Muscle Reaction

Question 1

Three Muscle tissue types

Answer 1

• Skeletal(>600/43% body mass)
• Smooth
• Cardiac

Question 2

Properties of Muscle Tissue

Answer 2

• contractility –ability to produce a force
• extensibility –ability to stretch
• elasticity –ability to return to original shape after contraction/stretching
• excitability –ability to respond to stimuli

Question 3

Props of smooth muscle?

Answer 3

• Involuntary
• Non-striated
• Greater elasticity than skeletal muscle

Question 4

Muscle Structure?

Answer 4

• covered with a connective tissue sheath called the epimysium
• contains many bundles of fibres (multi nucleated cells) sourounded by the endomysium
• Each bundle of fibres is called a fasiculusand it is surrounded by the perimysium.

Question 5

Skeletal Muscle structure?

Answer 5

Within each fibre are many myofibrils and each of these contains still smaller myofilaments
The functional or contractile unit of a myofibril is called a sarcomere
Primary contractile protiensare mysosin(thick filaments) and actin (thin filaments)

Question 6

1st Phase of RM

Answer 6

ATP sufficiently high to permit splitting of actin-myosin cross-bridges
•Rate of depletion depends upon initial concentration and the possibility of ATD-ADP recycling after death during

Question 7

2nd phase of RM

Answer 7

• ATP levels fall below a critical threshold level
• Cross-bridges remain intact
• Rigidity appears

Question 8

3rd Phase of RM

Answer 8

Rigidity fully developed and irreversible

•Post-mortem modifications of the muscle fibres destroy their ability to relax

Question 9

4th Phase of RM

Answer 9

Relaxation of rigor mortis is due to the breaking of actin-myosin bridges by the action of enzymes released by autolysis