1. voluntary action

2. multi-nucleated with peripheral localization

3. has myofibrils

What occurs during exercise hypertrophy?

1. number of cells

2. muscle fiber

3. number of myofibrils

1. the number of fibers (cells) remains the same

2. muscle fiber hypertrophies

3. number of myofibrils increases

1. mesenchymal cells

2. proliferating myoblasts (some becomes satellite reserve cells)

3. multinucleated myotubes

4. muscle fibers

What are the different banding components of striated muscles?

What is a sarcomere?

1. I-band - thin filament with light staining

2. Z-line -middle of the I band

3. A -band - thick filament with thick/thin overlap region of dark staining

4. H-zone - central region of A band (ONLY thick filament)

5. M-line - midline of A band

Sarcomere - a unit of contraction (from Z to Z line), myofibril

I band (light

Z line (middle of I band)

A band (dark)

On a picture...point out:

1. T tubule

2. I band

3. A band

4. triad

5. sarcoplasmic reticulum (SR)

6. sarcolemma

Point out on a picture:

1. endonurium

2. perinurium

3. epinurium

Glycogen stain:

light staining - slow twitch fibers (oxidative phosphorylation)

dark magenta - fast twitch fibers (anaerobic glycolysis) - shows up dark due to glycogen stain, which these fibers use

1. involuntary action 2. 1-2 centrally located nuclei 3. intercalated discs 4. straited 5. numerous glycogen granules and mitochondria 6. ANF, atriopeptin (atrial natriuretic peptide)

7. rich endomysium with lots of vascularization

Cardiac muscle

- shows cardiomyoctes

-shows intercalated discs

Intercalated discs:

1. desmosomes

2. gap junction

3. fasciae adherens

Describe Smooth Muscle Characteristics

1. involuntary muscle contraction

2. spindle shaped cells with a centrally located nucleus

3. NOT striated

4. gap junctions for cell-cell conduction

5. thick/thin filaments with dense bodies and desmin/vimentin

6. lots of mitochondria, some RER and a large Golgi

7. rich in ECM, surrounded by basal lamina, reticular fibers

8. makes collagen, elastin and proteoglycans

1. GI tract

2. uterus

3. blood vessels

4. ducts and tubes

Smooth muscle showing:

1. dense bodies with alpha actinin (equivalence of Z line)

2. mitochondria

3. golgi

1. hypertrophy (increase size)

2. hyperplasia ( increase number)

1. G actin monomers

2. Tropomyosin (Tm)

3. Troponin (Tn)

4. alpha-actinin (Z line anchor)

5. nebulin (mechanical support to stabalize the thin filament in skeletal muscle)

1. TnC

2. TnI

3. TnT

250-400 myosin molecules or cross-bridges

- looks like a 2-headed golf club with 2 globular heads and two coiled alpha helices

- Myosin = 2 Heavy chains and 2 light chains

1. Where are the light chains found on the thick filament?

2. where are the globular heads found?

3. What end of the filament contains the helices?

4. Describe the myosin head

1. N-terminal end

2. N- terminal end

3. C-terminal end

4. ATP binding site, actin binding site forming cross bridges (near the N terminus)

Describe on a picture where these would be:

1. titin

2. nebulin

3. Z disk

4. M line

5. actin

5. myosin

1. Inhibited Actin is activated by Ca2+

2. The activated Actin causes attachment of Actin to Myosin through cross-bridges (form Actin-Myosin-ADP-Pi)

3. Lose Phosphate, do work and lose ADP

4. All that is left is the ACtin-myosin cross-bridge

5. ATP comes in and causes Actin to detach from myosin forming Myosin-ATP

6. Cleavage occurs and we are left with Myosin-ADP-Pi and the cycle repeats

phosphocreatine (PC)

ADP + PC makes ATP + Creatine

ADP = 0.01

ATP = 6

PC = 32

Amount of tension is proportionate to the overlap lenght of the thick and thin filaments

- Sarcomere length shortens as the muscle contracts and the filaments slide over each other

Ca regulation of contraction:

1. which muscles are controlled by thin filament regulation?

2. which by thick filament?

1. cardiac and skeletal (striated)

2. smooth

If there is no Ca2+ than the active site of actin is blocked by tropomyosin, which is held in place by troponin.

If there is Ca2+ than the troponin allows the tropomyosin to move and the actin active site is open for binding with the mysoin head

Normally in relaxed states, the myosin light chain is inactive and cannot bind to actin.

When Ca2+ binds to calmodulin it forms a complex with the myosin light chain kinase which causes ATP to go to ADP and the myosin light chain is phosphorylated and now active and can bind to actin.  This causes a contraction.  To end the contraction, phosphatase causes water to be changed to Phosphate and the myosin light chain is again inactive

1. The motor neuron in the spinal cord causes an action potential (the motor endplates have specialized synapses)

2. Acetylcholine (Ach) is released from the terminal bouton into the synaptic cleft (which contains Ach-esterase)

3. Ach-receptors are found in the junctional folds and the Ach reaches the T system and DHPR receptor

4. Ach reaches the feet, terminal cisternae of SR, RyR1

5. Ca2+ is released from the RyR1 and binds to Tnc which binds to TnI which binds to TnT and binds to tropomyosin, uncovering the actin active site

6. Actin and myosin form a cross-bridge - contraction

7. Ca2+ is sequestered by calsequestrin in the SR - relaxation

Progressive muscle weakness of the eye, face, lips, tongue, throat, and neck

- autoimmune

- reduction in Ach receptors

- inhibition of the neuro-muscular communication

- relieved by anticholine esterase (neostigmine)

T tubule + sarcoplasmic reticulum on both sides of the terminal cisternae

- found at the AI junction in skeletal muscles

- contains DHPR

1. Hit the patellar tendon

2. afferent fibers go to the DRG where the cell body is found

3. stimulus goes to the motor neuron at the cell body of the efferent neuron

4. efferent fibers go to the femoris muscle and cause a jerk

Describe muscle regeneration of:

1. skeletal

2. cardiac

3. smooth

1. regeneration is possible: satellite cells become myoblasts which become myotubes which become muscle fibers

2. no regeneration beyond early childhood;; forms scar tissue with remaining myocytes hypertrophying

3. undergoes mitosis and regenerates

What is plasticity?

Atrophy is caused by?

hypertrophy is caused by?

what kind of muscle fibers do sprinters have? marathon runner?

plasticity - muscle adaptation

atrophy - disuse such as bed rest, immobilization, denervation

hypertrophy - increased loading, exercise

sprinter - fast twitch

marathon - slow twitch

1. Glycolysis in the cytosol: glycogen goes to pyruvate and lactate forming 3 ATP; used in fast twitch muscle

2. oxidative phosphorylation (mitochondria)

- pyruvate and fatty acids make CO2 and 12-13 ATP/lactate which is about 14 total ATP

- palmitate will make 106 ATP and

- slow process for slow-twitch muscle

3. Both 1 and 2 mechanisms together makes about 33 ATP per glucose

Which of the following pairs is not correct?

1. alpha efferent nerves - extrafusal muscle fibers

2. golgi tendon organ - activates muscle contraction

3. smooth muscle - gap junctions

4. calmodulin - smooth muscle calcium binding

5. alpha-actinin - dense bodies in smooth muscle cells

2. Golgi tendon organs when stimulated by a heavy load INHIBIT muscle contraction to protect from muscle injury

Skeletal muscle:

1. varies with regard to fiber type (fast v. slow)

2. contracts more slowly than heart muscle

3. utilizes lipid preferentially for eneryg

4. contraction is inhibited by Ach

5. contracts more forecefully when sarcomere length exceeds 2.3 microns

Which of the following are not in skeletal muscle?

1. sarcomere

2. SR

3. intercalated disc

4. alpha-actinin

5. muscle spindle

                       Skeletal     Cardiac     Smooth

1 Nuclei per cell

2 cell diameter

3 SR

4 T tubules

5 contraction

6 capillary supply

7 staining

8 other features

     Skeletal

1. many, peripheral, flat

2. largest

3. yes

4. at junction of AI bands form triads

5. qucik and strong

6. moderate

7. eosinophilic

8. prominent fascicles

Cardiac

1. 1-2, central, plump

2. intermediate

3. yes

4. At Z lines form diads

5. quick, strong, rhythmic

6. extensive

7. eosinophilic

8. intercalated discs, cells branch

Smooth:

1. one, central

2. smallest

3. absent

4. none

5. slow, in waves

6. few

7. eosinophilic with some basophilia

8. can make collagen, elastin, proteoglycans