Muscles

Question 1

Muscle Types

Answer 1

Skeletal Muscle   (multi unit type)
Heart Muscle       (single unit type)
Smooth Muscle   (single unit & multi unit types)

Question 2

Structure of the Muscle (Sarcomere)

Answer 2

Sarcomere: smallest unit of a muscle fiber
- Actin and Myosin filaments: proteins that lead to force development

• Contraction: rythmic activity, non synchronous bending and tilting of myosin heads
• Activation by Calcium

Question 3

Viscous Behavior (Relaxation)

Answer 3

strain step –> temporal decline of material stress

1) Relaxation: in a material that deforms abruptly and for which the deformation is maintained, it can be noticed that the stress in the material decreases

Question 4

Viscous Behavior (Creep)

Answer 4

load step –> progressive deformation

2) Creep: a material that is constantly stressed, a progressive deformation can be noticed

Question 5

Viscous Behavior (Hysteresis)

Answer 5

Loading and unloading phase have a different tensile modulus

3) Hysteresis: a material that is continuously stressed and unstressed and has different modula of elasticity in the stressed and unstressed stage

Question 6

Modeling of Viscoelastic Behavior

Answer 6

1) Maxwell Model: damper, spring in series
2) Voigt Model: damper, spring in parallel
3) Kelvin Model: damper, spring series connection, parallel to spring –> standard model of a linear solid body

Question 7

Graphics of Viscoelastic behavior

Answer 7

Creep behavior –> Load step (Rechtecks impuls)

Relaxation behavior –> Strain step (Sprungschritt)

Question 8

Types of muscle contraction

Answer 8

1) isometric contraction –> constant length (fixed clamping)
2) isotonic contraction –> constant force (free hanging weight)

Question 9

Energy balance for muscle contraction

Answer 9

total energy consumption = sum of activation energy, mechanical Work, heat released during shortening

Question 10

What is the relationship between the load and contraction velocity according to Hill?

Answer 10

Hyperbolic relation between force and velocity

–> the higher the load, the slower the contraction

Question 11

Why is the force development of a sarcomere greatest at medium contraction length?

Answer 11

because both expansion and shortening are possible

Question 12

What does the motor end plate describe?

Answer 12

connection between nerve cell and muscle

Question 13

Is the shear stress proportional to the derivative of the shear stress?

Answer 13

Yes