BSC2085 CH. 9.5
What is the 1st step of the Anaerobic pathway? What is used and what is created?
Glucose is degraded to 2 pyruvic acid molecules and produces 2 ATP per glucose molecule
What is the first step in the aerobic pathway?
Glycolysis citric acid cycle
Which muscle fibers experience the greatest result during aerobic training?
Greatest effect seen in SO fibers
Why is ATP important for skeletal muscle cells?
It is the only source used directly for contractile activities
What happens to ADP levels vs ATP? (muscle contracts and uses more ATP than it is making)
Leads to increase in ADP in sarcoplasm
What impact may this have a person's ability to excel at certain exercise activities?
This provides a partial explanation for why some people may be better at particular activities than others
What most likely determines the ratio of SO to FG fibers in different muscles?
genetically determined
Who needs more protein intake?
growing children, pregnant women, postsurgical patients, and athletes
How should one go about designing a training program for: Endurance
half marathons and three mile swims, will not lead to the strength and size gains desired by weight lifters
Bone density effects? (exercise important in elderly)
helps reduce bone density loss and loss of ROM in joints
What should a long-term fitness regimen include?
include both endurance and resistance training
Which muscle fibers experience the greatest result? (anaerobic)
increase in: number of mitochondria, glycogen stores, glycolytic enzymes
Why is exercise important in the elderly?
produce significant adaptation -Also helps reduce bone density loss and loss of ROM in joints
What are the effects of strenuous exercise on the muscle cell?
produces stress and damage to muscle fibers
Direct Phosphorylation-Where is most creatine found in the body?
(adding a phosphate) of ADP using creatine phosphate (CP) •Especially important in muscle fibers -95% of the body's creatine is found in skeletal muscle
Define Cramp and list causes
-Involuntary and often painful tetanicmuscle contractions -Caused by: •inadequate blood flow to muscles (such as in dehydration or blood clot) •nerve compression•overuse •Injury •abnormal blood electrolyte levels -calcium and magnesium levels important •Intra vs extracellular Na and K also important
Pre, during, and post workout supplements are typically bunk. Why are they dangerous?
-Many contain high amounts of various stimulants •May cause increases in blood pressure•May cause concentration issues •May increase rate of dehydration during activity -Typically contain low amounts of advertised ingredients •below amounts needed for physiologically relevant levels as based on scientific studies quoted by the supplement company
Anaerobic Pathway
(glycolysis -> lactic acid) •No O2 required •If Anaerobic, glycolysis is followed by fermentation
What are some of the negative effects in Females of stacking?
-Atrophy of breasts and uterus -Menstrual irregularities -Sterility -Increased male -pattern growth of body and facial hair (hirsutism) -Permanent deepening of voice -Clitoral enlargement
At 70% or above maximum contractile activity, what happens to muscle blood flow and delivery/removal of nutrients, O2, and wastes?
-Bulging muscles compress blood vessels -oxygen delivery impaired
Unfortunately, length of use and doses required to produce desired results can be dangerous. List the dangerous effects of long-term high-dose steroid use
-Cause many cells in the body to grow, including cancerous cells •Liver damage and various types of cancer is common with oral and injected steroids-Kidney damage -Stunted growth for those still growing-Mood swings in long -term users from affected neurotransmitter release in the brain •Increased irritability and aggression... Roid Rage! •Depression -Increased blood pressure and risk of heart disease -Increased LDL levels... these are the bad kind -Increased sebaceous gland secretion•Pimple Party!!! •...Backne and trapne -Users often combine different types of steroid and non-steroid drugs when undergoing a cycle-stacking
How long does muscle adaptation take?
-Changes in muscle in response to repeated periods of exercise occur over a period of weeks to months
What are some of the negative effects in Males of stacking?
-Decreased endogenous testosterone production -Conversion of excess testosterone to estradiol •Causes gynecomastia - female-like breast tissue in males -Testicular atrophy from decreased sperm production -Sterility -Baldness - increased development of androgenic alopecia for those with the affected
List and the three ways skeletal muscle fibers regenerate ATP to maintain contraction?
-Direct Phosphorylation -Anaerobic pathway -Aerobic pathway
When can protein intake become dangerous?
-Excess protein intake (over 200 g/day) may lead to kidney damage over time -High protein diets can lead to fat gain if total caloric intake greater than expenditure
How should one go about designing a training program for: Strength
-High weight/low rep resistance training will have little effect on a marathoner's ability to run long distance
What is the 1st step of the Anaerobic pathway?
-In the cytosol, glucose is degraded to 2 pyruvic acid molecules via enzyme catalyzed reactions -Produces 2 ATP per glucose molecule
What are anabolic Steroids? What are the typical beneficial effects?
-Mimics the effects of testosterone and DHT in the body -Cause an increase in muscle size and thus strength -Cause increase in lean muscle mass •With proper diet -Cause increased bone growth and remodeling -Stimulates red bone marrow •Increase in RBCs
What two molecules, normally confined to the inside of the muscle cell, can be found in the blood post exercise?
-Myoglobin -Creatine Kinase
How long does the anaerobic pathway allow for sustained, strenuous activity?
-Rapidly provides fuel for ~30 - 40 seconds of strenuous exercise
How are muscle fibers classified by function?
-Speed of contraction: •slow or fast fibers according to -Speed at which myosin ATPases split ATP -Pattern of electrical activity of motor neurons -Primary Metabolic pathways used for ATP synthesis while contracting •Oxidative fibers —use aerobic pathways•Glycolytic fibers —use anaerobic glycolysis
What happens to ATP levels when muscle contracts and uses more ATP than it is making?
-The excess ATP is used to make creatine phosphate(CP) -Creatine kinase (CK), an enzyme,catalyzes the transfer of one of the high energy phosphates from ATP to creatine forming CP and ADP
List muscle cell structures affected by strenuous exercise
-Torn sarcolemmas in some muscle fibers -Damaged myofibrils -Disrupted Z-discs
If O2 levels are low, what is the next step in the anaerobic pathway that is needed to allow glycolysis to continue?
-W/o oxygen, pyruvic acid converted to lactic acid in order to regenerate specific molecules needed for glycolysis to continue making ATP •Fermentation
What are some of the negative effects in Adolescents of stacking?
-stunted growth due to premature skeletal maturation and accelerated puberty changes -risk of not reaching expected height if steroid use precedes the typical adolescent growth spurt
What is the recommended daily intake for protein (in grams) per 2.2lbs of body weight?
0.8 grams
How much creatine do you require per day, on average?
2 grams of creatine a day
Define Spasm
A sudden involuntary activationof a motor unitwithin whole muscle - usually painless
At rest: When a phosphate is taken from ATP, what is left over?
ADP
During contraction: When a phosphate is added to ADP, what is created?
ATP
Compare ATP production in Anaerobic vs Aerobic (speed and amount)
Anaerobic respiration yields only 5% as much ATP as aerobic respiration, but produces ATP 2½ times faster
Define disuse atrophy and denervation atrophy
Atrophy can occur from simply not using them (disuse atrophy) or damage to the nerves that cause them to contract (denervation atrophy)
How long does accumulated ATP power the muscle contraction at its onset?
Available muscle stores of ATP depleted in 3-6 seconds from the onset of contraction
What is the first step in the aerobic pathway? What is used and what is created?
Breaks pyruvate down producing CO2 ,H2O, and a large amount of ATP
How does creatine kinase respond to the a decrease in ATP and a rise in ADP with respect to creatine phosphate? (muscle contracts and uses more ATP than it is making)
CK takes a phosphate back from CP and adds it to ADP forming ATP
At rest: When phosphate is added to creatine, what does creatine become
CP
How much additional contraction time does this allow for? (muscle contracts and uses more ATP than it is making)
CP catalyzed regeneration of ATP allow muscles to contract for roughly 15 seconds
At rest, contrast creatine phosphate vs ATP amounts.
CP is 3-6 times more plentiful than ATP in the sarcoplasm of a relaxed muscle fiber
What can it be converted back in to and what organ accomplishes this?
Can also be converted back into pyruvic acid or glucose by liver
What are some dietary sources?
Can also be obtained through milk, red meat, and some fish
What causes DOMS?
Causes of DOMS not completely understood. but studies reveal that microscopic muscle damage (microtrauma) may be a major contributing factor
When is the skeletal muscle at high activity? Describe ATP use
Contracting and using ATP at a rapid pace
What transfers a phosphate from ATP to creatine creating creatine phosphate?
Creatine kinase (CK)
How is it gotten rid of by the body? (metabolite of creatine)
Creatinine is filtered by the kidneys into the urine
What does DOMS stand for?
Delayed Onset Muscle Soreness
What can affect characteristics of muscle fibers?
Different types of activity induce changes in muscle fibers•Endurance vs. Strength
How is it removed from the muscle cell?
Diffuses through muscle transport proteins into the interstitial fluid and then bloodstream
Why is it called anaerobic?
Does not require oxygen
What are the effects of aerobic training on other systems beside muscle during aerobic training?
Endurance training also results in cardiovascular and respiratory adaptations that increase the nutrient transport and waste removal for skeletal muscle cells
What are the effects of exercise on a muscle's size and ATP production capacity?
Exercise can produce an increase in size as well as changes in a muscle cell's capacity for ATP production
What fibers may gradually alter their characteristics (transform) during aerobic training?
FG fibers to FOG fibers
What fibers may gradually alter their characteristics (transform)? (anaerobic)
FOG fibers to FG fibers
What is hypertrophy? What structures are increased in quantity in an enlarged muscle cell?
Increase in size/diameter, not in number •Enlargement of existing fibers due to increase in the number of: -Myofibrils»More contractile organelles = more tension generated -Mitochondria»Bigger muscle cells with more contractile organelles need more ATP to power them -Sarcoplasmic reticula»Need more Ca storage and release for new myofibrils -Other organelles and proteins necessary for increased metabolic capacity
List the effects of muscle adaptation to strength (anaerobic) training
Increases the size and tension production of FG fibers Increase in size and strength due to increase in number of myofilaments in muscle fiber. •Overall result is hypertrophy -Bulging muscles
List the effects of muscle adaptation to endurance (aerobic) training
Leads to increased •Muscle capillaries (blood flow) •Number of mitochondria (ATP production when oxygen present) •Myoglobin synthesis (more oxygen storage)
Define Aerobic endurance
Length of time muscle is capable of contraction using ATP primarily produced from aerobic pathway
Is there a difference in the number of muscle fibers in a large, muscular person vs a thin person?
Most people have roughly the same amount of muscle cells regardless of difference in body size
What happens to muscle fibers in response to damage?
Muscle fibers undergo repair and adaptation
Compare the strength in a 25 yr old vs an 85 yr old
Muscle strength at 85 is roughly 40%of what it was atage 25
How long post-exercise does it typically take DOMS to occur?
Muscles become sore 12-48 hours post exercise Greatest effects felt 24-72 hours post activity
List common proportions of muscle fiber types in each of the following: Why do you thing the above have those ratios (what is the common function/use of the above muscles)?
Neck and back: Primarily used for postural support Shoulder and arm: Used briefly to produce large amounts of tension for activities like lifting or throwing Leg and thigh: Used for support, walking, and running
What is the role of lactic acid in DOMS, how do we know?
Not caused by lactic acid build-up •Concentric contractions produce lactic acid and do not cause DOMS •Studies show lactic acid levels in blood return to normal within 1 hour after exercise
Define EPOC. Why is it necessary?
Oxygen Debt, or "Excess Post-Exercise Oxygen Consumption"; the amount of O2 repayment required after exercise in skeletal muscle to: -Replenish ATP stores-Replenish creatine phosphate and myoglobin stores -Convert lactic acid back into pyruvate so it can be used in the mitochondria to help replenish ATP -Balance hormones
Who may excel at long duration low to moderate intensity activities? List activity examples
People with a higher percentage of SO fibers may excel in endurance activities-Long distance cycling, running, swimming
Who may excel at resistance and short duration high-intensity activities? List activity examples
People with higher proportions of FG fibers may excel in activities involving short, powerful, intense activities-Weight lifting and sprinting
Define Anaerobic threshold
Point at which muscle metabolism converts to primarily anaerobic ATP production
When does the aerobic pathway dominate for ATP production in the muscle cell?
Produces ~95% of ATP during rest and light to moderate exercise -Slower process than anaerobic
What can slow the rate of loss?
Regular exercise
When is the skeletal muscle at low activity? Describe ATP use
Relaxed and using a moderate amount of ATP
How are muscles classified by appearance? Contrast the features of red and white muscle
Skeletal muscle fibers are not all alike in appearance and function. By appearance: -Red muscle fibers (the dark meat) have a high myoglobin content, many mitochondria, and rich vascularization (blood supply) -White muscle fibers (the white meat) have high amounts of glycolytic enzymes, low myoglobin content, fewer mitochondria, and less vascularization vs. red fibers
Describe the characteristics of slow vs fast fibers
Slow oxidative fibers (SO)(Type I) •Small, appear dark red, are the least powerful type. •Myosin heads hydrolyze ATP slowly leading to a lower rate of contraction... hence slow •They are very fatigue resistant •Low amount of glycogen stores compared to FOG and FG •Highly vascularized •Have a lot of mitochondria -Generate ATP mainly through aerobic respiration, hence oxidative •High myoglobin•Used for endurance activitieswhere big, powerful contractions are not needed -Ex: postural maintenance, long distance activities in running, swimming, and cycling Fast oxidative-glycolytic fibers (FOG) (Type IIa) •Intermediate in size, appear red to pink •More myofilaments than SO •As much to slightly less vascularized vs. SO •Moderately resistant to fatigue •Myosin heads hydrolyze ATP 3-5x faster than SO which make them contract faster-Twitches reach peak tension faster than SO and are briefer in duration - less than 100 msec •Have the most mitochondria of the different types-Generate considerable ATP through aerobic (oxidative) respiration to power the greater number of myofilaments vs. SO •High myoglobin •Have a moderate amount of intracellular glycogen and can use anaerobic pathway (fermentation) efficiently when oxygen drops •Contribute to exercises such as walking and sprinting
Why is EPOC also referred to as the "after burn"
The greater the EPOC, the more fat stores you may potentially use throughout the day to return muscle back to original state
What affects the properties of a muscle?
The regularity of muscle use, as well as the duration and intensity of activity
What is stacking and why is it dangerous?
Users often combine different types of steroid and non-steroid drugs when undergoing a cycle
Describe ATP production and ATP use by the muscle cell at rest
When relaxed, muscle fibers produce more ATP than is needed for resting metabolism -The excess ATP is used to make creatine phosphate(CP) -Creatine kinase (CK), an enzyme,catalyzes the transfer of one of the high energy phosphates from ATP to creatine forming CP and ADP •It does the reverse, too - CP and ADP to Creatine and ATP
Is a typical muscle made of just one type of muscle fiber? If not, what fibers are most common in the "average" muscle?
Within a particular motor unit, all the skeletal muscle fibers are of the same type
Are there different types of muscle fibers in a single motor unit or are they all of the same type? In what order, and why, are the different motor units of a muscle recruited?
Within a particular motor unit, all the skeletal muscle fibers are of the same type •Weak contractions usually require SO motor units only •If more force is required, FOG motor units are recruited •If maximal force is required, the big FG fibers are recruited!
What happens to muscle cells if they are not stressed? What is the term for this?
atrophy Decrease in size/diameter due to decrease in the things listed under hypertrophy slide
List common proportions of muscle fiber types in each of the following: Shoulder and arm
contain higher proportion of FG fibers
List common proportions of muscle fiber types in each of the following: Leg and thigh
contain large numbers of both SO and FOG fibers
During contraction: When a phosphate is taken from creatine phosphate, what is left?
creatine
What is the metabolite (breakdown product) of creatine called?
creatinine
What is the 1st step of the Anaerobic pathway? Where in the cell does it occur?
cytosol
What type of isotonic contraction causes DOMS, concentric or eccentric?
eccentric contractions (the negative rep)
What chemical environment is necessary in the muscle cell for this to occur (an abundance of ATP or a declining amount)?
excess ATP
What is made from the pyuvic acids in this process?
lactic acid
What organs can use it for fuel?
liver, kidneys, and heart
What happens as we age above ~30? List some causes
loss of muscle mass (sarcopenia) begins •due to decreased levels of physical activity •With aging,humans undergo a slow, progressive loss of skeletal muscle mass that is replaced largely by fibrous connective tissue and adipose tissue
What does this mean for the amount of ATP made and what waste products are produced?
lots of ATP -Beta oxidation of fatty acids (lipids) and oxidative deamination, followed by transamination, of amino acids provide substrates for aerobic respiration to produce ATP as well
What is the first step in the aerobic pathway? Where in the cell does it occur?
mitochondria
What happens if atrophy persists past 6 months to 2 years?
muscle fibers can be irreversibly replaced by fibrous connective tissue
What must occur if the muscle is to continue contraction?
muscles must make more ATP
Do the typical number of muscle fibers increase?
no
List common proportions of muscle fiber types in each of the following: Neck and back
often contain a higher proportion of SO fibers
If there is enough oxygen present in the cell, what are the next steps and where do they occur?
pyruvate is modified and enters the mitochondria where the breakdown of the modified pyruvate during the citric acid cycle produces molecules that are used in oxidative phosphorylation to produce a lot of ATP
Why is it called aerobic?
requires oxygen
What is creatine and where is it made in the body?
small, amino acid derived molecule that is synthesized in the liver, kidneys, and pancreas -it is then transported to muscle fibers
What other fuels can be used for this process? (aerobic) Can they be used as is or do they have to be modified first?
stored glycogen, blood borne glucose, pyruvic acid from glycolysis, amino acids, and free fatty acids
What happens to muscle if exercise ceases?
the muscle revert to their unexercised state
Who can actually benefit from vitamin supplements? Does the average American need them? Why not?
useful in those with nutritional deficiencies and professional athletes -average American does not need them because most vitamins obtained from healthy diet
What are the drawbacks to the anaerobic pathway?
uses huge amounts of glucose for relatively small amounts of ATP produced and creates lactic acid as byproduct
Cardiovascular effects? (exercise important in elderly)
•Aerobic training is of particular importance due to it's cardiovascular effects
What are some of the structures affected from exercise that are linked to DOMS?
•Damage to sarcomeres (z-discs, thin, and thick filaments can tear or become dislodged), calcium homeostasis in muscle cell disrupted, ATP production may slow, possible increase in sarcomere protein breakdown by the proteases
Muscle and joint effects? (exercise important in elderly)
•Strength training, even a modest amount, can partially prevent the loss of muscle tissue that occurs with aging
What causes variations in the ratio of the three muscle fiber types in muscles?
•The action of the muscle •Training program •Genetic factors
Aerobic Pathway
•glycolysis -> O2 and modified glycolysis products into mitochondria
