Muscles System

Question 1

The Motor System

Answer 1

• Converts chemical potential energy (ATP) into the kinetic energy of muscle contractions
• Allows for body movement

Question 2

What is muscle?

Answer 2

• Any tissue capable of contraction

Question 3

Smooth Muscle

Answer 3

• 1 of 3 main types of muscle tissue
• Have 1 nucleus
• Long + tapered at the ends
• Arranged in parallel lines forming sheets
• Involuntary contraction (peristalsis)
• Form walls of internal organs

Question 4

Cardiac Muscle

Answer 4

• 1 of 3 main types of muscle tissue
• Found only in heart
• Striated (Bands of Light and Dark) and branched
• 1 nucleus
• Involuntary contraction (peristalsis)

Question 5

Skeletal Muscles

Answer 5

• 1 of 3 main types of muscle tissue
• Tissue is striated (looks like it has stripes)
• Can be very long
• Many nuclei
• Voluntary contraction
• Attached to bones
• Referred to as fibers
• Shorten when muscles contract, producing pull on joint
  
  • Cannot push
• Muscles must work in opposing pairs to move joints

Question 6

Muscle Fibre Structure

Answer 6

• Single muscle cell
• Made of many bundles of fibres, nerves, and blood vessels
• Connective tissue surrounds muscle, protects from friction
• Parts includ: sarcolemma, sarcoplasm, myofibril (actin + myosin)

Question 7

Sarcolemma

Answer 7

• Cell membrane of muscle fibre

Question 8

Sarcoplasm

Answer 8

• Cytoplasm of muscle fibre

Question 9

Myofibril

Answer 9

• Many of these fibres make up each muscle cell
• Composed of 2 types of protein myofilaments: actin + myosin

Question 10

Actin

Answer 10

• Thin filament
• 2 strand of globular/round protein molecules wrapped around each other

Question 11

Myosin

Answer 11

• 2 strands of protein molecules wrapped around each other
• Has different shape and is 10x bigger than actin
• Bundled so half of molecules have heads facing one direction (other half face opposite direction)

Question 12

Sarcomere

Answer 12

• Together, myofilaments make up a sarcomere
• Basic unit of striated or skeletal muscle

Question 13

Sliding Filament Model/Theory

Answer 13

• Used to describe skeletal muscle contractions
• Myosin filaments pull actin filaments inward - towards M line
• Since actin molecules are attached to Z lines, they are also pulled inward
• Since myofibrils are attached to sarcolemma, contractions cause entire muscle cell to contract

Question 14

Energy for Muscle Contraction

Answer 14

• ATP is source of energy for muscles
• ATP is produced in 3 different ways

Question 15

Which source of energy do we use first?

Answer 15

1. Creatine phosphate - lasts for first 8 sec, fastest way to make ATP
2. Aerobic respiration - until O2 runs out
3. Anaerobic respiration - use for ~2-3 min until muscle cramping occurs