Exercise physiology exam Review copy

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EXAM REVIEW WORKSHEET
Immune System
What is the difference between the innate and the acquired immune systems?
The innate immune system is made up of both internal external defenses against foreign
invaders. The external defense is the first line of defense and it is made up of barriers
such as the skin and the mucous membranes that line our respiratory, digestive, and
genitourinary tracts. The internal defense is composed of specialized cells that include
phagocytes and natural killer cells which are designed to destroy the invader. It is also
made up of a complimentary system of proteins which work together to destroy the
foreign invader and signal other components of the immune system. The acquired
immune system functions to kill viruses that the innate immune system cannot destroy.
The adaptive immune system provides the human body with the ability to recognize and
remember specific pathogens and to mount stronger attacks when the repeating pathogen
is encountered. The acquired immune system is made up of B-cells which function as
antibodies that are required to protect us against invading antigens. T-cells are
categorized into the killer t-cells and helper t-cells. Killer t-cells can recognize and kill
against viruses because they can recognize and kill virus-infected cells. Helper t-cells
secrete cytokines that direct the action of other immune cells. They also prevent the body
from attacking itself, which would result in an autoimmune disease.
Explain how exercise can affect the immune system and what how different
environments can also contribute.
Exercising for 20-40 minutes per day at a moderate intensity exercise can promote a
beneficial effect on the immune system. Each bout of exercise causes an increase in blood
levels of natural killer cells, neutrophils, and antibodies. Intense or prolonged exercise
has been shown to have opposite effect on the body. There is a temporary depressive
effect on the immune system, which can be correlated to the increase in cortisol levels.
High levels of cortisol can inhibit the function of cytokines, suppress natural killer cell
function, and depress both the production and function of T-cells. Exercise can have both
a positive and negative effect on the body, depending on the exercise being performed,
but both effects are temporary. Current evidence has shown that exercising in extreme
heat and cold environments does not have detrimental effects on the immune system, but
exercising in high altitudes does depress immune function. This may arise from stresses
such as low arterial oxygen levels, high altitude related sleep disorders, and acute
mountain sickness.
Defend or refute whether you should exercise while you have cold.
If cold symptoms are above the neck, such as a runny nose, nasal congestion, and a mild
sore throat, then a light workout could be beneficial. Moderate intensity exercise will
help boost immune function, and may help fight off the cold. If cold symptoms lie below
the neck or include a fever, then exercise should be avoided.
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Physiology of Training
Please describe overload, specificity, and reversibility.
The overload principle refers to the fact that an organ system must be exercised at a level
beyond which it is accustomed to achieve a training adaptation. The principle of
reversibility indicates that the fitness gains by exercising at an overload are quickly lost
when training is stopped and the overload is removed. The principle of specificity refers
to the effect that exercise training is specific to the muscles involved in that activity, the
fiber types recruited, the principle energy system involved (aerobic vs anaerobic), the
velocity of contraction, and the type of muscle contraction. If a muscle is engaged in
endurance types of exercise, the primary adaptations are increases in capillary and
mitochondria number, which increase the capacity of the muscle to produce energy
aerobically. If the muscle is engaged in heavy resistance training, the primary adaptation
is an increase in the quantity of the contractile proteins, as the mitochondrial and
capillary densities may decrease.
Discuss VO2max…. What is it? How do we measure? How do we know it is truly at
maximal values? What are the values?
VO2 max is the measure of the maximal capacity of the body to transport and use oxygen
during dynamic exercise using large muscle groups. VO2 max is measured using a
spirometer, which measures how much oxygen the body consumes and how much CO2 is
produced. Truly maximal values occur when the RER value is equal to or greater than
1.1, blood lactate levels reach 8 to 9 millimoles per liter, there is a leveling off of VO2,
and the heart is within five beats of the subject’s max. VO2 max is typically expressed in
mL/kg/min.
Why does VO2max improve with training? Please explain the mechanisms. When do
you see these changes occur?
Training-induced changes in VO2 max must be due to an increase in the a-vO2 difference
or an increase in maximal cardiac output, or a combination of both. Per the fick equation
VO2= Q x a-vO2 difference. There is an increased cardiac output due to an increase in
stroke volume. With training, venous return increases, with increases end-diastolic
volume, which increases stroke volume due to the frank starling principle. With more
blood filling the ventricle, there is an increased pressure which causes a greater ejection
of the blood from the left ventricle, thus causing a larger stroke volume. Ventricular
contractility also increases with training, which will also increase stroke volume. There is
also a decrease in peripheral resistance, which increases blood flow, which will then
increase venous return. The increase in a-vO2 difference is due to increased O2
extraction from the blood. This is due to an increase in capillary density and an increase
in mitochondrial number. The greater capillary density allows for a slow red blood cell
transit time through the muscle, providing enough time for oxygen diffusion, which is
facilitated by the increased number of mitochondria. In the first four months of training,
VO2 max is increased due to increases in cardiac output and a-v O2. Although both
improved, the increases to cardiac output made a larger contribution than a-v O2 in the
first four months. After 28 months of training there was a larger increase in a-v O2
difference than cardiac output, thus making a-v O2 difference the major contributor in
increase VO2 max. This is primarily due to the plateauing of stroke volume when the
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subject has reached max. When max has been reached, cardiac output will no longer
increase.
Why would specificity of training be important? Would combining strength and
resistance training be advised?
Endurance training results in a fast to slow shift in muscle fiber types. This means that
type IIx will be converted to type IIa fibers, which have moderate oxidative capacity.
This will increase the mechanical efficiency and potentially improve endurance
performance. Endurance training also increases the capillary supply to skeletal muscle
fibers of trained individuals. The diffusion distance for oxygen and substrate deliver is
reduced, and the diffusion difference for the removal of waste is also decreased. This will
thus increase VO2 max. Endurance training also increases the number of subsarcolemma
and intermyofibrillar mitochondria. These increases will result in less stimulation of
glycolysis due to a better ability to transport ADP into the mitochondria. Endurance
training also increases fat metabolism during exercise.
Please describe the difference between hypertrophy and hyperplasia? When does
hypertrophy begin during a resistance training program? Before that time, what is
responsible for the increase in strength?
Hyperplasia refers to an increase in the total number of muscle fibers within a specific
muscle. Hypertrophy is an increase in the muscle size during long-term strength training.
Increase in muscle size is a gradual process that occurs during months to years of
training. Before that, the increase in muscle strength is due to increased neural function.
More fibers are innervated by a single motor neuron, thus increasing strength.
Fatigue
How do we define fatigue?
Fatigue is defined as the inability to maintain a power output or force during repeated
muscle contraction.
During performance of both aerobic and anaerobic exercises, what is the cause of
fatigue. Please define all the mentioned types of exercises as defined by their
duration.
In central fatigue, there can be a reduction in the motor units activated and the motor unit
firing frequency. Excessive training can reduce performance and cause prolonged fatigue.
Arousal of central nervous system during exercise can increase motivation thus
increasing strength.
Environmental Physiology
Why would exercise in any type of extreme environment be very dangerous?
Without commenting on the specific environment, please describe why exercising in
any environment may be dangerous.
Exercise produces large amounts of heat from the contracting skeletal muscles, so the
body must find a way to displace the heat so that the core temperature of the body does
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not fluctuate too much. In extreme environments, the body may not be able to produce or
dissipate enough heat needed to keep the core temperature in the normal range.
What is our core body temperature and what is the range for maintaining
homeostasis?
The body has a set point of 37 degrees Celsius, with having only small range of 0.5
degrees before the body’s mechanism must take over to protect the body from damage.
What is the difference between surface and core temp? How does this affect the core
to shell gradient?
The surface temperature of the human body is the temperature of the skin, which does not
reflect the core temperature. The core temperature of the human body is the temperature
of the internal environment of the body.
How does the core to shell gradient change in hot and cold environments?
In a hot environment, the shell will increase to dissipate heat to keep the core temperature
at 37. In a cold environment, the shell will decrease so that less heat is lost by the body
and the core temperature remains at the set point.
What are the 4 heat dissipation mechanisms we have? Are these + or – and how does
environment affect them?
The four heat dissipation mechanisms are radiation, conduction, convection, and
evaporation. Radiation is heat loss in the form of infrared rays where heat is transferred
from the surface of one object to the surface of another with no physical contact. At room
temperature, 60% of body heat loss occurs via radiation because the skin temperature is
greater than the temperature of the surrounding objects. On a hot day when the surface
temperatures are greater than skin temperatures, the body will gain heat via radiation.
Conduction is the transfer of heat from the body into molecules of cooler objects in
contact with its surface. Heat loss will occur if the surface the body is in contact with is
cooler than the skin, while gains will occur when the skin temperature is less than that of
the surface it is in contact with. Convection is a form of conductive heat loss in which
heat is transmitted to either air or water molecules in contact with the body. If the air or
water temperature is less than that of the skin, then heat loss will occur. Evaporation is
the heat transferred from the body to water on the surface of the skin. When the water
gains sufficient heat, it is converted to a gas and taken away from the body. At high
temperatures, humidity becomes an important factor. High humidity reduces the rate of
evaporation, so it is only the most effective under low humidity conditions.
What is the first physiology mechanism we have to deal with a hot environment?
And a cold environment?
In a hot environment, the body’s blood vessels will begin the vasodilate to increase heat
loss. In a cold environment, the opposite occurs and the vessel vasoconstrict and heat loss
is minimized.
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When we exercise in a hot environment, what happens to our basic physiological
functions and what changes do we see? What does this lead to? Please explain the
basic mechanisms.
When we exercise in heat, there is more cutaneous blood flow. This competes with the
blood flow going to the active skeletal muscles, causing a decrease in VO2 consumption,
a reduction in substrate availability to the skeletal muscle, and waste removal is
compromised. There is an increase in sweat production, which could lead to dehydration.
Blood plasma volume decreases, causing the blood to become ore viscous which leads to
less venous return.
When exercising in the cold, what are some factors we need to think about first? Is
exercise worth doing in the cold?
Heat production needs to exceed heat loss so that the core temperature remains at the set
point. Creating a microenvironment through insulation aids in reducing heat loss. A
person is at risk of hypothermia when exercising in the cold, so the intensity must be
increased so that heat production exceeds heat loss. Exercising in the cold should only be
a real concern when dealing with extreme conditions. For example, swimming in freezing
waters puts the individual at a huge risk of getting hypothermia, so one must decide if it
is worth putting themselves in danger.
•
Know the general difference between proprioceptors and kinesthesia
• Proprioceptors provide the CNS with information about body position and
are in the joints and muscles. Kinesthesia is the conscious recognition of
the position of body parts.
Describe the size principle and how it relates to strength of the contraction.
The smallest motor units are recruited first. So, the type I or slow twitch fibers are
recruited first, then the type IIA, then type IIx. Recruiting the smallest motor units first
produces larger excitatory post synaptic potentials and will result in an action potential
sooner.
Structure and Function of Skeletal Muscle
Be able to identify the following and describe what it is:
Epimysium
Outer layer that surrounds the entire muscle.
Perimysium
Surrounds the bundles of muscle fibers. In between the fascicles.
Muscle Fibers –
a single muscle cell is known as a muscle fiber
Composed of myofibrils that contract when stimulated.
Endomysium –
In between the muscle fibers
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Myofibrils –
Contain contractile proteins actin (thin) and myosin (thick)
Sarcomeres- most basic unit of the myofibril
Includes the I band, A band, H zone, m-line, and Z-disc
Sarcolemma –
Muscle cell membrane. Surrounds the bundle of myofibrils. Surrounds a single muscle
fiber.
Transverse tubules –
Extend from sarcolemma to sarcoplasmic reticulum. Lie above the Z-discs in ever
sarcomere.
Sarcoplasmic Reticulum –
Storage site for calcium. Stores, absorbs, and releases calcium.
Myofibrils
Each muscle fiber contains several hundred to thousand myofibrils
A sarcomere is the most basic functional unit of a myofibril and each myofibril is
composed of numerous sarcomeres.
Identify and describe the following:
I Band – Site on either side of the z-discs. Made up of actin.
A Band – Starts where the myosin starts. Consists of myosin and actin
H Zone – Part of the A band. Consists only of myosin and is centrally located
Z Disks – Lies on both sides of the A band. Is in the middle of the I band. Made
up of actin only.
Skeletal muscle is referred to as striated, why?
The I band and the A band are different colors, they are referred to as the light and dark
bands. The alternating light and dark bands of each sarcomere along the myofibrils gives
a striated appearance to skeletal muscle.
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Be able to identify and describe the myosin filament. Pay attention to the crossbridges and the myosin heads)
Thick filaments. Made up of club heads. Cross bridge occurs when myosin attaches to
actin.
What is tropomyosin and what is its function?
Tropomyosin is loosely wrapped around the actin and blocks the myosin head binding
sites. This prevents constant contraction of the muscle.
What is troponin and what is its function?
Sits on top of the tropomyosin, calcium attaches to troponin which causes tropomyosin to
move off the active sites of actin so a cross bridge can occur.
Muscle Fiber Action-How does a muscle contract?
What is the neuromuscular junction?
The junction between a motor neuron and muscle fiber.
What is the role of Ach?
Acetylcholine is released form the motor neuron and cause the depolarization of the
muscle fiber which will result in an action potential.
What is an action potential and where does it travel?
An action potential is a change in the resting membrane potential of a cell above
threshold. An action potential travels down the axon.
What is the role of calcium in the muscle fiber?
Calcium binds to troponin and causes position change in tropomyosin which exposes the
active sites on actin.
How is energy created for muscle action?
ATP-PC system
Glycolysis
Oxidative Phosphorylation
When does the muscle cell action end?
When repolarization occurs and resting membrane potential is restored.
Skeletal Muscle and Exercise
Endurance and speed during exercise depend largely on your muscles’ ability to
produce energy and force.
Single skeletal muscles contain fibers having different speeds of shortening and
strength.
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Identify the characteristics of ST, FTa, and FTx (or b) muscle fibers. Explain the
“why” of these differences.
Slow Twitch
 High aerobic (oxidative) capacity and fatigue resistant
 Low anaerobic (glycolytic) capacity and motor unit strength. Does not produce
ATP very quickly, less action potentials.
 Slow contractile speed (110ms to reach peak tension) and myosin ATPase
 10-180 fibers innervated per motor neuron.
 Low sarcoplasmic reticulum development, calcium not release or absorbed
quickly
 Endurance athletes
Fast Twitch IIa
 Moderate aerobic (oxidative) capacity and fatigue resistance
 High anaerobic (glycolytic) capacity and motor unit strength
 Fast contractile speed (50ms) and myosin ATPase
 300-800 fibers innervated per motor neuron
 High sarcoplasmic reticulum development, calcium is absorbed, released, and
rereleased faster.
 Power athletes, sprinters
Fast Twitch IIx
 Low aerobic capacity
 Rest is the same as fast twitch IIa
 Power athletes
Is the percentage of ST and FT in the same in all muscles?
No different muscles have different compositions
How do fiber types relate to exercise and performance?
ST fiber- Endurance athletes, distance runners
FT fiber- Power athletes, sprinters
How are muscle fibers determined? Can you change fiber type in the muscle?
Nervous impulses determine the muscle fibers. Hou cannot change the fiver type, it is
determined by your DNA. Hou are born with what you have and training will only change
the number of fibers innervated, not the fiber types.
Explain the all-or-none response and its role in muscle fiber recruitment.
Once a nerve impulse is initiated, it will travel the length of the neuron. The muscle only
knows one thing, and that is to contract maximally.
Can fiber type predict athletic success? Why or why not?
Hes, people are genetically predisposed with fibers that would favor certain things such as
sprinting or long distance running. This is not the only factor that goes into athletes
success.
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What are the two types of muscle soreness? What is the difference between the two?
(When do they start? What are they caused from? How do you reoccur from each?)
Acute Muscle Soreness
Immediately or right after the exercise bout. End products of metabolism, lactate,
hydrogen ions cause this. Can be reversed with a cool down.
Delayed Onset Muscle Soreness
Damage done to the muscle fibers. Tears in the muscle fibers. Power output decreases
will have inflammation in the muscle. Soreness can be helped with rest and protein
intake. Muscles need time to repair. Occurs 24-48 hours after workout.
HOROMONES:
Discuss what determines hormones interaction?
Hormones only affect tissue with specific receptors. Magnitude of effect dependent on
the concentration of the hormone, number of receptors on the cell, and the affinity of the
receptor for the hormone.
What is the difference between a steroid and non-steroid hormone?
Steroid hormones can enter the cell and go directly into the nucleus and alter the activity
of the DNA to modify protein synthesis. Non-steroid hormones activate second
messengers via a G protein. Alter membrane transport.
Know the major endocrine glands and the hormones they release.
Hypothalamus
Controls secretions from pituitary gland. Stimulates release of hormones from
anterior pituitary gland. Provides hormones for release form posterior pituitary.
Anterior Pituitary Gland
ACTH- Cortisol release from the adrenal glands
FSH
LH- production of testosterone and estrogen
TSH- controls thyroid hormone release from thyroid gland.
GH- increases protein synthesis and long bone growth.
Posterior Pituitary Gland
Oxytocin
ADH- Reduces water loss from sweat production. Increases during exercise at
>60% VO2max
How does growth hormone affect performance?
Increases protein synthesis in muscle. There is no evidence that it promotes strength
gains.
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How does cortisol maintain plasma glucose levels?
Stimulates protein breakdown for gluconeogenesis, stimulates FFA metabolism,
stimulates glucose synthesis, blocks uptake of glucose into the cells, promotes the use of
FFA as fuel.
What happens with insulin and glucagon during exercise?
Insulin levels decrease so that blood glucose levels don’t decrease during exercise.
Glucagon levels increase to increase the blood glucose levels.
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