Exercise Physiology Exam #3

Front 1

Skeletal Muscle Connective Tissues

Back 1

Epimysium

Fasciculus

Perimysium

Endomysium

Sarcolemma (Cell Membrane)

Front 2

Define: Epimysium

Back 2

Connective tissue surrounding entire structure

Front 3

Define: Fasciculus

Back 3

A bundle of muscle fibers (up to 150)

Front 4

Define: Perimysium

Back 4

Connective tissue surrounding individual muscle fibers

Front 5

Define: Endomysium

Back 5

Connective tissue surrounding individual muscle fibers

Front 6

Define: Sarcolemma

Back 6

The cell (plasma) membrane surrounding the muscle fiber

Front 7

Identify the Characteristics of Tendons

Back 7

(1) comprised of tough "non-living" fibers which are metabolically inactive compared to muscle and bear tremendous forces during muscle contraction

(2) Intramuscular network of connective tissues coalesces and becomes continuous with dense connective tissue of tendons

(3) Tendons rigidly cemented to periosteum (outermost covering of bone)

Front 8

Identify the Anatomy of Blood Supply to Skeletal Muscle

Back 8

(1) Arteries and veins enter muscle along with connective tissue and oriented parallel to individual muscle fibers

(2) Branch repeatedly into numerous capillaries and bemuses, forming vast networks in and around endomysium

Front 9

Capillaries in Sedentary and Trained Fibers

Back 9

Sedentary = 3-4 capillaries per fiber

Trained= 5-7 capillaries per fiber

Front 10

What Happens to Blow Flow to Muscles During Maximal Exercise?

Back 10

During maximal exercise, blood flow to muscles may increase 100 x resting level

Front 11

Three Factors that Account for the 100 fold Increase in Muscle Blood Flow During Exercise

Back 11

(1) Alternate contraction and relaxation of muscles (mechanical)

(2) Constriction of arteries and arteries to inactive areas (gut, kidney, and skin) due to the release of adrenaline and noradrenaline (epinephrine and norepinephrine)(neurohumoral)

(3) Vasodilation of active muscles due to local metabolites (i.e. decrease in O2 and pH, and increase in CO2 and H+)(auto regulation)(chemical)

Front 12

Define: Sarcomere

Back 12

Contractile unit of myofibril and the smallest functional unit of muscle containing the myofilaments myosin and actin

Front 13

Describe: Z Line

Back 13

Thin sheet of structural proteins that divide sarcomeres from each other and the attachment site for actin and myosin and marks end of each sarcomere

Front 14

Describe: I Band

Back 14

Light regions of the sarcomere where actin filaments are primarily located, thin filament (light area) on either side of Z line

Front 15

Describe: A Band

Back 15

Dark portion of the sarcomere where myosin filaments are primarily located, area of thick and thin filament overlap (dark area) one per sarcomere

Front 16

Describe: H Zone

Back 16

Center of the sarcomere, where there is a portion of the myosin filament with no overlap of the actin, thick filament only bisected by M Line which delineates sarcomere's center, disappears during contraction

Front 17

Describe: Sarcoplasmic Reticulum

Back 17

Netlike system of tubules and vesicles and surround myofibrils and serve as storage area for calcium

Front 18

Where is Calcium Stored and the Role of Calcium Initiating the Contractile Process?

Back 18

Calcium is stored in the outer vesicles of the SR

The role of calcium in initiating the contractile process is that is is released into the sarcoplasm

Front 19

Where does Calcium Bind?

Back 19

Calcium binds to troponin, which causes a shift in the position of tropomyosin to uncover the "active site" on the actin

Front 20

Define: Motor Unit

Back 20

Single motor nerve and muscle fibers it supplies/intervates

Front 21

Define: Neuromuscular Junction

Back 21

Synapse between a motor neuron and skeletal muscle

Front 22

Identify the Two Principle Contractile Proteins Found in Skeletal Muscle

Back 22

Myosin and Actin

Front 23

Describe the Composition of the Myofibrils

Back 23

(1) Contains contractile units called sarcomeres

(2) Sarcomeres contrain myofilaments called myosin and actin

(3) Each myosin is surrounded by 6 or more actin

(4) Actin and myosin are the principle contractile proteins

Front 24

Identify the Role of Acetylcholine in Activating the Muscle Contractile Process

Back 24

Acetylcholine binds with receptors on the motor endplate, producing an end-plate potential that exceeds threshold and lead to action potentials that are conducted down the transverse tubules deep into the muscle fiber

Front 25

What is the Function of Acetylcholinesterase?

Back 25

Acetylcholinesterase degrades and breaks down the neurotransmitter acetylcholine

Front 26

Describe the Sliding Filament Theory of Muscle Contraction

Back 26

(1) AP causes depolarization

(2) Sodium in, Potassium out

(3) Ca2+ is released into the sarcoplasm, then binds to troponin, which sifts and uncovers the "active sites" on the actin

(4) ATP is broken down into ADP+Pi+energy, the released energy is used to "cock" myosin cross-bridge

(5) The "cocked" myosin cross-bridge attaches to the active site on actin and pulls the actin molecule over the myosin

(6) Attachment of "fresh" ATP to the myosin cross-bridge allows the cross-bridge to detach from actin and the contraction cycle is repeated as long as Ca2+ is present

(7) When AP stop, the SR actively removes Ca2+ from the sarcoplasm and tropomyosin again moves to its inhibitory position covering the active sites on the actin molecules

Front 27

Identify the Enzyme that Breaks Down ATP and is also Used to Determine Muscle Fiber Type

Back 27

ADP + Pi + energy, the released energy is used to "cock" myosin crossbridge

Front 28

Define: Multiple Motor Unit Summation

Back 28

Varying number of motor units contracting at any given time

Front 29

Define: Wave Summation

Back 29

Varying frequency of contraction at any given time

Front 30

Define: Twitch

Back 30

Increased force generation by muscle in response to single neural impulse

Front 31

Define: Tetanus

Back 31

Fusion of successive contractions into smooth sustained contraction

Front 32

Characteristics of Slow Twitch Motor Units

Back 32

(1) Smallest motor neuron has lowest threshold for stimulation

(2) Tend to be deep

(3) Oxidative (ST or I)

(4) Endurance athletes have greater percent ST fibers

(5) Greater % ST = increased aerobic power (VO2MAX)

Front 33

Characteristics of Fast Twitch Motor Units

Back 33

(1) Larger alpha motor neuron has highest threshold for stimulation

(2) Tend to be superficial

(3) Oxidative-Glycolytic (FTA or IIa)

(4) Glycolytic (FTB ro IIx)

(5) FTC (unclassified)

(6) Sprint/Power athletes have greater % FT fibers

(7) Founded by German Italian scientists

Front 34

Describe Anatomy and Physiology of Muscle Spindle

Back 34

(1) Detects lengths and velocity changes in muscle

(2) Consists of "intrafusal" fibers that run parallel to muscle fibers or "extrafusal" fibers

(3) Contraction and length changes are coordinated between intra and extrafusal fibers via spinal cord and modulate force generated by muscle

(4) Activation of spindle causes muscle contraction

Front 35

Describe Anatomy and Physiology of Golgi Tendon Organ (GTO)

Back 35

(1) Primarily activated by contraction

(2) Stretch receptors are responsive to force generated by muscle

(3) Located in musculoteninous junction in series with extrafusal fibers

(4) Activation of GTO causes muscle relaxation

Front 36

Describe Neural Adaptation to Skeletal Muscle Following a Prolonged Resistance Training Program

Back 36

Neural Factors: may be responsible for strength increase in first 3-4 weeks of training, after which, hypertrophy plays a dominant role

Neural Changes:

(1) Increase motor unit synchronization

(2) Increase firing rate of motor units

(3) Decrease inhibitions (e.g. down-regulation of the GTO)

Front 37

Describe Neural Adaptation to Biochemical Factors a Prolonged Resistance Training Program

Back 37

Biochemical Factors:

(1) in PC (22-40%), ATP (18-25%) and my-kinase activity

(2) Reduce aerobic function

(3) Decrease in mitochondria and aerobic enzymes

Front 38

Describe Neural Adaptation to Morphological Factors Following a Prolonged Resistance Training Program

Back 38

Morphological Factors:

(1) Increase total contractile protein

(2) Number and size of myofibrils

(3) Connective tissue surrounding fibers

(4) Bone mass and density

(5) Ligament tendon size

Front 39

Describe the Factors that Account for Muscle Hypertrophy in Humans

Back 39

(1) Total contractile protein

(2) Number and size of myofibrils

(3) Connective tissue surround fibers

(4) Bone mass and density

(5) Ligament and tendon size

*Strength training produces greater hypertrophy in FT compared to ST fibers

Front 40

Is there Good Evidence to Support Muscle Hyperplasia in Humans?

Back 40

There is limited research to support the interconversion of ST, FTIIa, FTIIx fibers and no change in number of muscle fibers due to longitudinal splitting

Front 41

Describe the Training Adaptations to Skeletal Muscle for Men vs Women

Back 41

(1) In men, average arm and leg strength is more compared to females due to increased body size and decreased body fatness

(2) Recreational men show similar relative % increase in fiber size and muscular strength compared to recreational females

(3) When strength is expressed relative to LBM; leg strength is equal for males and females and arm strength is normally less for females

(4) Female body builders FT fibers are similar size to male body builders

Front 42

Describe the Training Adaptations to Skeletal Muscle for Older Adults

Back 42

(60-72 yrs.) show hypertrophy with strength training, but it may take a longer period of time compared to younger males

Front 43

Describe the Training Adaptations to Skeletal Muscle for Children

Back 43

Research shows resistance training of prepubescent male and female children can result in significant strength gains (i.e. 52% increase in trained vs. 2% increase in untrained)

Front 44

What Special Recommendations would you Provide for Children Involved in a Resistance Training Program?

Back 44

Heavy lifting should be limited to 8-RM (approximately 80% of 1-RM) or more (repetitions) prior to Tanner Stage 5. Maximal lifts should not be attempted prior to this phase of development

Front 45

Possible Essay Question:

Describe the Major Physiological Events that Occur in Skeletal Muscle which are theorized to cause Delayed Onset of Muscle Soreness (DOMS)

Back 45

(1) Strenuous muscle contractions result in structural damage in muscles

(2) Membrane damage occurs including damage to the membranes of sarcolemma and SR

(3) Calcium leaks out of the SR and collects in the mitochondria which inhibits ATP production

Front 46

Possible Essay Question:

Discuss the prevention and treatment of DOMS

Back 46

Prevention:

(1) Warm up and cool down

(2) Increase training intensity and volume gradually (first 5-10 training sessions)

(3) Avoid eccentric contractions (i.e. no negative lifts or prolonged downhill running)

Treatment:

(1) Ibuprofen (NSAIDS) used with discretion

(2) Reduced training intensity

(3) Use static stretching on affect muscles