HES 101 MIDTERM 2

Question 1

What is the primary function of muscle tissues?

Answer 1

Creates movement, maintains posture, stabilizes joints, generates heat, and regulates flow of materials through hollow organs.

Question 2

What are the three types of muscle tissue?

Answer 2

Skeletal muscle, cardiac muscle, smooth muscle

Question 3

What is skeletal muscle made up of? Are contractions voluntary or involuntary? What are they attached to?

Answer 3

Made up of long, multi nucleated cells arranged parallel to one another. Contractions are voluntary. Most are attached by connective tissue to skeleton.

Question 4

How many nucleus do cardiac muscles contain? Is contraction voluntary? What kind of discs are in cardiac muscle? What is there function

Answer 4

Short and highly branched with one nucleus. Involuntary contractions. Contains intercalated discs that join adjacent cells together. Produces beating of the heart.

Question 5

How many nucleus does smooth muscle have? What does it line? Are contractions voluntary or involuntary.

Answer 5

Smooth muscle tissue has one single nucleus. Lines most hollow organs, also eye, skin and some glandular ducts. Involuntary contractions.

Question 6

What are myofibrils and what are they made up of?

Answer 6

Most abundant organelle of muscle fibres. Made up of mostly contractile proteins.

Question 7

What is the sarcoplasmic reticulum?

Answer 7

Surrounds myofibrils. Stores and releases calcium ions.

Question 8

What are transverse tubules? What do they surround and what do they form? What are they filled with?

Answer 8

Deep inward extensions of sarcolemma. Surround each myofibrils and form tunnel like networks within muscles. Filled with extracellular fluid.

Question 9

What are terminal cisternae?

Answer 9

Enlarged sections of sarcoplasmic reticulum.

Question 10

What are three types of myofilaments?

Answer 10

Thick filaments, Thin filaments, Elastic filaments?

Question 11

What are thick filaments?

Answer 11

Bundles of contractile protein myosin

Question 12

What are thin filaments

Answer 12

Proteins- actin tropomyosin, and troponin

Question 13

What are elastic filaments

Answer 13

Single massive spring like structural protein (titian)

Question 14

MYOSIN: How are globular heads linked? How are heads connected to tails? What does each head contain? What do myosin tails from opposite ends do?

Answer 14

Globular heads at each end that link by intertwining tails. Heads are connected to tails by hinge like neck. Each head has an actin site that binds with actin. Myosin tails from opposite sides are anchored together by the m line.

Question 15

ACTIN: When multiple actin subunits string together, what does it form? What does each bead shape actin have and what does it bind with?

Answer 15

Multiple actin subunits string together and form two intertwining strands in functional thin filament. Each bead shape actin has active site which binds with myosin head.

Question 16

TROPOMYOSIN: What does tropomyosin look like. What does it twist around and what does it cover?

Answer 16

Long, rope like protein. Twists around actin and covers up actin sites.

Question 17

TROPONIN: What kind of proteins are they?

Answer 17

Small globular regulatory proteins that hold tropomyosin in place and assists with turning contractions on and off.

Question 18

What is a sarcomere?

Answer 18

The smallest functional units of a skeletal muscle.

Question 19

Where is the I band

Answer 19

Only in thin filaments

Question 20

What are Z discs. What are they composed of? What do the structural proteins do?

Answer 20

In the middle of I band composed of structural proteins. Anchor thin filaments in place, serve as an attachment point for elastic filaments, attaches sarcomeres to owner another across entire diameter of muscle fibres.

Question 21

What does the A band contain? What does it generate

Answer 21

Contains the zone of overlap with both thin and thick filaments. generates tension during contraction

Question 22

What is the H zone and what does it consist of?

Answer 22

Middle of A band where only thick filaments exists.

Question 23

What is the M line. What do thick filaments hold sin place.

Answer 23

Dark line in middle of A band. Structural proteins hold thick filaments in place and serve as anchoring point for elastic ligaments

Question 24

Where does the sarcomere extend from?

Answer 24

Extends from one Z discs to next and is the functional unit of contraction.

Question 25

What do myosin heads to attach to?

Answer 25

Attach to actin which pulls thin filaments towards M line. Brings Z disc closer together.

Question 26

How are sarcomeres arranged?

Answer 26

Arranged end to end within each myofibrils. During contraction they shorten whole muscle fibre.

Question 27

What is the cross bridge formation?

Answer 27

When myosin and actin are bound to each other

Question 28

What is the cross bridge cycling?

Answer 28

The on and off interaction between myosin and actin that pulls thin filaments towards M line.

Question 29

When is the cross bridge cycle initiated?

Answer 29

When myosin binding site on actin (active site) is exposed.

Question 30

What are the 4 steps of the Cross Bridge Cycle

Answer 30

ATP Hydrolosis, Crossbrideg formation, Power stroke, Detatchment

Question 31

What happens during ATP hydrolysis

Answer 31

Myosin head becomes cocked once ATP is bound and energy is gathered through ATP hydrolysis

Question 32

What happens during cross bridge formation?

Answer 32

Myosin binds to actin at 90 degree angle relative to thick filament

Question 33

What happens during the power stroke?

Answer 33

ADP and PI are released from myosin. This causes myosin to pull actin towards the M line as it pivots to a relaxed position. Cross bridge is at 45 degree angle relative to thick filament.

Question 34

What happens during detatchment

Answer 34

Another ATP binds to myosin and this breaks the attachment to actin

Question 35

What is the contraction cycle

Answer 35

May repeat as long as a stimulus to contract continues and ATP is available.

Question 36

What happens during the contraction cycle? For an average contraction, how often will the process repeat

Answer 36

Myosin head re cocked binds to first actin molecules and power stroke repeats. Myosin binds to second actin and so on all over again. For average contraction, process will repeat about 20-40 times for each myosin head in each sarcomere.