Exercise Physiology: Homeostasis and Feedback
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Questions and Answers

What is the primary location for aerobic ATP production?

  • Mitochondria (correct)
  • Cytoplasm
  • Sarcoplasm
  • Endoplasmic reticulum

Which substance serves as the universal stimulant for rate-limiting enzymes in ATP production?

  • NADH
  • ADP (correct)
  • PC
  • ATP

What is the main fuel source during short duration, high-intensity exercise?

  • Glucose
  • Intramuscular triglycerides (correct)
  • Glycogen
  • Free fatty acids

What is the role of cytochrome c oxidase in aerobic ATP production?

<p>It serves as the rate-limiting enzyme in the ETC (A)</p> Signup and view all the answers

What happens during EPOC concerning substrate use for ATP production?

<p>Primarily free fatty acids are used (D)</p> Signup and view all the answers

Which factor is inversely related to stroke volume during exercise?

<p>Mean arterial pressure (MAP) (D)</p> Signup and view all the answers

What characterizes the crossover concept during increased exercise intensity?

<p>A shift from predominantly fat to carbohydrate usage occurs (A)</p> Signup and view all the answers

What is the most significant factor affecting heat loss during exercise in a hot environment?

<p>Relative humidity (A)</p> Signup and view all the answers

What physiological adaptation occurs in the body within the first week of heat acclimation?

<p>Increased catecholamines (C)</p> Signup and view all the answers

What is a primary mechanism for heat loss during exercise?

<p>Evaporation (A)</p> Signup and view all the answers

Which factor is NOT an environmental consideration for cold injury?

<p>Altitude (D)</p> Signup and view all the answers

Which of the following factors contributes to an increase in maximal stroke volume (SV max)?

<p>Increase in contractility (C)</p> Signup and view all the answers

In terms of endurance training adaptations, what improves (a-v̅)O2 diff max?

<p>Increased mitochondrial count (A)</p> Signup and view all the answers

What are the training principles associated with overload and specificity?

<p>Intensity and volume (A)</p> Signup and view all the answers

How does gender affect individual susceptibility to cold injury?

<p>Women are at a disadvantage in cold environments (D)</p> Signup and view all the answers

What is the relationship between force and velocity in muscle contraction?

<p>Inverse; maximum shortening occurs at low force (C)</p> Signup and view all the answers

Which factors contribute to muscle fatigue?

<p>Both central and peripheral fatigue, depending on intensity and duration (C)</p> Signup and view all the answers

How do oxidation and reduction reactions transfer energy?

<p>By the transfer of electrons between compounds (D)</p> Signup and view all the answers

What is the primary end product of anaerobic ATP production via ATP-PC?

<p>ADP and inorganic phosphate (C)</p> Signup and view all the answers

Which hydrogen carrier is reduced to form NADH?

<p>NAD+ (D)</p> Signup and view all the answers

What is the replenishment time for ATP production using the ATP-PC pathway?

<p>10-15 seconds (C)</p> Signup and view all the answers

In rapid glycolysis, how many ATP molecules are produced from one molecule of glucose?

<p>2 ATP (C)</p> Signup and view all the answers

Which of the following best describes rate-limiting enzymes?

<p>They control metabolic pathways and can be regulated by metabolic products (C)</p> Signup and view all the answers

What is the primary role of muscle spindles?

<p>Respond to changes in length and maintain posture (A)</p> Signup and view all the answers

Which type of motor unit is characterized as the largest, fast, but also fatigable?

<p>Type IIx (B)</p> Signup and view all the answers

What occurs during the inverse stretch reflex facilitated by Golgi tendon organs?

<p>Relaxation to reduce tension via IPSPs (C)</p> Signup and view all the answers

What is the significance of the size principle in motor unit recruitment?

<p>Smallest motor units are recruited first to match external demands (D)</p> Signup and view all the answers

What component of the muscle fiber acts as a storage site for calcium?

<p>Sarcoplasmic reticulum (B)</p> Signup and view all the answers

What is the primary fuel source for shivering during cold exposure?

<p>Fat (C)</p> Signup and view all the answers

Which step in muscle contraction involves the binding of calcium to tropomyosin?

<p>Contraction-coupling (C)</p> Signup and view all the answers

What physiological change occurs during heat acclimatization regarding sweat?

<p>Earlier onset of sweating (C)</p> Signup and view all the answers

What role do satellite cells play in muscle physiology?

<p>Facilitate growth and repair of damaged tissue (B)</p> Signup and view all the answers

Which factor is crucial for achieving a response in VO2max for someone with a low initial VO2max?

<p>Training at 40-50% max effort (A)</p> Signup and view all the answers

What is the dominant mechanism for heat loss at rest?

<p>Radiation (C)</p> Signup and view all the answers

What happens to the muscle fiber when stimulation ends in the relaxation phase?

<p>Calcium is pumped into the sarcoplasmic reticulum (D)</p> Signup and view all the answers

What adaptation results from strength training at the neuromuscular level?

<p>Enhanced muscle fiber recruitment (B)</p> Signup and view all the answers

How does cold acclimatization affect shivering?

<p>Later onset of shivering (D)</p> Signup and view all the answers

What component of the Exercise Volume formula is NOT part of the standard definition?

<p>Type of exercise (C)</p> Signup and view all the answers

What physiological adaptation enhances cellular mechanisms during heat acclimation?

<p>Higher cellular shock protein levels (B)</p> Signup and view all the answers

What is the main driver of late strength gains in muscle tissue?

<p>Hypertrophy (D)</p> Signup and view all the answers

Which hormone is primarily responsible for promoting protein synthesis in response to resistance training?

<p>Testosterone (B)</p> Signup and view all the answers

What happens to muscle fiber types during resistance training?

<p>They change biochemically (B)</p> Signup and view all the answers

What is the effect of detraining on muscular strength?

<p>Slow loss primarily due to neural adaptations (B)</p> Signup and view all the answers

Which factor is enhanced by mTOR activation in response to muscle stretch?

<p>Protein synthesis (C)</p> Signup and view all the answers

What characterizes concurrent exercise training?

<p>Combining resistance and endurance training (D)</p> Signup and view all the answers

What is the primary physiological change in muscle fibers as a result of resistance training?

<p>Increase in myonuclei due to satellite cells (C)</p> Signup and view all the answers

Which of the following is true regarding the time course of retraining?

<p>Strength and muscle size regain occurs rapidly within 6 weeks (A)</p> Signup and view all the answers

Flashcards

Muscle spindle

A sensory receptor located within the muscle that detects changes in muscle length and helps maintain posture.

Myotatic reflex

A reflex that causes a muscle to contract in response to rapid lengthening of the muscle.

Golgi tendon organ

A sensory receptor located within the tendon that detects changes in muscle tension.

Inverse stretch reflex

A reflex that causes a muscle to relax in response to excessive tension.

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Motor unit

A single motor neuron and all the muscle fibers it innervates.

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Size principle

The principle that smaller motor units are recruited first during muscle contraction, followed by larger motor units as needed.

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Sarcomere

The basic contractile unit of a muscle fiber, responsible for muscle contraction.

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Excitation-contraction coupling

The process by which an action potential in a motor neuron leads to muscle fiber contraction.

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BFskin

Blood Flow to the Skin

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Acclimation

Short-term physiological adjustment to a new environment. It is lost within a few days.

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Acclimatization

Long-term physiological adjustment to a new environment that persists even after returning to the original environment.

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Muscular Strength

The maximum force a muscle can generate. Often measured by 1RM (one-repetition maximum).

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Muscular Endurance

The ability to perform repeated muscular contractions against a submaximal load for an extended period.

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Muscular Power

The rate at which muscular work is performed. It is the product of force and velocity.

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Hypertrophy

An increase in the size of existing muscle fibers

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Hyperplasia

An increase in the number of muscle fibers

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Force-velocity relationship

Describes the inverse relationship between the force a muscle exerts and its shortening velocity. The maximum shortening velocity (Vmax) is reached at the lowest force.

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Force-power relationship

Describes the direct relationship between the force a muscle exerts and the power it produces. Peak power is proportional to velocity and is reached at a moderate force level.

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Central fatigue

A type of muscle fatigue that occurs in the central nervous system (CNS), resulting in a decrease in the number of motor units activated and their firing frequency.

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Peripheral fatigue

A type of muscle fatigue that occurs at the muscle level, involving neural and mechanical factors that hinder muscle contraction.

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Endergonic reaction

A chemical reaction that requires energy input, typically in the form of ATP, which is hydrolyzed to ADP and Pi, to proceed.

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Exergonic reaction

A chemical reaction that releases energy, often in the form of ATP. It occurs when ADP and Pi combine to form ATP.

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Rate-limiting enzyme

An enzyme that controls the rate of a metabolic pathway, often by being sensitive to the levels of metabolic products that can act as inhibitors or activators.

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ATP-PC system

The fastest energy system, utilizing phosphocreatine (PC) to generate ATP. One PC molecule produces one ATP molecule.

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Neural Drive

The increase in the ability to recruit motor neurons, select and recruit higher threshold motor units (Type 2s), alter motor neuron firing rate, increase motor unit synchronization, and remove neural inhibition.

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mTOR

A protein kinase that plays a crucial role in protein synthesis, activated by muscle stretch and sarcolemma mechanoreceptors. It promotes protein synthesis and is essential for muscle growth.

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Satellite Cells

Stem cells involved in muscle repair and growth. They contribute to the increase in myonuclei in each muscle fiber during hypertrophy.

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Cortisol

A hormone involved in protein catabolism (breakdown) when muscle glycogen is low. It inhibits protein synthesis and acts more slowly.

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Testosterone

The main steroid hormone that directly influences increased protein synthesis, counteracts cortisol, and has a fast, acute effect from resistance training.

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Detraining

The gradual loss of muscle strength and size due to a lack of training. It primarily occurs due to loss of neural adaptations and takes about 7-8 months.

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Concurrent Training

Combining resistance training and endurance training in a single exercise session. It can negatively impact muscle protein synthesis due to endurance training adaptations interfering with mTOR activation.

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Vapor Pressure Gradient

The difference in water vapor pressure between the body and the environment. This gradient drives evaporation, a key heat loss mechanism during exercise.

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Heat Loss during Exercise

The process of dissipating excess body heat generated during physical activity.

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Relative Humidity

The amount of moisture in the air, expressed as a percentage of the maximum amount the air can hold at a given temperature.

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Cardiovascular Drift

A gradual increase in heart rate and a decrease in stroke volume during prolonged exercise, often observed in hot environments. This leads to a decline in cardiac output.

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Heat Acclimation

The physiological adaptations the body undergoes when exposed to hot environments over time, improving heat tolerance and exercise performance.

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Cold Injury

Tissue damage caused by exposure to cold temperatures, ranging from mild frostbite to severe hypothermia.

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Non-shivering Thermogenesis

The process of generating heat without shivering, primarily through increased metabolic activity of brown adipose tissue.

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V̇O2 max

The maximum rate of oxygen consumption during exercise, reflecting the body's aerobic capacity.

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Replenishment Time (Glycolysis)

The time it takes for the body to replenish ATP stores using glycolysis. It's relatively short, ranging from 30 to 60 minutes.

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Rate-Limiting Enzyme (Glycolysis)

The enzyme that regulates the overall rate of glycolysis. In this case, it's phosphofructokinase-1 (PFK-1).

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Oxidative Phosphorylation

The primary way our body produces ATP using oxygen. It's the final stage of aerobic metabolism, where energy from food is used to produce ATP.

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Rate-Limiting Enzyme (Oxidative Phosphorylation)

The enzyme that regulates the rate of the electron transport chain (ETC), the final stage of oxidative phosphorylation. This is cytochrome c oxidase.

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Crossover Concept

The point during exercise where the body shifts from primarily using fat as fuel to using more carbohydrates. This occurs when the respiratory exchange ratio (RER) reaches approximately 0.85.

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Intramuscular Triglycerides

Fat stored directly within muscle cells. These are a primary fuel source during short-duration, high-intensity exercise.

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Chemoreceptors

Specialized sensory receptors located in the carotid arteries and aorta. They detect changes in oxygen and carbon dioxide levels in the blood, playing a vital role in regulating breathing during exercise.

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Study Notes

Exam I Content

  • Exercise responses to constant load/work rate: no change in intensity level over time
  • Plateau at steady-state / positive or negative drift
  • Exercise-induced hormesis: low/moderate dose of a harmful stressor (exercise), results in an adaptive response
  • Homeostasis: maintenance of relatively constant internal environment during resting conditions
  • Variables vary around a “set point”
  • Steady-State: constant internal environment during sub-maximal constant-load exercise, different than resting values
  • Biological control systems: maintain a parameter at a near “constant value”
  • Components: Sensor/receptor, Control center, Effector
  • Gain: degree to which a control system maintains homeostasis
  • Negative feedback systems: response reverses the initial disturbance in homeostasis
  • Positive feedback systems: response increases initial stimulus
  • Exercise as a test of homeostatic control: body doesn't maintain homeostasis during exercise
  • Sub-maximal: most systems reach & maintain steady-state
  • Maximal: cannot maintain steady-state, results in fatigue or cessation of exercise

Chapter 7

  • CNS: brain & spinal cord
  • PNS: afferent & efferent divisions
  • Afferent: sensory - receptors > CNS
  • Somatic sensory
  • Visceral sensory
  • Special sensory
  • Efferent: motor - CNS > effector organs
  • Somatic motor (voluntary)
  • Autonomic motor (involuntary)
  • Synaptic Transmission: how impulses are transmitted via neurotransmitters along axons
  • Resting membrane potential: the negative charge inside cells
  • Depolarization: when the membrane potential becomes less negative
  • Repolarization: process of restoring membrane potential back to resting state
  • Hyperpolarization: when the membrane potential becomes more negative
  • IPSP: cause hyperpolarization
  • EPSP: stimulate muscle contraction
  • Joint proprioceptors: provide CNS with body position information
  • Free nerve endings
  • Golgi-type receptors
  • Pacinian corpuscles
  • Muscle proprioceptors: (mechanoreceptors) provide info about movement
  • Muscle spindles respond to length changes
  • Golgi tendon organs: monitors tension
  • Somatic motor neurons: carries message to muscles
  • Motor unit: motor neuron and all it innervates

Chapter 8

  • Innervation ratio: number of fibers innervated by alpha motor neuron
  • Types of motor units: Type I, Type IIa, Type IIx
  • Size principle: smallest motor units recruited first
  • Microstructure of muscle fibers: Sarcoplasm, Myofibrils, Sarcomere, Sarcoplasmic reticulum, Transverse-tubules
  • Myonuclear domain
  • Satellite cells
  • Neuromuscular junction
  • Muscle contraction: excitation-contraction coupling
  • Excitation
  • Contraction-coupling
  • Relaxation
  • Muscle fiber types: IIx, Ila, I
  • Biochemical properties of muscle fibers: Oxidative capacity

Chapter 3

  • Energetics of contraction: slowed rate of ATP utilization, accumulation of Pi
  • Endergonic: requires energy, ATP > ADP
  • Exergonic: energy released, ADP > ATP
  • Oxidation-reduction reactions (redox)
  • Oxidation
  • Reduction
  • Hydrogen carriers: NAD, FAD
  • High energy products of metabolism

Anaerobic ATP Production

  • ATP-PC
  • Rapid Glycolysis
  • Aerobic ATP Production
  • Oxidative phosphorylation

Chapter 4: Exercise Metabolism

  • Relative oxygen: mL/kg/min
  • Absolute oxygen: L/min
  • Fick Equation: VO2 = Q x (a - v)O2 difference
  • Central component: Q (O2 delivery)
  • Peripheral component: (a-v)O2 diff (O2 extraction)
  • Maximal Oxygen Uptake (VO2max)
  • Gold standard: Graded exercise test
  • Values during Rest-to-Exercise Transition
  • ATP production
  • O2 requirements
  • PCr levels
  • Values during Incremental Exercise
  • ATP production

Chapter 10

  • Respiratory system functions: Gas exchange, Regulation of acid-base balance, Pressure differentials
  • Conducting zone
  • Transport air
  • Warm, humidify & filter air
  • Respiratory zone
  • Gas exchange
  • Alveolar dead space
  • Mechanics of Breathing
  • Inspiration
  • Expiration
  • Boyle's Law
  • Airway Resistance
  • Blood Flow to Lungs
  • Rest
  • Light Exercise
  • Heavy Exercise
  • Henry's Law

Chapter 11

  • Fick's Law of Diffusion: Rate of gas transfer
  • Tissue area
  • Diffusion coefficient
  • Difference in partial pressure
  • Partial Pressure Through Circulation: Alveolar gas, Blood entering lungs
  • O2 Transport in the Blood: Amount of O2
  • Oxyhemoglobin Dissociation Curve
  • O2 Transport in Muscle: Myoglobin
  • Effects of Temperature
  • CO2 Transport in Blood
  • Bicarbonate
  • CO2 Transport in Tissue

Chapter 12

  • Homeotherms
  • Heat Balance
  • Temperature control system
  • Role of the hypothalamus
  • Responses in core temperature
  • Overview of heat production and heat loss -Involuntary heat
  • Voluntary heat
  • Heat loss, 4 mechanisms

Ch 13

  • Principles of Training: Overload, Reversibility, Specificity
  • Stress and primary and secondary messengers
  • mRNA levels
  • Adaptation of endurance or aerobic exercise
  • Training-induced changes to VO2max

14

  • Muscular Strength
  • Muscular Endurance
  • Muscular Power
  • Muscular Fitness
  • Neuromuscular Adaptations
  • Hyperplasia
  • Hypertrophy
  • Neural Changes
  • RT-induced changes
  • Primary signal
  • Cellular mechanisms
  • Strength and CSA
  • Protein synthesis
  • Protein degradation
  • Mechanism for hypertrophy
  • Hormone actions

Chapter 15

  • Detraining vs. re-training
  • Neural changes
  • Effect of Muscle fiber changes
  • Time course of changes
  • Concurrent training

Additional Notes

  • Effects of altitude training on saturation of hemoglobin.
  • Living at high altitude → increase in red blood cell mass
  • Heat/Cold adaptations
  • Cardiovascular drift
  • Factors that decrease SV
  • Factors that regulate cardiac output

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Description

Explore the principles of exercise physiology concerning homeostasis and feedback mechanisms. This quiz covers steady-state conditions, biological control systems, and the effects of exercise on the body's internal environment. Test your knowledge on how the body adapts to constant load and maintains equilibrium during physical activity.

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