Exercise Physiology Quiz

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Questions and Answers

What does steady-state refer to in the context of exercise?

Maintenance of a complete lack of activity.

Constant internal environment during sub-maximal constant-load exercise. (correct)

An unstable state with fluctuating internal parameters.

A temporary state of high exertion.

Which component of a biological control system is responsible for detecting changes in a variable?

Effector

Sensor/receptor (correct)

Control center

Feedback loop

How does a negative feedback system function in maintaining homeostasis?

It reverses the initial disturbance in homeostasis. (correct)

It ignores changes in the internal environment.

It amplifies the disturbances to the internal environment.

It prolongs the effects of an initial stimulus.

What is the primary effect of low to moderate doses of a harmful stressor, according to exercise-induced hormesis?

It triggers an adaptive response. Signup and view all the answers

In terms of biological control systems, what does 'gain' refer to?

The efficiency with which a control system maintains homeostasis. Signup and view all the answers

What primarily influences changes in resistance in blood vessels?

Vessel radius Signup and view all the answers

How is maximal aerobic performance affected at higher altitudes?

Poorer due to lower O2 availability Signup and view all the answers

Which mechanism of heat loss is primarily used at rest?

Radiation Signup and view all the answers

What happens to peripheral factors during aerobic exercise in trained individuals?

Continuous improvement in ventricular filling Signup and view all the answers

What effect does standing have on blood flow in the lungs?

Increased flow towards the base of the lungs Signup and view all the answers

In the context of temperature regulation, what role does non-shivering thermogenesis play?

It creates heat without muscular contraction Signup and view all the answers

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

Inverse relationship where Vmax is greatest at lowest force Signup and view all the answers

Which factor primarily leads to peripheral muscle fatigue?

Inability of the sarcoplasmic reticulum to uptake calcium Signup and view all the answers

Which of the following is NOT a mechanism for heat loss from the body?

Absorption Signup and view all the answers

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

ADP Signup and view all the answers

During submaximal aerobic exercise, responses include elevated heart rate due to which factor?

Higher oxygen transport demands Signup and view all the answers

Which molecule is reduced to form NADH during metabolic reactions?

NAD+ Signup and view all the answers

What primarily limits the rate of metabolic pathways in muscle contraction?

Rate-limiting enzymes Signup and view all the answers

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

2 Signup and view all the answers

What is the most important factor influencing heat loss during exercise in hot environments?

Relative humidity Signup and view all the answers

In terms of energy yield, how many ATP are produced from one molecule of FADH2?

1.5 Signup and view all the answers

What results from oxidation in redox reactions?

Removal of electrons Signup and view all the answers

Why does performance decline prior to heat acclimation during exercise?

Decreased efficiency in heat loss mechanisms Signup and view all the answers

Which factor is least likely to contribute to cold injury?

Increased muscle mass Signup and view all the answers

What physiological adaptation is expected after one week of heat acclimation?

Enhanced non-shivering thermogenesis Signup and view all the answers

What factors are known to increase maximal stroke volume (SV max)?

Increased preload and decreased afterload Signup and view all the answers

Which adaptation is associated with endurance training affecting blood oxygen content difference?

Increased capillaries and mitochondria Signup and view all the answers

What principle of training states that adaptations occur specifically based on the stress applied?

Specificity Signup and view all the answers

Which individual factor can put someone at a disadvantage to cold injury?

Gender Signup and view all the answers

What occurs during maximal exercise in relation to homeostasis?

Fatigue likely occurs due to inability to maintain steady-state. Signup and view all the answers

Which division of the peripheral nervous system is responsible for voluntary motor control?

Somatic motor division Signup and view all the answers

What is the primary effect of excitatory postsynaptic potentials (EPSPs)?

They cause depolarization in the neuron. Signup and view all the answers

What primarily marks the process of repolarization of a neuron?

Efflux of potassium ions from the cell. Signup and view all the answers

Which receptor type is involved in muscle contraction stimulation through the release of acetylcholine (Ach)?

Nicotinic receptors Signup and view all the answers

What characterizes hyperpolarization in a neuron?

Potassium ions leave the cell, making the inside more negative. Signup and view all the answers

What role do joint proprioceptors serve in the body?

They provide the CNS with body position information. Signup and view all the answers

What initiates the depolarization of a neuron?

Opening of sodium ion channels. Signup and view all the answers

What happens to venous return and end-diastolic volume (EDV) when there is an increase in blood flow to the skin?

Venous return decreases and EDV decreases Signup and view all the answers

What distinguishes short-term acclimation from long-term acclimatization?

Short-term acclimation is lost in a few days whereas long-term acclimatization is maintained Signup and view all the answers

During which scenario is the rate of heat loss significantly greater when compared to air of the same temperature?

Resting in water compared to resting in air Signup and view all the answers

Which adaptation is NOT a characteristic of cold acclimatization?

Earlier onset of shivering Signup and view all the answers

What is the primary fuel utilized for shivering to produce heat?

Fat Signup and view all the answers

What aspect of cardiovascular adaptations does NOT result from exercise training?

Increased vascular resistance Signup and view all the answers

Which training intensity is most likely required for an individual with a low initial VO2max to see a training effect?

40-50% of maximum Signup and view all the answers

Which term best describes the maximum force a muscle can generate?

Muscular Strength Signup and view all the answers

Study Notes

Exercise Responses to Constant Load/Work Rate

Exercise responses plateau at a steady state or exhibit positive or negative drift.
The initial response often shows an increase in a certain variable, followed by a plateau.
Positive drift shows a further increase in a variable.
Negative drift shows a decrease in a variable.

Exercise-Induced Hormesis

Low or moderate doses of harmful stressors (like exercise) result in adaptive responses.
This defines how exercise results in adaptations.
Homeostasis is the maintenance of a stable internal environment during rest.

Homeostasis

Internal variables fluctuate around a set point.
Steady state is a constant internal environment during submaximal, constant-load exercise. This differs from the resting state.
Variables can be unchanging but not normal.

Biological Control Systems

Interconnected components maintain a parameter near a constant value.
Training adaptations manifest through these systems.
Components include sensors/receptors, control centers, and effectors.
Gain reflects the effectiveness of a control system in maintaining homeostasis.
Negative feedback systems reverse initial disturbances.
Examples include heart rate returning to normal after exercise, blood pH normalization.
Positive feedback systems enhance the initial stimulus. Ex., nitric oxide's role in vasodilation.

Exercise as a Test of Homeostatic Control

Exercise disrupts homeostasis by changing pH, O2, CO2, and temperature.
Submaximal exercise allows systems to reach and maintain steady state.
Maximal exercise can't maintain steady state, leading to fatigue or cessation.

Central Nervous System (CNS)

The CNS includes the brain and spinal cord.
The peripheral nervous system (PNS) branches into afferent (sensory) and efferent (motor) divisions.
Afferent neurons carry signals from sensory receptors to the CNS.
Efferent neurons carry signals from the CNS to effector organs (e.g., muscles).
Somatic motor neurons control voluntary movements, and autonomic motor neurons control involuntary actions.

Synaptic Transmission

Neurotransmitters transmit signals along axons.
Resting membrane potential is the negative charge inside cells.
Depolarization occurs when sodium ions enter cells, making the inside more positive.
Repolarization restores the membrane potential to its resting state using potassium ions.
Hyperpolarization makes the membrane potential more negative than its resting state.

Joint Proprioceptors

Free nerve endings detect touch and pressure.
Golgi-type receptors respond to joint rotation (used during exercise).
Pacinian corpuscles detect the rate of joint rotation.

Muscle Proprioceptors

Muscle spindles respond to changes in muscle length.
Golgi tendon organs monitor tension during muscle contraction.

Muscle Fiber Microstructure

Sarcoplasm is the cytoplasm within muscle cells.
Myofibrils are protein filaments responsible for muscle contraction.
Sarcomeres are the functional units of muscle.
Sarcoplasmic reticulum stores calcium.
Transverse tubules extend from the sarcolemma to spread action potentials.
Myonuclear domain represents sarcoplasm around each nucleus.
Satellite cells facilitate muscle growth and repair.

Muscle Contraction

Excitation-contraction coupling involves a signal from a motor neuron causing Ach release that starts the process of muscle contraction.
Wave of depolarization triggers calcium release from the SR.
Calcium binds to tropomyosin allowing actin-myosin interaction, and muscle contraction happens.

Muscle Relaxation

Stimulation ends, and Ach release stops.
Calcium is pumped back into the SR.
Myosin heads detach from actin.

Muscle Fiber Types

Type I fibers are oxidative, slow, and fatigue-resistant (used for prolonged aerobic activities).
Type IIa fibers are intermediate, fast, and fatigue-resistant.
Type IIx fibers are fast, fatigable (used for short bursts of high-intensity activity).

Muscle Fiber Types Characteristics

Contractile properties are categorized by max. specific force, speed of contraction, max. power output, and fatigue resistance.
Fiber types differ by type of ATPase and relative abundance of oxidative enzymes, myoglobin, and capillaries.

Exercise Metabolism

Energy systems use and produce ATP to support various exercise intensities.
Anaerobic systems (ATP-PC and glycolysis) provide ATP during short, high-intensity exertion.
Aerobic systems (oxidative phosphorylation) sustain longer duration, lower-intensity exercise.
Redox reactions involve the removal and addition of electrons.
Hydrogen carriers transport electrons during energy production.

Oxygen Uptake

Oxygen uptake (VO2) is directly related to metabolic demands.
VO2 increases linearly with intensity until maximum is reached.
Relative VO2 is measured in mL/kg/min, absolute VO2 is L/min.
The Fick equation combines both cardiac output and the O2 extraction from tissues.

Maximal Oxygen Uptake (VO2 max)

This is the maximum rate of oxygen uptake a body can achieve during maximal exertion.
Determined via graded exercise tests with direct spirometry.
Measures indicate the body's efficiency concerning oxygen utilization and metabolic rate.
Criterion standard is achieved when a plateau is observed in oxygen consumption with increasing workload.

Rest-to-Exercise Transition

ATP production transitions from initially using anaerobic to aerobic pathways.
Steady-state is reached within 1-4 minutes.

Incremental Exercise

Oxygen consumption and heart rate increase linearly with work rate until maximal effort.
Stroke volume increases and plateaus at moderate intensities (40-60% VO2 max).

Prolonged Submaximal Exercise

Cardiovascular drift involves a decrease in stroke volume and a corresponding increase in heart rate.
This occurs despite constant workload.
Changes reflect circulatory and/or blood volume adjustments over prolonged exercise.

Oxygen Deficit

Lag or delay in achieving steady-state oxygen consumption when starting exercise.
Higher oxygen deficit in untrained individuals.
Results from the body's initial reliance on anaerobic pathways prior to aerobic systems becoming fully active.

Excess Post-exercise Oxygen Consumption (EPOC)

Elevated oxygen consumption after exercise.
Allows for replenishment of energy stores (phosphocreatine), rebuilding muscle glycogen reserves, and lactate removal.

Lactate Threshold

Intensity at which lactate accumulation in the blood rises systematically during exercise.
Higher for trained individuals.
Used as a performance indicator and to gauge adaptations to training.

Oxidative Phosphorylation

This is the process of energy production in cells' mitochondria using oxygen, glucose, and other substrates.
It yields large amounts of ATP, which cells then use for various functions.

Respiratory System

The respiratory system facilitates gas exchange and acid-base balance.
Conducting zone encompasses areas such as nasal cavity, throat, and trachea.
The respiratory zone involves structures responsible for gas exchange, like bronchioles and alveoli.
Adequate respiration enables the body to warm, humidify, and refine incoming air.

Respiratory Mechanics

Inspiration (inhalation) is an active process increasing lung volume and decreasing intra-pulmonary pressure.
Expiration (exhalation) is a passive process decreasing lung volume and increasing intra-pulmonary pressure.

Blood Flow to Lungs

Blood flow toward lung bases is influenced by gravity at rest.
Exercise increases blood flow to lungs due to cardiac output increase.

Fick's Law of Diffusion

The rate at which gases are exchanged is proportional to the difference in partial pressure, surface areas, and the diffusion coefficient.

Oxyhemoglobin Dissociation Curve

Shows the relationship between oxygen partial pressure and oxygen binding to hemoglobin.
The curve's shape reflects hemoglobin's cooperative binding.
Factors affecting the curve include temperature and pH.

CO2 Transport in Blood

CO2 is transported from tissue to the lungs in 3 ways: dissolved in plasma, bound to hemoglobin, or as bicarbonate ions.
The bicarbonate buffering system is critical for transporting CO2.

Cardiovascular System

The cardiovascular system directly impacts the body's ability to deliver oxygen efficiently throughout the body during exercise.
This includes the heart, blood vessels, and blood.
The cardiovascular response to exercise leads to increases in cardiac output, heart rate, and blood flow to working muscles.
Changes in blood vessel dimensions, and cardiac output are controlled to meet the metabolic demands of the body.
Regulation of the cardiovascular system are adjusted by different nerves signals, such as autonomic nervous systems.

Exercise Intensity and Fuel Selection

Low intensities utilize fat as the primary fuel source.
High intensities utilize carbohydrates as the primary fuel source.
The crossover concept describes the shift from fat to carbohydrate as exercise intensity increases..

Exercise Duration and Fuel Selection

Prolonged low intensity exercise utilizes fat as the primary fuel source, with glycogen levels depleting over time.
For prolonged exercise reliance on glucose and glycogen increase.

Lactate and CHO Metabolism Interaction

CHO use (through glycolysis producing Pyruvate) promotes fat utilization.
CHO depletion can impede the use of fats during prolonged exercise.

Muscle Glycogen and Blood Glucose

Muscle glycogen is a primary energy source during high-intensity exercise.
Blood glucose is primarily from liver reserves under lower-intensity conditions.
Liver glycogen is used under lower intensity but is stimulated under high intensity activities.

Sources of Fat During Exercise

Intramuscular triglycerides are a primary source during short, high-intensity exercise.
Plasma fatty acids (FFAs) from adipose tissue are primary sources under low-intensity exercise.

Lactate as a Fuel Source

Intracellular and extracellular shuttles convert lactate to pyruvate and use it in various metabolic processes.
Used to maintain cellular energy under very high intensity activities where oxygen supply is insufficient.
Lactate is carried through the Cori cycle.

Replenishing Fuel Sources

PC and glycogen require time for replenishment after exercise.
Fat utilization occurs constantly to provide continuous energy supply.

Altitude

PO2 (partial pressure of oxygen) decreases with altitude.
Lower PO2 at high altitude results in decreased aerobic performance.
Reduced oxygen availability has fewer effects on short-term, anaerobic activities.

Heat Regulation

The body maintains core temperature in a range that supports bodily functions.
Homeotherms maintain a constant body core temperature.
The hypothalamus plays a key role in regulating the body's temperature.
Mechanisms for heat loss include radiation, conduction, convection, and evaporation.
Physiological adaptations (such as earlier sweating, increased plasma volume) aid in acclimating to warm environments.
Individual characteristics, metabolic rate, and environmental factors (humidity) impact overall heat balance.

Training Principles

Principles of training include overload, specificity, and reversibility to improve adaptations, strength, and endurance.
Muscle tissue (motor units, fiber types, biomechanics) adapts through neural and biomechanical changes to training.

Muscle Fitness Differences

Strength, endurance, and power are distinct aspects of capacity that are often evaluated and trained separately.
Adaptations have different time courses reflecting tissue, hormonal, and neural level changes within the body.
Factors influencing training adaptations are training frequency, intensity, volume, etc.

Concurrent Training

Combining resistance and endurance training in one training program can reduce the overall effects of the combination of training, rather than increasing the effect.

Physiological Effects ("Adaptations") of

Endurance or Aerobic Exercise Training

VO2 max, maximal cardiac output, and maximal stroke volume increase.
Blood flow and oxygen use by muscles increase.
Mitochondrial density and oxidative enzymes increase.
Aerobic adaptations involve structural and biochemical changes.

Cardiovascular Adaptations

Increased stroke volume.
Enhanced heart rate.
Enhanced cardiac output.
Enhanced blood flow delivery.

Cellular Adaptations

Increased capillary density in the muscles.
Increased mitochondrial density and oxidative capacity.
Type IIx fiber may shift toward Type IIa.
Increased myoglobin content.

Biochemical Adaptations

Enzymes and factors for aerobic metabolism increase.
Oxidative capacity increases (i.e., muscles' ability to use oxygen).
Capacity for fat utilization and lactate clearance also increase.

Muscle Adaptations

Increased muscle size (hypertrophy)
Increased number of muscle fibers (hyperplasia).
Improved ability to recruit motor units and/or motor unit synchronization.

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Description

Test your knowledge on exercise physiology concepts, including the mechanisms of homeostasis, the impact of exercise on cardiovascular responses, and temperature regulation. This quiz covers topics such as negative feedback systems, aerobic performance at altitude, and muscle contraction dynamics.