D4: Muscles

Question 1

Muscles

Answer 1

Allow for locomotion by converting chemical energy to kinetic

Question 2

Smooth Muscle

Answer 2

Long w/ tapered ends
One nucleus,
Lines internal organs,
Involuntary
Slower to contract than skeletal
Sustains prolonged contractions
Doesn’t fatigue easy

Question 3

Cardiac Muscle

Answer 3

Tubular and striated
One nucleus
Walls of heart
Involuntary

Question 4

Skeletal (Straited) Muscle + Function

Answer 4

Long
Many nuclei (needs energy)
Voluntary (contractions are constantly done by nervous system)
Straited/Tubular
Functions: Stabilizes joints, maintains temperature homeostasis, supports body

Question 5

Muscle Structure Hierarchy

Answer 5

Muscle, muscle fiber bundle, muscle fiber, myofibrils, myofilaments

Question 6

Myofilaments

Answer 6

Myosin- Dark and thick filaments
Actin- Light and thing filaments

Straitions causes by sarcomeres (z band to next z band) next to eachother

Question 7

Sliding Filament Model

Answer 7

Muscle contractions=coordinated sliding and pulling motions between z-bands

Muscles relaxed=Myosin heads not bound to actin

Question 8

Calcium and Regulatory Proteins (Cycle)

Answer 8

1. High calcium= Binding sites for myosin exposed
2. Myosin head (contains ATPase) binds to actin
3. Heads will tilt to sarcomere center, sliding the bound actin with it
4. When atp binds to head, head releases grip on actin
5. ATP is hydrolyzed into ADP and myosin reverts to original postion
6. Cycle repeats if CA+ and ATP still present

Question 9

Energy sources for contraction

Answer 9

ATP reserve- Small amount found around myofibrils (brief contraction)

Creatine Phosphate- Initial source of energy to regenerate ATP (lasts 10 sec)

Cell Resp- Makes up to 38atp/glucose

Question 10

Slow vs Fast Twitch (Skeletal)

Answer 10

Slow- Long muscle contractions (posture muscles), rely on aerobic resp, break Atp slowly but are efficient (distance runners)

Long- Brief and rapid contractions, relays on glycolysis (anaerobic resp) (sprinters)

Question 11

Muscle Fatigue

Answer 11

Inability of contraction

Causes
1. Low O2
2. Low ATP
3. Accumulation of waste (lactic acid, pyruvic acid, acid phosphates)- Acids lower pH=High heart rate

Question 12

Nerve Control of Muscle Tension

Answer 12

Muscle Twitch- Skeletal are stimulated my nerves: nerve impulse=1 contraction/twitch

Muscle Tonus- slightly sustained contraction where muscle is ready for activity

Summation- Muscle fiber restimated before it relaxed=2nd twitch

Tetanus- Sustained muscle contraction (continuous due to activity)

Question 13

Use/Disuse of Muscles

Answer 13

Hypertrophy- Growth, increase in muscle size and in vascularization and in circulation (specific exercises)

Atrophy- Muscles weaker and get smaller due to dormancy

Dystrophy- Paralyzed muscles

Question 14

Interactions of Skeletal Muscles (Antagonistic Muscles)

Answer 14

A.M- Work in pairs and oppose eachother (flexors=bending and extensors=unbending

Biceps contracted = triceps relaxed and vice versa