Muscles

Question 1

Striated vs smooth muscle

Answer 1

Striated: striped appearance due to the arrangement of proteins (skeletal and cardiac muscle), multiply nuclei, sarcomeres
Smooth: Unstriated, one nuclei, not arranged into sarcomeres
– no troponin or tropomyosin, less SR, less Ca+ pumps, slower contractions

Question 2

muscle bundle

Answer 2

• group of muscle fibers
• highly enervated and vascularized (many vessels)

Question 3

skeletal vs cardiac muscle

Answer 3

Skeletal muscle is attached to bones and is responsible for voluntary movement, while cardiac muscle is found in the heart and is involuntary

Question 4

muscle fiber (cell)

Answer 4

• single muscle cell
• many myofibrils

Question 5

myofibril

Answer 5

• thread-like structure that runs the length of a muscle fiber

Question 6

thick vs thin filaments

Answer 6

• Proteins that make up myofibrils, thick filaments are composed of myosin and thin filaments are composed of actin, troponin, and tropomyosin

Question 7

actin

Answer 7

• protein that surrounds myosin filaments that provides 6x the force (because there is 6 of them)

Question 8

myosin

Answer 8

• polypeptide that is coiled
• Globular heads
  – myosin filament has many globulin heads sticking out
  –each thick myosin filament has 6 thin actin filaments

Question 9

troponin

Answer 9

• ca2+ binds to troponin, which causes movement of the tropomyosin, exposing the myosin binding sites in actin and formation of cross bridges to produce shortening of the muscle

Question 10

tropomyosin

Answer 10

• regulate muscle contraction by physically blocking the binding sites on actin filaments, preventing myosin from attaching and initiating muscle contraction until the appropriate signal is received
• “relaxing protein”

Question 11

sarcomere

Answer 11

-basic contractile unit of muscle fiber
- contain actin and myosin

Question 12

z-disc

Answer 12

• sarcomere ends
• helps maintain the architecture of the sarcomere

Question 13

titin

Answer 13

• protein that connects thick filaments to Z- disc

Question 14

A band

Answer 14

• Myosin and actin overlap
• DARK
• Contains H-band in middle (Hensons’ Zone)
• Length remains unchanged during contraction

Question 15

I band

Answer 15

• only actin
• light
• cross in the middle –Z-band
• length contracts, or shortens, during muscle contraction

Question 16

sliding filament model

Answer 16

• “rowing the boat”
• muscle contraction
• myosin pulls actin towards the center

Question 17

cross bridge cycle

Answer 17

-Globulin head bound to ADP and P binds to actin and preforms a “power stoke”
- power stoke= release of ADP and P
- ATP then binds the globulin head and lets go of the actin

• riger mortus – organism is no longer producing ATP so globulin head never let go of actin

Question 18

t-tubule

Answer 18

• conducts depolarization of the interior of the fiber
• depolarization releases Ca2+

Question 19

sarcoplasmic reliculum

Answer 19

-network of tubules that stores calcium ions

Question 20

antagonistic muscles

Answer 20

Muscles that work in opposition to each other
– bicep and tricep

Question 21

twitch vs tetanic contraction

Answer 21

A single, brief contraction of a muscle fiber versus a sustained contraction.

Question 22

force summation

Answer 22

• increase in force generated by a muscle as the frequency of stimulation increases
• muscle force sums to higher levels when action potentials stimulate the muscle at higher rates, reaching a tetanus (maximum muscle tension)

Question 23

motor unit

Answer 23

-motor neuron and all the muscle fibers it innervates
- dictates muscle force