EXS322 Bioenergetics Exam 2

What is the Sliding Filament Theory?

A theory suggesting that muscle shortening and lengthening is due to thick and thin filaments sliding past each other without changing length

What is the thick filament?

Myosin

What is the thin filament?

Actin

At rest, cross-bridges of _________ extend toward but do not interact with ________

Myosin globular heads; actin

What is at the end of a cross-bridge at rest?

Uncharged ATP molecule

At rest, there is an absence of ________ in muscle fibers, which is stored in the sarcoplasmic reticulum

Calcium

The absence of ________ and ________ at rest inhibits the cross-bridge from binding with actin.

Calcium; troponin

In excitation-coupling of cross-bridge formation, an impulse from the motor nerve reaching the motor end plate causes ________ to be released

Acetylcholine (ACH)

The release of acetylcholine stimulates ________ in the ________

Action potentials; sarcolemma

________ spread action potentials quickly throughout fibers

T-tubules

When passed through T-tubules, action potentials release ________ which binds to ________, in turn activating actin active sites. This is also due to the change of configuration of ________ and ________

Calcium; troponin

Troponin; tropomyosin

When active sites are turned on, ATP at the end of the myosin head becomes ________

Charged

The turning on of active sites and charging of ATP results in physical-chemical coupling of ________ and ________. This is known as the ________

Actin; myosin

Actomyosin complex

The formation of an ________ complex activates ________, which breaks ATP down into ADP and Pi

Actomyosin; myosin ATPase

The breakdown of ATP into ADP and Pi ________ energy

Releases

What is a power stroke?

Myosin movement

When energy is released, the cross-bridge can swivel to a new angle causing ________ to glide over ________, in turn creating concentric action

Actin; myosin

For a cross bridge to recharge, the breaking of an old bond between actin and myosin is
accomplished with a new __________ molecule

ATP

How many ATP are required for muscle contraction?

2

When a muscle relaxes, ________ is pumped back into the sarcoplasmic reticulum. This turns off ________, which removes the cross-bridge complex from the active site

Calcium; Actin

________ of the sarcomere and Z lines being ________ is considered concentric

Shortening; Towards the middle of the sarcomere

Type 1 Muscle Fibers

Slow twitch; aerobic (oxidative) metabolism

-Endurance

Type 2a Muscle Fibers

Intermediate fast twitch; aerobic (oxidative) and anaerobic (glycolytic) metabolism

Type 2x Muscle Fibers

Fast twitch; anaerobic (glycolytic) metabolism

-Strength

Fast twitch muscle fibers have a ________ form of myosin ATPase while slow twitch muscle fibers have a ________ form

Fast; slow

-ATP split more rapidly in fast twitch muscles

Fast twitch muscle fibers are better suited for ________ performance

Anaerobic

Why are type 2a muscle fibers considered intermediate?

They have a fast contracting speed combined with moderately well-developed capacity for both aerobic and anaerobic energy transfer

What muscle fibers are known as fast-oxidative-glycolytic (FOG)?

Type 2a

True or False: Type 2x muscle fibers have the greatest anaerobic potential and are considered true glycolytic fiber

True

Type ________ fibers are typically used in highly-explosive events

2x

True or False: Slow twitch fibers generate energy for ATP resynthesis predominately through
aerobic system for energy transfer

True

Slow twitch fibers have low activity levels of ________ and contain large amounts of ________

Myosin ATPase; mitochondria

________ fibers can be called “red” fibers due to high concentrations of mitochondria and myoglobin

Slow twitch

________ are required to sustain aerobic metabolism in slow switch muscle fibers

Mitochondrial enzymes

Slow twitch fibers are referred to as ________

Slow-oxidative

True of False: The nervous system recruits 100% of available fibers

False— not all muscle fibers are recruited to prevent damage to muscles and tendons

Peak tension in type I muscle fibers occurs in ________ ms. It occurs in ________ ms in type II

110; 50

At rest, neurons are ________ and have an ________ distribution of ions across the membrane

Polarized; unequal

Polarized nerve cells are ________ on the inside and ________ on the outside

Negative; positive

In polarized nerve cells, there are large amounts of ________ on the inside of the cell and large amounts of ________ outside of the cell

K; Na

Anions can not move outside cell since they are… (3)

Too large, protein bound, and have a negative charge

During free ion movements, the concentration gradient moves ________ K for every 1 Na

50-100

Action potentials of threshold intensity in nerve cells cause it to become ________

Depolarized (positive inside)

A threshold stimulus changes membrane permeability to ________. This cause more ________ charged ions inside relative to the outside

Na; positively

More Na is let into cell then K leaves

Depolarization is accomplished by letting ________ into the cell whereas repolarization is accomplished by letting ________ out of the cell

Na; K

When a cell depolarizes during synaptic transmission, voltage gates open to allow ________ to flood into the terminal end of the axon

Ca

When Ca reaches the dense bars in synaptic vesicles, the synaptic cleft is flooded with the neurotransmitter ________

Acetylcholine (ACH)

What does acetylcholine do?

Allows the impulse to continue down to the muscle fiber to the motor unit for muscle contraction

________ cleanses acetylcholine from the synaptic cleft by breaking it into ________ and ________

ACHesterase; acetate; choline

Nerves regenerate ________ to reform with choline to form ACH

Acetate

Energy

The capacity or ability to perform work, which is the application of a force through a distance

1 kcal =

The amount of heat needed to raise 1 kg or 1 liter of water by 1 degree celsius

How is basal metabolic rate (BMR) measured? What else can be measured this way?

By the amount of heat produced; VO2

________ ml/kg/min of O2 or ________ ml/min is needed to support the BMR of an average person

3.5; 250

Carbohydrates = ________kcal

4.2

Lipids = ________kcal

9.4

Proteins = ________kcal

4.0

RER (respiratory exchange ratio) =

VCO2/VO2

Relationship of CO2 produced to O2 consumed

During complete oxidation of a glucose molecule, ________ are consumed and ________ are produced

6 O2; 6 CO2

With lipids, ________ molecules of CO2 are produced for every ________ molecules of O2 consumed

16; 23

16 CO2/23 O2 = .7 fats

RER values, which represent a range between fat and glucose, are a range of ________

.7-1.0

At rest, normal RER values are approximately ________

.75-.81

When the high energy bonds of ATP are broken, ________ kcals of energy are released

7-12

What kind of reaction is the break down of ATP?

Hydrolysis— it requires water

________ is needed to reform ATP

Phosphocreatine (PCr)

When the breakdown of ATP occurs without oxygen it is called ________

Anaerobic metabolism

When the breakdown of ATP occurs in the presence of oxygen it is called ________

Aerobic metabolism

The aerobic conversion of ADP to ATP is called ________

Oxidative phosphorylation

The concentration of PCr in a cell is approximately ________ times greater than ATP

3-4

The release of energy from PCr is facilitated by ________

Creatine kinase (CK)

ATP-PCr Equation

PCr + ADP ←CK→ ATP + Cr

Is the ATP-PCr system aerobic or anaerobic?

Anaerobic

ATP and PCr stores can only maintain energy needs for ________ seconds

3-15

True or False: Pi and Cr can only be reformed into PCr using the energy released from the breakdown of ATP

True

Glycogen is synthesized by ________ via ________

Glucose; glycogenesis

The rate limiting enzyme in glycolysis is ________

Phosphofructokinase (PFK)

________ must be invested to begin glycolysis

2 ATP

How much ATP is used and produced in glycolysis? What about when glycogen is used?

2 ATP used, 4 ATP formed = 2 Net ATP

With glycogen 1 ATP used, 4 ATP formed = 3 Net ATP

What is the ultimate end product of glycolysis during moderate bouts of exercise?

Pyruvate/pyruvic acid

Pyruvate is converted into ________ in the presence of oxygen

Acetyl CoA

What is the terminal product of glycolysis during strenuous exercise?

Lactic Acid

True or False: Lactic acid can be used as fuel

True, in some instances

Formation of lactate with strenuous activity can be used for synthesis of ________ via the Cori Cycle

Glucose

Anaerobic glycolysis is the primary metabolic pathway for events lasting from ________ minutes

1-3

Where does glycolysis occur?

Outside mitochondria

Where does the TCA/Krebs Cycle occur?

In mitochondria

At the end of the Krebs cycle, ________ ATP have been formed and ________ has been broken down into carbon and hydrogen

2; carbohydrates

________ molecules of pyruvate are formed from 1 glucose molecule in glycolysis

2

Glycogen stores can provide ________ kcal of energy whereas lipids can provide ________ kcal of energy

1200-2000; 70000-75000

3 Classes of Lipids

-Triglycerides

-Phospholipids

-Cholesterol

________ are the major lipid energy source

Triglycerides

Triglycerides are stored in fat cells and skeletal muscle fibers and must be broken down into ________ and ________ to be used for energy

Glycerol; 3 Free fatty acids

The breakdown of fats for entry into the Krebs cycle is known as ________

Beta-oxidation

Where does beta-oxidation occur?

In the mitochondria

What does beta-oxidation do?

Breaks the carbon chain of FFA into 2 separate units of acetic acid with are then converted to acetyl coA

True or False: Oxygen does not need to be present for beta-oxidation

False— oxygen must be available to accept hydrogen in beta-oxidation

What happens if oxygen is not present during beta-oxidation?

Hydrogen remains with NAD and FAD and lipid breakdown stops, in turn forming lactic acid