factors

A

traits that increase pathogenicity

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87
Q

episomes

A

plasmids that cna integrate into the genome

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88
Q

transformation

A

genetic material from the surroundings is taken up by a cell, which can incorporate this material into its genome

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89
Q

conjugation

A

transfer of genetic material from one bacterium to another across a conjugation bridge

unidirectional transfer from donor male (+) to recipient female (-)

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90
Q

conjugation bridge

A

facilitates the transfer of genetic material during conjugation

made from sex pili that are found on donor male

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91
Q

F (fertility) factor

A

sex factor in e coli

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92
Q

Hfr cell

A

portion of genome transferred from Hfr cell to recipient for conjugation

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93
Q

transduction

A

transfer of genetic material from one bacterium to another via a bacteriophage vector

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94
Q

transposons

A

genetic elements that can insert into or remove themselves from the genome

95
Q

steps of bacterial growth

A
  1. lag phase: bacteria adapt to new local conditions
  2. exponential (log) phase: growth increases exponentially
  3. stationary phase: as resources are reduced, growth levels off
  4. death phase: as resources are depleted, they die
96
Q

virus structure

A

genetic material, capsid, sometimes a lipid-containing envelope

obligate intracellular parasites - cannot survive and replicate outside of a host cell

97
Q

capsid

A

protein coat on a virus

98
Q

virions

A

individual virus particles

99
Q

bacteriophages

A

viruses that target bacteria

inject their genetic material into the bacteria

contain tail sheath and tail fibers

100
Q

tail sheath

A

injects genetic material into the bacterium

101
Q

tail fibers

A

help bacteriophage recognize and connect to the correct host cell

102
Q

viral genomes

A
  • may be made of various nucleic acids
  • may be composed of DNA or RNA and may be single or double stranded
103
Q

single stranded RNA viruses can be either

A

positive or negative sense

104
Q

positive sense

A

single stranded RNA virus that can be translated by the host cell

105
Q

negative sense

A

single stranded RNA virus that requires a complementary strand to be synthesized by RNA replicate before translation

must carry an RNA replicate in the virion to ensure that the complementary strand is synthesized

106
Q

retrovirus

A

single stranded RNA genome from which a complimentary DNA strand is made using reverse transcriptase

the DNA strand can then be integrated into the genome

107
Q

reverse transcriptase

A

synthesizes DNA from single stranded RNA

108
Q

how do viruses infect cells

A

attach to specific recetpors

enter into the cell by fusing with plasma membrane, being brought in by endocytosis, or injecting their genome into the cell

109
Q

how to viruses reproduce

A

replicating and translating genetic material using the host cell’s ribosomes, tRNA, amino acids, and enzymes

110
Q

how are viral progreny released?

A

through cell death, lysis, or extrusion

111
Q

extrusion

A

virus leaves the cell by fusing with its plasma membrane

this process keeps the host cell alive and loows for the continued use of the host cell by the virus

112
Q

bacteriophages’ lfie cycles

A

have two: lytic cycle, lysogenic cycle

113
Q

lytic cycle

A

bacteriophage produces massive numbers of new virions until the cell lyses

bacteria in this phase are called virulent

114
Q

virulent bacteria

A

bacteria in lytic cycle

115
Q

lysogenic cycle

A

virus integrates into the host genome as a provirus or prophage, which can then reproduce all with the cell

the provirus can remain in the genome indefinitely or may leave the genome in response to a stimulus and enter the lytic cycle

116
Q

superinfection

A

simultaneous infection by viruses

117
Q

prions

A

infectious proteins that trigger misfolding of other proteins, usually converting an alpha-helical structure to a beta-pleated sheet

this decreases the solubility of the protein and increases its resistance to degradation

118
Q

viroids

A

plant pathogens that are small circles of complementary RNA that can turn off genes, resulting in metabolic and structural changes and potentially cell death

119
Q

CRB Compare the Cytoplasm and Cytosol.

A

The cytoplasm is essentially the total contents of the cell, excluding the nucleus.
The Cytosol is the part of the cytoplasm that isn’t held by the other organelles, and is the fluid that fills the cell. The Cytosol is what allows for molecular diffusion throughout the cell.

120
Q

CRB True or false? The Cytoplasm is what allows for molecular diffusion throughout the cell.

A

False. The Cytosol is what allows for molecular diffusion throughout the cell.

121
Q

So what then is the difference between the Outer and Inner Membrane of a Mitochondria?

A

The Inner Membrane is impermeable while the Outer Membrane is permeable to small molecules.

122
Q

What is the key difference between proteins produced in the Cytoplasm versus those produced in the Rough Endoplasmic Reticulum?

A

Proteins produced in the Cytoplasm end up in intracellular locations.

Proteins produced in the Rough Endoplasmic Reticulum will end up in extracellular locations, embedded in the cell membrane, or in the Endomembrane System (ER, Golgi, or Lysosome).

123
Q

Which of the following is closest to the Endoplasmic Reticulum?

(A) Medial Stack
(B) Trans Stack
(C) Cell Membrane
(D) Cis Stack

A

(D) Cis Stack

124
Q

The Basement Membrane is composed of fibers such as Collagen. What is the purpose of the Basement Membrane?

A

The purpose of the Basement Membrane is to act as a site of attachment for Epithelial Cells.

125
Q

Which of the following are examples of Connective Tissue?

I. Cartilage
II. Blood
III. Adipose

(A) I Only
(B) III Only
(C) I and II Only
(D) I, II, and III

A

D) I, II, and III

The following are examples of Connective Tissue?

  • Cartilage
  • Blood
  • Adipose
  • Bone
  • Membranes covering brain and spinal cord
126
Q

The primary types of fibers that make up the cytoskeleton are Microfilaments, Microtubules, and Intermediate Filaments. Match each of the following functions to one of these three fibers:

(1) Make up flagella
(2) Help the cell move.
(3) Involved in the Mitotic Spindle
(4) Make up Cilia
(5) Provide structural support to the cell by resisting mechanical stress
(6) Help transport substances into the cell

A

(1) Make up flagella - Microtubules
(2) Help the cell move - Microfilaments
(3) Involved in the Mitotic Spindle - Microtubules
(4) Make up Cilia - Microtubules
(5) Provide structural support to the cell by resisting mechanical stress - Intermediate Filaments
(6) Help transport substances into the cell - Microtubules

127
Q

CRB Which of the following statements is the most accurate on Microfilaments’ role in Cytokinesis?

(A) Microfilaments help to pull the chromosomes from the midplate towards each kinetochore.
(B) Microfilaments help to form the Cleavage Furrow, helping split the cell in half during Telophase.
(C) Microfilaments actually disassemble right before Cytokinesis to allow for the Cleavage Furrow to close.
(D) Microfilaments play no role in Cytokinesis.

A

(B) Microfilaments help to form the Cleavage Furrow, helping split the cell in half during Telophase.

128
Q

There are two main Microtubule Organizing Centers (MTOs): (1) The Centrosome and (2) The Basal Body. What is the primary role of each?

A

The Centrosome is what produces the Mitotic Spindle during Mitosis and Meiosis, allowing for cell division.

The Basal Body is the MTO in Cilia and Flagella, allowing for cell movement.

129
Q

Compare the Centrosome and Centrioles.

A

Two Centrioles are what make up the Centrosome.

130
Q

How many microtubules comprise each Cilia/Flagella? How are they organized?

A

Each Cilia/Flagella is composed 20 Microtubules organized with 9 pairs of fused Microtubules with a single pair of 2 unfused Microtubules in the center (“9 + 2 arrangement”).

131
Q

Instead of having a Nucleus, what is the name of where the DNA is concentrated in Prokaryotes?

(A) Nucleolus
(B) Nucleoid Region
(C) Transcriptional Region
(D) Nucleic Acid Pool

A

(B) Nucleoid Region

The Nucleoid Region is where the DNA is concentrated in Prokaryotes.

132
Q

True or false? Archaea may look a lot more like Bacteria, but their genes and metabolic pathways are more similar to Eukaryotes than Bacteria.

A

True. Archaea may look a lot more like Bacteria, but their genes and metabolic pathways are more similar to Eukaryotes than Bacteria.

133
Q

Which of the following are possible targets of antibiotics that can discriminate between Bacteria and Eukaryotes?

I. Ribosomes, because Bacteria have much smaller subunits.
II. Plasma Membranes, because Eukaryotes incorporate no trans-fatty acids naturally.
III. Flagella, because the biochemical makeups of Bacterial and Eukaryotic Flagella are significantly different.

(A) I only
(B) I and III only
(C) II and III only
(D) I, II and III

A

(B) I and III only

Each of the following are Antibiotic Targets that can discriminate between Bacteria and Eukaryotes:

I. Ribosomes, because Bacteria have much smaller subunits.
III. Flagella, because the biochemical makeups of Bacterial and Eukaryotic Flagella are significantly different.

134
Q

What is the structure of a Nucleoid? How does it compare to the Eukaryotic Nucleus?

A

A Nucleoid is a circular double-stranded piece of DNA that is free-floating in the cytoplasm.

135
Q

Compare the Cell Wall of a gram-positive bacteria to that of a gram-negative bacteria.

A

The Cell Wall of a gram-positive bacteria is much thicker than that of a gram-negative bacteria.

136
Q

Along with Peptidoglycan, what other molecule will be in Gram-Positive Cell walls? (Hint: This molecule can actually activate the human immune system)

(A) Arachidonic Acid
(B) Lipoteichoic Acid
(C) Prostaglandins
(D) MHC Class III antigens

A

(B) Lipoteichoic Acid

Lipoteichoic Acid is in Gram-Positive Cell Walls and can activate the Human Immune System.

137
Q

True or False? It is possible to have a Virus with dsDNA and ssRNA at the same time.

A

False. Viruses can be either dsDNA (Double Stranded DNA), ssDNA (Single Stranded DNA), dsRNA, or ssRNA. They cannot be more than one of these at once.

138
Q

Why are Viruses known as “obligate intracellular parasites”?

A

Viruses cannot survive without a host (“obligate”), they need to enter the host (“intracellular”), and they use the hosts machinary without benefiting the host and often times harming the host (“parasite”).

139
Q

CRB True or false? The Negative Sense RNA Viruses can use an RNA Replicase enzyme from its host.

A

False. The Negative Sense RNA Viruses must use an RNA Replicase that the virus itself carries.

140
Q

Subviral Particles and Viruses are together termed “nonliving infectious agents.” Compare the two main types of Subviral Particles: Viriods and Prions.

A

Viriods are small pieces of circular RNA that can self cleave to create more of themselves.

Prions are small misfolded proteins that can cause normal proteins to misfold (α-helices will become β-sheets).

141
Q

Viriods and Virions are commonly mixed up. What’s the difference between these two things?

A

Viriods are small pieces of circular RNA that can self cleave to create more of themselves.

Virions are mature viruses that are complete with a capsid. They have not entered a host and undergone uncoating yet.

142
Q

neurons

A

highly specialized cells responsible for the conduction of impulses

143
Q

two ways that neurons communicate

A

electrical and chemical communication

144
Q

electrical communication

A

occurs via ion exchange and the generation of membrane potentials down the length of the axon

145
Q

chemical communication

A

occurs via neurotransmitter release from the presynaptic cell

+ the binding of these neurotransmitters to the postsynaptic cell

146
Q

dendrites

A

recieve signals from other cells

147
Q

soma

A

cell body

location of the nucleus as well as organelles such as ER and ribosomes

148
Q

axon hillock

A

where cell body transitions to the axon

where action potentials are intiated

149
Q

nerve terminal

A

aka synaptic bouton

end of the axon from which neurotransmitters are released

150
Q

nodes of ranvier

A

exposed areas of myelinated axons that permit saltatory conduction

151
Q

synapse

A

consists of never terminal of presynaptic neuron, membrane of postsynaptic cell, and space between the two

152
Q

synaptic cleft

A

space between presynaptic and postsynaptic neuron

153
Q

action potentials

A

transmission of electrical impulses down the axon

all or nothing messages

154
Q

axon

A

long appendage that terminates in close proximity to a target structure

155
Q

myelin

A

insulating substance that prevents signal loss

prevents dissipation of the neural impulse and crossing of neural impulses from adjacent neurons

156
Q

oligodendrocytes

A

creates myelin in CNS

157
Q

schwann cells

A

create myelin in PNS

158
Q

node of ranvier

A

small breaks in myeline sheath with exposed areas of axon membrane

159
Q

nerves

A

can carry multiple types of info

including sensory, motor, or both

160
Q

tract

A

contains bundled axons with only one type of info

161
Q

ganglia

A

nerve clusters of the same type of neurons in PNS

162
Q

nuclei

A

nerve clusters of the same type of neurons in CNS

163
Q

neuroglia or glial cells

A

other cells within nervous system in addition to neurons

includes: astrocytes, ependymal cells, microglia, oligodendrocytes, schwann cells

164
Q

astrocytes

A

type of glial cell

  • nourish neurons
  • form blood brain barrier
165
Q

blood brain barrier

A

controls the transmission of solutes from the bloodstream into nervous tissue

166
Q

ependymal cell

A

type of glial cell

  • line ventricles of brain
  • produce cerebrospinal fluid
167
Q

cerebrospinal fluid

A

physically supports the brain and serves as shock absorber

168
Q

microglia

A

type of glial cell

phagocytic cells that ingest and break down waste products and pathogens in the CNS

169
Q

which two types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?

A
  • astrocytes: nourish neurons and form blood brain barrier, which protects brain from foreign pathogens
  • microglia: break down waste products and pathogens
170
Q

resting membrane potential

A

-70 mV

net electric potential difference that exists across the cell membrane, created by movement of charged molecules across that membrane

171
Q

resting potential is maintained by using…

A
  • selective permeability of ions
  • Na+/K+ ATPase
172
Q

potassium leak channels

A

facilitate the outward movement of potassium

allow the slow leak of potassium out of the cell

173
Q

sodium leak channel

A

facilitate the inward movement of sodium

causes a buildup of electric potential in the cell

174
Q

at resting membrane potential

outside cell: which is more K+ or Na+

A

Na+ >> K+

net positive charge

175
Q

at resting membrane potential

inside cell: which is more K+ or Na+

A

Na+ << K+

net negative chagre

176
Q

Na+/K+ ATPase

A

pumps 3 Na+ out of cell

2 K+ ions in

(pumpKin)

177
Q

excitatory signals cause ____ of the neuron

A

depolarization

178
Q

inhibtory signals cause ____ of the neuron

A

hyperpolarization

179
Q

temporal summation

A

integration of multiple signals near each other in time

180
Q

spatial summation

A

addition of multiple signals near each other in space

181
Q

action potential steps (+ graph)

A
  1. cell depolarized to threshold voltage –> voltage gated Na+ channels open
  2. Na+ flows into cell (due to strong electrochemical gradient) –> depolarizing neuron further
  3. at peak (+35 mV), Na+ channels inactivated and K+ channels open
  4. K+ out of neuron –> repolarization
  5. hyperpolarization as K+ channels say open
  6. K+ channels close
  7. Na+/K+ ATPase brings neuron back to resting potential
182
Q

repolarization

A

restoration of negative membrane potential

K+ cations are driven out of cell

183
Q

hyperpolarization

A

K+ flows out

makes neuron refractory to further action potentials

184
Q

absolute refractory period

A

cell is unable to fire another action potential

185
Q

relative refractory period

A

cell requires larger than normal stimulus to fire an action potential

186
Q

impulse propagation

A

action potential can only travel in one direction

  • influx of Na+ in one segment of the axon brings the next segment of the axon to threshold
  • preceding segment is in refractory period
187
Q

saltatory conduction

A

sitnal hopes from node to node

188
Q

effector

A

gland or muscle that neuron is sending a signal to

189
Q

chemical conduction steps

A
  1. when action potential arrives at nerve terminal, Ca+ channels open
  2. Ca+ influx –> fusion of vesicles filled with neurotransmitters with the presynaptic membrane, resulting in exocytosis of neurotransmitters into synaptic cleft
  3. neurotransmitters bind to receptors on post synaptic cell
190
Q

ways that neurotransmitters can be cleared from postsynaptic receptors to stop the propagation of the signal

+ ex

A
  • neurotransmitter can be
    • broken down
      • ex: ACh
    • absorbed back into presynaptic cell by reuptake channels
      • ex: 5ht, DA, NE
    • diffuse out of synaptic cleft
      • ex: NO
191
Q

during the action potential, which ion channel opens first? what effect does the opening of this channel have on the polarization of the cell? how is this channel regulated?

A
  • ion channel: Na+ opens first
  • effect: depolarization
  • regulated by: inactivation
    • can only be reversed by repolarization
192
Q

during the action potential, which ion channel opens second? what effect does the opening of this channel have on the polarization of the cell? how is this channel regulated?

A
  • ion channel: K+ opens second
  • effect: repolarization and eventually hyperpolarization
  • regulated: closing at low potentials
193
Q

sensory neurons

A

aka afferent neurons

transmite sensory info from senory recetpors to spinal cord and brain

194
Q

motor neurons

A

aka efferent neurons

transmite motor info from the brain and spinal cord to muscles and glands

195
Q

interneurons

A

found between other neurons

196
Q

CNS

A

brain and spinal cord

197
Q

PNS

A

craanial and spinal nerves and everything else

198
Q

white matter

A

myelinated axons in CNS

199
Q

grey matter

A

unmeylinated cell bodies and dendrites in CNS

200
Q

in the brain, white matter is ____ than grey matter

A

deeper

201
Q

in the spinal cord, white matter is ____ than grey matter

A

shallower

202
Q

spinal cord structure

cell bodies and motor neurons

A
  • cell bodies: in dorsal root ganglia toward the back of spinal cord
  • motor neurons: run from brain along the opposite side of the spinal cord and in ventral root
203
Q

somatic nervous system

A

part of PN

voluntary

204
Q

autonomic nervous system

A

part of PNS

automatic

205
Q

autonomic nervous system

neurons that transmit messages from spinal cord

A

preganglionic neuron

postganglion neuron

206
Q

preganglionic neuron

A

ANS

soma in CNS

axon travels to ganglion in PNS

207
Q

parasympathetic nervous system

A

part of ANS

rest and digest

208
Q

sympathetic nervous system

A

part of ANS

flight or fight

209
Q

reflex arcs

A

use the ability of interneurons in spinal cord to relay info to the source of a stimulus while simultaneously routing it to the brain

210
Q

monosynaptic reflex arc

+ ex

A

sensory (afferent, presynaptic) neuron fires directly onto the motor (Efferent, postsynaptic) neuron

ex: knee jerk reflex

211
Q

polysynaptic reflex arc

+ ex

A

sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons

ex: withdrawal reflex - retracting foot while also maintaining balance

212
Q

Match each of the following to the structure they are derived from:

(A) Forebrain
(B) Midbrain
(C) Hindbrain

(1) Mesencephalon
(2) Prosencephalon
(3) Rhombencephalon

A

(A) Forebrain –> (2) Prosencephalon
(B) Midbrain –> (1) Mesencephalon
(C) Hindbrain –> (3) Rhombencephalon

213
Q

Which of the following statements about the Nervous system after leaving the spinal cord is NOT true?

(A) There are two types of neurons that pass the message from the spinal cord: Pre- and Post-Ganglionic Neurons.
(B) The soma of the Pre- and Post-Ganglionic Neurons are both in the CNS
(C) The Preganglionic Neuron synapses onto the Postganglionic Neuron.
(D) The Postganglionic Neuron innervates the target tissue.

A

(B) The soma of the Pre- and Post-Ganglionic Neurons are both in the CNS

Only the Soma of the Preganglionic Cells are in the CNS. Their axons exit the CNS, and the Postganglionic Neurons are entirely part of the PNS.

214
Q

Compare Nerves and Ganglia.

A

Nerves contain the axons of neurons in a bundle.

Ganglia contain the soma (cell bodies) of neurons.

215
Q

True or false? For the spinal nerve roots, the afferent neurons travel through the posterior spinal nerve roots and the efferent neurons travel through the anterior spinal nerve roots.

A

True. For the spinal nerve roots, the afferent neurons travel through the posterior (dorsal) spinal nerve roots and the efferent neurons travel through the anterior (ventral) spinal nerve roots.

216
Q

Afferent Neurons carry information via the _______________ root while Efferent Neurons carry information via the ___________ root.

(A) Dorsal, Dorsal
(B) Dorsal, Ventral
(C) Ventral, Ventral
(D) Ventral, Dorsal

A

Afferent Neurons carry information via the Dorsal root (the one in the back) while Efferent Neurons carry information via the Ventral root (the one in the front).

217
Q

A sympathetic nervous system response would likely result in which of the following:

I. Increased blood flow to the intestines
II. Increased cardiac output
III. Increased pupil dilation

(A) I Only
(B) II Only
(C) I and II Only
(D) II and III Only

A

(D) II and III Only

A sympathetic nervous system response would likely result in the following:

(1) DECREASED blood flow to the intestines
(2) Increased cardiac output
(3) Increased pupil dilation

218
Q

A parasympathetic nervous system response would likely result in which of the following:

I. Decreased sweating
II. Decreased salivation
III. Decreased blood flow to the kidney

(A) I Only
(B) II Only
(C) I and II Only
(D) II and III Only

A

(A) I Only

A parasympathetic nervous system response would likely result in:

(1) Decreased sweating
(2) INCREASED salivation
(3) INCREASED blood flow to the kidney

219
Q

How do the locations of the gray and white matter in the spinal cord and brain differ?

A

Spinal cord –
Gray matter inside/white matter outside

Brain –
gray matter outside/white matter inside

They are opposite.

220
Q

Summation at the trigger zone caused the membrane potential to increase to -65mV from -75mV. Will an action potential be fired?

A

No, it will not. The membrane potential at the trigger zone needs to be closer to -50mV to reach the threshold potential for an action potential to be fired.

221
Q

Will a Graded Potential occurring closer to the trigger zone be more likely to generate an action potential than a Graded Potential of the same size occuring on a distant dendrite?

A

Synapses closer to the trigger zone will experience less decay, so they have a higher chance of producing an action potential.

222
Q

In a resting membrane neuron, please indicate whether the following ions are in majority on the inside of the membrane or the outside and if they are anions or cations.

1) Organic Anions
2) Chlorine
3) Potassium
4) Sodium
5) Calcium

A

1) Organic Anions – Inside (Anions)
2) Chlorine – Outside (Anions)
3) Potassium – Inside (Cations)
4) Sodium – Outside (Cations)
5) Calcium – Outside (Cations)

223
Q

If there was an open channel, in which direction would each ion move considering just the electric gradient?

1) Organic Anions
2) Chlorine
3) Potassium
4) Sodium
5) Calcium

A

Remembering the charge difference across the neuron will help conceptualize this question. Just outside the neuron the charge is positive, and just inside the neuron the charge is negative.

1) Organic Anions - move out
2) Chlorine - move out
3) Potassium - move in
4) Sodium - move in
5) Calcium - move in

224
Q

Remembering the charge difference across the neuron will help conceptualize this question. Just outside the neuron the charge is positive, and just inside the neuron the charge is negative.

1) Organic Anions - move out
2) Chlorine - move out
3) Potassium - move in
4) Sodium - move in
5) Calcium - move in

A

Remembering which ions are in the majority inside and outside the membrane will help conceptualize this question. In diffusion, ions will go from areas of high concentration to areas of low concentration.

1) Organic Anions - move out
2) Chlorine - move in
3) Potassium - move out
4) Sodium - move in
5) Calcium - move in

225
Q

Which of the following can trigger the Inactivation mechanism of Sodium Voltage-Gated Channels?

I. Membrane Depolarization
II. Increased Na/K/ATPase action
III. Increased Potassium current

(A) I only
(B) I and II only
(C) II and III only
(D) I, II and III

A

(A) I only

Membrane depolarization will both open the Sodium Voltage-Gated Channel and activate the Inactivation mechanism.

226
Q

If the sodium channels had not been inactivated and the middle of an axon were electrically stimulated, in which direction(s) would Impulse Propagation occur?

(A) Towards the Synaptic Bouton only
(B) Towards the Soma only
(C) Towards both the Synaptic Bouton and the Soma
(D) The Action Potential would not propogate because the inactivation is necessary for impulse propogation.

A

(C) Towards both the Synaptic Bouton (Axon Terminal) and the Soma

227
Q

True or false? The resting membrane potential is not affected equally by all ions because ions have different solubilities.

A

False: The resting membrane potential is not affected equally by all ions because ions have different MEMBRANE PERMEABILITIES.

228
Q

Which of the following channels aid in maintaining the resting membrane potential?

I. Na+/K+ ATP Pump
II. Cl-/K+ Pump
III. Ca2+/Na+ Pump

(A) I and II only
(B) I and III only
(C) I only
(D) I, II, and III

A

(D) I, II, and III

All three pumps help maintain the resting membrane potential of about -60mV

229
Q

The “All or None” Principle applies to Action Potentials, Graded Potentials, or both? Explain.

A

The “All or None” Principle is the idea that you will either get a complete Action Potential or no Action Potential at all. Graded Potentials, however, will be either small or large depending on the stimulus, so the “All or None” Principle does not apply to them.

230
Q

Will action potentials be able to survive a particularly long axon? Or will they decay like graded potentials?

A

This is one of the differences between graded potentials and action potentials. Action potentials will NOT decay throughout the length of the axon; They remain unchanged.

231
Q

Do larger diameter axons or smaller diameter axons result in faster action potentials? Why?

A

Larger diameter axons will result in faster action potentials because there is less resistance. In other words, there are more paths for the ions to travel down the axon, allowing them to move faster.

232
Q

Myelin increases or decreases the capacitance across the membrane? What does this mean? Why is this the case?

A

Myelin decreases the capacitance across the membrane, meaning that less ions are lined up along the membrane. In other words, less charge is stored along the membrane. This occurs because the Myelin increases the distance between the charges, making them less attracted to each other.

233
Q

Action potentials require less energy when the axon is myelinated. Why is this the case?

A

Myelin decreases the membranes permeability to ions. If less ions leave, the Na+/K+ pump will not have to use as much energy to pump these ions back to their original location.

MCAT (26 decks)

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