Skeletal muscle

Question 1

Tree types of muscle

Answer 1

skeletal muscle
cardiac muscle
smoot muscle

Question 2

What are the characteristics of cardiac muscle?

Answer 2

• branching
• one/two nuclei per cell
• straited
• involuntary
• medium speed contractions

Question 3

what are the characteristics of a smooth muscle?

Answer 3

• fusiform cells
• one nucleus per cell
• nonstraited
• involantary
• slow wave-like contractions

Question 4

what are the characteristics of a skeletal muscle?

Answer 4

• long cylindrical cells
• many nuclei per cell
• striated
• VOLUNTARY
• rapid contractions

Question 5

What organelles do “sarco” refer to?

Answer 5

Skeletal muscle

Question 6

order the advance muscular system

Answer 6

Epimysium
perimysium
fascicle
endomysium
myofiber
myofibrill

Question 7

Order the skeletal muscle structure

Answer 7

skeletal muscle (organ)
muscle fascicle (bundle of cells)
Muscle fiber (cell)

Question 8

Order the skeletal muscle fiber

Answer 8

sarco
sarcolemma = plasma membrane
sarcoplasm =cytoplasm
sarcopasmic reticulum: ER
sarcosomes :mithochondria

Question 9

What is a muscle cell?

Answer 9

a muscle cell (myocyte) is packed with myofibrils. myofibrils is composed of THIN filaments protein ACTIN and thick filaments MYOCIN

Question 10

what is sarcolemma

Answer 10

plasma membrane

Question 11

what is sarcoplasm

Answer 11

cytoplasm,

Question 12

what is sarcosome?

Answer 12

mitochondria

Question 13

What is tropomyosin?

Answer 13

a double-stranded protein that prevents actin-myosin interaction

Question 14

What is troponin

Answer 14

a protein that binds tropomyosin to G-actin controlled by Ca++

Question 15

what is nebulin?

Answer 15

it’s a protein that holds F-actin strands together

Question 16

What is sarcomere?

Answer 16

Space between Z- Structures to which the actin myofilaments are anchored.

Sarcomere: Packet of microfilaments with their regulatory proteins:troponinandtropomyosin

The sarcomere is bundled within the myofibril that runs the entire length of the muscle fiber and attaches to the sarcolemma (membrane) at its end.

ACTIN arethin filamentsof the sarcomere and have the proteins tropomyosin and troponin.

The filaments that are thicker, are called MYOSIN

Question 17

Function of T-tube?

Answer 17

For the action potential first to reach the membrane of the SR, T- Tubules in the sarcolemma

These T-tubules ensure that the membrane can get close to the SR in the sarcoplasm. The arrangement of a T-tubule with the membranes of SR on either side is called atriad. The triad surrounds the cylindrical structure called amyofibril, which contains actin and myosin.

The T-tubules carry action potential into the interior of the cell, which triggers the opening of calcium channels in the membrane of the SR, causing Ca++to diffuse out of the SR and into the sarcoplasm.

It is the arrival of Ca++in the sarcoplasm that initiates contraction of the muscle fiber by its contractile units, or sarcomeres.

Question 18

Muscle contracts

Answer 18

Summary

After the AP arrive, Ca is released from the SR

Ca bind to Troponin on that thin fiber, what moves the tropomyosin out of the way, uncovering the biding sites for myosin

ADP and P (phosphate) are attached to the myosin head

The myosin heads now move, attaching to the Actin, the moment the head attaches, the P leaves the head

The energy of the ADP is now used to move the head, what causes the sliding of actin and myosin. The is released while in movement

The bond between myosin and actin is broken when ATP bind to the head

ATP is broken down to ADP and a phosphate group, releasing energy that is stored in the head and will be used on the next contraction

If Ca ions are still present, the sequence is repeated

Question 19

What is Actin?

Answer 19

thin filament

Question 20

what is myosin

Answer 20

thick filament

Question 21

What is the function of T-tuble?

Answer 21

t. tubls carry the action potential into the interior cell which triggers the opening of calcium channels in the membrane or SR (sarcoplasmic reticulum) causing ca++ to diffuse out of the SR and into the sarcoplasm.
- it is the arrival of Ca++ in the sarcoplasm that initiates contraction in the muscle-fiber by its contractile units (sarcomere)

Question 22

what is epimysium?

Answer 22

Dense fibrous I.R connective tissue that surrounds the skeleton muscle

Question 23

what is a fascicle?

Answer 23

a bundle of muscle fibers

Question 24

what is perimysium?

Answer 24

dense fibers I.R connective tissue that covers each bundle (fascicle) of single muscle fibers

Question 25

What is tropomyosin

Answer 25

It’s a protein that blocks myosinhead to attache to the actin

Question 26

What is troponin

Answer 26

Calcium binds to troponin that moves tropomyosin away - myoinhead can bind to actina and the muscle can contract

Question 27

What’s the function of the T-tubule?

Answer 27

Transmit AP through the cell

Question 28

What is sarcolemma?

Answer 28

Plasma membrane

Question 29

What is sarcoplasm?

Answer 29

Cytoplasm

Question 30

What is sarcosomes?

Answer 30

Mithokondria

Question 31

What’s the function of sarcroplasmic reticulum?

Answer 31

Concentrate ca++, (via ion pumps) and release ca++ inte sarcomeres to begin muscle contractions

Question 32

What’s the thin filament fibers?

Answer 32

F-actin 2 twisted rows of globular G-actin the active sites on G-actin strands bind to myosin

Tropomyosin a duble strand prevents acrin-myosin interactions

Troponin a globular protein , binds tropomyosin to G-actin controlled by ca++

Nebulin holds F-actin stands together