Ch 9 Part 3) Muscles Flashcards
1
Q
Energy for Contraction
A
- ATP supplies the energy needed fot muscle fiber too
- Move and detach cross bridge
- Pump calcium back into SR
- and Pump Na+ and K+ in and out of cell
- ATP in muscles is depleted in 4-6 seconds
- Because of this it must be regenerated via one of three mechanisims.
2
Q
Creatine Phosphate (CP)
A
- Creatine Phosphate (CP) is a high energy molecule used to donate a phospate to ADP to make ATP
- Creatine Phosphate + ADP → ATP
- Done so by enzyme creatine kinase
- Creatine creates enough ATP to power muscles for about 15 seconds
3
Q
Anerobic Pathway (Glycolosis and Lactic Acid)
A
- ATP can also be generated by breaking doww and using glucose as energy
- Glycolysis) first step in glucose breakdown
- Does not require oxygen (anerobic)
- Glucose is broken down into 2 pyruvic acid molecules
- 2 ATP’s made per glucose (2 total)
- When in work, mucles can not get any oxygen to start conversion of pyruvic acid.
- Pyruvic acid is made into Lactic Acid if no Oxygen is present
- Latic Acid
- Diffuses into bloodstream where it is made back into pyruvic acid/ glucose in the liver.
- Anerobic Respiration only yealds about 5% of the ATP that Aerobic Respriation provides, but it is about 2 1/2 times faster
- With CP and ATP stores, muscle activity can continue for about 20 seconds.
4
Q
Aerobic Respriation
A
- Produces 95% of ATP during rest or during moderate excercise
- must have O2 present
- Consists of a series of chemical reactions that occur in the midocondria
- Glucose (C6H12O6) is broken into CO2 and H2O plus a large ammount of ATP (32 total)
- C6H12O6→ CO2 + H2O + 32ATP
- Fuel for Aerobic Respriation
- First Glycogen stored in Mucscles
- Second Bloodbourne Glucose
- Lastly Free Fatty acids will be burned
- Main fuel after 30 mins of excercise.
5
Q
Which Pathway predominated during excercise?
A
- If the muscle has O2, Aerobic Respriation is used to create ATP. When the excercise demands exceede the capicity of Aerobic excercise we will switch to Anerobic pathways to generate ATP
- Aerobic Endurance) Length of time muscle contracts using aerobic pathways
- Anerobic Threshold) Point at which metabolism changes to anerobic pathway.
6
Q
Muscle Fatuige
A
- Defined as the physilogical inability to contract despite continued stimulation
- Possibe Causes of muscle fatuige include
- Ionic Imbalances) K+, Na+, Ca2+ levels can be disturbed after continuious contraction
- Increased Inorganic Phosphate levels may intefere with calcium release
- Decreased Glycgoen levels
- Muscles almost never run out of ATP.
7
Q
Excess Postexcercise Oxygen Consumption (EPOC)
A
- For a muscle to return to its pre-excercise state:
- Oxygen reserves in myoglobin are replenished
- Lactic acid is reconverted to pyruvic acid
- Glycogen stores are replenished
- ATP and Creatine Phosphate (CP) reserves are restored
- These steps to restore the body need extra oxygen so this process is refered to as Excess Postexcercise Oxygen Consumption (EPOC)
8
Q
Force of Contraction
A
- Depends on number of cross bridges formed
- Affected by four factors
- Number of muscle fibers stimulated (recruitment)
- more fibers = more force
- Relative size of Fibers
- Bulkier Fibers = more tenstion it can hold
- Frequcney of Stimulation
- higher= more force
- Degree of Muscle Stretch
- Sarcomeres are at optimal strength at 80-120% length
- any more or less and not all myosin heads form crossbridges.
- Number of muscle fibers stimulated (recruitment)
9
Q
Velocity and Duration of Contractions
A
- How fast a muscle contracts and how long are influenced by
- Muscle Fiber Type
- Load
- and Recritument
10
Q
Muscle Fiber Type
A
- Classified according to two charcteristice
- Speed of Contraction (Slow or Fast)
- How fast ATPases split ATP
- pattern of eletrical acticity
- Metabolic pathways used for ATP synthesis
- Oxadative) use aerobic pathways
- Glycolytic) use anerobic pathways.
- Speed of Contraction (Slow or Fast)
- Sketeltal muscles can be classified into three types
- Slow Oxidative Fibers) Low Intensity, Used for endurance activities
- Fast Oxidative Fibers) Medium- intensity activities
- Contract quickly but still depend on O2
- Fast Glycolytic Fibers) Short-Intense movment
- No O2 used
- All fibers in one Motor unit will be the same
- Genetics Dictate individual’s precentage of each type of fiber.
11
Q
Load and Recritment
A
- Load) Muscle Contract faster when there is no load
- Greater the load, shorter the duration of contaction
- More load = slower contraction
- Recritument) More units contracting = faster and longer contraction
12
Q
Aerobic Excercise (effects)
A
- Leads to incresesed
- Muscle capillaries
- Number of mitochondria
- Myoglobin synthesis
- Results in greater endurance, strenght and resistance to fatuige.
- Fast Glycotic Fibers may convert into Fast Oxidative Fibers
13
Q
Resistance Excercise (effects)
A
- Resistance (anerobic) excercice leads to muscle hytrophy
- Increase in muscle strenght and size
- Increased mitochondria, myofilaments, glycogen stores, and conenctive tissue
14
Q
Atrophy
A
- Muscles must be used to remain healthy
- Atrophy is the loss of muscle mass due to unuse
- Can be imobilized or have no stimulation
- Begins almost immediately
15
Q
Regeneration of Muscle
A
- Skeletal Muscle) limited regenerative capicity
- Cardiac Mucle (cardiomyocytes) devide at a modest rate
- Injuries to heart are generally replaced with CT
- Smooth Muscle) regenrated through life
- Aging muscles = Loss of muscle mass (sarcopenia)
- Begins at age 30