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Foundations of Medicine > FOM: week 5 > Flashcards

FOM: week 5 Flashcards

1
Q

What kind of relationship does passive diffusion have to concentration of substance?

A

Linear relationship/directly proportional

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2
Q

What kind of relationship does facilitated diffusion have to concentration of ligand?

A

hyperbolic relationship; saturates at high concentrations

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3
Q

GLUT 1

A

found in most cells, has a high affinity for glucose, found in BBB

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4
Q

GLUT 2

A

found in the liver and pancreas, has a low affinity for glucose

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5
Q

GLUT 3

A

found in most cells, has a high affinity for glucose

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6
Q

GLUT 4

A

insulin induced transporter, medium affinity for glucose

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7
Q

GLUT 5

A

found in intestinal epithelia and kidney; acts as a fructose transporter as well

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8
Q

What is the free energy equation in both log and ln forms?

A 
deltaG = 2.303 RT log (C2/C1)
deltaG = RT ln (C2/C1)
R = 1.987x10-3
T = temperature (K)
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9
Q

What are some features of Na-K ATPases?

A
  • pump 2 K+ out of cell, pump 3 Na+ into cell (against concentration gradient) – requires energy!
  • helps establish the concentration gradient used in facilitated and passive diffusion
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10
Q

What is the primary role that ABCs play in drug resistance?

A

Cells usually become resistant to drugs through use of transporters by increasing the efflux of the drug from the cell.

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11
Q

What are ionophores and what is its mechanism?

A

Ionophores are inhibitors of ion channels. They are able to bind to ion and dissolve it in the membrane effectively reducing the concentration gradient.
ex. gramicidin – forms a dimer channel that allows ions to flow through it

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12
Q

What are aquaporins and what is their function in cells?

A

Aquaporins are specific ion channels for the transport of water into and out of cells. These allow cells to remain isotonic.

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13
Q

What are some differences between transporters and channels?

A

Channels - passive (use electrochemical gradient), have direct pore through membrane, move ions and small molecules, very fast! (millions of ions/sec)

Transporters - can be active or passive; have the ability to go with or against concentration gradient, never directly connected between inside and outside of cell, can move ions, glucose, and water; fast (hundreds-thousands molecules/sec)

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14
Q

How can channels be selective?

A

Channels have a selectivity filter, gate, and/or selectivity domain to ensure correct ions pass through

AAs through pore aid in selectivity!

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15
Q

What are some features of Na+ channels?

A
  • have four similar domains that form a “donut” hole
  • some transmembrane domains have positive lysine transmembrane units which cause it to be open or closed:
    - Closed: + AAs interact with - membrane charges and close channel
    - Open: depolarization of membrane thought to repel + charge and cause rotation axially and outwardly toward surface which opens channel
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16
Q

What are some features of K+ channels?

A
  • have a similar structure to Na channels, four subunits make-up the channel
  • has a selectivity domain (plug) in addition to selectivity filter
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17
Q

What is the cause of Cystic Fibrosis?

A

CF is caused by a mutation in the CTFR chloride transporter: F508G

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18
Q

What are the normal and defective functions of CTFR?

A

Normal: transport Cl- across cell membranes and regulate transport of other ions; normally Cl- secretion is stimulated by PKA –> cAMP
Defective: production of sweat and salt increases – reabsorption of Cl- does not occur; causes mucus to accumulate in lungs

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19
Q

What toxins block Na+ channels?

A

Tetrodotoxin (pufferfish)
Saxitoxin (dinoflagellates)

Both bind to the selectivity pore in Na channels

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20
Q

What toxin blocks K+ channels?

A

Tetra-ethylammonium ion – blocks K channels on nerve cells, presumably hinder passage of this cation through “plugging” the channel and blocking transport of K

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21
Q

How are cyclins and Cdk-cyclins regulated?

A
  • Wee1 kinase phosphorylates complex, inactivating it; Cdc26 phosphorylase removes the inhibitory phosphorylation of Wee1 kinase and the Cdk-cyclin can become active again
  • p27 can bind to Cdk-cyclin which inhibits it’s activity
  • Cyclins can be degraded by being marked by APC (anaphase promoting factor) – adds ubiquitin to cyclin and causes cyclins to be degraded through a proteasome
  • CKIs (cyclin-dependent kinase inhibitors) also inhibit Cdk-cyclin complexes by binding to them and inactivating
  • CAK activates Cdk-cyclin complexes
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22
Q

How is S-phase triggered?

A

ORCs (origin of replication complexes) bind to DNA marking sites of replication early in G1. If ORCs don’t bind then, the cell will likely end up in Go.

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23
Q

What is the pathway that is activated by ORC?

A

G1: ORCs bind to DNA, Cdc6 and Cdt1 associate with ORC, MCM helicase then associates forming pre-replicative complex (pre-RC)

S: S-Cdk triggers S-phase and causes Cdc6 and Cdt1 to be degraded/inhibited respectively, preinitiation complex associates with ORC and MCM helicase which phosphorylates ORC; DNA replicates

G2/M: phosphorylated ORC remains on DNA

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24
Q

How does growth factor signaling occur in cells?

A

Growth factor binds to GFR –> Ras –> MAPK –> causes transcription of c-myc which acts as a TF for transcription of other genes such as G1-cyclins –> G1-Cdk phosphorylates Rb-E2F complex inactivating Rb and allowing E2f to cause transcription of G1/S and S cyclins – >active S-Cdks –> DNA synthesis (S-phase)

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25
Q

What are the cell cycle checkpoints?

A
  • In G1 (start/restriction point) – cells either go on for replication (S phase) are disassemble their biosynthetic machinery and go into Go
  • G2 – M transition – checks to make sure all DNA is replicated and environment is favorable
  • Metaphase-anaphase transition – regulated primarily by proteolysis, checks to make sure all the chromosomes are attached at the mid-line - done by pulling on the kinetochores with the microtubules
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26
Q

What are oncogenes?

A

usually are in the form of proto-oncogenes in genome and for multiple reasons become active; these are genes that have potential to cause cancer

Considered gain-of-function

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27
Q

What are tumor suppressor genes?

A

genes that have anti-oncogenic properties that protect cells from cancer – usually mutated so cannot inhibit

Considered loss-of-function

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28
Q

What is p53 and what is its pathway?

A

p53 = a tumor suppressor protein that regulates the cell cycle through p21 which binds to active G1/S-Cdk or S-Cdk complexes to inactivate them.

Does this in response to DNA damage so that the cell doesn’t replicate the damaged DNA.

Cancer cells often have mutant p53…

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29
Q

What are some general features of ion channels?

A
  • can be opened or closed
    - leak or gated: mechanical, ligand, voltage
  • selective based on charge and size of ion
  • can be bi-directional due to osmosis/concentration gradient
  • three main structural components: selectivity filter, gate, and/or selectivity domain (plug)
  • move ions in bulk and is VERY fast!
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30
Q

What is the resting membrane potential (reversal potential) equation?

A

Erev = 61/Z log (Co/Ci)

Z = charge of ion
Co = extracellular concentration
Ci = intracellular concentration
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31
Q

What are the extracellular and intracellular concentrations (mV) of Na+?

A

Extra - 135-145

Intra - Muscle = 10, Neuron = 5-10

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32
Q

What are the extracellular and intracellular concentrations (mV) of K+?

A

Extra - 3.5-5

Intra - Muscle = 155, Neuron = 140

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33
Q

What are the extracellular and intracellular concentrations (mV) of Ca2+?

A

Extra - 1-2

Intra - Muscle = 10^-4, Neuron = 10^-4

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34
Q

What are the extracellular and intracellular concentrations (mV) of Cl-?

A

Extra - 95-105

Intra - Muscle = 10-20, Neuron = 4-30

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35
Q

What are the equilibrium potentials of Na+ and K+?

A 
Na+ = ~+60 mV
K+ = ~ -88 mV
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36
Q

What is Ohm’s Law?

A 
V = IR; R = 1/C (conductance
I = VC

I = current/ flow – if not transporters then there is NO current/flow!!!!!!

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37
Q

What is a resting membrane potential (RMP)?

A

RMP = the membrane voltage that exists in cells; living cells have a negative potential relative to extracellular fluid

Excitable cells (neurons and myocytes) have a much larger RMP (-30 – -70 mV) due to larger number of K+ channels open at rest

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38
Q

What does depolarization mean?

A

Depolarization is the change of the membrane potential value toward zero so that cell interior becomes less negative than resting level

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39
Q

What does hyperpolarization mean?

A

Hyperpolarization is the change of a membrane potential so cell interior becomes more negative than its resting state

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40
Q

What are the three types of cell death?

A

Necrosis, apoptosis, and autophagy

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41
Q

What are the morphological steps of apoptosis?

A
  1. Condensation of chromatin – occurs first along the periphery of the nucleus
  2. Blebbing of plasma membrane, cytoplasm appears to be vacuolated
  3. Entire cell shrinks
  4. Nucleus (and eventually entire cell) fragments
  5. Macrophages phagocytose apoptosed cell – triggered by changes in plasma membrane (phosphatidylserine flips to outer monolayer)
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42
Q

What are the biochemical changes that occur concomitantly with the morphological changes in apoptosis?

A
  • acidification of cytoplasm
  • specific proteases are activated and kill cell by destroying cellular components
  • nuclear destruction of lamins (become phosphorylated)
  • nucleases are activated and degrade DNA
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43
Q

What is the pathway of extrinsic apoptosis?

A

TNF family ligand binds (i.e. Fas) to trimerized fas death receptors are the target cell surface. These activated receptors then have adapter proteins and pro-caspases (8, 10) associate to make DISC. The pro-caspases self-cleave themselves to become caspases and recruit executioner caspases (3, 6, or 7) that then act on their targets.

Some targets include: CAD (cleaves DNA into fragments), Bcl-2 (destroys an inhibitor of apoptosis), lamins, proteins involved in DNA repair, etc.

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44
Q

What is the pathway of intrinsic apoptosis?

A

This involves the activation of the following signaling pathways to promote apoptosis: Akt and p53.

Pro-apoptotic proteins are on the surface of the mitochondria and are separated due to the presence of Bcl-2 (anti-apo). Bcl-2 is inactivated by an Akt activated BH3-protein (pro-apo) which allows the pro-apo BH123 proteins to aggregate forming a channel to release cytochrome c. The p53 pathway makes Bax and can also cause aggregation of pro-apo BH123 proteins to release cyto c. Cytochrome c then binds to Apaf1 forming a CARD domain which assembles with other CARD domains forming an apoptosome. The apoptosome recruits pro-caspases (9) which become caspases and recruit other executioner caspases (3, 6, or 7) to act on their targets.

Possible Targets: Gelsolin (disassemble microfilament cytoskeleton - actin), phosphorylates lamins, CAD (cleaves DNA), etc.

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45
Q

What do DISC and the apoptosome have in common?

A

Both organize in a structured manner and activate pro-caspases to become caspases which carry out the apoptotic agenda

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46
Q

What are the different types of pro-apoptotic proteins?

A 
BH123 = Bax, Bak
BH3 = Bid, Puma, Noxa, Bad, Bim
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47
Q

What are the different types of anti-apoptotic proteins?

A

BH1234 = Bcl-2, Bcl-X2

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48
Q

The intrinsic pathway is stimulated by two different pathways that occur in response to cell stress. What are these pathways?

A
  1. p53 pathway:
    - activated through DNA damage (cell cycle) –> ATM/ATR –>Chk1/2 –> removal of MDM2 from p53 –> p53 (P) –> Bax –> activates aggregation of pro-apo proteins to make a channel for cyto c to be released
  2. Akt pathway:
    - acts by activating a BH3 (pro-apo protein) to inhibit Bcl-2 which then allows aggregation of BH123 pro-apo proteins and release of cyto c
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49
Q

What are the cell survival pathways?

A

These pathways inhibit apoptosis through two methods:

  1. Survival factor binds to receptor which activates a gene regulatory protein, this binds to DNA and causes transcription of Bcl-2 mRNA which becomes translated and inhibits apoptosis
  2. Survival factor binds to receptor which activates it eventually activating Akt kinase (aka PKB) which causes Bad to release inactive Bcl-2 making it active. Bcl-2 is now able to inhibit apoptosis.
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50
Q

What is the pathway of autophagy?

A

The pathway is activated by cell stress, growth factor limiting, or low energy environments. These conditions inhibit mTOR pathway and promote AMPK (which inhibits mTOR) and the JNK pathway. The JNK pathway inhibits Bcl-2 which dissociates from Beclin-1 so that it can bind to class III PI3K and promote autophagy.

NB: both AMPK and JNK pathways are activated by low energy environments

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51
Q

What is autophagy best described as: cell death or cell survival pathway? Why?

A

Autophagy is best described as a cell survival pathway because it removes the components of a cell that are detrimental, which allows the rest of the cell to remain intact and functioning

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52
Q

How are apoptosis and autophagy involved in cancer?

A

When both of these pathways are disregulated they allow defective cells to proliferate making more defective cells –> cancer

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53
Q

What is the significance of Bcl-2?

A

Bcl-2 is involved in both apoptosis and autophagy and inhibits both processes (think about survival pathways). Thus if Bcl-2 is mutated to become constitutively active then both apoptosis and autophagy will be blocked and cell proliferation will occur –> cancer

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54
Q

What is the ‘Reverse Warburg Effect’?

A

Warburg effect = tumor preferential utilization of glucose

Reverse: Tumor cells are thought to send out ROS that act on surrounding fibroblasts in microenvironment which causes them to undergo autophagy. This causes lactate and pyruvate to be released for the cancer cell to take up to make glucose for energy.

Summary: Reverse Warburg effect is when surrounding cells are stripped from lactate and pyruvate through induced autophagy by cancer cells.

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55
Q

What is a light microscope used for?

A

routine laboratory microscope used for studying tissue sections

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56
Q

What is a transmission electron microscope (TEM) used for?

A

used to study cytology or internal structures of cells; study of electron micrographs

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57
Q

What is a scanning electron microscope (SEM) used for?

A

used to study the surface features of cells and tissues; obtain a 3-dimensional picture of the tissue

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58
Q

What is a polarizing microscope used for?

A

permits one to determine whether biological materials have different refractive indices along different optical axes

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59
Q

What is a phase microscope used for?

A

used to study living tissue; works on principal of different refractive indices of cellular and sub-cellular components

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60
Q

What is a interference microscope used for?

A

a modification of the phase microscope used for the study of living tissue

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61
Q

What is a fluorescence microscope used for?

A

uses UV light as the light source; used to examine the presence of fluorescent material in tissue sections

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62
Q

What is a confocal scanning microscope used for?

A

uses a laser energy beam; used to optically section a cell and with the appropriate computer equipment can reconstruct a 3-D image of the cell

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63
Q

What is the process of tissue sample preparation?

A
  1. Fixation – preserves tissue, makes tissue insoluble by precipitating proteins and carbs
  2. Dehydration – removes water (usually with alcohol)
  3. Clearing – used to replace alcohol for paraffin (usually use toluene, xylene, or benzene)
  4. Infiltration and embedding – replace clearing agent with embedding material (i.e. paraffin)
  5. Sectioning – produce thin sections of tissue (use a microtome)
  6. Staining – impart color to tissue (i.e. H & E)
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64
Q

How can frozen histological sections be useful?

A

Frozen sections are used in surgical biopsies and also in research to study the localization of enzymes.

Steps involved:

  1. surgeon takes tissue to pathologist/tech
  2. specimen frozen and cut on freezing microtome
  3. section stained (H & E) and examined by pathologist
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65
Q

What are artifacts in relation to fixing/staining?

A

Artifacts are any features evident in tissue sections that are a result of imperfect technique.

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66
Q

What are some examples of artifacts? And no, I don’t mean bowls or bones…

A
  • post-mortem degeneration (due to lysosomal digestion of cells)
  • shrinkage (tissue shrinks which leaves clear space that was once occupied by tissue)
  • precipitates (occurs when formalin not buffered properly)
  • wrinkles and folds (defect in paraffin sectioning)
  • nick in microtome knife
  • mishandling of tissue

NB: damages in preparation can lead to misinterpretation of tissue section.

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67
Q

What is an acidic dye?

A

An acidic dye is capable of forming a salt linkage with a positively charged tissue group; dye molecule is negatively charged (anionic)

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68
Q

What is a basic dye?

A

A basic dye is a positively charged (cationic) dye that forms a salt with a negatively charged tissue group

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69
Q

What is an acidophilic tissue?

A

An acidophilic tissue is a tissue that has an affinity for an acid dye, thus it has a net positive charge

i.e. many proteins are acidophilic tissues due to high amounts of positively charged AAs
Stain = eosin (red to pink)

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70
Q

What is a basophilic tissue?

A

A basophilic tissue is a tissue that has an affinity for a basic dye, thus it has a net negative charge

i.e. DNA and RNA
Stain = hematoxylin (blue to purple)

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71
Q

What does trichrome stain, stain?

A

Connective tissue, specifically collagen

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72
Q

What do elastic stains stain?

A

Elastic stains stain for the elastic fibers or elastic tissue in connective tissue

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73
Q

What does silver impregnation stain, stain?

A

It stains for reticular fibers in connective tissue; also used for cells in the CNS

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74
Q

What does fat stain, stain?

A

Fat stains, such as oil red O (stains fat red) and Sudan black (stains fat black) are commonly used and both are soluble in alcohol and fats.

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75
Q

What is a common nucleic acid stain?

A

Feulgen –> mild HCl hydrolysis cleaves purine base from backbone and the backbone carbon forms an aldehyde which reacts with a schiff reagent in the dye to give the DNA color

76
Q

What is a common carbohydrate stain?

A

Periodic acid-Schiff (PAS) –> cyclic sugars are cleaved which results in two aldehyde functional groups that a schiff base within the dye reacts to giving the carbohydrates color

77
Q

How are cellular proteins stained?

A
  1. Inject antigen (protein) into animal
  2. Animal produces antibody to foreign protein
  3. Isolate antibody
  4. Couple antibody with fluorescent compound, perioxidase or ferritin
  5. Prepare fresh frozen or alcohol fixed section of tissue
  6. Add tagged antibody
  7. Wash off excess and localize tagged site in tissue section
78
Q

What are the three common methods for labeling and identifying proteins and their locations?

A
  1. Fluorescent antibody tags
  2. Peroxidase coupled antibodies – antigen-Ab complex subjected to H2O2 which makes a brownish black precipitate
  3. Ferritin or gold coupled antibody
79
Q

What are the different modes of cell-cell signaling?

A
  1. endocrine - hormone secreted into bloodstream and travels to target
  2. paracrine - cells secrete hormones that act on adjacent cells
  3. autocrine - cell releases hormones that act on itself
  4. juxtacrine - cell-cell contact elicits a response; needs to be bound to another cell (found in immune system)
80
Q

What is the biosynthesis of NO and its function in the body?

A

Biosynthesis: arginine –> hydroxyarginine –> citrulline + NO

Pathway/function: arginine is converted to NO when NO synthase is activated by ACh at nerve terminal. NO rapidly diffused across membrane and binds to guanylyl cyclase to make cGMP which relaxes smooth muscle and allows more blood flow through.

Used as drugs for ED and coronary artery vasodilator

81
Q

What are the three main classes of cell-surface receptors?

A
  1. ion channel receptors (i.e. nicotinic receptor)
  2. receptor kinases (i.e. tyrosine kinases)
  3. heptahelical receptors (i.e. GPCRs)
82
Q

There are three classes of ATPases. What are they?

A 
P class
V class
F class
83
Q

What are some features of the P class of ATPases?

A
  • located primarily on the plasma membrane
  • are autophosphorylated during catalysis
    ex. Na-K ATPases, Ca ATPases
84
Q

What are some features of the V class of ATPases?

A
  • located in secretory vesicles like synaptosomes

- transport H+ into vesicle, multimeric

85
Q

What are some features of the F class of ATPases?

A
  • located int he mitochondria (and chloroplasts)

- physiologically ATP is formed (synthesized), multimeric

86
Q

A cell’s phospholipid bilayer limits the passage of charged molecules (especially ions) across the cell membrane (i.e., the lipid part of the cell membrane has high electrical resistance). _____ ___________, ___________ _________ , and ____ ___________ provide routes for charged molecules to cross the cell membrane. Transporters and channels have fundamentally _________ properties.

A

Gap junctions, membrane transporters and ion channels

Different

87
Q

Fundamental ion channel characteristics include __________ and _______. Channels differ in the number and types of ions they will pass (selectivity). Channels can be ___________, _______, and/or ________ gated. In addition to gating, some channels have additional __________ mechanisms that can _____ the flow of ions through the channel.

A

selectivity, gating

mechanically, ligand, voltage

inactivation, prevent

88
Q

All cells have a specific complement of channels, transporters and receptors that, in part, defines their unique physiology. By definition, all cells have a membrane potential. Ohm’s Law defines the relationship among membrane potential (voltage), current and conductance (the inverse of resistance): ________. Live cells have a resting membrane potential (Vm or RMP) that is ________ with respect to the extracellular fluid. Electrically excitable cells (neurons and myocytes) have a much larger RMP (-30 to -70 mV) because they have a ________ number of ____ channels open at rest.

A

I = VC

negative

larger, K+

89
Q

The primary function of neuronal Na+/K+ ATPase is the establishment of the ___________ gradients for Na+ and K+ that are needed to generate resting, graded and action potentials. The actions of Na+/K+ ATPase are only mildly ___________: the net result of the actions of Na+/K+ ATPase is a Vm of ~-5 to -12 mV.

A

concentration

electrogenic

Na-K ATPase is involved in setting up concentration gradients but contribute little to electric gradient. This activity is left to ion channels.

90
Q

For each ion, the equilibrium (or reversal) potential is the membrane potential where the net flow through any open channels is ______. In other words, at Erev, the chemical and electrical forces are in __________. Erev can be calculated using the Nernst equation ______________. In mammalian neurons, the equilibrium potential for Na+ is _____ mV and for K+ is _____ mV.

A

zero

balance

Erev = 61/Z log ([Co]/[Ci]) (mV)

Na+ = ~ +60 mV
K+ = ~ -88 mV
91
Q

In order to calculate the RMP, we must account for the ___________ contribution of each channel type, which is expressed in terms of ____________. The resting membrane potential will be close in value to the reversal potential for the ion that carries the __________ of the resting current.

A

RELATIVE

permeability (P)

majority

92
Q

What are the two major functions of meiosis?

A

Meiosis allows for genetic variability in the haploid gametes that are produced.

1) genetic variability
2) haploid gametes

93
Q

What are the differences between mitosis and meiosis?

A

Meiosis has one S-phase followed by two M-phases –> haploid daughter cells
- also allows for genetic variability (recombination)

Mitosis has one S-phase and one M-phase –> daughter cells are diploid

94
Q

What are germ cells called before the first meiotic division?

A

Primary oocytes or spermatogonia

95
Q

What are germ cells called after the first meiotic division?

A

secondary oocytes or spermatogonia

96
Q

What are germ cells called after the second meiotic division?

A

Mature eggs or spermatids

97
Q

What are the two factors that regulate genetic variability in meiosis?

A
  1. recombination (cross-over)

2. random assortment of homologous chromosomes

98
Q

What are some unique features of prophase I in meiosis I?

A
  1. Bivalent chromosomes (pair of homologous chromosomes) bind physically (thought to associate due to recognizing complementary DNA base sequences); synaptonemal complexes link homologous chromosomes along their length
  2. recombination occurs through a recombination nodule which involves cutting DNA and splicing strands back together (chiasma) – (2-3/homologous chromosome pair)
99
Q

Homologous recombination

A

involves cross-over between pairs of homologous chromosomes through chiasma; allows genetic variability to occur

100
Q

random assortment

A

homologous chromosomes are allowed to go wherever in metaphase plate, which chromosome faces a particular pole is random (not regulated)

101
Q

nondisjunction

A

refers to the aberrant separation of chromosomes during meiosis, and gives rise to daughter cells with an abnormal number of chromosomes

102
Q

Give a summary of spermatogenesis.

A
  1. Primordial Germ Cells (PGCs) – form during development
  2. In fetal development PCGs become spermatogonia through mitosis and become dormant until puberty and are stored in the testes
  3. In Puberty spermatogonia are stimulated by retinoic acid to enter mitosis forming a primary spermatocyte which undergoes meiosis I and II becoming spermatids
  4. Spermatids then differentiate into mature sperm
103
Q

Give a summary of oogensis.

A
  1. PGC becomes an oogonium which undergoes mitosis to become a primary oocyte
  2. This primary oocyte is arrested in prophase I in meiosis I until puberty
    •This is the reason why females have a set number of oocytes in her lifetime (~400,000)
  3. Retinoic acid stimulates progression of meiosis I at puberty
  4. After completion of Meiosis I, the oocyte becomes a secondary oocyte
    •This can be arrested unless fertilization occurs
  5. After fertilization, meiosis II is completed and the egg becomes mature
104
Q

What are the molecular steps in the fertilization process?

A
  1. Capacitation
  2. Acrosomal reaction
  3. Sperm-egg bind and fuse
  4. First cell cycle of zygote
105
Q

What does capacitation involve?

A

Capacitation involves changes in the sperm plasma membrane (glycoprotein and lipid content changes) which results in fertilizability

106
Q

What is involved in the acrosomal reaction?

A
  1. sperm contact the zona pellucida by binding to the ZP-3 glycoprotein and activates Na+/H+ and Ca2+ transporters
  2. Results in an influx of Ca2+ and sperm cytoplasmic pH to increase
    • Ca2+ influx thought to occur by sperm PLC –> IP3 –> open Ca2+ channels
107
Q

What is involved in the binding and fusion of egg and sperm?

A

Once the sperm binds to ZP-3 and there is an influx of Ca2+, this triggers exocytosis of cortical granules, which prevents polyspermy (ZP-3 is modified), stimulates the oocyte to complete meiosis II, and activates developmental program of the oocyte.

108
Q

What happens in the first cell cycle of the zygote (fertilized egg)?

A
  1. Ca2+ wave stimulates the egg to increase its rate of mRNA and protein synthesis.
  2. Ca2+ wave leads to destruction of certain s factor (CSF) and subsequent activation of APC, allowing meiosis II to be completed (oocyte haploid pronucleus formed)
  3. Sperm nucleus decondenses and both pronuclei enter S phase where they approach each other through actions of microtubules and actin
  4. Pronuclei enter M-phase and pair up along metaphase plate to prepare for division
109
Q

Where is the site of fertilization?

A

In the oviduct

110
Q

IVF-ET

A

in vitro fertilization- embryo transfer; eggs and sperm combined in petri dish and allowed to undergo fertilization which is monitored microscopically

111
Q

GIFT

A

gamete intrafallopian transfer; a few eggs (1-4) and about 100,000 sperm are placed directly in oviduct

112
Q

SUZI

A

sub-zonal insemination; 2-10 sperm are injected with a micropipette directly in the space between the zona pellucida and oocyte plasma membrane, fertilization is monitored and zygotes placed in uterus/oviduct

113
Q

ICSI

A

intracytoplasmic sperm injection; a single sperm is placed in a micropipette and microinjected directly into the egg cytoplasm (sperm doesn’t need to be motile or alive!!!), fertilization monitored and transferred to uterus/oviduct

114
Q

What are the four major types of tissue in the body?

A
  1. Epithelia
  2. Connective –> CT proper and specialized
  3. Nervous
  4. Muscle
115
Q

Epithelia are classified based on two criteria. What are they?

A

Shape and number of cells:
#: simple, stratified, pseudostratified
Shape: squamous, cuboidal, columnar

116
Q

Go study some histo slides online!! :)

A

Yea, histo!!!

117
Q

What are some features of tight junctions (zonula occludens)?

A

Proteins: occludens and cloudins

  • form a belt around apical layer of cell to adjacent cell; very close together!
  • have many anastamosing ‘ridges’; more ridges = better seal
  • Significance: materials must be transported through cell, restricts plasma proteins to particular regions of cell
    ex. intestinal epithelial cells
118
Q

What are some features of zonula adherens junctions (belt desmosomes)?

A

Proteins: cadherins

  • cytoplasmic domain of cadherins interact with action via linker proteins
  • extracellular domain of cadherins interact with adjacent cells extracellular cadherin domain
  • forms a belt like tight junction, but is not as close
119
Q

What are some features of macula adherens (“spot” desmosomes)?

A

Proteins: cadherins – desmogleins and desmocollins

  • cytoplasmic domains associate to intermediate filaments through desmoplakins
  • extracellular domains on adjacent cells associate with one another to form a dense line
  • forms localized spots of adherence
120
Q

What is the disease associated with macula adherens dysfunction?

A

Pemphigus vulgaris
- autoimmune disease that attacks desmosomal junctions (forms Ab to desmogleins) and presents as widespread blistering and loss of extracellular fluid

121
Q

What are some features of hemidesmosomes?

A

proteins: integrins
- cytoplasmic domain interacts with intermediate filaments via linker proteins to ECM
- extracellular domain interacts with laminin found in basal lamina
- half of a desmosome (macula adherens)
- forms between cell membrane on basal epithelial cell to the adjacent basal lamina

122
Q

What disease is associated with faulty hemidesmosomes?

A

Bullous pemphigoid (BP)

  • autoimmune disease that is caused by IgG directed against BP antigen in the dense plaque
  • presents as blistering in the lamina lucida
123
Q

What is a terminal bar (aka junctional complex)?

A

A terminal bar consists of the following distinct junctions in a close, serial relationship:

  • zonula occludens (tight junctions)
  • zonula adherens (belt desmosome)
  • macula adherens (“spot” desmosome)
124
Q

What are gap junctions (nexus)?

A

Proteins: six connexins make up one connexon; two connexons on adjacent cells create a channel that connects the cytoplasm of the two cells

  • many connexons form between the two cells
  • thought that connexons can regulate being open or closed through conformational changes in the connexin subunits
  • a way that electrical impulses are passed between cells
125
Q

What is a terminal web and what does it do?

A

A terminal web is an apical localization of actin filaments that go into microvilli and provide movement for the structures.

126
Q

What are the components for basal lamina?

A
  • lamina lucida
  • lamina densa
  • lamina reticularis
127
Q

What are some features of the lamina lucida?

A
  • is rich in the glycoproteins: laminin and entactin

- contains extracellular domain portions of epithelial cell integrins

128
Q

What are some features of the lamina densa?

A
  • meshwork of type IV collagen which is sandwiched between perlacan which contains heparan sulfate side chains
  • tightly anchored to reticular lamina by several factors including fibronectin
129
Q

What are some features of the lamina reticularis?

A
  • forms interface between basal lamina and underlying connective tissue
  • composed of type I and III collagen
  • basic groups of collagen bind to acidic glycosaminoglycans (heparan) in lamina densa
  • fibronectin is a linker protein between lamina densa and reticularis (has binding sites for heparan and collagen)
130
Q

What is the internal structure of a cilium?

A

The core structure is called an axoneme and contains:

  • two central microtubules
  • nine peripheral microtubule pairs: A and B subfibers
  • dynein arms: inner and outer, nexin links (involved in cilia bending and ATPase activity)
131
Q

What are the different types of ciliary rhythms?

A

Isochronal - cilia beat together

Metachronal - sequential beating of cilia (most common) – results in waves that sweep across epithelial surface

132
Q

What are some features of stereocilia?

A
  • very long; ends are able to twist
  • non-motile
  • increase absorptive surface of cells
  • found in epididymis and organ of Corti (inner ear)
133
Q

What are some features of microvilli?

A
  • covered in glycocalyx which is comprised of glycosaminoglycans (PAS+)
  • core has actin microfilaments that run from terminal web to tip of microvillus
  • allow for greater absorption due to increased surface area
  • contains enzymes for hydrolysis of sugar phosphates and splitting disaccharides
  • primarily located in the small intestine
134
Q

serous membrane

A
  • mesothelium (simple squamous) + basement membrane + underlying connective tissue
  • Line closed cavities in the body
135
Q

mucous membrane

A
  • surface epithelium (many types) + basement membrane + underlying loose connective tissue (lamina propria)
  • Lines cavities and canals which connect to exterior
136
Q

epitheloid

A

epithelial-like appearance of non-epithelial cells

137
Q

metaplasia

A

an abnormal change from one distinctive type of cell to another

138
Q

neoplasia

A

an abnormal change from one distinctive type of cell to a tumor cell
- can be malignant or benign

139
Q

hyperplasia

A

an increase in the number of cells in a tissue or organ, excluding tumor formation; increases the bulk of the organ –> hypertrophy

140
Q

hypertrophy

A

overgrowth or general increase in bulk of a part or organ

141
Q

anaplasia

A

reversion of differentiation (become ‘stem cells’); prevalent in malignant neoplasms

142
Q

Glands have two parts. What are they and what are they associated with?

A
  • stroma: connective tissue that supports parenchyma

- parenchyma: epithelial component of gland

143
Q

How are glands classified?

A
  • presence/absence of ducts
  • method of discharge
  • number of cells in gland
  • nature of secretory product
144
Q

What are the classifications for the presence/absence of ducts?

A
  • exocrine = have ducts, secretions pass onto an epithelial surface
  • endocrine = no ducts, secretions enter blood or lymphatic streams
  • mixed glands = contain both exocrine and endocrine glands, i.e. pancreas
145
Q

What are the classification for the method of discharge in glands?

A
  • merocrine = cells remain intact, product released (exocytosed) through membrane
  • apocrine = portion of the cell that is lost during the secretory process
  • holocrine = entire cell becomes part of secretory product
146
Q

What are the classifications for the number of cells in the gland?

A
  • unicellular i.e. goblet cells

- multicellular i.e. mammary glands

147
Q

How are multicellular glands classified?

A
  • extent of branching: simple (no branching) or compound (branching)
  • shape of secretory unit: tubular, alveolar (flasklike, sac-like), tubuloalveolar
148
Q

What are the secretory products glands produce and what are some features of these products?

A 
Serous: 
- thin, watery secretion
- cytoplasm is strongly basophilic due to free ribosomes and RER
- nuclei are round near base of cell
- apical surface occupied by granular material
Mucous: 
- viscous, slippery secretion
- cytoplasm is not basophilic
- nuclei are flattened at base of cells
- apical surface appears bubbly or foamy
Mixed:
- mucous portion forms inner cell layer with outer layer being serous -- demilune
149
Q

What is a demilune?

A

Demilunes are crescent-shaped groups of serous cells capping mucous secreting units

150
Q

What are myoepithelial cells and where are they commonly found?

A

Myoepithelial cells are found in sweat, mammary, and salivary glands between the basal lamina and base of secretory cells

  • structure: star-shaped with central nucleus and long cytoplasmic processes; filaments in cytoplasm can be contractile
  • function: help secretory process by pressing on secretory cells
151
Q

What -derm is connective tissue derived from?

A

mesoderm

152
Q

What -derm is epithelial tissue derived from?

A

ectoderm, mesoderm, and endoderm

153
Q

What is the structure of collagen fibers?

A

Collagen fibers are comprised of small fibrils composed of three α chains of tropocollagen wrapped in a triple helix and held together by hydrogen bonding. They are aligned in parallel with staggered starting and stopping points which gives rise to light and dark bands upon staining with a metal dye.

154
Q

What is are the chemical components of collagen fibers?

A

glycine, proline, hydroxyproline, hydroxylysine

155
Q

What is type I collagen used in?

A

ordinary connective tissue (loose, dense, and bone)

156
Q

What is type II collagen used in?

A

hyaline cartilage

157
Q

What is type III collagen used in?

A

loose CT, blood vessel walls; dermis, placenta; source of reticular fibers

158
Q

What is type IV collagen used in?

A

basement membranes

159
Q

What is the cell of origin for collagen fibers?

A

fibroblasts

160
Q

What is the chemical composition of elastic fibers?

A

Fibrillin-1 (glycoprotein) and elastin (high proline and glycine content; desmosine and isodesmosine – important in polymerization of elastin)

161
Q

What is the cell of origin for elastic fibers?

A

fibroblasts, smooth muscle cells (aorta)

162
Q

What is the structure of reticular fibers?

A

Reticular fibers tend to for branching, delicate networks and are attached to the basement membrane through the lamina reticularis.

163
Q

What is the chemical composition of reticular fibers?

A

type III collagen fibers with disaccharide sugars (PAS+)

164
Q

What is the function of reticular fibers?

A

They support lymphatic and hemopoietic tissues.

165
Q

What are the cells of origin for reticular fibers?

A

fibroblasts, reticular cells (lymphatic and hemopoietic tissues)

166
Q

What are glycoasminoglycans (GAGs)?

A

They are long unbranched polysaccharides consisting of a repeating disaccharide unit; can be sulfated or not
- Ex. heparan (sulfated), hyaluronic acid (non-sulfated)

167
Q

What are proteoglycans?

A

They are proteins that are heavily glycosylated.

- ex. aggrecan

168
Q

Why is fibronectin important for adhesion to the ECM?

A

Fibronectin is the most abundant glycoprotein in connective tissue and is involved in stucture of basement membranes.

It functions to organize the ECM because it can bind many different molecules such as collagen, herparan, and integrins.

169
Q

Why is laminin important for adhesion to the ECM?

A

Laminin is found in the lamina lucida of basement membrane and serves both structural and adhesive functions due to multiple binding sites.

Produced by epithelial cells since they are adjacent to lamina lucida.

170
Q

What are the functions of ground substance?

A
  1. space filler
  2. permits passage of gases, ions, and small particles (acts as a filter)
  3. helps immobilize large molecules/organisms (bacteria)
171
Q

What is the function and structure of fibroblasts?

A

Function: produce fibers (collagen, elastic, reticular); produce amorphous ground substance (fluid)

Structure: can be active (oval nuclei, basophilic cytoplasm – RNA) or inactive (smaller nuclei, cytoplasm slightly acidophilic)

These are the most abundant cell type in CT.

172
Q

What is the function and structure of macrophages?

A

Function: go to sites of inflammation and increase in number (monocytes –> macrophages); phagocytosis of flagged substances (have Fc and C3 receptors)

Structure: irregularly shaped cells; round, smaller, and darker nucleus than fibroblasts, when active the cytoplasm is full of granules and vacuoles

173
Q

What is the function and structure of mast cells?

A

Function: secrete heparan (staining properties) and histamine (acts as a bronchoconstrictor and a vasodilator)

Structure: large, ovoid cells, nucleus is small and ovoid, cytoplasm has many granules and is basophilic (stain reddish though due to high amounts of GAG heparan); water soluble cells thus do not show up well with H&E staining

174
Q

What is the function and structure of plasma cells?

A

Function: produce humoral antibodies

Structure: have a spherical and eccentrically placed nucleus (appears as a ‘wagon-wheel’), cytoplasm is very basophilic due to massive amounts of RER, golgi adjacent to nucleus stains lighter due to more acidophilic environment

Cell of origin: B-lymphocytes

175
Q

What is the function and structure of neutrophils?

A

Function: acts as the first line of defense against invasion by microorganisms; actively phagocytose organisms, sacrifice themselves and die forming pus cells

Structure: multi-lobed nucleus, granular cytoplasm

176
Q

What is the function and structure of eosinophils?

A

Function: increase due to parasitic infections, allergic hypersenstivitiy, control of local responses to allergic reactions; attracted to antibody

Structure: have a bi-lobed nucleus, numerous and large eosinophilic granules (stain pink/red)

177
Q

What is the function and structure of monocytes?

A

Function: migrate to sites of inflammation from the bloodstream, become macrophages and phagocytose flagged molecules

Structure: has a horseshoe-shpaed nucleus

178
Q

What is the function and structure of lymphocytes?

A

Function: produces T, B, and NK lymphocytes

Structure: has a dark staining nucleus that occupies majority of cell, filled with granules

179
Q

What is the function and structure of adipocytes?

A

Function: nutrients (TAG –> beta-oxidation), carbohydrate and fat metabolism, endocrine functions (leptin and adiponectin)

Structure: signet-ring shape, surrounded by fine network of reticular fibers

180
Q

What is the function and structure of foreign body giant cells?

A

Function: used when the organism is too big to be phagocytosed by just one macrophage

Structure: fusion of two macrophages; often multi-nucleated…

181
Q

What is the structure, components, and location of loose CT?

A

Structure: Fibers are irregularly arranged and interlaced, large amount of space (areolae) due to presence of ground substance
Constituents: fibroblasts, macrophages; most abundant fiber is collagen, but elastic and reticular fibers are present too to a lesser extent; ground substance
Location: composes most superficial and deep fascia, forms a framework for most organs, surrounds blood vessels and nerves, fastens membranes to underlying tissues (lamina propria)

182
Q

What is the structure, components, and location of dense irregular CT?

A
  • Structure: fibers are irregularly arranged
  • Constituents: fibroblasts, macrophages; coarse collagen fibers predominate (eosinophilic), but elastic and reticular fibers are present too; ground substance
  • Location: dermis of skin, capsules of certain organs (spleen)
183
Q

What is the structure, components, and location of dense regular CT?

A
  • Structure: collagen or elastic fibers are lined up in parallel arrays
  • Constituents: predominately collagen fibers (ligaments, tendons, aponeroses); predominately elastic fibers (ligament flava, vocal cords, suspensory ligament of penis)
184
Q

What is the structure, function, and location of adipose CT?

A

Structure: adipocytes arranged in lobules, surrounded by fine collagen, reticular, and elastic fibers
Function: nutrition, endocrine capabilities (leptin, adiponectin)
Location: subcutaneous CT, mesenteries, grooves of heart, etc.

185
Q

What is the structure, components, and location of reticular CT?

A

Structure: provides a fibrillar network in lymphoid tissue
Constituents: reticular cells –> produce reticular fibers
Location: around lymph nodes, spleen, in bone marrow

186
Q

What are the four major causes of edema?

A

increased formation of tissue fluid:
1. due to hydrostatic pressure (impeded venous return)
2. due to increased capillary permeability (histamine)
decreased formation of tissue fluid:
3. due to decreased blood colloid (starvation)
4. due to decreased lymphatic drainage (elephantiasis)

Foundations of Medicine (8 decks)

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