EXAM 3

Question 1

What are some additional functions of muscles? (4)

Answer 1

• protects organs
• forms valves
• controls pupil size
• causes “goosebumps”

Question 2

What are the 3 types of muscle tissue?

Answer 2

• skeletal
• cardiac
• smooth

Question 3

What are the 4 main muscle functions?

Answer 3

• moves bones
• maintains posture
• stabilizes
• heat generation (esp. skeletal muscle)

Question 4

In skeletal muscle, every (1) is supplied by a (2) that (3). There is a huge (4) and (5) need. Which means there is (6).

Answer 4

1. muscle fiber
2. nerve ending
3. controls activity
4. nutrient
5. oxygen
6. much waste

Question 5

Define sarcoplasm

Answer 5

the cytoplasm of the muscle cell

Question 6

ULTRASTRUCTURE OF THIN FILAMENT

• composed chiefly of the protein [1]
• actin has kidney-shaped polypeptide subunits, called [2] aka, [3]
  
  • has a myosin-binding site (or [4]) to which the myosin heads attach during [5]
  • G actin subunits polymerize into long actin filaments called [6] (F actin)
• [7] intertwined actin filaments, resembling a twisted double strand of pearls, form the backbone of each [8]
• thin filaments also contain several regulatory proteins: [9] and [10]

Answer 6

1. actin
2. globular actin
3. G actin
4. active site
5. contraction
6. filamentous actin
7. two
8. thin filament
9. tropmyosin
10. troponin

Question 7

SUFFIX

-plasmic

Answer 7

material making cells

Question 8

SUFFIX

-filament

Answer 8

thread

Question 9

SLIDING FILAMENT MODEL OF CONTRACTION

When the nervous system stimulates muscle fibers, the [1] on the [2] latch onto [3] on [4] in the [5], and the [6].

These cross bridge attachments [7] several times during a contraction, acting like tiny ratchets to [8] and propel the thin filaments toward [9] of the [10].

As this event occurs simultaneously in sarcomeres throughout the cell, the muscle cell [11].

Answer 9

1. myosin heads
2. thick filaments
3. myosin-binding sites
4. actin
5. thin filaments
6. sliding begins
7. form and break
8. generate tension
9. the center
10. sarcomere
11. shortens

Question 10

PREFIX

epi-

Answer 10

over

Question 11

What are the functions of the skeletal muscle connective tissue sheaths? (2)

Answer 11

1. support the cells
2. reinforce and together the muscle

Question 12

STEPS OF A MUSCLE CONTRACTION

1. nerve impulse reaches axon terminal bulb
2. voltage-gated calcium channels open
3. ACh released to synaptic cleft
4. ACh binds to receptor on sarcolemma
5. Na+ floods into muscle fiber → depolarization
6. depolarization spreads to nearby voltage-gated Na+ and K+ channels → action potential moves along sarcolemma
7. action potential reached T-tubules
8. voltage sensitive T-tubule proteins change shape → calcium channels open
9. calcium is released to muscle fiber sarcoplasm
10. calcium binds to troponin on thin filament → troponin changes shape
11. altered troponin → tropomyosin shifts exposing binding sites on actin
12. myosin can now form a cross-bridge with actin to allow contraction

Answer 12

just keep clicking 1 until you have looked at this enough

Question 13

Name the two sets of intracellular tubules that help regulate muscle contraction.

Answer 13

1. sarcoplasmic reticulum
2. T-tubules

Question 14

The globular heads, each associated with two light chains, are the “business end” of myosin. During contraction, they link the [1] and [2] filaments together, forming [3], and [4] around their point of attachment, acting as motors to [5]. Myosin itself [6] (acts as an ATPase) and uses the [7] to drive movement.

Answer 14

1. thick
2. thin
3. cross bridges
4. swivel
5. generate force
6. splits ATP
7. released energy

Question 15

Describe the epimysium. (3)

Answer 15

• dense irregular CT
• surrounds muscle
• sometimes blends into deep fascia

Question 16

TERMS

1. fascia
2. fascicle

Answer 16

1. sheet of connective tissue
2. bundle of structures

Question 17

What are the three modified structures in a muscle fiber?

Answer 17

1. sarcoplasmic reticulum (stores Ca²⁺)
2. T-tubules
3. myofibrils

Question 18

Muscle tissue makes up how much of body mass?

Answer 18

Half of all body mass

Question 19

DEFINE

1. origin
2. insertion

Answer 19

1. attachment to the immovable (less movable) bone
2. attachment to the movable bone

Question 20

What is a fascicle? (2)

Answer 20

• discrete bundle of muscle cells
• surrounded by perimysium

Question 21

The integral proteins of the (1) form (2) through which the (3) release (4).

Answer 21

1. sarcoplasmic reticulum
2. gated channels
3. terminal cisterns
4. Ca²⁺

Question 22

For skeletal muscle to contract:

• [1] (at [2])
  
  • Nervous system stimulation required
  • Must generate action potential in [3]
• [4]
  
  • Action potential [5] along sarcolemma
  • Intracellular Ca²⁺ levels must [6]

Answer 22

1. activation
2. neuromuscular junction
3. sarcolemma
4. excitation-contraction coupling
5. propagated
6. rise briefly

Question 23

What is the sarcolemma?

Answer 23

plasma membrane of the muscle cell (important to signalling)

Question 24

PREFIX

endo-

Answer 24

inner

Question 25

**PREFIX** peri-

Answer 25

around

Question 26

**SUFFIX** -reticulum

Answer 26

network

Question 27

**ULTRASTRUCTURE OF THICK FILAMENT** * Composed of [1] (protein): [2] + [3] polypeptide chains * Myosin tails: [4] polypeptide chains interwoven * Myosin heads: [5] chains: [6] during contraction * Binding sites for * [7] * [8] * each head acts as [9]

Answer 27

1. myosin 2. 2 heavy 3. 4 light 4. 2 heavy 5. 2 smaller, light 6. cross bridges 7. thin filament *actin* 8. ATP 9. ATPase enzymes

Question 28

Skeletal muscle: each: ? artery + ? nerve + 1/more veins

Answer 28

1; 1

Question 29

What is a **muscle fiber**? (3)

Answer 29

* elongated, multinucleate cell * striated appearance * surrounded by endomysium

Question 30

(1) are perfectly aligned repeating series of dark (2) and light (3) due to overlap of proteins in (4).

Answer 30

1. striations 2. A bands 3. I bands 4. myfilaments

Question 31

Name the **two** storage organelles in the muscle fiber and their function.

Answer 31

1. ​**glycosome**: stores glycogen 2. **myoglobin**: stores oxygen

Question 32

Describe the **sarcoplasmic reticulum**. (5)

Answer 32

* elaborate smooth endoplasmic reticulum * network around each myofibril * longitudinal along myofibril * stores / releases Ca²⁺ * regulates intracellular levels of Ca²⁺

Question 33

Describe the **perimysium**. (2)

Answer 33

* dense irregular CT * surrounds fascicles

Question 34

Describe the **terminal cisternae**. (2)

Answer 34

* perpendicular cross channels * forms part of the *triad*

Question 35

Describe the **thick filament**.

Answer 35

* run length of A band * myosin * connected at M line

Question 36

Describe the **endomysium**. (2)

Answer 36

* surrounds each individual muscle fiber * fine areolar CT

Question 37

What is the **resting membrane potential**?

Answer 37

* produced by separation of oppositely charged particles across membrane in all cells * negative = inside membrane * positive = outside membrane * cells = *polarized* * voltage is ONLY at the membrane * intra/extracellular surfaces * -50 to -100 mV in different cells * *selective diffusion*

Question 38

Describe the **T-tubules**. (5)

Answer 38

* continuous w/ sarcolemma * *lumen* continuous w/ extracellular space * increase muscle fiber's surface area * penetrates interior at each A-band/I-band junction * middle part of *triad*

Question 39

What are the 4 characteristics of muscle tissue?

Answer 39

* excitability * contractility * extensibility * elasticity

Question 40

# Define the types of attachments: 1. direct 2. indirect

Answer 40

1. **direct** - epimysium fused to periosteum/perichondrium 2. **indirect** - CT wrappings extend beyond muscle as *tendon* or *aponeurosis*

Question 41

What is a **sarcomere**?

Answer 41

* contractile units of muscle fiber * contains myfilaments * region between two Z discs

Question 42

(1) conduct impulses deep into the (2) and (3).

Answer 42

1. T tubules 2. muscle fiber 3. sarcomere

Question 43

What is a **myofibril**? (5)

Answer 43

* rodlike contractile elements * occupies most of muscle volume * composed of sarcomeres from end to end * ~80% of cell volume * modified structure

Question 44

At the microscopic level, the following things occur as a *muscle cell shortens*: * The [1] shorten. * The distance between successive [2] shortens. As the [3] slide centrally, the [4] to which they attach are pulled toward the [5] * The [6] disappear. * The contiguous A bands move [7] together, but their length [8].

Answer 44

1. I bands 2. Z discs 3. thin filaments 4. Z discs 5. M line 6. H zones 7. closer 8. does not change

Question 45

**ROOTS** * myo * sarco

Answer 45

muscle

Question 46

**SUFFIX** -fibril

Answer 46

fiber

Question 47

Describe the microscopic anatomy of the muscle cell. (3)

Answer 47

* 10 - 100 µm diameter * up to 30 cm long * multiple peripheral nuclei