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274 Cards in this Set
- Front
- Back
Teleological
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use of purpose as an explanation
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mechanistic
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the use of cause and effect as an explanation
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Formula for Quantity
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Q = CV
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Formula for Volume
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Quantity/Concentration
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Formula for Flow
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Flow = Foce x conductance
i.e. Diffusion = Delta C x permeability |
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Another equation for Flow
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Flow = Force / Resistance
i.e., TPR = MAP / CO |
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Delta C =
CO = MAP = TPR = |
Delta C = concentration gradient
CO = Cardiac output MAP = mean arterial pressure TPR = total peripheral pressure |
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What's the concetration of Na+, Cl-, HCO3- and Protein like in the plasma?
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HIGH NA
Medium Cl- low HCO3 low Pr- |
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What's the concetration of Na+, Cl-, HCO3- and Protein like in the Interstitial Fluid?
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HIGH NA
Medium Cl but more than plasma low HCO3 NO PROTEIN |
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What's the concetration of K+, Cl-, HCO3- and Protein like in the Intracellular Fluid?
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HIGH K+
HIGH PROTEIN low HCO3 (lower than plasma and interstitial fluid) VERY LOW CL- |
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In which cell compartment is Cl- the highest?
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interstitial fluid
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Which compartment has the highest [ ] of Protein?
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intracellular fluid
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___ is in the outside of the cell, ____ is in the inside of the cell.
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Na; K
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Biggest difference b/w plasma and intersitial fluid is...?
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Interstitial fluid has no proteins!!
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How many liters of fluid are there b/w cells?
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12L
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How many L of fluid are in the plasma? Intracellular fluid? Interstitial fluid?
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plasma = 3L
intracellular fluid = 25L Intersitital fluid = 12L |
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What's the function of the skin?
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T- regulation
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What's the function of the Skin?
What's fxn of: GI tract? Lungs? Kidneys? |
skin = Temperature Regulation; GI = takes in what we ingest, little regulation
Lungs= gas exchange AND acid/base regulation b/c of CO2 Kidneys: what they leave behind is impt! |
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What's the concept of steady state?
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As the intake of water increases, plasma osmolarity decreases, so the body urinates in order to maintain the plasm osmolarity [ ]. (Experiment done on med students)
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Goldman-Hodgkin-Katz Equation
(GHK) |
describes changes in membrane potential, but is no longer valid.
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Now have GFCE:
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Em =
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If one permeability equation is overwhelmingly greater than the others, what equation do we use?
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Nernst
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At rest, Permeability of K is _____ than Permeability of Na, therefore membrane potential is closer to Ea, the reverse potential for sodium!
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greater
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All living cells' PM have a ____ ___
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membrane potential (polarized electronically)
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Separation of opposite charges across ____ ___
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PM
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How does membrane potential occur?
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through differences in [ ] and permeability of key ions
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Nerve/Muscle cells
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-have ability to produce rapid, transient changes in their membrane potential when excited
-EXCITABLE CELLS |
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Resting Membrane Potential
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- the constant mem pot in cells of NONEXCITABLE TISSUES and also those of excitable tissues when at rest
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What do Ion channels do?
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control membrane protential
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What's the effect of the K/Na pump?
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makes a dsmall direct contribution to membrane potential through its unequal transport of positive ions
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K/Na potential is "____ ___"; it's there to maintain [ ] gradient but doesnt have an effect membrane potential per-se. WHY IS IT THERE?
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weakly electrogenic; present to maintain a relative [ ] of K+ and kick out Na+ in the cell.
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Galvani, L (1786)
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animal electricity (FROGS)
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Volta, S (1790)
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voltaic pile - electrical batteries MADE FIRST BATTERY
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BERNSTIEN, J (1902)
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"The Ionic Hypothesis" - explained action potential conduction in squid axon
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Hodgkin/Huxley (1952)
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shows that action potentials reverse the interior polarity of nerve cells to POSITIVE values --> lead to "Sodium Theory" of conduction. showed membrane depended on K and NA.
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Why was bernsteins theory of nerve conduction wrong?
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he thought the nerve action caused the "breakfdown of the membrane potential"
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berstein thought the membrane was only permeable to ____, and developed the ___ Equation= ?
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K+
nernst equation = Em= 60log10 [K]inside / [K] outside |
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At membrane equilibrium, the force exerted by ion [ ] gradient eliciting movement is ______ by the force exerted by?
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balanced; voltage gradient aligned in opposite direction
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Nernst equation is very useful when you want to determine?
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contribution a SINGLE ion makes to the membrane potential
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hodgkin/hukley elaborated on bernsteins theory and showed that the membrane potential arises from?
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COMBINATION of ionic condutances and specific membrane permeability's.
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When cell is at rest, membrane is moderately permeable to ___ and ____, but IMPERMEABLE to ___.
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K+, Cl-; impermeable to NA
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At onset of action potential, what happens?
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Na permeability increases momentarily leading to further depolarization.
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Na influx continues until?
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high intracellular positivity repels Na+ ions [Em=Ena]
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After the ap peaks, what happens?
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Na gate switches off and a large outwardly directed K current REPOLARIZES the interior negativity.
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The hodgkin/hukley discovery led to what equation?
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GHK - very similar to nernst!
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Nernst is no longer valid because?
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only thought there was 1 ion
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KNOW GOLDMAN EQUATION AND HOW IT FITS INTO NERNST AND THAT HISTORY!
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KNOW GOLDMAN EQUATION AND HOW IT FITS INTO NERNST AND THAT HISTORY!
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Sakmann, B and Nehr, E
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PATCH CLAMP (patch clamp allows you to visualize the portion of the membrane with channels, allowed for study)
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Smith, M
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Site-directed mutagenesis
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Agre, P
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Aquaporins
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MacKinnon, R
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K & Cl Channels. SAW HOW CHANNELS ACTUALLY WORK
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Depolarization
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to abolish membrane potential
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Hyperpolarization
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to increase the resting membrane potential
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HypOpolarization
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reduce the resting membrane potential (i.e., reduction in negativity); NA+ ENTRY IN DENDRITIC SITES ON MOTOR NEURONS
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Receptors for neurotransmitters work how?
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make the membrane more sensitive so they can fire quicker!
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Local Anesthetics
|
- weak basis, exist at equilibrium
- uncharged forms are lipid soluble -accumulated charged forms reversibly bind to voltage gated Na channels - cause a reduction in nerve transmission at synapses by inhibiting AP conduction - primarily affect the function of ion channels and neurotransmitter receptor proteins in nerve cell membranes |
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Local Anesthetics contd
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they passively enter membrane down [ ] gradient, charged species bind to series of sites blocking the channel --> BLOCKS PAIN
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what's the MV resting membrane potential?
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-60mV
|
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What is membrane most permeable to at rest?
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K
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At rest, interior of cell is ____ charged relative to exterior because of???
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-negative
-large negatively charged proteins! |
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(note- I skipped most of the PM copmsition stuff, w/ polar heads/nonpolar tails b/c I already knew that)
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slides 5-8 on Gorfe
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How do forces of PM help the cell?
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keep it all together- and it's malleable so allows for flexibility
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Most important function of a membrane is?
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---Barrier! Helps as a passage-way for water-soluble substances b/w the intracellular and extracellular fluids.
---controls movt of molecules b/w cell and its environment --semi-permeable (solubility, size, charge/polarity) |
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Another fxn of membrane?
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Cell-to-cell adhesion (helps cells talk to each other)
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How do carbohydrates play in with membrane function?
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-serve as self-identity markers
|
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How do extrinsic/peripheral proteins play in with membrane function?
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docking-markers
enzymes receptors CAM's |
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How do Intrinsic/integral membrane porteins play in wich membrane function?
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1) Membrane Channels
- always open (water, solutes, leak channels) - Gated Channels: voltage and ligand gated 2) Carriers - accomplished by membrane carrier changing its shape |
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What are the two types of membrane transport?
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1) Unassisted Membrane Transport
2) Assisted Membrane transport |
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Unassisted Membrane transport (UMT)
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Simple (passive) Diffusion
- uniform spreading out of molecules (thermal motion) - Molecules move from higher --> lower [ ] (concen. gradient) |
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What portion of UMT is crucial to survival of every cell?
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1) exchange of O2 and CO2 b/w blood and air in lungs
2)Movt of substances across kidney tubules |
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Diffusion and Brownian Motion
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discovered that a diff in [ ] in each compartment will cause it to equalize
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Passive diffusion through membrane includes molecules such as?
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nonpolar! O2, Co2, fatty acids...
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Membrane thickness is inversely related to?
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distance traveled
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What factors affect the net rate of diffusion?
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rate of diffusion has to be directly proportional to the change in concentration
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What's Fick's Law
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Q = ((DeltaC)(A)(B)/ (sq rt of MW)(deltaX)
Delta C = [ ] gradient of substance B = lipid solubility A= membrane surface area MW = molecular weight Delta X = membrane thickness |
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2 Types of Assisted Membrane Transport (AMT)
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1) Carrier-mediated
2) Vesicular transport |
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Carrier mediated transport
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1) facilitated diffusion
2) active transport |
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Carrier mediated transport is accomplished by?
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- carrier changing its shape!
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In regards to carrier mediated transport, the kind and amount of material transferred across the membrane depends on?
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1) specificity
2) saturation 3) competition |
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Why does competition exist?
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there are only so many binding sites!
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Carrier mediated transport is directly proportional to the change in ___ until all space is ____
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concentration; occupied
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What's an example of facilitated diffusion?
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Glucose going into cells!
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Explain steps of Facilitated Diffusion
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1. Carrier protein exposes binding sites
2. solute molecule binds to carrier protein 3. carrier protein changes shape 4. transport solute is released and carrier protein returns confirmation to step 1 |
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Active Transport
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- moves substance AGAINST [ ] gradient
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Primary Active transport pumps require?
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direct use of ATP
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Secondary Active transport is driven by?
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ion [ ] gradient established by a primary active transport system
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Explain process of active transport
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1. carrier protein splits ATP-> ADP
2. ion to be transported binds to carrier (on low [ ] side) 3. ion binding makes carrier protein change shape so binding site is exposed to opposite side of membrane 4. carrier releases ion to other side (phosphate group also released) 5. binding site being freed allows carrier to go back to original shape |
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Vesicular Transport
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material is moved into or out of the cell wrapped in membrane
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Vesicular transport is an ___ method of ___ ___
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active; membrane transport
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What are the 2 types of vesicular transport?
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1. Endocytosis
2. Exocytosis |
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Endocytosis
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process by which substances MOVE IN TO CELL
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Other types of endocytosis?
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pinocytosis = nonselective uptake of ECF
Receptor-mediated - selective uptake of a large molecule Phagocytosis - selective uptake of multi-molecular particle |
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Exocytosis
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mech for secreting large polar molecules
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Exocytosis also enables cell to?
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add specific components to membrane!
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Water transport across PM is?
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slow!! not efficient!!
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Water transport is aided by specific protein channels on the pm known as?
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aquaporins
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Y
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Yttrium
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How many water molecules can pass through single-file through an aquarporin channel every second?
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1 billion!!
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Is the density/water solubility the same in every aquaporin?
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No, it varies in different cell types
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Which aquaporin set is involved in the generation of saliva, tears and pulmonary secretions?
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hAQP5
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What's osmosis?
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net diffusion of water down its [ ] gradient
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When does water reach equilibrium?
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osmotic pressure = hydrostatic pressure
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When does hydrostatic pressure build up?
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when solute can't pas through and volume expansion in the high solute compartment occurs --> pressure tends to push the fluid backward!
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osmotic pressure is a measure of?
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tendency for osmotic flow of water in the solution b/c of its relative [ ] of nonpenetrating solutes and water
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Osmolarity
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measure of a solutions total solute [ ] given in terms of the # of particles expressed in osmoles/liter (Osm)
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What is the normal osmolarity of body fluid?
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290-300
|
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Fe
|
Iron
|
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Van't Hoff's law is more exact when?
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the more dilute the solute
|
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In an ideal solution, osmotic coefficient equals ___
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1
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Osmotic coefficient depends on?
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nature of solute and its concentration
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What happens to osmotic flow as the membrane becomes more permeable?
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less osmotic flow is induced
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When there is not a permeability issue, do you get a chance in cell volume as solutes are passing through?
What about osmotic differences? |
no; no
|
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In non--penetrating solutions, the high [ ] side can ____ until solute [ ] are ____. There won't be any ___ pressure, but there is a change in cell ____.
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expand; equal; hydrostatic; volume
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What's tonicity?
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the effect of the [ ] of nonpenetrating solutes (in a solution) has on cell volume
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Where does tonicity come from?
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osmotic pressure
|
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Tonicity contrasts osmolarity in that tonicity describes the relative [ ] of _____ solutes vs. cell, and osmolarity measures ____ solutes, regardless of ___.
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nonpenetrating; ALL; penetration.
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Hypotonic results in?
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higher CELL volume; has a below normal [ ] of nonpenetrating solutes
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At capillaries things are different than in aquaporins; pretty much everything goes through easily except?
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proteins! proteins directly contribute to capillary osmosis
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Capillary bed
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- thin walled
- sites of exchange b/w blood and surrounding tissues |
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Capillary bed has maximal ___ ___ and minimized ___ ___
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surface area; diffusion distance
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Velocity of blood flow through capillary is ___, providing adequate ___ time.
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slow; exchange
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What are the 2 types of exchange in capillary bed?
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1. diffusion
2. bulk flow |
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Capillaries
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-narrow, water filled pores lie at jxns b/w cells
-permits passage of water-sol substances |
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how do lipid soluble substances get through capillaries?
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through endothelial cells by dissolving in lipid bilayer barrier
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osmotic pressure diff's across capillary walls is due to?
|
PROTEINS
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The reflection coefficient for all solutes in the plasma and interstitial fluid are close to ____ except for ____ which it is close to 1.
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zero; proteins
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What are the 4 neural functions?
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communication
decision making memory homeostasis |
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What are the four regions of a neuron?
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1. input zone (receives signal)
2. trigger zone (initatites AP) 3. Conducting zone (conducts AP over long distances) 4. Output zone (releases neurotransmitter that influences other cells |
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The input zone consists of ______
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dendrites
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Neural signaling is based on changes in?
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membrane potential relative to the neuron's resting potential
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Resting potential
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negative inside relative to outside
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Neurons transmit information by changing the ____ potential; comes in form of _____ or ____.
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electircal; depolarizations; hyperpolarizations
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Depolarization =
Repolarization = Hyperpolarization = |
dep= decreases in potential (membrane less negative)
repol= return to resting potential after depolarization hyperpol= increase in potential, membrane more negative) |
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changes in membrane potential represent changes in?
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distribution of ionic charge across the membrane
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net accumulation of charge only occurs on each ____ of the membrane; within each solute there is _______, with no bulk separation of charge that is measurable within the ___ or ___.
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face; electroneutrality; ECF or ICF
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Depolarizations occur when ___ come into the cell.
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cations (or on occasion, when anions flow out)
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Triggering event opens ion channels, most commonly permitting ___ entry
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Na
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the entering positively charged cations move towards surrounding ____ charge on the inner surface of the membrane, ____ Adjacent regions of the membrane.
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negative; depolarizing
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decrease in charge separationn across the membrane is reflected as a decrease in?
|
membrane polarization (depolarization) and this affect wanes with distance
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unlike other changes in potential used for biological signaling, ACTION potentials do not...?
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decrement with distance from initiation site- it's an ALL or none response!
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Most AP's depend on?
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sequential opening of voltage-sensitive Na and K channels that are each activated ("gated") by depolarization
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the all-or-none property of neuronal action potentials depends upon?
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positive feedback relationship b/w depolarization and opening of Na-channels
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After the AP reaches a peak (near Ea), the membrane begins to ____, by closing ___ channel and opening ____ channel.
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repolarize; Na; K
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Nerve block by local anesthetics occurs b/c?
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drugs block the inner-portion of the Na channel, reduces permeability of Na and preventing the positive feedback cycle from progressing.
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AP's propagate b/c?
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they depolarize adjacent segments of axon, continuously reigniting the positive feedback cycle
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Inactivation of Na channels and prolonged activation of K channels makes the membrane...?
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temporarily refractory to additional AP's
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Conduction of axonal AP's is speeded by?
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insulating layers of myelin produced by glial cells
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glial cells are called __ cells in the periphery and _____ in the CNS
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schwann; oligodendrocytes
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Sensory receptors have channels that _____ neuronal terminals when activated by specific ___ ___
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depolarize; sensory stimuli
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What are the 3 steps in a sensory receptor channel?
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1. stimulus opens stimulus-sensitive channel, permitting net Na+ entry
2. local current flow b/w depolarized receptor ending and adjacent region opens voltage-gated Na channels 3. Na entry initiates AP in afferent fiber that self-propagates to CNS |
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Na channels are only in the ____ nodes; AP's ___ from node-to-node.
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uncovered; jump
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AP's in sensory neurons travel to central _____, causing ____ of neural circuits that produce ___ responses
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synapses; excitation; reflex
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Activation of sensory neurons can also pdce more complex responses that depend on?
|
excitation of various networks, such as emotional and autonomic responses
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Afferent division =
Efferent divison = |
A= motor
E= sensory |
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Which divison receives sensory and visceral stimuli?
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Afferent
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Efferent division produces ___ and ____ nervous system function
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somatic; autonomic
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Somatic nervous system comprises
|
motor neurons (which affect SKELETAL MUSCLE)
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Autonomic nervous system comprises the ___, ____, and ____ nervous system.
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Sympathetic; Parasympathetic; Enteric
|
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Sympathetic and Parasympathetic nervous system affects?
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smooth muscle
cardica muscle exocrine glands some endocrine glands |
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Enteric nervous system affects?
|
digestive organs only
|
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Sympathetic and Parasympathetic fibers innervate?
|
the same target tissues and they usually produce opposite affects!
|
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All efferent autonomic pathways involve what two peripheral synapses?
|
1. from the preganglionic to the postganglionic neuron
2. from the postganglionic to effector cell |
|
Sympathetic functions
|
- flight or fight response
- massive activations during emergencies - often antagonistic to parasympathetic - homeostatic reflexes - background activity |
|
Parasympathetic function
|
- "Rest- and digest" system
- maintenance of homeostasis - mediates numerous reflexes - rare but medically important (extreme terror) |
|
Sympathetic and parasymp modulation occurs in ___ tissues. What's the major exception?
|
ALL; sympathetic fibers innervate the vasculature
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Where due synapses b/w neurons occur?
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on dendrites and cell bodies
|
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Several types of synapses exist, with different _____ effects and mech's of action.
|
post-synaptic
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Neurotransmitter release at chemical synapse is an example of?
|
Ca-dept exocytosis. (neurotransmitter binds to nearby postsynaptic receptors, often opening ion channels)
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Binding of neurotrasnmitter by ____ receptors opens channels that either ___ the membrane (EPSP) or _____ the membrane (IPSP)
|
ionotropic; depolarize; hyperpolarize
|
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EPSP's bring the membrane potential ____ to the ____ ____ threshold, whereas ______ push it farther away from ____.
|
CLOSER; Action potential; IPSP's; threshold
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Neurons receive both ___ and ___ simultaneously, by adding them together the nruon makes the decision whether or not to fire an __.
|
EPSP's; IPSP's; AP.
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|
Which neurotransmitters activate excitatory ionotropic receptors (causing EPSP's)?
|
Glutamate (in CNS) and Ach (in Periphery)
**they open channels that permit simultaneous Na entry and K outflow, with the net effect being depolarization towards ~mV |
|
Ionotropic IPSP's are most commonly evoked by?
|
GABA - this opens channels that allow Cl- inflow, causing hyperpolarization towards ~ -75mV
|
|
Describe process of neurotransmitter release in an axon of presynaptic neuron
|
1. AP reaches axon terminal of presynaptic neuron
2. Ca enters synaptic knob (presynaptic axon terminal) 3. neurotransmitter is released by exocytosis into synaptic cleft 4. neurotransmitter binds to receptors 5. receptor opens specific channel |
|
Describe process of a chemically gated receptor- channel
|
1. extracellular message binds to receptor
2. binding of messenger leads to opening of channel 3. ions enter 4. ion entry brings about desired result (cellular reponse) |
|
Metabotropic receptors
|
activated by diverse neurotransmitters (including ones that activate ionotropic receptors (Glu, Ach, etc.))
|
|
Explain process of G-protein coupled receptor
|
1. extracellular messenger binds to receptor
2. receptor activates G protein 3. G protein activates effector protein 4. effector protein produces second messenger 5. second messenger activates protein kinase 6. protein kinase activates desired protein 7. active designated protein brings about desired response |
|
Autonomic synapses onto peripheral effector cells are ____ _____ synapses.
|
chemical metabotropic
|
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In motor pathways in the ANS, the first synapse is primarily ____ and the second is _____
|
ionotropic; metabotropic
|
|
Autonomic synapses have characteristic _____ and ______ receptors.
|
neurotransmitters; postsynaptic
|
|
Somatic synapses onto peripheral effector cells occurs at?
|
neuromuscular jxn (NMJ) in skeletal muscle
|
|
EPSP's at the NMJ are designed for?
|
rapid, reliable activation of fibers
|
|
NMJ is an ____ chemical synapse in which Ach binds to ____ receptors, opening ___/___ channels that depolarize the fiber
|
ionotropic; nicotinic; Na/K
|
|
Autonomic tone
|
continuous background firing of autonomic fibers
|
|
Autonomic tone allows?
|
antagonists to have effects even at rest
|
|
Nicotinic (list agonist and sites)
|
Agonist: Ach, nicotine
site: NMJ and postganglionics |
|
Muscarinic
|
Agonist: ACh, muscarine
Site: parasympathetic effectors |
|
a-adrenergic
|
Agonist: Epinephrine > Agonists: Norepinephrine>isoproternol
site: sympathetic effectors |
|
b-adrenergic
|
Agonists: Isoproternol>Epinephrine>norepinephrine
Site: sympathetic effectors |
|
Which are the two striated muscles?
|
cardiac and skeletal
|
|
Which are the involuntary muscles?
|
cardiac and smooth
|
|
Each muscle fiber is a single, long, _____ cell, bundled together and surrounded by?
|
multi-nucleated; connective tissue
|
|
What makes up muscle fibers?
|
myofibrils
|
|
Is there cell-cell communicatoin b/w myofibers?
|
NO
|
|
Dark and light bands seen in the myofibril arise due to?
|
overlapping and the arrangement of overlapping proteins.
|
|
Sarcoplasm is full of ____
|
myofibrils
|
|
Sarcolema
|
"plasma membrane" for muscles!
|
|
Myofibrils extend the ___ of the cell and are the ____ proteins that allow muscle to generate ___.
|
length; contractile; force
|
|
What % of muscle is made up of myofibrils?
|
80!
|
|
Dark (__ bands) and light ( __ bands) give appearance of ____.
|
A; I; striations
|
|
Myofibrils are a regular arrangement of ___ and ___ ____ and are made of ___ and ___.
|
think; thin filaments; myosin; actin (Respectively)
|
|
What do the Z lines look like? From one to the other, what does it delineate?
|
dark strong band crossing fibril; one sarcomere
|
|
A band =
|
thick middle band, "thick filaments"
|
|
Middle of A band is the?
|
M-line
|
|
Light area =
|
I band --> isotropic and made up of thin filaments
|
|
The thick/thin filaments DO NOT ____
|
SHORTEN
|
|
Myosin and actin form ____-____
|
cross-bridges
|
|
What do troponin/tropomyosin do?
|
regulate ability of thick/thin to interact with each other
|
|
Titin
|
acts as a spring for contraction so things don't fall apart -- extend from z line to m line
|
|
Thick Filaments:
Made of two _____ subunits of protein; in which way do they orientate themselves? |
intertwining; head-to-tail fashion(GOLF CLUBS)
|
|
What are the 2 sites on myosin thick filaments critical to contraction?
|
1. actin-binding site
2. myosin ATPase site |
|
Actin Thin Filaments:
Within an actin polymer, each monomer can bind a ___ ___. What are the two regulatory components of actin thin filaments? |
myosin head; topomyosin/toponin;
|
|
At rest, tropomyosin/troponin...
|
cover and block myosin binding sites
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After nerve impulse, what ion allows displacement of tropomyosin/troponin, allowing opening of myosin binding site?
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Ca2+
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Troponin works by?
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anchoring tropomyosin to myosin head
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Appr how many myosin molecules are in 1 thick filament?
Each myosin thick filament is surrounded by ___ thin filaments. |
300; 6
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Describe basis of CONTRACTION
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1. activated myosin heads bind uncovered actin thin filaments "cross bridge" forms
2. "power-stroke"- myosin head SWIVELS and pulls towards M line 3. thin filaments are pulled to center of sarcomere |
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Describe the cross-bridge cycle.
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1. (at rest) myosin head cocked and ready --> atp already hydrolyzed, energy is stored in this confirmation
2. nerve impulse: myosin head can bind to thin filament -> swivels -> POWER STROKE 3. not until fresh ATP comes in and displaces bound ATP that cross bridge releases; changes confirmation |
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Which distances on the sarcomere actually shorten?
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Z-Z distances (H zones and I bands narrow)
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Simultaneous shortening of thousands of sarcomeres causes?
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muscle contraction
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How is simultaneous sarcomere shortening accomplished?
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-one nerve terminal per myofiber
- Ach released at NMJ - sarcolemma is depolarized, crossbridge sliding occurs |
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T-Tubule (makes E-C coupling possible!)
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specialized perpendicular invagination of sarcolemma
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AP propagates down ____; opening ___ channels on SR -- occurs at ____
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t-tubule; Ca; A-I junction
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SR stores large amounts of ___, warps around individual ____ like a meshed sleeve
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Ca2+; myofibrils
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Describe Ca release process from SR (i.e., initiating contraction)
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1. SR Ca channels open, flows down steep gradient
2. ca binds troponin, tropomyosin releases 3. cross bridges form |
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RELAXATION/Ending Cycle:
1. __ is degraded; AP's cease 2. __ is pumped back into SR, bound by ____ 3. ___/___ return to normal inhibitory position 4. ___ restores M-Z thin filament placement (spring) |
ach; Ca; calsequestrin; troponin/tropomyosin; TITIN
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All structural components are made of ___
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PROTEINS
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How long does an entire E-C cycle take? Peak force not seen until?
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~100ms; ~50ms after AP
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What are the two types of muscle mechanics?
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Isometric and Isotonic
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Isometric
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- "constant length" (WALL SIT)
- tension doesn't move a load, muscle doesn't shorted - POSTURAL Support |
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Isotonic
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"constant tension"
- muscle changes length to move an object |
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Motor nerve + myofibrils =
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motor unit
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What are the 3 determinants of isometric force?
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1. # of motor units stimulated
2. freq of stimulation 3. length of myofiber at onset of stimulation |
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Single stimulus, single contraction =
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TWITCH
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Repeated stimulus before full relaxation =
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summation
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High frequency stimulation, forceful, smooth contraction =
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Tetanus
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Describe what happens in a twitch
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complete ca release,
cross bridge cycling, ca reuptake, relaxation |
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Summation:
AP is ___ than contraction * ca signal is ___, more ___ __ cycling Elastic Elements: Takes time to fully ____; already stretched, thus more contraction with ___ pulse |
shorter; sustained, cross-bridge
stretch; second |
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AP comes BEFORE _____/____ ___, so ca is more sustained in ____ and more xbridging occurs.
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relaxation/ca uptake; cytoplasm
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TETANUS
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1. each pulse elicits an AP but Ca is still elevated
2. Continual Ca = continual cross-bridging 3. Elastic elements stretched completely, full force of cross-bridge cycling is transferred to end of the muscle |
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HAVE TO HAVE ____ LENGTH
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optimum
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what two things dictate force of contraction that we can measure?
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1. freq of stimulation
2. length of muscle |
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What's the Isotonic-velocity-force relationship?
But?? |
light objects are moved faster than heavy objects
BUT, tension and velocity are also a function of the LENGTH of the muscle at onset of contraction |
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So, force, length, and velocity of contraction depends on what 4 things?
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1. length of muscle
2. motor unit recruitment 3. frequency of simulation 4. load |
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In vivo, many muscles are held at L= +/_ ___%
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15
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ATP Utilization in Skeletal Muscles:
1. What's the direct energy source? 2. What is ATP supplied by? |
1. ATP
2. anaerobic and aerobic pathways |
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How is ATP used 1) at rest and 2) during contraction
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1) AT REST:
Fuels Na-K and Ca pumps 2) CONTRACTION - crossbridge interactions - increased activity of ion pumps, especially SR Ca pump |
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What are the sources of ATP in skeletal muscle and how long do each last (seconds)?
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1. Basal levels of ATP ~1 sec
2. Creatine Phosphate to ATP, ~10 seconds 3. Anaerobic glycolysis (~30-40 seconds) 4. Oxidative Phosphorylation (after 30 seconds, this is 100% where ATP is made) |
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Creatine Phosphate
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- direct phosphorylation of ADP by muscle-creatine kinase
- lasts ~15 seconds - REVERSIBLE reaction |
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Anaerobic Glycolysis
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-anaerobic breakdown of glucose
- RAPID - only ~2 ATP/glu molecule - supports HIGH INTENSITY contraction ***LACTATE MUST BE OXIDIZED |
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Which process makes the largest amount of ATP
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fatty acid degredation (~130 ATP!)
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Oxidative Phosphorylation
1. occurs in ___ through ___ 2. ATP generated via? 3. Fuels what type of exercise? |
1. mito; krebs
2. electron transport and phosphorylation 3. endurance |
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Fate of Lactate:
1. ___ not ___ muscle soreness 2. Diffuses into ____ to go to ___ (converts to glucose). Used directly by? 3. Can contribute to? 4. What molecule needed for conversion? |
1. acute; delayed
2. blood; liver; heart, brain, type I fibers 3. metabolic acidosis 4. oxygen |
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O2 being needed for conversion of lactate is part of ____ _____ ____.
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intramuscular oxygen debt
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What cycle in liver converts lactate to glucose?
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cori cycle
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Myoglobin
1. similar to ___, specific to ___, higher affinity for ___ 2. enriched in fibers specialized for? 3. endows ___ color |
1. hb, muscle; o2
2. endurance exercise 3. red |
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Fatigue from prolonged exercise:
1. manifests as what 3 things? |
1. a. decreased force of contraction
b. decreased velocity of contraction c. prolonged relaxation time |
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Fatigue from prolonged exercise has what 4 possible causes?
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1. lactate build up- o2 debt
2. reduced ion pump efficiency 3. psychological fatigue 4. glycogen depletion |
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fatigue from prolonged exercise is NOT caused by ___ depletion!!
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ATP
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TYPE I Muscle Fibers
1. Myosin ATPase 2. Mb Content 3. Mitochondrial content 4. Glycogen Content 5. Glycolytic capacity |
1. slow
2. high 3. high 4. low 5. low |
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TYPE IIa Muscle Fibers
1. Myosin ATPase 2. Mb Content 3. Mitochondrial content 4. Glycogen Content 5. Glycolytic capacity |
1. fast
2. high 3. high 4. intermediate 5. high 5. |
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TYPE IIb/x Muscle Fibers
1. Myosin ATPase 2. Mb Content 3. Mitochondrial content 4. Glycogen Content 5. Glycolytic capacity |
1. fast
2. low 3. low 4. high 5. high |
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Type I fibers are known as?
Type IIa " "? Type IIB/x""? |
1. slow oxidative
2. fast oxidative 3. fast glycolytic |
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Type I has more ____ fibers than type II
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mitochondrial
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all myofibers in one motor unit are the ___
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same
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Freq of stimulation dictates?
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gene expression
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Adapatation occurs with
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exercise training
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Weight Training
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- myofiber hypertrophy
- addition of myofibrils in parallel to existing - additional protein, membrane, and RNA synthesis |
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Endurance Training
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- metabolic adaptation
- increases in slow contractile proteins, fatty acid oxidation proteins, myoglobin - may include growth of fibers also |
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What are the three fiber type differences?
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contraction
metabolism function |
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What clinical correlates exist?
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Muscular dystrophies
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What's an example of a SR Ca mutation?
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malignant hyperthermia (5-10% mortality rate)
triggered by potent inhales anesthetics. |
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what's an autoimmune disease that attacks NMJ in face?
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Myasthenia Gravis
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What happens during muscle atrophy?
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myofiber shrinks
major risk factor for poor outcome in chemo patients |