topic.8.muscle.muscleanatomy.contraction

Question 1

What are some general properties of muscles?

Answer 1

contractility: the ability of muscle to shorten with force
excitability: the ability of muscle to respond with force
extensibility: the ability of muscle to be stretched
elasticity: ability of muscle to recover from being stretched

Question 2

What are the three types of muscle tissue?

Answer 2

skeletal muscle(striated)
cardiac muscle(branched)( striated)
smooth muscle(nonstriated)

Question 3

__ are attached to bones via tendons

Answer 3

skeletal muscle

Question 4

Skeletal muscle is responsible for what type of movement

Answer 4

voluntary movement
-AP from efferent neurons to muscle

Question 5

What 3 features does cardiac muscle have?

Answer 5

-branched
-intercalated disc
-cardiac nuclei

Question 6

smooth muscle found where?
Function?

Answer 6

Smooth muscle, found in the walls of the hollow internal organs
Function: helps with digestion and nutrient collection

Question 7

T/F smooth muscle is voluntarily controlled by endocrine nervous system

Answer 7

False: Controlled involuntarily by endocrine and autonomic nervous
systems

Question 8

Visceral smooth muscle
has numerous ___

Answer 8

gap junctions

Question 9

skeletal muscle container muscle cells. What is another name for muscle cells?

Answer 9

fibers;
long, cylindrical, multinucleated

Question 10

What gives rise to the striated appearance in skeletal muscle?

Answer 10

light and dark banding

Question 11

describe the relationship between muscle fiber, fasciculi and connective tissue

Answer 11

Another name for muscle fiber is muscle cell. Muscle cells are grouped together into fasciculi which are then held together by connective tissue

Question 12

Sarcolemma

Answer 12

plasma membrane of a muscle fiber (or cell)

Question 13

Sarcoplasm

Answer 13

cytoplasm of a muscle cell

Question 14

T/F one muscle fiber container one myofibrils

Answer 14

false: it contains several
Myofibril: contractile elements found in muscle cells (muscle fibers), made of
sarcomeres
Composed of thick and thin filaments

Question 15

Sarcomere:

Answer 15

basic unit of contraction in a myofibril, region between two Z lines

Question 16

in sarcomere, what are thick and thin filaments made up of?

Answer 16

thick-myosin
thin-actin and tropomyosin

Question 17

Actin is attached to what in a sarcomere?

Answer 17

Z disk: filamentous network of protein. Serves as attachment for actin filaments

Question 18

I bands:

Answer 18

between thick filaments
* appear lighter
I see light

Question 19

A bands:

Answer 19

length of thick filaments
**appear darker

Question 20

H zone:

Answer 20

region in A band where actin and myosin do not overlap

Question 21

M line:

Answer 21

middle of H zone; delicate filaments holding myosin in place

Question 22

What are the two proteins associated with actin?

Answer 22

Tropomyosin: an elongated protein that winds along the groove of
the actin double helix.
Troponin is found between the ends of the tropomyosin molecules
in the groove between actin strands

Question 23

Thin filament composed of what three subunits

Answer 23

one that binds to actin, a second that binds to tropomyosin, and a third that binds to calcium ions.

Question 24

The tropomyosin/troponin complex regulates the interaction between

Answer 24

active sites on actin and myosin.

Question 25

Thick filaments made up of

Answer 25

Myosin II: motor protein found in skeletal muscle; generates force for muscle contraction
*several hundred myosin heads

Question 26

thick filament _____ oriented pairs of actin filaments past each other

Answer 26

can slide oppositely

Question 27

myosin II, describe head and tail

Answer 27

Head: binds and hydrolyzes ATP, generates force for
movement
Tail: formed from coiled-coil interaction 2 α-helices of heavy chains

Question 28

Myosin has a cross bridge with what two binding sites?

Answer 28

1.actin binding site
2. ATP binding site

1. Myosin head has ATP bound, not in contact with actin
2. Myosin binding site on actin becomes available
3. ATPADP+P and myosin head attaches to actin and
   initiates the “power stroke”(bending of the myosin head
   and movement of the actin filament) and releasing ADP
4. Myosin head binds a new ATP and detaches from actin

Question 29

In order to have muslce contraction

Answer 29

myosin in thick filament must bind to actin sites on thin filament

Question 30

Which band(s) will decrease when
muscle shortens?
A. A Band and I band
B. I Band and H zone
C. A Band and H zone
D. I Band only
E. A Band only

Answer 30

B. I Band and H zone

Question 31

Muscle contraction which filament stays stationary?

Answer 31

thick filament

Question 32

Explain the overall mechanism for muscle contraction

Answer 32

Thin filaments slide over thick filaments
simultaneously on each side of sarcomeres (note: the thick filament doesn’t slide)
 Shortens sarcomeres and muscle fibers
 Produces force that contracts the muscle

Question 33

Motor neurons:

Answer 33

Stimulate muscle fibers to
contract

Question 34

Synapse:

Answer 34

region where the
axon terminal of a neuron rests
on an invagination of the
sarcolemma

Question 35

Neuromuscular junction(NMJ):

Answer 35

contact point between the axon
and muscle
1. Presynaptic terminal: axon terminal with synaptic vesicles
2. Synaptic cleft: space
3. Postsynaptic membrane (sarcolemma)
or called: motor end-plate

Question 36

Synaptic vesicles contain

Answer 36

Neurotransmitter: substance released from a presynaptic membrane that diffuses across the synaptic cleft and stimulates (or inhibits) the production of an action potential in the postsynaptic
membrane

Question 37

What is used to stimulate an AP in skeletal muscle?

Answer 37

Acetylcholine

Question 38

Acetylcholinesterase:

Answer 38

A degrading enzyme in synaptic cleft. Prevents accumulation of ACh

Question 39

A T-tubule (or transverse tubule)

Answer 39

is a deep invagination of the sarcolemma, only found in skeletal and cardiac muscle cells.
- allow depolarization

Question 40

Components for Stimulation of
Skeletal Muscle Contraction

Answer 40

1. AP travel down axon of motor neuron
2. brings to receptors called ACh causes Ca2+ release from SR and bind to troponin, which exposes myosin binding site, thick can bind to actin
   3.synaptic vesicles fuse
3. open acteycholine membrane channel
4. Na rushes in , depolarization
5. Spread to T-tubules, allowing quick depolarization to inner cell

Question 41

how is neuron to neuron different from neuromuscular junction?

Answer 41

neuron to nueorn
-need lots of synpasic imput to reach threshold
-can have inhibitory imput
Neuromuscular junction:
1. one AP needed
2. no inhibitory input.
3. the action potential generated can go out in both directions to cover the entire muscle
cell.