question

How much moisture can air hold at 20 degrees Celcius?

answer

18 g/m

question

How does a nerve impulse cause a muscle contraction?

answer

1. AP arrives at neuromuscular junction 2. Ca diffuse into synaptic knobs 3. Synaptic vesicles release Ach 4. Ach binds to nicotinic sites in sarcolemma 5. Ion channel opens in sarcolemma, Na moves in and cause dep. 6. AP spreads in all directions

question

AP arrives at the _________

answer

Neuromuscular junction

question

In a muscle contraction, what do the synaptic vesicles release?

answer

Ach

question

In a muscle contraction, what does Ach bind to? Where?

answer

Nictotinic receptor sites in sarcolemma

question

In a muscle contraction, what cause depolarization?

answer

Ion channels open in sarcolemma and Na+ moves in

question

After depolarization, where does the AP go?

answer

It spreads in all directions and reach the T-Tubules

question

AP reach t-tubles which does what?

answer

Carries depolarization from outside of muscle to the inside

question

T tubules depolarization causes what?

answer

Ca+ to be released in the sarcoplasm

question

Ca+ then binds to troponin-C which does what?

answer

Causes conformational change in troponin complex

question

In the presence of Ca+, the conformational change in troponin causes what to get out of the way to expose myosin binding sites on actin?

answer

Tropomyosin moves to expose binding sites

question

Cross bridges form by the binding of _____ and _____. ____ hydrolyses ATP inbto ADP and Pi. This releases energy to create the ___. Myosin then binds to another ATP which releases the actin and myosin head. What causes this?

answer

1. Actin 2. Myosin 3. Myosin ATPase 4. Power stroke 5. Recovery stroke

question

Durinf muscle contraction, what is actually moving to shorten the muscle?

answer

The actin is sliding down the myosin heads via power and recovery strokes

question

Relaxation of a muscle occurs when Ach is inactivated by ____. This inhibits nerve impulse conduction. Then ___ is pumped from sarcoplasm to the ___ via the Ca+ ATPase pump

answer

1. AchEsterase 2. Ca+ 3. SR

question

In the SR, Ca+ binds to ___ and is stored until the fiber is stimulated again. Exiting Ca+ from sarcoplasm causes the troponin complex to do what?

answer

1. Calsequestrin 2. Revert to its original shape covering up the binding sites once again

question

In the resting state, Na+ volatage channels are closed because the ___ gate is closed

answer

Activation gate

question

As soon as Na+ starts to rush in after its activation gates are opened, the ___ gate closes after 2msec. Simultaneously, ___ gates are opened

answer

1. Inactivation 2. K+ activation gate

question

Period in which Na+ inactivation gates are closed and cannot be reopened until repolaization has occured

answer

Absolute refractory period

question

Begins when absolute refractory period end? Lasts about ___ to ___ as long as ARP and overlaps with period of ___

answer

1. Relative refractory period 2. 1/4 to 1/2 3. Hyperpolarization

question

Depolarization cause ___ gates to close. Which gates remain open? At the same time ___ openes. ___ gates stay open longer than the ___ gates.

answer

1. Na inactivation gates to close and Na activation gate remain open 2. K+ gates 3. K+ gates stay open longer than Na+ gates

question

Whewn a neuron is in Reletive refractory period, a ____ can elicit a second AP.

answer

Stronger than normal

question

Spider toxin blocks ___ channels

answer

N-Calcium channels

question

Activation of voltage gated Na and K channels

answer

1. Both inactivation and activation gates open allowing Na+ in. 2. Inactivation gates start to close while K+ gates start to open 3. K+ gates open when there is an increases in memebrane potential via the Na comming in. 4. Depolarization has occured!

question

Ca/Na pumps in the heart : What enters the heart? How many of what enters and leaves?

answer

Ca enters the heart and this cause contraction. As Ca+ increases in heart an antiport system of Na-Ca pumps it out. 3Na+ enter the cell and 1Ca+ leaves at the expense of 1 ATP

question

Cardiac glycolysis disrupts the phosphorylation-dephosphorilation...because of this, ___ cannot get out of the cell and ___ cannot get in

answer

Na cannot get out and K cannot get in...pumps is non-functional

question

Cystic fibrosis is caused by genetic defects in ___? What is the result?

answer

CFTR : Cl- flow is defective resulting in increaswe in salt through sweat, reccurent respiratory infections and increased absorption of electrolytes. Net result = dehydration of repiratory secretions

question

K+ ions leaving are greater than Na+ entering which may cause a ___. Gradually, diffusion and Na-K pump restores normal resting state.

answer

Hyperpolarization (slightly more negative than normal)

question

Largest protein in the body, springy and acts as a framework that lines up actin and myosin to make the contractile mechanism work.

answer

Titin

question

Titin is responsible for :

answer

Acts as a framework that lines up the myosin and actin to make the contractile mechanism work

question

Toxin that blocks voltage gates Na+ channels and prevents action potentials

answer

Lidocaine

question

Toxin that blocks Na+ channels on the ISF side

answer

Tetradotoxin (TTX)

question

Toxin that blocks Na+ channels and causes lethal paralysis within half an hour (shellfish)

answer

Saxitoxin

question

What is the importance of Ca+ channels?

answer

Increase intracellular Ca+ which promotes neurotransmitter relase and activation of enzymes

question

Significance of voltage gated channels?

answer

Producing eletrical impulases over long distances in a nerve fibers

question

Significance of ligang-gated channels? Why are they so fast?

answer

Enables rapid communication between neurons and other organs : saltatory conduction

question

Describe the donnan effect?

answer

1. If there is a higher distribution of charges on one side of a memebrane they will flow down the gradient 2. This leads to higher concentration of solute on one side... Water will move towards the high solute via osmosis

question

Primary active transport?

answer

ATP is the main source of energy. 1. Na-K pumps, Ca ATPase in SR, H-K pumps in stomach

question

Secondary ative transport

answer

Electrochemical gradient is main source of energy: glucose-Na

question

Transport of molecules in diffrent directions?

answer

Antiport = primary active transport

question

Transport in which 2 solutes move in the same direction (in secondary active transport) What is usually transported?

answer

1. Symport 2. Na + glucose, Na + amino acids

question

Describe the Na-K pumps? How many Na and K are pumped? Is it electrogenic? How mnay ATP used?

answer

1. 3 Na pumped out and 2 K pumped in 2. Yes 3. 1 ATP

question

The Na-K pump makes for a ___ environment in the cell

answer

Negative

question

The Ca+ pump in skeletal muscles pumps __ Ca against their gradient at the expense of ___ ATP

answer

1. 2 2. 1

question

The H-K pump is found in the ___ It pumps ___ into the stomach making it acid.

answer

Stomach : H

question

2 types of ion channel gates?

answer

Voltage gates channels and Ligand gated channels

question

What controls the 2 ion channel gates?

answer

VG channels = change in membrane potential LG channels = Hormones and neurotransmiters

question

What passes through the ion channel gates?

answer

VG channels = Na+ and K+ LG channels = Na+, K+ and Ca+

question

Two types of Ca+ channels?

answer

L channels and N channels

question

L-type Ca channels are involved in?

answer

Muscle excitation

question

To treat ___ disorders, the L-channels are blocked

answer

Cardiovascular

question

How many mV needed for depolarization? Hyperpolarization?

answer

1. -90 to -60 2. -92

question

What is the refractory period?

answer

Period after an AP in which another AP connot occur

question

What is the effect of hypercalcemia on AP and muscle contraction?

answer

Na channels open with very little stimulus therefor fibers start firing impulses rapidly with no stimulus creating tetany

question

True or false, Na+ channels open with very little stimulus?

answer

True

question

In the resting state, 2 types of channels that are always opened?

answer

Na+ and K+ leak channels

question

Electrical charge developed across a membrane when ions diffuse down their concentration gradient?

answer

Diffusion potential

question

Diffusion potential that ballances or opposes the tendancy for diffision down the concentration gradiant

answer

Equilibrium potential

question

Example of equilibrium potential

answer

Na-K voltage gates 1. When Na moves in you have the diffusion potential but when the K+ moves out you acheive equilibrium potential

question

Purpose of the Nearnst equation?

answer

To determine the voltage necessary to acheive equilibrium potential

question

Define action potential

answer

Property of electric excitibility that underlies basic nerve impulse

question

Rapid phase of AP where the inside of the membrane becomes positive. From ___ to ___ mV?

answer

Depolarization : -90 to 35 mV

question

Returns the membrane to resting potential? From ___ to ___ mV?

answer

Repolarization : -70 to -90 mV

question

Membrane potential becoming more negative than the normal resting state for a few milisecondes?

answer

Hyperpolarization

question

Define threshold. What is the threshold for an AP?

answer

The minimum amount of stimulus that can elicit and AP : -60mV

question

What is the resting membrane potential? What is reponsible for this?

answer

-70 to -90 mV. K+ leak channels are opened, thus K+ conductance is high and Na+ conductance is low. K+ leaks out for a net charge of -90 inside the cell.

question

During depolarization the membrane becomes very permeable to ___. The membrane potential rises in the ____.

answer

1. Na 2. Positive

question

In what way is the Na-K pump electrogenetic?

answer

More Ca (3) and leaving than K (2) comming in

question

___ channels are slow channels and are prevalent in what type of muscles?

answer

Voltage gates Ca-Na and are present in cardiac and smooth muscles

question

___ channels are fast and are located in which type of muscle?

answer

Na+ channels and are located in skeletal muscles.

question

3 factors that account for plateaus

answer

1. Opening of fast Na+ channels cause a pike 2. Slow but prolonged opening of slow channels 3. Very slow opeing of K+ channels delays the return of RMP

question

Which channels oppen at the end of the plateau?

answer

Very slow volatage gates K+ channels

question

Where do we have plateaus?

answer

Cardia muscles

question

Rythmicity in some excitable cells are important for what?

answer

1. Heart beat 2. Peristalsis 3. Rythmic Breathing

question

AP that occurs in one spot on the axon excites nearby segments of the membrane top produce their own AP. This wave of movement is called what?

answer

Propagation

question

Sequence of events in propagation?

answer

1. AP is triggered by axon hillock 2. Electrical signals encountered VG Na+ channels 3. Current is carried by inflow of Na+ ion that fidduse in both directions of axon 4. Local depol initiates a new AP at adjacent seg. 5. Self propagates

question

What part of the axon triggers the AP?

answer

Hillock

question

In propagation, the current is carried by an inflow of what ion?

answer

Na+

question

Does initial AP travel all the way down to axon terminal or does it decay?

answer

It decays but does propogate itself

question

Speed at which APs are conducted along a nerve or muscle fiber

answer

Conduction velocity of nerve fiber

question

2 factors that increase conduction velocity

answer

1. Increase in the diameter of nerve 2. Myelinating the nerve

question

Myelation allows nerve impulses to jump very rapidly between segments. What is this called?

answer

Saltatory conduction

question

2 disease of nerve impulse conduction

answer

1. MS (demyselination) 2. Tay-sachs (ganglisides, hexoseaminidase, demyelimation)

question

Which muscle have intercalated discs? What do they do?

answer

Cardiac muscles. Enables electrical impulse to travel rapidly from one cell to another

question

Which muscles are not striated?

answer

Smooth

question

Muscle cell that contains sarcolemma, sarcoplasm and all organelles.

answer

Muscle Fiber

question

Contractile protein filament responsible for muscle contraction.

answer

Myofilament

question

In the sarcoplams, 1 to 2 micrometers in diameter, thousands in muscle fiber

answer

Myofibrils

question

Contractile unit of muscle

answer

Sarcomere

question

Filament composed of myosin

answer

Thick

question

Filament composed of actin

answer

Thin

question

Actin is ___ in globular form and ___ in filament form. It is ___ in structure

answer

1. G-Actin 2. F-Actic 3. Double hellical

question

Blocks binding site on actin in resting state. It is a filamentous protein

answer

Tropomyosin

question

3 globular proteins located at regular intervals along the tropomyosin

answer

Troponin (T, I, C)

question

Troponin T does what?

answer

Attaches troponin to tropomyosin

question

Troponin I does what?

answer

Inhibits actin and myosin interaction

question

Troponin C does what?

answer

Binds calcium and plays crucial role in initiation of contraction

question

The 4 light chains of myosin for the myosin ___

answer

Tails

question

The 2 heavy chains of myosin for the ___

answer

Heads

question

Do light or heavy chains of myosin interact with the actin filaments?

answer

Heavy

question

Fillamentous molecule of protein that allows side by side relationship of actin and myosin filament

answer

Titin

question

Links thick filaments to Z-Lines

answer

Titin

question

Links thin filament to Z-Lines

answer

Nebulin

question

Myosin binding protein present on the M-Line

answer

Myomesin

question

Bundles of actin filaments attached to the Z-Lines

answer

Alpha actin

question

What cause rigor mortis and why do muscles relax after a day or two?

answer

1. Body runs out of ATP 2. Deterorating SR releases Ca+ into sarcoplasm 3. Ca+ cannot be removed because of lack of ATP therefor the muscle stays contracted. 4. Muscles relax after a few days because the proteins are gradually borken down

question

Continuous contraction of muscle is called ___. Caused by what?

answer

Spastic paralysis : ACHesterase inhibitor don<t allow ACH to be broken down

question

Phenomena in which there is no contraction. What can cause this?

answer

Flaccid paralysis : Poison such as curare competes with ACH and dosen't allow it in the nicotonic receptors to allow contraction

question

The sum of active tension developed by contractile elements of the sarcomere + passive tension = ?

answer

Total tension

question

Total tension - passive tension = ?

answer

Active tension

question

Tension developed when a muscle is stimulated to contract at diffrent preloads?

answer

Total tension

question

Define rest lenght

answer

The lenght at which a muscle develops maximum tension in response to a stimulus

question

When is Vmax of muscle contraction?

answer

When afterload is zero

question

When will a muscle have a zero velocity contraction?

answer

When the afterload increases to higher levels

question

Rapid force response to a single stimulus. A quick cycle of stimulus and relaxation. Lasts 7-100 msecs

answer

Muscle twitch

question

Weakest stimulus from a neuron that can initiate a contraction?

answer

Threshold stimulus

question

A delay of about 2 miliseconds between the stimulus and the onset of a twitch.

answer

Latent period

question

Staircase phenomena of successive contraction increasing in force from repeated force at regular time intervals?

answer

Treppe

question

Two stimuli ariving close together. Second arrives after refractory period but before it relaxes.

answer

Temporal summation

question

In treppe contraction, does the muscle have ample time to recover between stimuli?

answer

yes

question

Muscle is able to relax only partially between contractions. Occurs when stimuli are so frequent . Muscle cannot completely relax.

answer

Incomplete tetany

question

Muscle does not relax between contraction. Twitches fuse to form a smooth, prolonges contraction

answer

Complete tetany

question

What is ATP required for in the muscle?

answer

1. Provides energy for Na-K pumps 2. Cross bridge cycle 3. Ca+ pump in SR 4. Detaching cross bridge

question

Source of ATP: Anerobic respiration. What does this produce?

answer

Glucose and FA catabolize in mitochondria (anerobic glycolisis). This produces lactic acid

question

How is ATP made in aerobic respiration

answer

Surplus ATP is used to build energy reserves of ATP, PCr and glycogen

question

Resting muscle stores ATP as what?

answer

PCr = phosphocreatine

question

Muscle cramps are a result of what? Because of this what may occur?

answer

Low O2 levels. ATP synthesis will be reduces due to slow anerobic respiration (glycolysis) This slows 1. Na-K pump 2. Increases lactic acid production 3. Increases pH

question

How do pro athletes develop endurance a few days before a game?

answer

Carb-loading. 4-5 grams of glycogen in 100 grams of muscle

question

What is malignant hyperthermia?

answer

Sensitivity to anethetics

question

What causes hyperthermia?

answer

Anethetic agents fully activates skeletal muscles - enormus amount of heat generated - positive feedback loop - death

question

Fast twitch (type 2)

answer

low mitochondria, low oxidative enzymes, high glycolitic function, low myoglobin, high SR, low capillary bed density

question

Slow twitch (type 1)

answer

Small diameter, high mitochondria, high oxidative enzymes, low glycolytic function, high myoglobin, low SR, High capillary bed density

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