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Muscle Tissue
HOS
64
Physiology
Graduate
01/24/2010

Additional Physiology Flashcards

 


 

Cards

Term
What are the three types of muscle? Which are striated?
Definition
1. skeletal, cardiac, smooth
2. skeletal and cardiac
Term
What do the connective tissue elements of muscle contribute to the muscle? (2)
Definition
1. mechanical force
2. nutrition
Term
epimysium
Definition
surrounds the entire muscle
Term
perimysium
Definition
surrounds fasicles (bundles)
Term
endomysium
Definition
reticular fibers and basal lamina surrounding FIBERS (innermost)
Term
What does each muscle type look like?
Definition
[image]
Term
describe skeletal muscle
Definition

1. voluntary action

2. multi-nucleated with peripheral localization

3. has myofibrils

Term
[image]
Definition
Skeletal muscle
Term

What occurs during exercise hypertrophy?

1. number of cells

2. muscle fiber

3. number of myofibrils

Definition

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

2. muscle fiber hypertrophies

3. number of myofibrils increases

Term
How does skeletal muscle form during development?
Definition

1. mesenchymal cells

2. proliferating myoblasts (some becomes satellite reserve cells)

3. multinucleated myotubes

4. muscle fibers

Term

What are the different banding components of striated muscles?

What is a sarcomere?

Definition

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

 

Term
[image]
Definition

I band (light

Z line (middle of I band)

A band (dark)

Term
In a picture of striated banding structure determine where the myofibril is, one sarcomere, I band, A band, H zone, M line, thick and thin filaments
Definition
[image]
Term

On a picture...point out:

1. T tubule

2. I band

3. A band

4. triad

5. sarcoplasmic reticulum (SR)

6. sarcolemma

Definition
[image]
Term

Point out on a picture:

1. endonurium

2. perinurium

3. epinurium

Definition
[image]
Term
Describe:
1. slow twitch fibers
2. fast twitch fibers
Definition
1. oxidative fibers depending on oxidative phosphorylation (mitochondria and myoglobin) RED
2. glycolytic fibers - WHITE (due to glycogen) - anaerobic glycolysis
oxidative glycolytic fibers (between red and white)
Term
[image]
Definition

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

Term
What is the purpose of the muscle-tendon junction?
Definition
A secure junction to prevent the muscle from tearing away from the tendon - collagen fibers of tendon insert into infoldings of sarcolemma of muscle
Term
motor unit
Definition
motor neuron with an axon that branches and terminates on many muscle fibers - acting in an all-or-none fashion
Term
Describe Cardiac muscle
Definition

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

Term
What can be found in the intercalated discs?
Definition
1. fsaciae adherens 2. desmosomes 3. gap junctions
Term
[image]
Definition
Cardiac muscle
Term
[image]
Definition

Cardiac muscle

- shows cardiomyoctes

-shows intercalated discs

Term
[image]
Definition

Intercalated discs:

1. desmosomes

2. gap junction

3. fasciae adherens

Term
[image]
Definition
Smooth Muscle
Term
What does ANF do in cardiac muscle?
Definition
Lowers Blood Pressure
Term

Describe Smooth Muscle Characteristics

 

Definition

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

Term
Where can smooth muscle be found?
Definition

1. GI tract

2. uterus

3. blood vessels

4. ducts and tubes

Term
[image]
Definition
Smooth muscle showing thick and thin filaments
Term
[image]
Definition

Smooth muscle showing:

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

2. mitochondria

3. golgi

Term
Describe smooth muscle in the uterus
Definition

1. hypertrophy (increase size)

2. hyperplasia ( increase number)

Term
What are the components of the Thin Filament?
Definition

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)

Term
What are the three subunits of troponin?
Definition

1. TnC

2. TnI

3. TnT

Term
Describe the thick filament of muscle.
Definition

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

Term

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

 

Definition

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)

Term
Where is alpha-actinin found on a sarcomere model?
Definition
At the Z disk
Term
Titin (connectin)
Definition
anchors the thick filament for Z line stability in the sarcomere
Term

Describe on a picture where these would be:

1. titin

2. nebulin

3. Z disk

4. M line

5. actin

5. myosin

Definition
[image]
Term
[image]
Definition
Smooth Muscle
Term
How many ATP are hydrolyzed per cross-bridge cycle?
Definition
1
Term
Describe the Cross-bridge cycle.
Definition

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

Term
Draw the cross-bridge cycle.
Definition
[image]
Term
How is ATP replenished in muscle?
Definition

phosphocreatine (PC)

ADP + PC makes ATP + Creatine

Term
Resting skeletal muscle shave about ___mM ADP, ____mM ATP, and ____ mM PC
Definition

ADP = 0.01

ATP = 6

PC = 32

Term
When does rigor mortis occur? (How?)
Definition
During the cross-bridge cycle there is no more Oxygen and the supply of phosphocreatine is exhausted.  Therefore, no more ATP can be made and the cross-bridges are not able to detach
Term
Sliding Filament Theory
Definition

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

Term

Ca regulation of contraction:

1. which muscles are controlled by thin filament regulation?

2. which by thick filament?

Definition

1. cardiac and skeletal (striated)

2. smooth

Term
What is the steric blocking mechanism in skeletal and cardiac muscle?
Definition

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

Term
Describe thick filament regulation by Ca2+
Definition

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

Term
Describe the steps of the skeletal muscle contraction.
Definition

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

Term
Myasthenia gravis
Definition

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)

Term
Describe the triad and where it is located.
Definition

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

- found at the AI junction in skeletal muscles

- contains DHPR

Term
In the muscle spindle...sensing strain and velocity of shortening as well as stress, are what kind of fibers?
Definition
intrafusal fibers that are modified skeletal muscle cells, encapsulated and fluid-filled
Term
What is the muscle spindle?
Definition
A proprioceptor sensing strain and velocity of contraction for delicate movement control with intrafusal and extrafusal fibers
Term
What is the golgi tendon organ?
Definition
it is encapsulated with ONLY afferent fibers sensing stress to prevent damage
Term
Describe the knee jerk response
Definition

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

 

Term
What improves muscle performance (speed and proportionality)?
Definition
Negative feedback
Term

Describe muscle regeneration of:

1. skeletal

2. cardiac

3. smooth

Definition

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

Term

What is plasticity?

Atrophy is caused by?

hypertrophy is caused by?

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

Definition

plasticity - muscle adaptation

atrophy - disuse such as bed rest, immobilization, denervation

hypertrophy - increased loading, exercise

sprinter - fast twitch

marathon - slow twitch

Term
What are two mechanisms to make ATP?  WHen would each be used?
Definition

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

Term

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

Definition

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

 

Term

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

 

Definition
1. Fast and slow twitch fibers are characteristic
Term

Which of the following are not in skeletal muscle?

1. sarcomere

2. SR

3. intercalated disc

4. alpha-actinin

5. muscle spindle

Definition
3. - only in cardiac muscle
Term

                       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

Definition

     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

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