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274 Cards in this Set

  • Front
  • Back
Teleological
use of purpose as an explanation
mechanistic
the use of cause and effect as an explanation
Formula for Quantity
Q = CV
Formula for Volume
Quantity/Concentration
Formula for Flow
Flow = Foce x conductance

i.e.

Diffusion = Delta C x permeability
Another equation for Flow
Flow = Force / Resistance

i.e.,

TPR = MAP / CO
Delta C =
CO =
MAP =
TPR =
Delta C = concentration gradient
CO = Cardiac output
MAP = mean arterial pressure
TPR = total peripheral pressure
What's the concetration of Na+, Cl-, HCO3- and Protein like in the plasma?
HIGH NA
Medium Cl-
low HCO3
low Pr-
What's the concetration of Na+, Cl-, HCO3- and Protein like in the Interstitial Fluid?
HIGH NA
Medium Cl but more than plasma
low HCO3
NO PROTEIN
What's the concetration of K+, Cl-, HCO3- and Protein like in the Intracellular Fluid?
HIGH K+
HIGH PROTEIN
low HCO3 (lower than plasma and interstitial fluid)
VERY LOW CL-
In which cell compartment is Cl- the highest?
interstitial fluid
Which compartment has the highest [ ] of Protein?
intracellular fluid
___ is in the outside of the cell, ____ is in the inside of the cell.
Na; K
Biggest difference b/w plasma and intersitial fluid is...?
Interstitial fluid has no proteins!!
How many liters of fluid are there b/w cells?
12L
How many L of fluid are in the plasma? Intracellular fluid? Interstitial fluid?
plasma = 3L
intracellular fluid = 25L
Intersitital fluid = 12L
What's the function of the skin?
T- regulation
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!
What's the concept of steady state?
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)
Goldman-Hodgkin-Katz Equation
(GHK)
describes changes in membrane potential, but is no longer valid.
Now have GFCE:
Em =
If one permeability equation is overwhelmingly greater than the others, what equation do we use?
Nernst
At rest, Permeability of K is _____ than Permeability of Na, therefore membrane potential is closer to Ea, the reverse potential for sodium!
greater
All living cells' PM have a ____ ___
membrane potential (polarized electronically)
Separation of opposite charges across ____ ___
PM
How does membrane potential occur?
through differences in [ ] and permeability of key ions
Nerve/Muscle cells
-have ability to produce rapid, transient changes in their membrane potential when excited
-EXCITABLE CELLS
Resting Membrane Potential
- the constant mem pot in cells of NONEXCITABLE TISSUES and also those of excitable tissues when at rest
What do Ion channels do?
control membrane protential
What's the effect of the K/Na pump?
makes a dsmall direct contribution to membrane potential through its unequal transport of positive ions
K/Na potential is "____ ___"; it's there to maintain [ ] gradient but doesnt have an effect membrane potential per-se. WHY IS IT THERE?
weakly electrogenic; present to maintain a relative [ ] of K+ and kick out Na+ in the cell.
Galvani, L (1786)
animal electricity (FROGS)
Volta, S (1790)
voltaic pile - electrical batteries MADE FIRST BATTERY
BERNSTIEN, J (1902)
"The Ionic Hypothesis" - explained action potential conduction in squid axon
Hodgkin/Huxley (1952)
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.
Why was bernsteins theory of nerve conduction wrong?
he thought the nerve action caused the "breakfdown of the membrane potential"
berstein thought the membrane was only permeable to ____, and developed the ___ Equation= ?
K+
nernst equation =
Em= 60log10 [K]inside / [K] outside
At membrane equilibrium, the force exerted by ion [ ] gradient eliciting movement is ______ by the force exerted by?
balanced; voltage gradient aligned in opposite direction
Nernst equation is very useful when you want to determine?
contribution a SINGLE ion makes to the membrane potential
hodgkin/hukley elaborated on bernsteins theory and showed that the membrane potential arises from?
COMBINATION of ionic condutances and specific membrane permeability's.
When cell is at rest, membrane is moderately permeable to ___ and ____, but IMPERMEABLE to ___.
K+, Cl-; impermeable to NA
At onset of action potential, what happens?
Na permeability increases momentarily leading to further depolarization.
Na influx continues until?
high intracellular positivity repels Na+ ions [Em=Ena]
After the ap peaks, what happens?
Na gate switches off and a large outwardly directed K current REPOLARIZES the interior negativity.
The hodgkin/hukley discovery led to what equation?
GHK - very similar to nernst!
Nernst is no longer valid because?
only thought there was 1 ion
KNOW GOLDMAN EQUATION AND HOW IT FITS INTO NERNST AND THAT HISTORY!
KNOW GOLDMAN EQUATION AND HOW IT FITS INTO NERNST AND THAT HISTORY!
Sakmann, B and Nehr, E
PATCH CLAMP (patch clamp allows you to visualize the portion of the membrane with channels, allowed for study)
Smith, M
Site-directed mutagenesis
Agre, P
Aquaporins
MacKinnon, R
K & Cl Channels. SAW HOW CHANNELS ACTUALLY WORK
Depolarization
to abolish membrane potential
Hyperpolarization
to increase the resting membrane potential
HypOpolarization
reduce the resting membrane potential (i.e., reduction in negativity); NA+ ENTRY IN DENDRITIC SITES ON MOTOR NEURONS
Receptors for neurotransmitters work how?
make the membrane more sensitive so they can fire quicker!
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
Local Anesthetics contd
they passively enter membrane down [ ] gradient, charged species bind to series of sites blocking the channel --> BLOCKS PAIN
what's the MV resting membrane potential?
-60mV
What is membrane most permeable to at rest?
K
At rest, interior of cell is ____ charged relative to exterior because of???
-negative
-large negatively charged proteins!
(note- I skipped most of the PM copmsition stuff, w/ polar heads/nonpolar tails b/c I already knew that)
slides 5-8 on Gorfe
How do forces of PM help the cell?
keep it all together- and it's malleable so allows for flexibility
Most important function of a membrane is?
---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)
Another fxn of membrane?
Cell-to-cell adhesion (helps cells talk to each other)
How do carbohydrates play in with membrane function?
-serve as self-identity markers
How do extrinsic/peripheral proteins play in with membrane function?
docking-markers
enzymes
receptors
CAM's
How do Intrinsic/integral membrane porteins play in wich membrane function?
1) Membrane Channels
- always open (water, solutes, leak channels)
- Gated Channels: voltage and ligand gated

2) Carriers
- accomplished by membrane carrier changing its shape
What are the two types of membrane transport?
1) Unassisted Membrane Transport
2) Assisted Membrane transport
Unassisted Membrane transport (UMT)
Simple (passive) Diffusion
- uniform spreading out of molecules (thermal motion)
- Molecules move from higher --> lower [ ] (concen. gradient)
What portion of UMT is crucial to survival of every cell?
1) exchange of O2 and CO2 b/w blood and air in lungs
2)Movt of substances across kidney tubules
Diffusion and Brownian Motion
discovered that a diff in [ ] in each compartment will cause it to equalize
Passive diffusion through membrane includes molecules such as?
nonpolar! O2, Co2, fatty acids...
Membrane thickness is inversely related to?
distance traveled
What factors affect the net rate of diffusion?
rate of diffusion has to be directly proportional to the change in concentration
What's Fick's Law
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
2 Types of Assisted Membrane Transport (AMT)
1) Carrier-mediated
2) Vesicular transport
Carrier mediated transport
1) facilitated diffusion
2) active transport
Carrier mediated transport is accomplished by?
- carrier changing its shape!
In regards to carrier mediated transport, the kind and amount of material transferred across the membrane depends on?
1) specificity
2) saturation
3) competition
Why does competition exist?
there are only so many binding sites!
Carrier mediated transport is directly proportional to the change in ___ until all space is ____
concentration; occupied
What's an example of facilitated diffusion?
Glucose going into cells!
Explain steps of Facilitated Diffusion
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
Active Transport
- moves substance AGAINST [ ] gradient
Primary Active transport pumps require?
direct use of ATP
Secondary Active transport is driven by?
ion [ ] gradient established by a primary active transport system
Explain process of active transport
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
Vesicular Transport
material is moved into or out of the cell wrapped in membrane
Vesicular transport is an ___ method of ___ ___
active; membrane transport
What are the 2 types of vesicular transport?
1. Endocytosis
2. Exocytosis
Endocytosis
process by which substances MOVE IN TO CELL
Other types of endocytosis?
pinocytosis = nonselective uptake of ECF

Receptor-mediated - selective uptake of a large molecule

Phagocytosis - selective uptake of multi-molecular particle
Exocytosis
mech for secreting large polar molecules
Exocytosis also enables cell to?
add specific components to membrane!
Water transport across PM is?
slow!! not efficient!!
Water transport is aided by specific protein channels on the pm known as?
aquaporins
Y
Yttrium
How many water molecules can pass through single-file through an aquarporin channel every second?
1 billion!!
Is the density/water solubility the same in every aquaporin?
No, it varies in different cell types
Which aquaporin set is involved in the generation of saliva, tears and pulmonary secretions?
hAQP5
What's osmosis?
net diffusion of water down its [ ] gradient
When does water reach equilibrium?
osmotic pressure = hydrostatic pressure
When does hydrostatic pressure build up?
when solute can't pas through and volume expansion in the high solute compartment occurs --> pressure tends to push the fluid backward!
osmotic pressure is a measure of?
tendency for osmotic flow of water in the solution b/c of its relative [ ] of nonpenetrating solutes and water
Osmolarity
measure of a solutions total solute [ ] given in terms of the # of particles expressed in osmoles/liter (Osm)
What is the normal osmolarity of body fluid?
290-300
Fe
Iron
Van't Hoff's law is more exact when?
the more dilute the solute
In an ideal solution, osmotic coefficient equals ___
1
Osmotic coefficient depends on?
nature of solute and its concentration
What happens to osmotic flow as the membrane becomes more permeable?
less osmotic flow is induced
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
In non--penetrating solutions, the high [ ] side can ____ until solute [ ] are ____. There won't be any ___ pressure, but there is a change in cell ____.
expand; equal; hydrostatic; volume
What's tonicity?
the effect of the [ ] of nonpenetrating solutes (in a solution) has on cell volume
Where does tonicity come from?
osmotic pressure
Tonicity contrasts osmolarity in that tonicity describes the relative [ ] of _____ solutes vs. cell, and osmolarity measures ____ solutes, regardless of ___.
nonpenetrating; ALL; penetration.
Hypotonic results in?
higher CELL volume; has a below normal [ ] of nonpenetrating solutes
At capillaries things are different than in aquaporins; pretty much everything goes through easily except?
proteins! proteins directly contribute to capillary osmosis
Capillary bed
- thin walled
- sites of exchange b/w blood and surrounding tissues
Capillary bed has maximal ___ ___ and minimized ___ ___
surface area; diffusion distance
Velocity of blood flow through capillary is ___, providing adequate ___ time.
slow; exchange
What are the 2 types of exchange in capillary bed?
1. diffusion
2. bulk flow
Capillaries
-narrow, water filled pores lie at jxns b/w cells
-permits passage of water-sol substances
how do lipid soluble substances get through capillaries?
through endothelial cells by dissolving in lipid bilayer barrier
osmotic pressure diff's across capillary walls is due to?
PROTEINS
The reflection coefficient for all solutes in the plasma and interstitial fluid are close to ____ except for ____ which it is close to 1.
zero; proteins
What are the 4 neural functions?
communication
decision making
memory
homeostasis
What are the four regions of a neuron?
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
The input zone consists of ______
dendrites
Neural signaling is based on changes in?
membrane potential relative to the neuron's resting potential
Resting potential
negative inside relative to outside
Neurons transmit information by changing the ____ potential; comes in form of _____ or ____.
electircal; depolarizations; hyperpolarizations
Depolarization =
Repolarization =
Hyperpolarization =
dep= decreases in potential (membrane less negative)

repol= return to resting potential after depolarization

hyperpol= increase in potential, membrane more negative)
changes in membrane potential represent changes in?
distribution of ionic charge across the membrane
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 ___.
face; electroneutrality; ECF or ICF
Depolarizations occur when ___ come into the cell.
cations (or on occasion, when anions flow out)
Triggering event opens ion channels, most commonly permitting ___ entry
Na
the entering positively charged cations move towards surrounding ____ charge on the inner surface of the membrane, ____ Adjacent regions of the membrane.
negative; depolarizing
decrease in charge separationn across the membrane is reflected as a decrease in?
membrane polarization (depolarization) and this affect wanes with distance
unlike other changes in potential used for biological signaling, ACTION potentials do not...?
decrement with distance from initiation site- it's an ALL or none response!
Most AP's depend on?
sequential opening of voltage-sensitive Na and K channels that are each activated ("gated") by depolarization
the all-or-none property of neuronal action potentials depends upon?
positive feedback relationship b/w depolarization and opening of Na-channels
After the AP reaches a peak (near Ea), the membrane begins to ____, by closing ___ channel and opening ____ channel.
repolarize; Na; K
Nerve block by local anesthetics occurs b/c?
drugs block the inner-portion of the Na channel, reduces permeability of Na and preventing the positive feedback cycle from progressing.
AP's propagate b/c?
they depolarize adjacent segments of axon, continuously reigniting the positive feedback cycle
Inactivation of Na channels and prolonged activation of K channels makes the membrane...?
temporarily refractory to additional AP's
Conduction of axonal AP's is speeded by?
insulating layers of myelin produced by glial cells
glial cells are called __ cells in the periphery and _____ in the CNS
schwann; oligodendrocytes
Sensory receptors have channels that _____ neuronal terminals when activated by specific ___ ___
depolarize; sensory stimuli
What are the 3 steps in a sensory receptor channel?
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
Na channels are only in the ____ nodes; AP's ___ from node-to-node.
uncovered; jump
AP's in sensory neurons travel to central _____, causing ____ of neural circuits that produce ___ responses
synapses; excitation; reflex
Activation of sensory neurons can also pdce more complex responses that depend on?
excitation of various networks, such as emotional and autonomic responses
Afferent division =
Efferent divison =
A= motor
E= sensory
Which divison receives sensory and visceral stimuli?
Afferent
Efferent division produces ___ and ____ nervous system function
somatic; autonomic
Somatic nervous system comprises
motor neurons (which affect SKELETAL MUSCLE)
Autonomic nervous system comprises the ___, ____, and ____ nervous system.
Sympathetic; Parasympathetic; Enteric
Sympathetic and Parasympathetic nervous system affects?
smooth muscle
cardica muscle
exocrine glands
some endocrine glands
Enteric nervous system affects?
digestive organs only
Sympathetic and Parasympathetic fibers innervate?
the same target tissues and they usually produce opposite affects!
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
Where due synapses b/w neurons occur?
on dendrites and cell bodies
Several types of synapses exist, with different _____ effects and mech's of action.
post-synaptic
Neurotransmitter release at chemical synapse is an example of?
Ca-dept exocytosis. (neurotransmitter binds to nearby postsynaptic receptors, often opening ion channels)
Binding of neurotrasnmitter by ____ receptors opens channels that either ___ the membrane (EPSP) or _____ the membrane (IPSP)
ionotropic; depolarize; hyperpolarize
EPSP's bring the membrane potential ____ to the ____ ____ threshold, whereas ______ push it farther away from ____.
CLOSER; Action potential; IPSP's; threshold
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.
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
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
After nerve impulse, what ion allows displacement of tropomyosin/troponin, allowing opening of myosin binding site?
Ca2+
Troponin works by?
anchoring tropomyosin to myosin head
Appr how many myosin molecules are in 1 thick filament?

Each myosin thick filament is surrounded by ___ thin filaments.
300; 6
Describe basis of CONTRACTION
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
Describe the cross-bridge cycle.
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
Which distances on the sarcomere actually shorten?
Z-Z distances (H zones and I bands narrow)
Simultaneous shortening of thousands of sarcomeres causes?
muscle contraction
How is simultaneous sarcomere shortening accomplished?
-one nerve terminal per myofiber
- Ach released at NMJ
- sarcolemma is depolarized, crossbridge sliding occurs
T-Tubule (makes E-C coupling possible!)
specialized perpendicular invagination of sarcolemma
AP propagates down ____; opening ___ channels on SR -- occurs at ____
t-tubule; Ca; A-I junction
SR stores large amounts of ___, warps around individual ____ like a meshed sleeve
Ca2+; myofibrils
Describe Ca release process from SR (i.e., initiating contraction)
1. SR Ca channels open, flows down steep gradient
2. ca binds troponin, tropomyosin releases
3. cross bridges form
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
All structural components are made of ___
PROTEINS
How long does an entire E-C cycle take? Peak force not seen until?
~100ms; ~50ms after AP
What are the two types of muscle mechanics?
Isometric and Isotonic
Isometric
- "constant length" (WALL SIT)
- tension doesn't move a load, muscle doesn't shorted
- POSTURAL Support
Isotonic
"constant tension"
- muscle changes length to move an object
Motor nerve + myofibrils =
motor unit
What are the 3 determinants of isometric force?
1. # of motor units stimulated
2. freq of stimulation
3. length of myofiber at onset of stimulation
Single stimulus, single contraction =
TWITCH
Repeated stimulus before full relaxation =
summation
High frequency stimulation, forceful, smooth contraction =
Tetanus
Describe what happens in a twitch
complete ca release,
cross bridge cycling,
ca reuptake,
relaxation
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
AP comes BEFORE _____/____ ___, so ca is more sustained in ____ and more xbridging occurs.
relaxation/ca uptake; cytoplasm
TETANUS
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
HAVE TO HAVE ____ LENGTH
optimum
what two things dictate force of contraction that we can measure?
1. freq of stimulation
2. length of muscle
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
So, force, length, and velocity of contraction depends on what 4 things?
1. length of muscle
2. motor unit recruitment
3. frequency of simulation
4. load
In vivo, many muscles are held at L= +/_ ___%
15
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
How is ATP used 1) at rest and 2) during contraction
1) AT REST:
Fuels Na-K and Ca pumps
2) CONTRACTION
- crossbridge interactions
- increased activity of ion pumps, especially SR Ca pump
What are the sources of ATP in skeletal muscle and how long do each last (seconds)?
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)
Creatine Phosphate
- direct phosphorylation of ADP by muscle-creatine kinase
- lasts ~15 seconds
- REVERSIBLE reaction
Anaerobic Glycolysis
-anaerobic breakdown of glucose
- RAPID
- only ~2 ATP/glu molecule
- supports HIGH INTENSITY contraction
***LACTATE MUST BE OXIDIZED
Which process makes the largest amount of ATP
fatty acid degredation (~130 ATP!)
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
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
O2 being needed for conversion of lactate is part of ____ _____ ____.
intramuscular oxygen debt
What cycle in liver converts lactate to glucose?
cori cycle
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
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
Fatigue from prolonged exercise has what 4 possible causes?
1. lactate build up- o2 debt
2. reduced ion pump efficiency
3. psychological fatigue
4. glycogen depletion
fatigue from prolonged exercise is NOT caused by ___ depletion!!
ATP
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
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.
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
Type I fibers are known as?
Type IIa " "?
Type IIB/x""?
1. slow oxidative
2. fast oxidative
3. fast glycolytic
Type I has more ____ fibers than type II
mitochondrial
all myofibers in one motor unit are the ___
same
Freq of stimulation dictates?
gene expression
Adapatation occurs with
exercise training
Weight Training
- myofiber hypertrophy
- addition of myofibrils in parallel to existing
- additional protein, membrane, and RNA synthesis
Endurance Training
- metabolic adaptation
- increases in slow contractile proteins, fatty acid oxidation proteins, myoglobin
- may include growth of fibers also
What are the three fiber type differences?
contraction
metabolism
function
What clinical correlates exist?
Muscular dystrophies
What's an example of a SR Ca mutation?
malignant hyperthermia (5-10% mortality rate)

triggered by potent inhales anesthetics.
what's an autoimmune disease that attacks NMJ in face?
Myasthenia Gravis
What happens during muscle atrophy?
myofiber shrinks

major risk factor for poor outcome in chemo patients