EXSC 352 Exam 1 Review

Exam 1 Review for Exercise Physiology

What are the main substrates used as fuel during exercise

What are the main substrates used as fuel during exercise

Carbs, Fats, Proteins

How many kcals/gram are in Carbohydrates, when is it used?

4.1 kcal/gram, primary ATP substrate

How many kcals/gram are in Fats, when is it used?

9.4 kcals/gram, used for prolonged exercise

How many kcals/gram are in Protein, when is it used?

4.1 kcal/gram, used in lipogenesis

How much glycogen is in the body

Liver (110 g), muscle (500 g), body fluids (15)

How much fat is stored in the body

Subcutaneous (7,800 g), visceral (161 g), body fluids

What is ATP

Stored energy in small amounts until needed

How do we get energy from ATP

Breakdown of ATP, ADP + Pi is energy

What are the three ATP Synthesis Pathways

1. ATP-PCr system (Anaerobic)

2. Glycolytic system (Anaerobic)

3. Oxidative system (Aerobic)

What is ATP-PCr system energy system, how long does it last? What is the yield?

3-15s, 1 mol ATP / 1 mol PCr

Anaerobic system

What is the ATP PCr recycling

PCr + Creatine Kinase creates Creatine, Pi, and Free Energy

Free Energy + Pi + ADP = ATP

What is Glycolytic energy system, how long does it last? What is the yield?

15s-2 min, 2-3 mol ATP / 1 mol substrate

Anaerobic System

Glucose or glycogen as a substrate we use Glucose-6-phosphate and a pyruvic acid, how many enzymatic reactions occur, where does it occur, and what is the ATP yield for glucose and glycogen?

10-12 enzymatic total reactions

Occurs all in the cytoplasm

ATP Yield: Glucose 2 ATP, Glycogen 3 ATP

What is glycolysis

Breakdown of glycogen into glucose

Used under 2 minutes max during exercise

Cons of the Glycolytic System

Low ATP yield

Inefficient use of the substrate

Low O2 converts pyruvate to latic acid

Lactic acid impairs glycolysis causing muscle contraction

Pros of Glycolytic System

Allows muscle to contract with low O2

Short-term, high-intensity exercise when oxidative metabolism sustains energy

What is Phosphofructokinase (PFK)

Rate limiting enzyme

Low ATP (Increased ADP) → Increase PFK activity

Increase ATP → Decrease PFK activity

What is the Oxidative energy system, how long does it last? What is the ATP yield?

Aerobic system

Can last for hours

ATP yield: 32-33 ATP / 1 glucose

ATP: 100+ ATP / 1 FFA

What is the Krebs cycle? What is the Ratio? What does 2 acetyl-CoA create? What is the ATP Yield

Krebs Cycle: Creation of ATP energy

1 Molecule of Glucose → 2 acetyl-CoA

2 acetyl-CoA → 2 GTP → 2 ATP

ATP Yield: 1 glucose → 32 ATP / 1 glycogen → 33 ATP

What are the broken down totals of the Krebs Cycle

Glycolysis = +2 ( or +3) ATP

GTP (Transports Pi to ADP) = +2 ATP

10 NADH = +25 ATP

2 FADH = + 3 ATP

How does fat enter the Krebs Cycle

Lipids go through Beta-Oxidation and is added to the Acetyl-CoA during Krebs

What is the electron transport chain? How is ATP created? What is the ATP yield?

H+ and electrons are carried to ETC via NADH and FADH molecules

H+ travel down the chain combining with O2

Electrons and O2 create ATP

NADH: 2.5 ATP

FADH: 1.5 ATP

What is lactate acid, what are the three pathways

Fuel for exercise

1. Cytoplasm

2. Transported to another cell

3. Liver

What is the lactate acid pathway in the cytoplasm

Taken up by mitochondria of the same muscle and is oxidized

What is the lactate acid pathway into another Cell

Transported by MCP transporters and is oxidated there

What is the lactate acid pathway in the liver

Recirculated into the liver to be converted back into pyruvate, then to glucose (via gluconeogenesis)

What is the Respiratory Exchange Ratio (RER)

Volume of both CO2 and O2 that is produced

RER = VCO2 / VO2

What does it mean when the RER is around 0.7

Gluconeogenesis is produced at an RER of <0.7

What does it mean when the RER is around 1.0

Can be inaccurate when lactate buildup increases over the CO2 exhalation

What is fatigue

Inability to maintain required power output at a given intensity

Fatigue Causes

1. Inadequate energy delivery

2. Accumulation of by-product

3. Failure of muscle contraction

4. Altered neural control

Fatigue Recovery

Rest

Fatigue from PCr Depletion

Phosphorus accumulation

PCr gets depleted faster than ATP

Fatigue from Glycogen Depletion

Limited and gets depleted quickly

Depletes faster at a higher intensity

FFA Oxidation is slow

What are the metabolic by products

Pi: From PCr and ATP

Heat from sweat

Carbs from heat

Lactic Acid from glycolysis

What is direct calorimetry

Measurement of Calories over time, good for RMR measurements

It is expensive and slow, heat can be added by exercising, sweat can cause errors

What is Neural Transmission fatigue

Failure of muscle activation (Cramp)

What is CNS Fatigue

Stress from exercise taxing the CNS

Discomfort of fatigue

What is indirect calorimetry

Estimate of total energy expenditure via O2 and CO2 production, accurate only with a steady-state of oxidative metabolism

Old methods are accurate but slow

What are the three types of muscle tissue

Skeletal, Smooth, Cardiac

What is the anatomy of the entire muscle

Surrounded by Epimysium

Made up of fasciculi

What is the anatomy of Fasciculi

Surrounded by perimysium

Made up of muscle fibers

What is the anatomy of muscle fiber

Surrounded by endomysium

Made of myofibrils (sarcomeres)

What is the structure of the Cell Membrane (Plasmalemma)

Fused with the tendon that conducts the Action Potential (AP), it maintains the pH levels and transports nutrients

What are satellite cells? What do they help do?

They promote muscle growth and development

Helps with injury, immobilization, and training

The Sarcoplasm serves as? What is its unique features

Serves as cytoplasm of the muscle cell

Unique Features: Glycogen storage and myoglobin

What are the transverse tubules (T-Tubules)

Serves as extension of the Cell membrane

Carries the AP deeper into the muscle fibers

Why is the Sarcoplasmic reticulum (SR) unique

Ca2+ storage

What is the pathway of the myofibrils and how many are there?

Muscle → Fasciculi → muscle fiber → myofibril

Contains over +100K per muscle fiber

What is a sarcomere

Basic contractile element of the skeletal muscle

Know the structure of a muscle fiber and sarcomere

Be able to label the following:

A-band → Dark stripes

I-Band → Light stripes

H-Zone → middle of the A-Band

M-Line → Middle of H-Zone

What are the three myofilaments

Actin, Myosin, Titan

What is Myosin (Thick Filaments), what does it use as a stabilizer

Two intertwined filaments

Contains Globular Heads

→ Interacts with actin filaments to contract

Uses Titin as stabilizer

What is Actin ( Thin Filaments), how does it interact with other filaments

Composed of three proteins:

1. Actin - the myosin-binding site

2. Tropomyosin - Convers active sites at rest

3. Troponin → Moves tropomyosin

Anchored at Z-Disk

Uses nebulin to keep equal space constant between actin

What is Titan (Third Myofilament), what does it prevent

Acts as a spring

1. Extends from Z-disk to M-band

2. Calcium bind to titan, increasing muscle force

Stabilizes sarcomeres and centers myosin

Prevents overstretching of the muscle

What is a motor unit

Consists of an Alpha motor-neuron + all fibers around it

More active motor units = stronger contraction

Define the Neuromuscular junction

Synapses between Alpha Motor-neurons and muscle fibers

Serves as a Communication site

What is the Excitation-Contraction Coupling theory

1. AP starts at the brain

2. AP arrives at Axon Terminal, releases ACh

3. ACh crosses synapse and binds to ACh receptor on cell membrane

4. AP travels down the cell membrane and T-tubules

5. Triggers Calcium release from the Sarcoplasmic reticulum

6. Calcium activates actin-myosin contraction

What is the Sliding filament theory

Relaxed:

1. No interaction occurs at the binding site

2. Myofilaments overlap a bit

Contraction:

1. Myosin head pulls actin to the center of sarcomere (Powe rstroke)

2. Filaments slide past each other

3. Everything shortens

What happens when the power stroke ends?

1. Myosin detaches

2. Myosin goes back to original position and moves down to another active site

Process continues until Z-Disk reaches myosin filaments or AP stops

How does a muscle return to its resting length

1. AP Stops

2. Calcium is pumped back into sarcoplasmic reticulum

What are the muscle fiber types

Type 1 and Type 2

What is Type 1 muscle fiber

About 50% of fibers in the muscle

Slow twitch muscle

<300 fibers due to smaller neuron

What is a Type 2 muscle? What are the classifications of it

Fast twitch

2 types

1. Type 2a (25%)

2. Type 2x (25%)

>300 due to larger neuron

What is a twitch speed muscle

What is the oxidative vs glycolytic

What are the fatigue rates of each muscle

Type 2x → Fast then rapid decline

Type 2a → Medium force then rapid decline

Type 1 → Slow build, slow decline

Describe Motor Units, what happens when we alter the force?

Method for altering force production

Less force = Less motor units

More force = More motor units

What are fiber determinants

Genetics, training , aging, and any possible influence from the nervous system

How is each fiber typed influence an athlete

Type 2 fatigue quickly

Type 2a → Short, intense endurance

Type 2x → Short explosive sprints

Type 1 is used in endurance training

What is a static muscle contraction

Muscle produce a lot of force but don’t change length

Joint angle doesn’t change

No sliding filaments

What is a dynamic muscle contraction

Muscle produces force and changes length

Joint movement occurs

What is the length-tension relationship and pennation angle will influence for production

Optimal sarcomere length equals optimal overlap

If it is too short or over stretched, then little to no force is developed

What is the CNS

Central nervous system

Contains Brain and spinal cord

What is the PNS

Sensory (Afferent) → Incoming

Motor (Efferent) → Outgoin

1. Somatic: Voluntary

2. Autonomic: Involuntary

   1. Sympathetic

   2. Parasympathetic:

Know the basic structure of a neuron

3 regions

1. Cell body → Nucleus

2. Dendrites → Receives information

3. Axon → Sends signals

What’s the purpose of a neuron

Send and receives different signals

What is the purpose of the Sodium-Potassium pump

Maintains the resting membrane potential of the neuron and creates the concentration difference in the cell

3 Ka+ in

2 Ca2+ out

How is an action potential created

When the Graded potential either excites or inhibits the neuron into an Action potential

Needs to cross the All-Or-Nothing Complex (-50mV)

What is an absolute refractory period

Neuron is unable to respond to another stimulus

What is a relative refractory period

Neuron only responds to a very strong stimulus

How is a neurotransmitter used during exercise

ACh stimulates skeletal muscle contraction, mediates the parasympathetic NS effects

Norepinephrine mediates sympathetic NS effect

What neurotransmitter is important for exercise

Endorphins

What parts of the brain deal with exercise

Frontal → Motor control, general thought

Temporal → auditory processing and interpretation

Parietal → General sensory processing and interpretation

Occipital → Visual processing and interpretation

Insular → Emotion and self-perception

Which regions of the brain are important for exercise physiology

Frontal Lobe, Basal Ganglia, and Parietal Lobe

What are the two major divisions of the PNS

Sensory and Motor

What are the major families of sensory receptors

1. Mechanoreceptors → Pressure, touch, vibration, stretch

2. Thermoreceptors → Heat

3. Nociceptors → Pain

4. Photoreceptors → Light

5. Chemoreceptors → Chemical stimulus

What is the somatic nervous system

Stimulates skeletal muscle

What is the autonomic nervous system?

Regulates visceral muscle (smooth muscle)

What is the sympathetic nervous system

Fight, Flight, Fawn, Freeze

What is the parasympathetic nervous system?

Rest and Digest