Exercise Physiology, Final Exam
Pons function
"bridge" of conduction; controls breathing
Red Blood Cells
"erythrocytes;" carry oxygen in circulation (contain Hb) *1 Hb carries 4O2, buffers increase in H+ ions*
White Blood Cells
"leukocytes;" 5 main types - lymphocytes, monocytes, eosinophils, basophils, and neutrophils; contain a nucleus, but not Hb; classified as granular or agranular; combat infection
Anaerobic training
"sprint-type" training using short but repeated high intensity exercise bouts; mostly performance related benefits
Platelets
"thrombocytes;" stop bleeding; attracted to the site of a vascular injury, adhere and aggregate, form a plug, and either stop bleeding or stimulate a second coagulation
ATP
(adenosine triphosphate) 1 adenosine, 1 ribose, 3 phosphate groups; energy-storing molecule; breaking bonds = energy fro muscle contraction
Cell-to-cell lactate shuttle
(aka intracellular lactate shuttle) *lactate can be transported from cytosol into mitochondria, converted to pyruvate, and metabolized via Kreb's Cycle* the shuttle takes lactate from muscle cells with few/no mitochondria to those with more in order to allow this metabolism
Free weights
(bars and dumbbells) weight used to train the muscle is limited by the weakest point(s) in the range of motion (max flexion and extension) so that the strongest position is never maximally taxed; preferred due to similarities in competition, stimulation of stabilized muscles (you have to isolate the needed muscle yourself instead of depending on a machine to keep your motion within a specific plane -> improved joints and coordinating muscles - an adaptation that can be used in everyday life)
Volume of training's impact on magnitude of improvement in aerobic fitness
(can overcome genetics) dose-response relationship -> amount of exercise = magnitude of outcome
beta-oxidation
(creation of Acetyl-CoA -> NADH & FADH -> ATP through 2 carbon fragments) each fatty acids goes through the cycle multiple times; each cycle creates 1 Acetyl-CoA = 12 ATP, 1 NADH = 3, 1 FADH = 2 *because Acetyl-CoA has 2 carbons, it indicates the # of cycles required -> the number of cycles = Acetyl-CoAs created -1*
Hormone receptors
(power outlet analogy) hormone response is carried out with the aid of a receptor; receptors are specific for each hormone - "target response specificity;" may number in the thousands on a single cell
Respiratory adaptations with aerobic training
*expiratory volume and diffusion* Max: EV increases due to increase in TV and frequency (respiratory muscle adaptations, lung size is constant), diffusion increases due to increased EV and Q; Submax: VE is constant or decreases - depends on intensity and changes in PCO2 and pH - diffusion is constant
Myosin releasing actin
*muscle contraction requires myosin to let go of actin and continue binding and pulling constantly to occur* once myosin binds to actin, it is "spent" and does not want to unbind; ATP must bind to a myosin head in order to force it to release actin, it then is burnt in order to re-energize the myosin; myosin can grab and pull again to create a contraction
Myoglobin changes with aerobic training
*myoglobin is an oxygen transport compound, similar to hemoglobin in the blood - may move O2 from the cytosol to mitochondria in muscle* efficiency of myoglobin may/may not change with training (proven in animals)
cardiac conduction pathway
*the heart is depolarized in the right order and direction to work properly* SA node -> AV node -> AV bundle/bundle of His -> R and L bundle branches -> Purkinje fibers -> ventricles
Activation threshold
+15-20 mV; passing this begins the action potential
Slow-twitch (Type I) muscle fibers
-High aerobic (oxidative) capacity and fatigue resistance -Low anaerobic (glycolytic) capacity and motor unit strength -Slow contractile speed (110 ms) and myosin ATPase -10-180 fibers per motor neuron -Low sarcoplasmic reticulum development (low calcium storage)
Fast-twitch (Type IIa)
-Moderate aerobic (oxidative) capacity and fatigue resistance -High anaerobic (glycolytic) capacity and motor unit strength -Fast contractile speed (50 ms) and myosin ATPase -300-800 fibers per motor neuron -High sarcoplasmic reticulum development (high calcium storage) *hybrid of slow- and fast-twitch abilities*
Impact of the speed of muscle contraction on force generation
Concentric: the higher the force required, the slower the velocity of the movement; Eccentric: the higher the force required, the faster the velocity of movement
Axon hillock
Cone shaped region of an axon where it joins the cell body; integrates potentials and decides which impulses to follow
Systole
Contraction of the heart, pumps blood out of the heart
BP and training with moderate hypertension
Endurance training (no effect on healthy BP): may decrease resting SBP and DBP in hypertension cases; Resistance training (long believed to have no BP effect): some recent findings indicate it may cause BP decreases
Which of the following could be considered a normal hematocrit reading?
40
Resting heart rates of elite endurance athletes can be approximately
45 beats/min
Ideal weekly caloric expenditure for aerobic training
5,000-6,000 kcal (1,000-2,000 to be "healthy")
Usage of protein
5-10% of fuel for rest and exercise
Partial pressure of nitrogen
593 mmHg (79%)
If membrane potential changes from -70 mV to -55 mV, what will happen?
An action potential will be generated
Deficit length and anaerobic training
Anaerobic training increase the amount of time spent in oxygen deficit
Which is easier to utilize: fat or CHO?
CHO, better location-wise and takes fewer steps to process CHO: 5 kcal/L-O2 > Fat: 4.7 kcal/L-O2
VCO2 (carbon dioxide production)
CO2 in expired air = VCO2
CO2 diffusion
CO2 in tissues is diffused into the bloodstream because of a slight gradient and then from the blood into the lungs by a severe gradient
Fates of lactate
Cell-to-cell lactate shuttle and Cori Cycle; *not a waste molecule*
Two models of periodization
Classic (linear): "big picture" training plan (e.g. a year), broken into smaller phases (meso- and microcycles) to reach a peak Nonlinear: "undulating," "this week" training plan; variation used within each microcycle -> 4-5 distinct workouts in a 7-10 day period
Troponin
Regulatory protein that pulls tropomyosin aside to allow binding (contraction); troponin in conjunction with calcium makes tropomyosin roll away from actin
Diastole
Relaxation of the heart, allows heart to fill with blood
Muscle fiber types
Slow-twitch (Type I), Fast-twitch (Type IIa), and Fast-twitch (Type IIx)
Divisions of the Motor Nervous System
Somatic (voluntary) and Autonomic (involuntary)
Sodium and potassium channels
Some potassium channels are not gated; all sodium channels are gated at rest; sometimes sodium sneaks through potassium channels (the pump has to continue working to rebalance)
Considerations for improved athletic performance
Specificity: energy systems, movement patterns Interval training: allows more overload on an energy system in a workout Exercise above LT to improve LT: cannot be sustained -> interval training *frequency, intensity, and duration may be greater than traditional prescription (health training vs performance)*
Comparison of glycolysis and fat oxidation
Speed: glucose > fat; ATP: fat > glucose
Classification of hormones
Steroids and non-steroids (differ in structure, method of transportation, and function)
Main reason anaerobic training improves anaerobic performance
Strength gains are the main portion of performance improvements
BP in response to cardiovascular endurance exercise
Systolic: pressure increases in direct proportion to increased exercise intensity (more forceful contraction); Diastolic: changes little, if any
Solutions for ETC problems
The aerobic part: O2 fixes both issues by bonding with the electron and a free hydrogen to form H2O
Tunica media
The middle and thickest layer of tissue of a blood vessel wall, smooth muscle used in dilation and constriction
neuromuscular junction (motor end plate)
The point where the end of a nerve fiber meets a skeletal muscle fiber; not actually connected, joined by a synapse
Propagation
The spread of the action potential down an axon, caused by successive changes in electrical charge along the length of the axon's membrane; Na+ channels open one by one
In untrained individuals, motor units are recruited asynchronously
True
T/F: An excitatory postsynaptic potential depolarizes the postsynaptic membrane.
True
T/F: As RER values decrease, fat metabolism increases.
True
T/F: Free fatty acids can only be used to produce ATP via aerobic metabolic pathways
True
T/F: Glucose is the primary ATP substrate for the muscles and brain
True
T/F: In a resting neuron, the intracellular environment is more negative compared to the extracellular environment.
True
T/F: Lactate threshold is an important determinant of endurance exercise performance
True
T/F: Not all muscle exhibit the same degree of oxidative capacity
True
T/F: Saltatory conduction occurs in myelinated axons.
True
T/F: Spirometry can be used to diagnose pulmonary diseases.
True
T/F: Steroid hormones can diffuse through the cell membranes and attach to receptors located somewhere inside the cell
True
T/F: The anterior pituitary, thyroid gland, adrenal glands, and pancreas are the major endocrine glands responsible for regulating metabolism
True
T/F: The renin-angiotensin-aldosterone system helps restore blood volume and blood pressure by a combination of systemic vasoconstriction and Na+ (followed by water) retention by the kidneys
True
T/F: The unloading portion of the oxyhemoglobin dissociation curve has a steeper slope than the loading portion.
True
T/F: VO2 max is the best single measurement of cardiorespiratory endurance capacity
True
T/F: When solutes (such as Na+) move from one fluid compartment to another, water usually follows due to osmosis
True
T/F: at rest, the majority the majority of cardiac output is directed to the liver
True
T/F: blood is responsible for regulating body temperature and pH
True
The respiratory centers regulate breathing by stimulating contraction of skeletal muscles that control ventilation.
True
Women respond to resistance training in a way that is similar to men
True
Immobilization primarily affects
Type I fibers
Time to onset of action of the nervous system:
Typically within milliseconds
Aerobic adaptations at maximal exercise
VO2 max increased by 15-20% in a previously untrained person
VO2 at constant intensity
VO2 stays the same if the exercise intensity is constant
Cardiac output (Q)
Volume of blood pumped out by the ventricle per minute in L/min; Q = heart rate (HR) x stroke volume (SV, expressed in L/beat)
Hormone transportation in circulation
Water-soluble (Non-steroid): transported freely -> unbound to any carriers; Fat-soluble (Steroid): bound to a transport protein (usually synthesized in the liver, must release the hormone for it to bind to the receptor, primary functions - improve transport because it water-soluble, minimize filtration of the kidney, provide a readily available reserve of the hormone)
Temporal summation
a few excitatory impulses fire repetitively and close together in time
Plasma glucose concentration
a function of muscle extraction vs liver release: the muscle removes glucose (decreasing concentration) and the liver releases glucose (increasing concentration)
Motor unit
a motor neuron and all the muscle fibers it innervates *all muscle fibers within a motor unit are the same type*
Muscle relaxation
a pump take calcium back to the sarcoplasmic reticulum, allowing tropomyosin to cover actin's binding sites again
Kreb's Cycle/Citric Acid Cycle
a series of enzyme reactions that produces 12 ATP per pyruvate (NADH = 3 ATP, FADH = 2 ATP within the mitochondria)
If PO2 is high, a large change in PO2 would lead to _____________ in hemoglobin saturation.
a small change
a-VO2 diff and exercise
a-VO2 diff increases with increasing rates of exercise as more oxygen is being taken from the blood -> the amount of O2 in arteries doesn't change with exercise, the amount of O2 in veins decreases with exercise intensity
secondary coagulation
activated (flattened) platelets attract other platelets that stack together, the next step is a coagulation cascade
Maintenance plasma glucose concentration
additional glucose that enters the bloodstream without ingesting more fuel; occurs through gluconeogenesis and glycogenolysis, which are regulated by hormones
host gland for aldosterone
adrenal cortex
host gland for cortisol
adrenal cortex
host gland for epinephrine
adrenal medulla
host gland for norepinephrine
adrenal medulla
Aerobic training and VO2
aerobic training doesn't impact resting or submax VO2; aerobic training increases VO2 max
HR recovery adaptation to aerobic training
aerobic training hastens HR recovery (probably due to enhanced PNS activity)
VO2 steady state
after the oxygen deficit, aerobic ATP production takes over and VO2 levels off (given that the intensity is constant)
activation and translation of fat
after uptake, the fatty acid enters the cytosol and is activated by 1 ATP to become Acyl-CoA; carnitine then helps Acyl-CoA cross the mitochondrial membrane into the mitochondria
Type I Diabetes Mellitus (IDDM)
decreased insulin secretion results in decreased glucose uptake; food -> blood glucose -> pancreas -> decreased insulin and glucose -> muscle (decreased glucose -> decreased glycogen); high glucose levels remain in the blood (damages blood vessels and neurons, creates issues healing)
Type II Diabetes Mellitus (NIDDM)
decreased insulin sensitivity prevents glucose uptake; food -> blood glucose -> pancreas -> increased insulin and glucose --no--> muscle (decreased glucose -> decreased glycogen); high glucose levels remain in the blood (causing health issues); pancreas registers high glucose levels and releases more insulin (high circulating insulin also negatively impacts health)
Agonist vs antagonist
agonist: muscle doing the lift; antagonist: muscle opposing the lift
Which of the following are cases of elevated post-exercise oxygen consumption (EPOC)?
all of the above (increased core temperature, replenish oxygen stores, Cori cycle, replenish stores of ATP)
Factors limiting performance of 10s to 180s (i.e. 400/800m)
decreased pH (increased need for lactate clearing), fast glycolytic capabilities (amount of enzymes available), oxygen delivery for longer events (appropriate aerobic capability)
Total Lung Capacity (TLC)
all volumes involved; 4000 ml total
Nonlinear periodization
allows for variation in intensity and volume with each workout; rotation through different protocols, such as: very heavy, heavy, moderate, power, or light (strength hypertrophy, endurance, power); if a training session is missed, you can do it at the next possible time; number of workouts, not weeks, guides this program
The anatomical "dead space" is composed of all of the following EXCEPT
alveoli
Gas exchange location
alveoli and surrounding capillaries
Expiratory reserve volume (ERV)
amount of air exhaled past the normal expiration of a tidal volume
Inspiratory reserve volume (IRV)
amount of air inspired above a normal tidal volume
Tidal volume (TV)
amount of air moved in a single breath
Residual volume (RV)
amount of air that allows remains in the lungs
Stroke volume (SV)
amount of blood pumped per contraction = EDV-ESV *what is actually pumped out, expressed in L/beat*
Route of an action potential
an action potential travels down a myofibril and enters the fiber through a T-tubule opening, releasing calcium from the sarcoplasmic reticulum and causing tropomyosin move (myosin and actin bind)
Steady state + change in intensity
an increase in intensity during a VO2 steady state would create another slight oxygen deficit before VO2 readjusts
Performance changes with anaerobic training
anaerobic exercise training = improved anaerobic performance, increased muscle power may be just as important (or more) than enzymatic changes
Anaerobic training and fatigue adaptation
anaerobic training increases muscle buffering capacity, thus delaying fatigue (better at dealing with lactate)
Desmosomes (anchoring junctions)
anchor neighboring muscle fibers together to prevent them from pulling apart during a contraction
host gland for growth hormone
anterior pituitary
Individuality
any training program must consider the specific needs and abilities of the individual for whom it is designed
a-VO2 difference
arterial-venous oxygen difference: the amount of oxygen extracted from the blood as it travels through the body; calculated as the difference between oxygen content of arterial blood and venous blood
__________ are blood vessels that carry blood away from the heart
arteries
In the blood, how is most CO2 transported?
as bicarbonate
Lactate production and blood lactate during exercise
as exercise intensity increases, lactate production increases; however, blood lactate remains the same because of lactate clearing mechanisms
major functions of renin
assists in blood pressure control
Lactate production at rest
at rest you are producing some lactate through anaerobic ATP production
Purkinje fibers
at the apex of the heart; release action potential to travel up through the ventricles
Plasma levels of FFA and exercise
at the beginning of exercise, fatty acids are being pulled out of the bloodstream and not yet being replaced (so plasma levels of FFA drop)
Principle of training and testing
athletes should be trained using the same muscle, metabolic systems, movements, etc. that are used during performance
During diastole
atria and ventricles fill with blood
P wave
atrial depolarization (contraction)
Resistance training can decrease inhibitory impulses to agonist muscles by reducing
autogenic inhibition
Which region of the nerve cell integrates all incoming EPSPs and IPSPs?
axon hillock
Fiber splitting results from detraining and manifests as muscle atrophy.
False
It is unsafe for children and adolescents to engage in a resistance training program.
False
Older adults have the same response to resistance training as younger adults
False
Resistance training is only beneficial for competitive athletes
False
Strength gains cannot occur unless there is an increase in muscle size.
False
T/F: A hallmark of acute muscle soreness is increased concentrations of muscle enzymes circulating in the bloodstream.
False
T/F: ADH promotes the retention of water by stimulating the retention of Na+
False
T/F: Air flows into the lungs in this order: nose, nasal conchae, larynx pharynx, trachea, respiratory, bronchioles, bronchial tree, alveoli.
False
T/F: Carbon dioxide and oxygen directly compete with each other for hemoglobin binding.
False
T/F: Cells can store large quantities of ATP in anticipation of the prolonged intense exercise
False
T/F: Enzymes trigger the onset of chemical reactions
False
T/F: Given that atmospheric pressure is 760 mmHg, the partial pressure of oxygen is 105 mmHg.
False
T/F: Glucagon is a potent glucocorticoid that promotes mobilization of stored fuel substrates and exerts anti-inflammatory effects
False
T/F: Growth hormone (secreted by the adrenal gland) is a potent catabolic agent, stimulating breakdown of glucose during exercise
False
T/F: If James and his big brother (who is 3 years older and 50 lb heavier) both have a of 4.5 L/min, they are equally aerobically fit.
False
T/F: Isotopic measurements of energy expenditure are dangerous and not accurate enough to justify their use.
False
T/F: Lactate is a waste molecule that is of no use to a skeletal muscle cell
False
T/F: Motor units can contain multiple types of muscle fibers.
False
T/F: The level of a given hormone's activity is determined solely by its plasma concentration
False
T/F: The pectoral (chest) muscles are used during forced expiration.
False
T/F: There are time during which one single metabolic pathway contributes 100% of the ATP production
False
T/F: Very few hormones in the body are categorized as nonsteroidal
False
T/F: red blood cells and white blood cells each make up half of the total hematocrit reading
False
T/F: the P wave on an ECG represents atrial repolarization
False
T/F: veins cannot constrict since they have no smooth muscle
False
Under basal conditions, elderly people have less fractional protein synthesis and greater protein breakdown
False
site of mediator action in endocrine system
Far from site of release (usually); binds to receptors on or in target cells
Muscle factors of strength gains (hypertrophic factors)
Fiber transition from IIx to IIa (fast twitch with lower activation energy), fiber hypertrophy - growth in size (more myofibrils, more actin and myosin, more sarcoplasm, more connective tissue), fiber hyperplasia - growth in numbers (growth of new muscle cells - theories: fiber splitting from damage and subsequent regrowth, satellite cells or stimulated stem cells that grow in skeletal muscle)
Impact of joint angle on force generation
Force is strongest when the direction of the lever lines up with the direction of contraction; a 90 degree angle is ideal (no force is wasted on unnecessary movement)
ACSM guidelines for aerobic exercise
Frequency: 3-5 days/week Intensity: 50-85% VO2 reserve Duration: 20-60 minutes Mode: large muscle groups, rhythmic activity *higher end of the scale will see a greater magnitude of improvement*
Plasma levels of growth hormone (and FFA) and exercise
GH rises at around 50 minutes into exercise, serves to further promote FFA mobilization
Outcomes of protein
Glucose alanine cycle -> glucose: muscle proteins are broken into individual amino acids that, after a few reactions, end up as alanine (AA + pyruvate); alanine goes to the liver and is transformed into glucose ("reverse glycolysis"); doesn't make mathematical sense because it costs 6 ATP (more than will be created) Intermediaries: protein can also be broken down to provide intermediaries of the glycolytic pathway (supporting the metabolism of other macronutrients)
Taking into account both oxygen requirements and ATP yield, which substrate is more efficient, fat or glucose?
Glucose is more efficient
Many marathon runners "hit the wall" around mile 20. What does this tell you about glycogen?
Glycogen stores are mostly depleted by mile 20
ATP totals
Glycolysis (glucose -> pyruvate) = 2-3 ATP; Glycerol phosphate shuttle (in cytosol) = 4 ATP; PDH (in mitochondria) = 6 ATP; Kreb's Cycle (2 Acetyl-CoAs) = 24 ATP ---> 36-37 total ATP
Aerobic adaptations at submaximal exercise
HR and blood lactate concentration decrease at a given exercise intensity
Increasing cardiac output
HR is increased via withdrawal of parasympathetic (vagus nerve) tone and increased sympathetic stimulation (flight or flight response); SV is increased by sympathetic stimulation and increased venous return (contraction is more forceful ---so ESV is lower making SV higher--- and blood is moved from the reservoir back to the heart faster)
Cardiac output at rest (5 L/min)
Heart 4% (200 ml), Liver 27% (1350 ml), Kidneys 22% (1100 ml), Muscles 20% (1000 ml), Brain 14% (700 ml), Skin 6% (300 ml), and Other 7% (350 ml)
Cardiac output during moderate exercise (17.6 L/min)
Heart 4% (200 ml), Muscles 71% (12500 ml), Skin 12% (1900 ml), Brain 4% (750 ml), Liver 3% (600 ml), Kidneys 3% (600 ml), and Other 3% (600 ml)
Effects of Strength Training on Muscle
Hypertrophy (growth of muscle fibers), hyperplasia? (increase in number of muscle fibers), improved body fat % (decreased percentage, more lean body mass), does NOT increase VO2 max (circuit training may have mild results, the main function of strength training is building muscle mass)
A 10K runner who incorporates short-interval speed work and high-intensity resistance training may see a conversion of type ___ fibers to type ____ fibers
I, IIa
Why epinephrine is not ideal in shunting blood?
It directs blood to both skeletal muscles at work and those at rest (meaning it is not focused specifically on need)
Why is protein the most difficult substrate to utilize?
It has to become glucose or an intermediary before it can be used
Why can't anaerobic glycolysis happen constantly?
It would cause the build-up of lactic acid (H+ from NADH breaks away from La- and makes the cell pH drop)
In a resting neuron, which ion gates are open?
K+
Factors limiting performance of >1 hour (i.e. half, full marathon)
LT, economy, VO2 max, carbohydrate availability (glycogen store is being depleted)
heart size adaptation to aerobic training
LV chamber size and volume increase, wall thickness increases
Which of the following is associated with the parasympathetic nervous system?
Lower blood pressure
The somatic nervous system most specifically belongs to which division of the nervous system?
Motor
Divisions of the Peripheral Nervous System
Motor (efferent) and Sensory (afferent)
types of target cells in nervous system
Muscle (smooth, cardiac, and skeletal) cells, gland cells, other neurons
Explanation for high cardiac output to muscles and skin during exercise
Muscles: oxygen-rich blood to compensate for higher uptake of O2 and greater need for CO2 clearing; Skin: blood flow to the surface allows dissipation of heat and activates sweating
Motor neuron firing
Must depolarize to fire and then repolarize in order to fire again
Glycerol Phosphate Shuttle
NADH from aerobic glycolysis cannot cross the mitochondrial membrane to produce ATP, so glycerol phosphate takes the H from the cytosol to the mitochondria to make FADH (produces 2 ATP each = 4 total from cytosol NADH)
Aldosterone release leads to
Na+ retention followed by water retention
Which ion transporter is engaged at rest to maintain resting membrane potential?
Na+-K+-ATPase pump
afferent neurons
Nerve cells that carry impulses towards the central nervous system
efferent neurons
Nerve cells that conduct impulses away from the central nervous system
Electrocardiogram (ECG/EKG) Phases
P wave, QRS Complex, T wave
Creating ATP with PCr (phosphocreatine)
PCr + creatine kinase -> (creatine, phosphate) and energy -> ADP + Pi -> ATP
Blood plasma volume and acute exercise
PV decreases with exercise (goes to interstitial space, creating sweat for cooling); more is lost if the intensity is high enough cause extreme sweating *muscles appear swollen after a workout because of this fluid accumulation*
Divisions of the Autonomic Nervous System
Parasympathetic and Sympathetic
ACSM Recommendations for Resistance Training (for a healthy adult)
Perform exercises for all major muscle groups (8-10 exercises); minimum of 1 set of 8-12 repetitions to the point of volitional fatigue (to failure: 10-15 reps total for the elderly); perform exercises 2-3 days/week with rest between; adhere to proper technique (limit injury, maximizing adaptations); perform exercises through full ROM; perform concentric and eccentric contractions in a controlled manner; maintain normal breathing pattern - avoid Valsalva maneuver (maneuver is appropriate for trained individuals); if possible, exercise with a training partner (adherence and safety)
Enzymatic adaptations with anaerobic training
Phosphagen: increased creatine kinase (ADP + PCr -> ATP + Cr), increased myokinase (ADP + ADP -> ATP + AMP) Glycolytic enzymes: (especially for anaerobic glycolysis) increased HK, PFK, PHOS -> enhanced synthesis of ATP
Rate limiting enzyme for glycolysis
Phosphofructokinase (PFK) - turns process on and off
acute exercise response of insulin
decreases with increasing rates of work
Protein synthesis _____ during exercise and _____ after exercise
decreases, increases
Spinal cord
delivers signals from the brain
Oxyhemoglobin dissociation curve
demonstrates the relationship between % Hb saturation and PO2; hemoglobin saturation decreases when PO2 is low because hemoglobins release their oxygens to compensate in the partial pressure; hemoglobin saturation increases when PO2 increases because it can keep its oxygens attached
Structures of the neuron
dendrites, cell body, axon, myelin sheath, axon hillock
Mitochondria changes with aerobic training
density increases (size and number increase) to provide more sites for oxidative energy production -> higher pyruvate oxidation (lower lactate production) and higher fat oxidation
Velocity of an action potential
depends on diameter of neuron and myelination (all motor neurons all myelinated) *velocity is proportionate to contraction force*
If membrane potential changes from -40 mV to -35 mV, this is an example of
depolarization
Internal dimensions of LV
depth increases due to the increase in ventricular filling (provides more room for blood, higher EDV)
Gas exchange
diffusion of oxygen into blood; diffusion of CO2 into lungs from blood
Shunting of blood to working muscle
directing blood away from tissues that don't immediately need it (by constricting) to the muscle that requires oxygenated blood (by dilating)
CO2 transport
dissolved in solution - 5% attached to plasma proteins - 5% attached to hemoglobin - 20% dissolved in red blood cells - 5% as bicarbonate (HCO3-) - 65% *CO2 + H2O <--> H2CO3 <--> HCO3- + H+*
Static lung volumes and training
do not change in response to training (no shift in resting VE, tidal volume, or respiratory rate)
Muscle fibers and motor neurons
each muscle fiber only receives information from one motor neuron; each neuron may innervate thousands of muscle fibers
Detraining by Cessation of Training (less extreme than immobilization)
effects depend on age, sex, length and volume of training prior to, magnitude of adaptations, amount of time off, etc. (women and less trained individuals tend to lose faster); leads to a decrease in 1-RM
Saltatory conduction
electrical signal jumps from one Node of Ranvier to the next, skipping myelin sheaths
Limbic system
emotional center of the brain; contains hippocampus and amygdala
Habenular nuclei function
emotional response to odors
Stroke volume and endurance training
endurance training increase SV at rest and during submit and max intensity exercise *EDV increases due to an increase in blood plasma and and greater diastolic filling time (lower HR), contributing to SV* -> the increased size of the heart allows the left ventricle to stretch and fill with more blood (higher EDV) and pump it more forcefully (lower ESV)
Aerobic training
endurance training using prolonged activities like running and cycling; has health and performance benefits
Significance of plasma glucose
energy source for muscles and the CNS
How much PCr do we store?
enough for 20s of high intensity movement (found naturally in meat, leafy greens, supplements)
How much ATP do we store?
enough for 3-5 seconds of high intensity movement
Which of the following is responsible for lowering the activation energy of a chemical reaction?
enzyme activity
Oxidative enzyme changes with aerobic training
enzyme activity of the Kreb's Cycle, beta oxidation, and the ETC increases
Exercise and glucose-regulating hormones
epinephrine, norepinephrine, cortisol, and glucagon all increase with prolonged aerobic exercise *glucose concentrations remain stable because liver release is balanced by muscle uptake*
Which of the following is not an adrenal hormone
erythropoietin
Importance of maintaining fluid balance
essential for temperature regulation, blood flow and BP regulation, and metabolic and cardiovascular function
Neural factor 2: reduction or counteraction of "autogenic inhibition" allowing greater force production
essentially makes the Golgi Tendon Organ less sensitive so that more overload and resulting gains are possible
sinoatrial node (SA node)
establishes the fastest rhythm of depolarization ("pacemaker" of the heart); spreads action potential from the right atrium to left atrium (ventricles are blocked by septum)
BP response to resistance exercise
exaggerates BP responses to as high as 480/350 mmHg (temporary -> not extremely dangerous for health); attributed to the valsalva maneuver
If chemoreceptors stimulate an increase in breathing rate and depth, this occurs because
excess CO2 needs to be removed
Capillaries
exchange zone for O2 and CO2; between arteries and veins; smaller and thinner walls
Exercise impact on anterior pituitary and thyroid function
exercise increases TSH release -> short-term: T4 increase (delayed), prolonged exercise: T4 is constant and T3 decreases
Overall lung function and aerobic training
exercise training does not impact lung function, unless it causes weight loss which lessens the mass pushing down on the lungs and allows for improved breathing
Functional Residual Capacity (FRC)
expiratory reserve volume + residual volume
Venous Return (VR)
facilitated by one-way valves and smooth muscle bands (used both at rest and during exercise) and contracting skeletal muscle (during exercise) -> contracting muscle compresses veins to push blood up
Exercise and Type I Diabetes
food -> blood glucose -> pancreas -> decreased insulin and glucose + exercise -> muscle (glucose -> glycogen); acute and chronic exercise causes increased insulin sensitivity (less need for exogenous insulin)
Exercise and Type II Diabetes
food -> blood glucose -> pancreas -> insulin and glucose + exercise -> muscle (glucose -> glycogen); Acute: decreased [glucose] because of higher muscle uptake; Chronic: less insulin (increased sensitivity) and decreased glucose
Normal insulin secretion and sensitivity
food -> blood glucose -> pancreas -> insulin and glucose -> muscle (glucose -> glycogen)
all-or-none principle
for a motor neuron to be recruited into activity , the motor nerve impulse must meet or exceed the activation threshold; when this occurs, all muscle fibers in the unit act maximally
The internal intercostals are engaged during
forced expiration
Valsalva maneuver
forcible exhalation against a closed glottis, resulting in increased intrathoracic pressure -> can induce passing out or stroke in older people
Triglyceride
form fat is stored in (1 glycerol and 3 fatty acids - all the same length, chains of carbons usually in even numbers)
Hippocampus function
formation and retention of memories
Gluconeogenesis
formation of glucose from noncarbohydrate sources: occurs in the liver; lactate is converted to glucose through the Cori Cycle, glycerol (triglyceride) is converted into glucose, or alanine is converted into glucose through the glucose-alanine cycle
Oxygen deficit
from rest to a set intensity of exercise, VO2 takes 3 minutes to adjust; during this period, you aren't consuming enough oxygen to produce the ATP you will need to continue; we make it through this deficit by running mainly on anaerobic pathways
fat uptake into muscle
from the bloodstream fatty acids enter muscle cells; uptake is constant and always at a rate of around 50% (every other fatty acid)
Which of these factors is most critical in determining the rate of pulmonary diffusion?
gas partial pressure
Duration of action in nervous system
generally briefer (milliseconds)
duration of action in endocrine system
generally longer (seconds to days)
As RER values approach 1.0,
glucose/glycogen metabolism is maximal
Glycolytic enzyme exception
glycogen phosphorylase (increases glycogen storage)
Why do plasma glucose concentrations start to decline after prolonged endurance exercise?
glycogen stores are depleted
The arterial-venous oxygen difference is ___________ in a capillary bed across an exercising muscle compared to a resting muscle.
greater
How does heat buildup in muscle contribute to fatigue?
hastens oxygen depletion
Muscle fiber changes with anaerobic training
hypertrophy (especially in Type II fibers), which may lead to increases in force, biggest impact on performance; some evidence of increase in number of Type IIa at the expense of Type I and IIx fibers *Type I to IIa (toward anaerobic) and Type IIx to IIa (more ideal activation threshold - easier recruitment)*
Which region of the diencephalon oversees homeostatic control of blood pressure, heart rate, breathing, and body temperature?
hypothalamus
GLUT4 function
if GLUT4 is at the surface, glucose uptake can occur; it can be up- and down-regulated (endo- and exocytosis) *insulin activates a second messenger to move GLUT4*
Capillarization changes with aerobic training
increase in capillary density (more, utilize latent capillaries) -> enhanced diffusion of nutrients and gases
Starling Principle (Frank-Starling mechanism)
if more blood enters the heart. the heart will contract more forcefully because of the length-tension relationship in myocardial sarcomeres -> ideal length occurs during exercise, when the heart is more full
Increasing muscle glucose uptake
increase in the release of glucose into the blood is not sufficient to increase the amount of glucose taken into the muscle; insulin stimulates glucose uptake by activating a glucose transporter mechanism (GLUT4 = channel form blood to muscle)
Rule of thumb for resistance
if you are lifting a weight that is 20+-RM, you will not see the adaptations that you are shooting for
During exercise, glucagon concentrations __________, and insulin concentrations ___________
increase, decrease
Which of the following is not a likely cause of the lactate threshold
increased core temperature
The sympathetic nervous system would contribute to
increased heart rate
Blood flow/blood pressure adaptation to aerobic training
increased muscle blood flow (increased capillarization, better BF distribution and O2 distribution, increased blood flow, recruitment of previously dormant capillaries, and increased vasodilation); MAP = Q x TPR - Max: (MAP is constant/increases, cardiac output increases, TPR decreases - improved vasodilation), Submax: (MAP is constant/increases, cardiac output is constant, TPR is constant)
major functions of glucagon
increases blood glucose; stimulates breakdown of protein and fat
major functions of thyroxine
increases rate of cellular metabolism; increases rate and contractility of the heart
major functions of aldosterone
increases sodium retention in kidneys; increases potassium excretion through the kidneys
Wall thickness of the LV
increases to make the potential contraction more forceful (less ESV -> higher SV)
acute exercise response of ADH
increases with increasing rates of work
acute exercise response of aldosterone
increases with increasing rates of work
acute exercise response of glucagon
increases with increasing rates of work
acute exercise response of growth hormone
increases with increasing rates of work
acute exercise response of norepinephrine
increases with increasing rates of work, starting at about 50% of VO2 max
acute exercise response of epinephrine
increases with increasing rates of work, starting at about 75% of VO2 max
Electron Transport Chain meaning
inner mitochondria membrane process of getting ATP from hydrogens (only aerobic portion of Kreb's Cycle)
tunica intima (interna)
inner single cell (endothelial) coating inside a blood vessel
Lung capacities
inspiratory capacity, vital capacity, functional residual capacity, total lung capacity
Which of the following pairs of hormones typically act in opposition?
insulin, glucagon
Golgi Tendon Organ (GTO)
integrated into the tendon and attached to sensory neuron; senses small changes in tension --> inhibits contracting (agonist) muscle and excites antagonist muscles; prevents damage to the muscles because of extreme tension (keeps you from performing a stronger contraction than your muscle can handle)
Training intensity vs performance intensity
intensity of training must be the same or more than the intensity you want to perform at
Fluid compartment
intercellular fluid (within cells) and extracellular fluid (blood plasma and interstitial fluid from between cells)
Relationship between aldosterone and plasma volume
inversely related: as PV decreases, aldosterone level increase; promotes water retention by increase reabsorption of Na+
periodization of training
involves systematic manipulation of acute program variables (intensity and volume) over time with planned rest/recovery periods; both models are considered superior to standard progressive overload for the purposes of building muscle mass and strength
Rate limiting enzyme of Kreb's Cycle
isocitrate dehydrogenase
Protein can serve as an energy substrate if
it is first converted to glucose
Elevated post exercise oxygen consumption (EPOC)
immediately after exercise you consume more oxygen than you need at rest
Immediate effects of anaerobic training
improved efficiency of movement -> reduced energy expenditure (metabolic)
Main contribution of muscle adaptations to aerobic performance
improved endurance, small impact on VO2 max
Neural factor 5: changes in the neuromuscular junction (neuron meets fiber)
improved release of neurotransmitters into the synaptic cleft, more efficient/numerous receptors
Mechanoreceptors
in active muscles; sense movement
Peripheral chemoreceptors
in blood vessels; sense PO2, PCO2, and pH
Central chemoreceptors
in brain and CSF; sense pH and PCO2
Thermoreceptors
in the hypothalamus; sense core temperature increase
atrioventricular (AV) node
in the right atrium; receives action potential from SA node and transports it to the AV bundle/bundle of His
Importance of Cooling Down
keeps blood from pooling to the legs (causes light-headedness, fainting, etc.)
host gland for erythropoietin
kidney
host gland for renin
kidney
Renin is released when the
kidneys sense low blood volume and pressure
Cori Cycle
lactate is circulated to the liver and transformed into glucose then circulated back to the muscle to be metabolized or converted into glycogen and stored if glucose isn't currently needed; negative - process costs 6 ATP, like glucose alanine
Factors limiting performance of 21 min to 60 min (i.e. 10k run)
lactate threshold (predictor of endurance performance - highly aerobic at this point), exercise economy, VO2 max
Why does aerobic performance continue to improve with training after VO2 max has plateaued?
lactate threshold continues to increase
In the absence of oxygen, the final product of glycolysis is
lactic acid
Which chamber of the heart has the thickest walls?
left ventricle
The body utilizes _____ oxygen when metabolizing carbohydrate compared to fat
less
Excessive loss in PV
limited performance -> less volume to transport oxygen and dissipate heat; reduced PV = hemoconcentration (denser blood slows flow)
Myofibril structure
line of sarcomeres; z-disc (where sarcomeres meet, outer edge), m-line (middle of a sarcomere); myosin, actin, and troponin filaments
At rest, the __________ receive(s) about 50% of cardiac output
liver and kidneys
An example of a target cell for glucagon is
liver cells
Cerebrum
lobes of the brain; intellect and motor control
Spatial summation
many excitatory impulses flood the neuron and axon hillock simultaneously
Appropriate resistance for building muscular endurance
many reps and low resistance (20-RM)
heart rate adaptation to aerobic training
max HR is constant or slightly decreases, submax HR decreases (PNS activity increases: lower HR @ lower intensity; SNS activity decreases:lowers HR @ higher intensity
Cardiac output adaptation to aerobic training
maximal exercise: Q increases - SV increase offsets decrease in HR submaximal exercise: Q remains constant - decrease in HR is equal to increase in SV
a-vO2 difference adaptation to aerobic training
maximal exercise: a-vO2 difference increases -> increase in Q and BF, enhanced capillaries improve diffusion submaximal exercise: a-vO2 difference is constant
Sub-max ventilation (and RR) and training
may go down with training because of a change in lactate threshold (not related to the lungs themselves)
Max intensity ventilation (and TV, RR) and training
may go up with training because exercise leads to the ability to attain higher max intensity (not related to the lungs themselves)
Action potential
means that a muscle contraction will occur; 1) resting state, 2) depolarization, 3) propagation, 4) repolarization, 5) resting state
Indirect calorimetry
measures O2 intake and CO2 output (metabolic cart)
Sensory receptor types
mechanoreceptors, nociceptors, thermoreceptors, photoreceptors, and chemoreceptors
Functions of the sympathetic nervous system
mediates fight-or-flight response; ups HR and BP, increases the liver's release of glucose, enhances fat use, activates sweat and adrenal glands, decreases blood flow to the kidneys (slows urine production)
Graded potential
membrane potential climbs because the inside of the membrane is becoming more positive; is reversible; occurs when sodium channels are open (electrically positive)
Absolute strength gains are typically greatest in
men
In which part of the cell does oxidative phosphorylation occur?
mitochondria
causes of LT/factors impacting LT
mitochondrial availability, oxygen supply/tissue oxygenation, and fast-twitch fiber recruitment *can be changed with aerobic training*
hormones of fat metabolism
mobilization of FFAs: cortisol, epinephrine, norepinephrine, and growth hormone; storage of fatty acids: primarily insulin
Which intracellular change likely contributes the most to increases in fiber size, cross-sectional area, and strength?
more actin and myosin filaments
Neural factor 6: cerebral adaptations?
more activity in the premotor cortex and primary motor cortex (speculated)
Appropriate resistance for building muscle size
more than 3 sets of 6-RM to 12-RM loads; short rest periods (hypertrophy = more sets: 5?)
Isotope/tracer methods
most commonly use doubly labeled water (2H218O): 2H is lost in water and 18O is lost in water and CO2; tracer methods measure H and O concentrations in urine, blood, and saliva - estimates CO2 production *accurate over days, cannot be pinpointed to a certain bout of exercise*
Spinal reflex
motor impulses from the spinal cord, separate from the brain; receptor --> sensory neuron --> integration center --> motor
Strength is most accurately a property of the
motor system
Ventilation
movement of air in and out of the lungs (L/min) (through airways to alveoli); calculated by multiplying liters per breath and breaths per minute (frequency)
Midbrain function
movement of eyes, head, and trunk in response to sound; eyeball and pupil movement
fat circulation
movement through the bloodstream; albumin (a transport protein) carries fatty acids in the blood *albumin is needed because the water in blood and fats don't mix (dissolve), so fatty acids need assistance*
Cardiac muscle cells are all of the following except
multinucleated, like skeletal muscle
Cardiac muscle structure
muscle fibers line up end to end, meeting at intercalated discs; they split and fork in different directions; pass electrical impulses between fibers using gap junctions
Fuel storage changes with aerobic training
muscle glycogen concentration and intramuscular fat concentration increases (more glycogen = longer time to depletion)
During normal quiet breathing, expiration is accomplished by
none of the above (contraction of diaphragm and external intercostals - passive)
Factors influencing force generation
number of motor units activated, types of motor units used, muscle size, initial muscle length, joint angle, and speed of muscle contraction
Factors limiting all-out performance of less than 10s (i.e. 100m sprint)
number of muscle fibers recruited (ability to continuously fire = ability to perform), fiber type distribution (Type II recruitment must be high), ATP/CP levels (stored), skill and technique
Acute muscle soreness (AMS)
occurs during or right after exercise and usually disappears within minutes or hours; results from the accumulation of end products of exercise (lactate) in the muscles
Delayed-Onset Muscle Soreness (DOMS)
occurs for one or two days after exercise, peaking 12-48 hours after strenuous activity; caused primarily by eccentric action and associated with damage to the muscle (may be an inflammatory reaction in the muscle or edema - fluid accumulation)
Glycolysis basics
one molecule of glucose goes through many enzyme reactions, using two ATP to create four ATP; meaning +2 ATP are new/available (+3 ATP beginning with glycogen)
Exercise and blood glucose
overall exercise decreases blood glucose concentration, impacted by muscle compensation; acute response - contraction mediated glucose transport (Ca 2+); training adaptation - increased insulin sensitivity, less insulin needed to stimulate uptake *exercise stimulates glucose uptake independent of insulin; muscle contraction leads to muscle uptake and storage*
Current causes of EPOC
oxidize lactate, temperature (cooling mechanism), energy cost of increased ventilation and heart rate, ion redistribution, and residual hormone effects
Acute exercise and VO2
oxygen consumption increases with increasing exercise intensity
What is the term used to describe the phenomenon that occurs when oxygen supply does not meet the oxygen need at the onset of exercise?
oxygen deficit
Factors limiting performance of 3 min to 20 min (i.e. 1-3 miles)
oxygen delivery capabilities/VO2 max (combination of aerobic and anaerobic), lowered pH (both metabolism types), biochemical characteristics of fibers (should lean toward Type IIa - balance between slow-haul aerobic Type I and sprint anaerobic Type IIa)
Oxygen diffusion
oxygen diffuses into the bloodstream because the partial pressure of blood returning to the lungs is lower than the partial pressure in the lungs; this occurs again when oxygen in the blood reaches tissues (muscle)
An example of an energy substrate is
palmitic acid
host gland for glucagon
pancreas
host gland for insulin
pancreas
Passage of air to lungs
pharynx, larynx, trachea, bronchi, bronchioles, alveoli
Parts of the epithalamus
pineal gland and habenular nuclei
Composition of blood
plasma (55%) and formed elements (45% - RBCs, WBCs, and platelets)
Production of Anti-diuretic hormone (ADH)
plasma volume drops -> hemoconcentration, high plasma osmolality -> activates osmoreceptors in the hypothalamus, stimulates posterior pituitary to release ADH -> acts on kidneys to increase H2O reabsorption
Parts of the brain stem
pons, medulla oblongata, midbrain , and reticular formation
Gap junction
portal in intercalated disc that allows the passing of electrical impulses
Physiological dead space
portion of alveolar volume with poor perfusion (blood flow) (not able to be exchanged functionally)
Anatomic dead space
portion of minute ventilation that does not enter the alveoli (not able to participate in gas exchange because of location)
host gland for ADH
posterior pituitary
Hard/Easy
programs must alternate high-intensity workouts with low-intensity workouts to help the body recover and achieve optimal training adaptations
Actin filament
projects in from the z-discs, pulled in by myosin
major functions of growth hormone
promotes development of body tissues; increases protein synthesis and mobilization
major functions of estrogen
promotes development of female sex organs and characteristics; increases fat storage; regulates menstrual cycle
major functions of testosterone
promotes development of male sex characteristics; hair growth, voice change, muscle growth
A major consideration when prescribing resistance to children and adolescents is
proper training technique
Non-steroid hormones
protein based, water-soluble; bind to surface receptors outside of cell (on membrane); activates 2nd messenger cAMP - creates cellular changes: activates protein synthesis, stimulate secretions, alter metabolism
End product of aerobic glycolysis
pyruvate (reactant in Kreb's Cycle)
Start of Kreb's Cycle
pyruvate crosses the mitochondrial membrane with help form PDH (pyruvate dehydrogenase - lives on the membrane); pyruvate can then become Acetyl-CoA
Rapid movement or ballistic-type training may be particularly effective in stimulating increases in motor unit
rate coding
Dendrites
receive impulses from other neurons and carry impulses to the cell body
Bundle of His (AV bundle)
receives the action potential from AV node; splits into right and left branches that run down to Purkinje fibers at the apex of the heart
Functions of the sensory division
receptors sense stimuli and relay information to the CNS
Erythropoietin release is the primary stimulus for
red blood cell production
Medulla oblongata function
regulates circulation, respiration, muscles for swallowing; governs heart rate, vessel dilation/diameter
Hypothalamus function
regulation of heart rate and temperature
Aerobic interval training
repeated bouts of short, high-intensity performance followed by short rest periods--- and continuous training--- one prolonged, high intensity exercise bout: both help generate aerobic benefits
Traditional causes of EPOC
replenish ATP/PCr stores, convert lactate to glycogen (Cori Cycle), replenish O2 stores for future use
Fick equation
represents the relationship between oxygen consumption, a-VO2 difference, and cardiac output; VO2 (oxygen consumption) = Q (cardiac output) x a-VO2 difference (extraction rate)
The volume of air that remains in the lungs after expiration and cannot be exhaled is the
residual volume
Variable Resistance Training
resistance is decreased at the weakest points in the ROM and increased at the strongest points -> overcomes the limitation of free weights; muscle contracts at higher percentages of maximal strength throughout the ROM (best stretch/contraction the whole time)
Neural factor 7: cross education
resistance training one arm ("unilateral training") leads to increased strength/endurance of the other, untrained arm
Blood pressure ideal
rest: 120/80, aerobic exercise: 250/115, weights: 480/350
Synaptic vesicles
sac-like structures that hold neurotransmitters; merge with the muscle membrane during action potential and release their contents
Muscle fiber parts
sarcolemma (outer coating), transverse tubules (glycogen transport passages), openings of T-tubules (surface pores), sarcoplasmic reticulum (stores calcium), sarcoplasm (gel-like lining of the fiber), and myofibrils (create muscle contractions)
Loss in fat free mass that accompanies aging is called
sarcopenia
time to onset of action of endocrine system
seconds to hours or days
Alpha motor neurons
send signals for reflexive contraction; protect the muscle from overstretching damage
Thalamus function
sensory information (other than olfaction)
Fat mobilization
separating the fatty acid from the glycerol backbone; occurs when hormone-sensitive lipase is activated and breaks the bond *epinephrine activates the process to activate HSL -> mobilization*
Appropriate resistance for building power
several sets of few reps and moderate resistance (8-RM to 12-RM); emphasize speed of movement (rapid)
Slow component rise in VO2
situation in which VO2 slowly rises, despite exercise being at a constant intensity; occurs when you are above your lactate threshold
In the heat, blood flow will be redirected to the
skin
What term describes the continuous rise in VO2 that is observed during constant-intensity exercise that is above the lactate threshold?
slow component rise of VO2
ATP production from fat is ______ ATP production from glucose
slower than
a-VO2 difference adaptations and performance
small impact on performance: trained healthy people and endurance athletes have similar a-VO2 differences at VO2 max
Problem in neuron firing
sodium-potassium pump is too slow to repolarize and keep the impulses constant for contraction, instead the Na+ channels close and the K+ channels open to allow adequate repolarization (occurs in a cycle until the brain's signal ends)
Muscle fiber changes with aerobic training
some hypertrophy (Type I increase in size); transformation of Type IIx to IIa, IIa to I (all shift toward higher aerobic capacity)
Reticular formation function
some respiratory control; coordinates skeletal muscle; controls arousal/sleep cycles
Muscle spindles
sometimes called "intramural fibers;" only have actin and myosin at the ends of the fiber; wrapped in sensory neurons that register stretch
Motor unit recruitment order
specific units are called on each time a specific activity is performed - the number and type of units recruited is proportionate to the force needed; motor units with smaller neurons (ST units) are called on before larger neurons (FT units) because of lower activation thresholds
This term describes the phenomenon that occurs when aerobic metabolism meets all of the energy needs during exercise
steady state
major functions of epinephrine
stimulates breakdown of glycogen in the liver; increases blood flow, heart rate, and oxygen consumption
major functions of erythropoietin
stimulates erythrocyte production
major functions of norepinephrine
stimulates lypolysis in adipose tissue and muscle; constricts vessels and elevates BP
Tetanus
stimulation of such high frequency that the muscle in unable to relax
Blood reservoir meaning
store blood that can be directed to the location(s) it is needed based on stimuli
Recovery from Detraining by Cessation of Training
strength losses can be regained quickly; the new RM matches or exceed the old
Recovery from detraining by immobilization
takes more weeks to retrain than the immobilized (detraining) period
Examples of steroid hormones
testosterone, estrogen, progesterone, cortisol, and aldosterone
Parts of the diencephalon
thalamus, hypothalamus, epithalamus
Why is the CNS more glucose dependent than muscle?
the CNS cannot store glucose (which is the only substrate it can metabolize), while muscle stores glycogen and can metabolism fat also
Anterior pituitary and thyroid relationship
the anterior pituitary releases thyrotropin (thyroid stimulating hormone - TSH) which travels to the thyroid and stimulates T3 and T4 release
Above VO2 max intensity
the body adds (supplements) with anaerobic ATP production to make up the difference in demand
ETC structure
the chain has bodies embedded in it that contain cytochromes; cytochromes pass hydrogens along that chain and hold them within the membrane
How does the ETC work?
the energy from the electron passing expels H+ into the intermembrane space; creates a proton gradient when hydrogens accumulate (makes hydrogen want to return into the mitochondria); hydrogens return through ATP synthase to create 1 ATP
increasing fat uptake into muscle
the every other fatty acid pattern will not change, so the rate of blood flow and the concentration of fatty acids in the blood would need to increase in order to get more fatty acids into the muscle (as >50% is needed during exercise)
Axon
the extension of a neuron, ending in branching terminal fibers, through which messages pass to other neurons or to muscles or glands
Hemoglobin saturation
the extent to which hemoglobins are filled with oxygen (4/Hb = full); total hemoglobin saturation is usually around 98% and the leftover percentage is the partial pressure of oxygen
Periodization
the gradual cycling of specificity, intensity, and volume of training to achieve peak levels of fitness for competition (over time we increase specificity and intensity while decreasing volume, aiming for an optimal performance at a specific time)
A disadvantage of direct calorimetry is that
the heat generated by exercise equipment must be taken into account
VO2 max's impact on magnitude of improvement in aerobic fitness
the initial level of VO2 max determines the amount of change possible (a naturally high VO2 max = low percent of adaptation)
Resting conditions of a neuron
the inside of the membrane is more negative than the outside (electrical gradient - 70 mV); the sodium-potassium pump maintains this polarization
Neural factor 8: bilateral deficit
the max force by two arms together is less than the sum of both limbs contracting independently (possibly because it is impossible to recruit enough high threshold MUs), this deficit is significantly reduced with training
VO2 max
the most oxygen you can consume (best measure of aerobic fitness)
Down-regulation
the number of receptors is decreased when exposed to high levels of a hormone (endocytosis - the cell becomes less sensitive to the hormone)
Up-regulation
the number of receptors is increased when exposed to low levels of a hormone (exocytosis - the cell becomes more sensitive to the hormone)
tunica adventitia (externa)
the outer layer of a blood vessel, provides structure
A normal resting heart rate is determined by
the parasympathetic nervous system
Cell body (soma)
the part of a neuron that coordinates information-processing tasks and keeps the cell alive
Hematocrit
the percentage of blood volume made up by formed elements (solid); Female - 42%, Male - 46%
Lactate threshold
the point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels, where lactate clearance is no longer able to keep up with lactate production.
diastolic pressure
the pressure in the arteries when the heart is at rest (no active pumping)
Blood pressure
the pressure that is exerted by the blood against the walls of blood vessels (essentially rakes the inside of blood vessels -> important health factor)
Returning to resting state
the sodium-potassium pump returns the neuron to its initial electrical gradient by "balancing" the Na+ and K+ ions
Thyroid regulation of metabolism
the thyroid secretes triiodothyroxine (T3) and thyroxine (T4) -> T3 and T4 lead to increases in: metabolic rate of all tissues, protein synthesis, number and size of mitochondria, glucose uptake by cells, rate of glycolysis and gluconeogenesis, and free fatty acid mobilization
host gland for thyroxine
thyroid
Examples of non-steroid hormones
thyroid, epinephrine, norepinephrine
Inspiratory Capacity (IC)
tidal volume + inspiratory reserve volume
Vital Capacity (VC)
tidal volume + inspiratory reserve volume + expiratory reserve volume
TV/RR response to exercise
tidal volume plateaus @ approximately 60% FVC or 80% VO2 max; increases in ventilation beyond this point have to come from increased respiratory rate (frequency)
Lung volumes
tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume
Acute overload
to cause an adaptation, a system or tissue must be exercised at a level beyond which it is accustomed (could be increasing frequency, intensity, etc.)
Specificity
to cause favorable adaptations, training must utilize the specific movements, systems, and tissues that need to be improved
The maximal volume of air that can be accommodated by the lungs is the
total lung capacity
Blood functions
transportation of gases (O2 and CO2) to and from lungs and nutrients and hormones to cells, regulation - maintaining homeostasis (pH, temperature, BP), and protection - blood clotting and immune functions
Neurotransmitter to muscle
travels across cleft and binds to muscle surface receptors, triggering depolarization of the muscle fiber ("muscle action potential")
Which of these substrate stores in the body can provide the most overall kilocalories?
triglycerides
Blood vessel layers
tunica adventitia, tunica media, tunica intima
Relative tension scale
twitch (single stimuli), summation (successive stimuli), tetanus (back-to-back stimuli for an extended period)
End product of anaerobic glycolysis
two lactate molecules
Cardiac muscle fibers are most similar to which skeletal muscle fiber?
type I
Resistance training can lead to the conversion of _____ fibers into _____ fibers
type IIx, type IIa
Lactate threshold and VO2 max
typically lactate threshold is at 65% of you max intensity/VO2 max
Lactate shuttle
up to a certain intensity, lactate is cleared as fast as it is produced; past the intensity that the lactate shuttle can handle, the blood lactate levels will rise (eventually crossing the lactate threshold)
End Diastolic Volume (EDV)
volume of blood in the ventricle before contraction (after diastole)
End Systolic Volume (ESV)
volume of blood remaining in each ventricle after contraction (after systole)
Plasma is composed primarily of
water
Myofibril in a contraction
z-discs are pulled toward the m-line *contraction is the shortening of sarcomeres*
Which of these does not help increase plasma glucose concentrations during exercise?
ADH
Static resistance training
AKA Isometric Training (length of the muscle doesn't change); important for post-surgical patients (facilitates recovery in the case of an immobilized limb), reduces muscle atrophy and strength loss; improves strength only at the specific joint angle that is trained (potential to alleviate the "sticking point")
Plyometrics
AKA stretch-shortening cycle exercise (stretch -> rapid shortening); speed and strength training staple that uses stretch reflex to facilitate recruitment of motor units (muscle spindle - involuntary contraction reflex)
Stroke Volume and Exercise
Acute: lower and plateaus; Training: climbs
Deficit length and aerobic training
Aerobic training decrease the length of oxygen deficit
Similarities between cardiac and skeletal muscle
Both rely on actin and myosin, both utilize the sliding filament theory, similar sarcomere arrangement *alike in most parts of structure but different in function*
systolic pressure
Blood pressure in the arteries during contraction of the ventricles (actively pumping)
Resistance training components
Both bilateral and unilateral strength exercises
Bohr effect
During exercise, the oxyhemoglobin dissociation curve shifts to the right, causing hemoglobin to release oxygen more easily at a PO2 to provide more oxygen to the muscles being used
Eccentric training
Emphasizes eccentric (negative) phase -> muscle is getting longer *muscle's ability to resist force is greater than concentric contraction* Important in maximizing strength gains (and in muscle hypertrophy); requires a partner to help serve as the concentric phase (not practical, known to cause more pain/damage/soreness)
Line between aerobic and anaerobic
bouts of anaerobic training lasting beyond 30s rely on oxidation for energy -> muscle aerobic capacity is improved with this type of training
Parts of the CNS
brain and spinal cord
Glycogenolysis
breakdown of glycogen to glucose; occurs in the muscle and liver (muscle uses); only the liver can release glucose into the blood
Overrreaching
brief period of heavy and intense overload -> improvement in performance after initial decrements (heavy overload followed by recovery = better performance than conventional overload)
Steroids
cholesterol based, fat-soluble; bind to intracellular receptors (cytoplasm or nucleus) -> passes through the phospholipid bilayer because of fat-solubility; activate protein synthesis in the nucleus - creates enzymes, structural proteins, and regulatory proteins
Calorimetry
calculation of energy expenditure; measurements come from corollaries to energy, such as isotope/tracer methods and direct calorimetry *food + O2 = energy + heat + H2O + CO2*
Alveoli are structurally and functionally most similar to which part of the cardiovascular system?
capillaries
Main factors in respiratory regulation
carbon dioxide and oxygen; PO2 goes down or PCO2 goes up --> increased ventilation
Differences between cardiac and skeletal muscle
cardiac muscle has one nucleus, cardiac muscle is shorter with a larger diameter, cardiac muscle had spontaneous depolarization (contracts separate from brain) *cardiac muscle is more oxidative -> "ultimate ST/Type I muscle fiber"*
Venous vessels
carry deoxygenated blood; thinner and less smooth muscle -> less elastic; ONE WAY VALVES prevent regurgitation
Arterial vessels
carry oxygenated blood; thicker walls and more smooth muscle
Which group of hormones exerts metabolic and cardiovascular effects during exercise?
catecholamines
up and down regulation
cells choose how much they will be influenced by specific hormone
types of target cells in endocrine system
cells throughout the body (liver, kidneys, pancreas, etc.)
site of mediator action in nervous system
close to site of release, at synapse; binds to receptors in postsynaptic membrane
Capacity
combination of two or more volumes
Isotope
common element with unusual atomic weight (differing in number of neutrons); easy to track in the body (can be radioactive or not)
Gamma motor neurons
communicate with the ends of the muscle spindle; the middle of the spindle is stretched at this impulse; activated in normal voluntary muscle contraction
Primary determinants of hormone activity
concentration in the blood and receptor availability
Isokinetic training
conducted with equipment that keeps movement speed constant (electronics, hydraulics, or air restrict contraction speed); allows an individual to potentially contract muscle involved at maximal force at all points in the ROM; expensive, atypical, and not practical for multiple exercises as it must be adjusted
Myosin filament
connected to the m-line, projections called "myosin heads:" grab and pull to bring actin in
Functions of the parasympathetic nervous system
constricts pupils, stimulates flow of saliva, constricts bronchi, slows heartbeat, ups digestion, contracts bladder
Controlled and coordinated movements are integrated in the
cerebellum
Which provides more energy: fat or CHO?
1 gram of fat > 1 gram of carb
Number of impulses
1 impulse = twitch, constant impulses = actual contraction
Fast-twitch (Type IIx) muscle fibers
-Low aerobic (oxidative) capacity and fatigue resistance -High anaerobic (glycolytic) capacity and motor unit strength -Fast contractile speed (50 ms) and myosin ATPase -300-800 fibers per motor neuron -High sarcoplasmic reticulum development (high calcium storage) *completely fast-twitch in nature; low mitochondria* *highest activation threshold, difficult to recruit, rarely used; adopt better recruitment when used*
Partial pressure of CO2
0.3 mmHg (< 1%)
Product of PDH use
1 NADH = total 6 ATP, 24 ATP/cycle
Typical RMR values are
1,200 to 1,400 kcal/day
Values for Q max range
14-20 L/min in untrained people, 25-30 L/min in trained individuals, and 40 L/min in endurance athletes *these adaptations have huge impacts on performance*
Partial pressure of oxygen
159 mmHg (21%)
The anaerobic glycolytic system would be the primary source of ATP for which running event?
800 m (1/2 mi) run
Plasma composition
91.5% water and 8% solutes (proteins, electrolytes, glucose, fatty acids, etc.) *can be quickly replenished because of high water content*
Oxygen transport
98.5% bound to hemoglobin (4O2/Hb) 1.5% dissolved in plasma (calculated in partial pressure)
Fastest method of recreating ATP
ATP through phosphocreatine (PCr)
Most common neurotransmitter
Acetylcholine (ACh)
Which neurotransmitter binds to receptors on the motor end plate of a neuromuscular junction?
Acetylcholine (ACh)
Hormones that increase glucose entry into the blood
Epinephrine & Norepinephrine: increases liver glycogenolysis Cortisol: increases liver glycogenolysis and muscle proteolysis Glacagon: increases liver glycogenolysis and gluconeogenesis
Aerobic training response of hormones
Epinephrine, norepinephrine, growth hormone, insulin, glucagon, and ADH: attenuated response at the same rate of work; Aldosterone: unchanged
Exercise reaction to passing lactate threshold
Exercise intensity has to drop quickly after LT because the accumulating lactate impacts pH
Impact of exercise of respiratory muscles
Heavily taxed during exercise, taking up to 11% of the total oxygen consumed; more resistant to fatigue than muscles in extremities
Mechanisms for increasing muscle blood flow
Increasing cardiac output via increases in SV and HR and shunting of blood to working muscle
Hormone that increases glucose removal from the blood
Insulin: lowers blood glucose levels by increasing glucose uptake into cells
What part of the heart adjusts most due to aerobic training?
Mainly the left ventricle adapts (it has the largest role in pushing blood out to the rest of the body)
Detraining by Immobilization (of a limb)
Major changes after 6hr (lack of muscle use = reduced rate of protein synthesis, initiates process of muscle atrophy); first week: strength loss of 3-4% per day (decrease in size due to atrophy, decrease neuromuscular activity); reversible effects on Type I and Type II fibers (cross-sectional area decreases and cell contents degenerate; type I are affected more than type II)
Blood volume
Males: 5-6 liters Females: 4-5 liters
muscle contraction steps
Neuron: 1) Depolarization past the point of graded potential, crossing activation threshold of +15-20 mV 2) Propagation of the action potential down the neuron through the opening of Na+ channels (1 twitch) 3) Repolarization of the neuron by opening the the K+ channels in order to create gradient again 4) Repetition of the depolarization and repolarization, sending the action potential down the neuron until the brain stops sending the signal (impulses) 5) The sodium-potassium pump restores the original gradient (neuron is back to a resting state) Chemical Synapse: 1) Synaptic vesicles are expelled from the axon terminal ending into the cleft between fibers 2) The neurotransmitters within bind to the muscle fiber surface receptors to trigger depolarization of the muscle fiber (muscle action potential) Muscle Fiber: 1) The action potential travels down a myofibril and enters the fiber through a T-tubule opening, which releases calcium from the SR 2) Calcium causes tropomyosin to move, allowing myosin to bind to actin and create a single twitch 3) ATP binds to myosin heads to get them to release actin and is burnt to re-energize myosin 4) Myosin can grab and pull again; these repeated motions cause an actual muscle contraction 5) Contraction continues until the brain ends the signal
VO2 (oxygen consumption)
O2 in room air - O2 in expired air = VO2; the portion oxygen used out of what we take in
When the oxyhemoglobin curve shifts during exercise, what is the result?
O2 unloading become easier at muscles
Adjustments in breathing frequency and tidal volume
Occur unconsciously and are naturally well-regulated; intentional adjustments in respiration can hurt not help
Special cases for respiratory performance
Pulmonary ventilation is a limiting factor for 1) elite athletes/highly trained people or 2) people with obstructive or abnormal respiratory disorders (and therefore lessened function)
Limited performance?
Pulmonary ventilation is not a limiting factor in most people's performance
Cardiac Output and Acute Response
Q climbs and plateaus before max
Cardiac Output and Exercise Training
Q doesn't change at rest or during submit intensity (with training HR drops and SV increases, cancelling each other out) *any change might be explained by increased a-VO2 difference due to greater oxygen extraction by tissues* Q increases dramatically at maximal exertion due to the increase in maximal SV
Blood Plasma Volume and Training
RBC volume increases and plasma increases (extreme) -> a few weeks = spike in PV overall; hematocrit goes down as the proportion of created plasma is lower than the portion of new formed elements (RBCs)
Respiratory Exchange Ratio (RER)
RER = VCO2/VO2; ranges from .7 to 1.0; indicates what sources of fuel you are relying on: .7 means burning fat only and 1.0 means burning CHO only
RER and exercise
Respiratory exchange rate increases with increased exercise intensity (as dependency on glucose increases)
The pacemaker cells of the heart are found in the
SA node
If you sit and breathe quietly into a spirometer, which lung volume is being recorded?
Tidal volume
Insulin and exercise (impact on fat metabolism)
[insulin] decreases with exercise so mobilization and metabolism increase
Neural factor 3: reduced coactivation of agonist and antagonist muscles
^^ ability to withstand higher intensities because another of the muscle's defenses against strain; only a small contribution to overall increased strength (hand in hand with GTO disruption)
Neural factor 1: recruitment of additional motor units, more synchronously, with greater force production
changes in neural connections may result in MUs being activated all at once (synchronous -> controversial), could just be that more MUs are being activated (proven)
Reversibility
beneficial effects of exercise are transient and reversible (positive changes can be lost if you stop training)
For aerobic metabolism, free fatty acids must be converted to Acetyl-CoA via
beta oxidation
Genetics' impact on magnitude of improvement in aerobic fitness
biggest factor (82%); monozygous twin studies (identical, same DNA) showed that each pair has a similar amount of change
Pineal gland function
biological clock, secretes melatonin
Blood volume adaptation to aerobic training
blood volume increases with aerobic training (PV increases and RBC volume increases, hematocrit decreases because of the ratio of increase), significance: increased PV is highly related to increased stroke volume and VO2 max
Blood circulation rate at rest
blood volume is circulated one time per minute at rest
Plasma levels of norepinephrine & epinephrine (and FFA) and exercise
both bind to receptors on fat cells to cause mobilization of FFA (upward curve with exercise)
Hormone role
chemical messenger (conveys a command)
Reflexes associated with Golgi tendon organs prevent skeletal muscles from
contracting with too much force
Partial pressure
contribution to the total air pressure
major functions of insulin
controls blood glucose levels by lowering glucose levels; increases use of glucose and synthesis of fat
major functions of cortisol
controls metabolism of carbs, fats, and proteins; exerts anti-inflammatory action
major functions of ADH
controls water excretion by the kidneys; elevates BP by constricting blood vessels
Functions of cerebellum
coordinates complex movements; regulates balance and posture
Plasma levels of cortisol (and FFA) and exercise
cortisol spikes at minute 15 of constant exercise -> promotes all types of metabolic activity (protein, fat, and glucose); promotes additional slow rise in FFA in the blood
Primary purpose of Kreb's Cycle
create hydrogens with electrons
The release of energy for PCr is catalyzed by
creatine kinase
Where does glycolysis occur?
cytosol of the muscle cell/fiber
"fats burn in a carbon flame" meaning
fat oxidation only works when CHO is also present because carbs are essential to metabolize fat; each Acetyl-CoA requires an oxaloacetate to enter Kreb's Cycle, pyruvate (glucose product) can be made into oxaloacetate, carb metabolism to create pyruvate and then oxaloacetate must occur before Kreb's cycle can begin and fat metabolism can occur
Myelin sheath
fatty coating that speeds up the transfer of impulses
Appropriate resistance for building strength
few reps and high resistance (6-RM)
Compared to fat fat molecules, glucose, glucose molecules contain _____ carbon atoms
fewer
Tropomyosin
fiber covering the binding sites of actin; myosin heads want to constantly grab and pull actin to cause muscle contraction, but tropomyosin keeps this from happening all the time
Blood vessel pathway through body
heart -> artery -> arteriole -> capillary -> venule -> vein
Heart rate and aerobic training
heart rate from rest to submax intensity decreases; max heart rate might be the same or slightly lower
Heart rate and acute response
heart rate goes up as the intensity of exercise increase
Cardiac output = __________ x ___________
heart rate, stroke volume
Parts of the Cardiovascular System
heart, blood vessels, blood
Cross-training concept (multiple movements/types of training)
helpful in injury rehabilitation or prevention (prevents overuse damage to a specific muscle group), common in multiple sport training (i.e. triathlon)
Long-term impacts of RT
high muscle adaptations, low neural adaptations *at different points in strength training, different factors contribute different amounts to the increased strength/endurance*
Which of the following is not an important predictor of a successful endurance athlete?
high type II fiber percentage
Neural factor 4: changes in the discharge firing rates of the motor units ("rate coding")
higher frequency of firing = greater peak force, this might occur with resistance training (ballistic type exercise is most effective for this)
Metabolism changes with aerobic training
higher lactate threshold (occurs at higher VO2, % VO2 max) and lower respiratory exchange ratio (identifies fuel source - increased fat use and decreased CHO use)
Mediator molecules of endocrine system
hormones delivered to tissues throughout body by blood
Exercise economy
how efficiently you are using metabolic products during exercise (more economical = faster, less economical = burning more calories)
Classic (linear) periodization
long-term training program, typically complete one macrocycle in one year; several mesocycles (about 1 month) make up one macrocycle; a group of 2-4 microcycles (about 1-2 weeks); the goal is to increase intensity and decrease volume (reps x sets) from one microcycle to the next; believed to maximize performance better than traditional ST (can't sustain peak performance - "early ripe, early rotten"); best prepares athletes for only one performance not a full season; assumes that all sport skills are developed simultaneously (unlikely for ball and combat sports, other that require more than general speed or strength)
During endurance exercise, fatigue correlates best with
low glycogen stores
Short-term impacts of RT
low muscle adaptations, high neural adaptations *at different points in strength training, different factors contribute different amounts to the increased strength/endurance*
pH impact on ventilation
lowered pH itself leads to increased ventilation; when pH decreases after lactate threshold, the accumulated H+ ions are buffered through bicarbonate, which produces CO2 and creates additional ventilation
Expiration
lung pressure is higher than atmospheric pressure; passive at rest and active during exercise
Inspiration
lung pressure is lower than atmospheric pressure; active process - both at rest and during exercise
Muscle receptors
muscle spindles, golgi tendon organs, and joint kinesthetic
The fastest impulses travel on axons that are
myelinated and large
Unit of muscle contraction
myofibril (in a bundle, within the muscle fiber)
Sliding filament theory
name for the process of myosin pulling actin to shorten sarcomeres and create contraction
How do products of a metabolic pathway typically help control the rate of chemical reactions?
negatively feed back on the rate-limiting enzyme
Strength increases in older populations is primarily due to
neural adaptations
The basic structural unit of the nervous system is the
neuron
Function of the motor division
neurons transmit signals away from the CNS
mediator molecules of nervous system
neurotransmitters released locally in response to nerve impulses
Force summation
successive stimuli that result in progressively stronger contractile force (calcium cannot return to the SR fast enough)
The accumulation of multiple EPSPs on a postsynaptic cell is called
summation
Production of Aldosterone
sweating/exercise -> decreased PV reduces BF and BV to kidney -> kidney releases renin -> renin converts angiotensinogen to angiotensin I -> ang I is converted to ang II in the lungs -> ang II travels to adrenal gland and binds to release aldosterone (causes increased sodium and water reabsorption at the kidney)
Distribution of circulation
systemic veins and venules (blood reservoirs) - 64%, systemic arteries and arterioles - 13%, pulmonary vessels - 9%, heart - 7%, systemic capillaries - 7%
Direct calorimetry
use of a chamber to calculate the heat released form exercise by measuring heat exertion in terms of raising the temperature of surrounding water (flawed because machinery and friction adds heat -> not accurate for normal types of exercise)
Sodium-potassium pump
uses 1 ATP, pushes 3 Na+ out and pulls 2 K+ in to create the resting membrane potential
In general, the stimulation of the sympathetic nervous system causes __________ blood vessels
vasoconstriction
Results of increased [epinephrine]
vasoconstriction in other tissues and vasodilation in skeletal muscles (caused in all skeletal muscles, meaning those exercising and those at rest)
Results of sympathetic stimulation
vasoconstriction in skeletal muscles and vasoconstriction in other tissues (liver and kidneys)
Results of exercise inspired local changes (K+, heat, H+, adenosine, contraction, increases in CO2 and decreases in PO2)
vasodilation in active skeletal muscles
Functions of the pulmonary system
ventilation and gas exchange
QRS complex
ventricular depolarization (and atrial repolarization)
T wave
ventricular repolarization
The primary purpose of ADH is to promote
water retention
Fluid distribution between compartments during exercise
water shifts from the plasma to the intracellular and interstitial spaces; may drop 5-15%, moving from plasma to muscles and glands
ETC problems
when H+ returns into the mitochondrial matrix, a new gradient slows the reactions (acidic pH); final cytochrome is filled by an electron, so the electrons in previous cytochromes cannot move on in the chain to create ATP
Function of Bicarbonate
when bicarbonate combines with excess H+ ions (lactate accumulation), the product can be converted into water and CO2 (which is exhaled); therefore, bicarbonate fosters the buffering of lactic acid
Impact of initial muscle length on force generation
when muscle is stretched out/extended, it is weaker because the sarcomeres are so long that myosin can't reach actin to pull; when muscle is completely flexed, the sarcomeres are shortened to the point that the outside myosin are crumpled into the z-disc (less strength); optimal initial muscle length is in the middle ground between complete extension and flexion
The increase in heart rate at the very beginning of exercise is due to
withdrawal of parasympathetic (vagal nerve) stimulation
