TISSUE TYPES- MUSCULAR

Question 1

What are the different muscle types

Answer 1

Smooth muscle

Striated muscles - Cardiac and skeletal muscle

Question 2

Describe the function of skeletal muscle

Answer 2

• Force production for locomotion and breathing
• Force production for postural support
• Heat production during cold stress
• Largest protein store in the body

Question 3

Describe the structure of muscle cell

Answer 3

Muscle cell is also known as fibre
They are stripy and have multiple nuclei that lie towards the edge of the cell. The fibres are arranged into bundles surrounded by connective tissue

Question 4

What is the epimysium

Answer 4

Connective tissue covering

Surrounds entire muscle

Question 5

What is the perimysium

Answer 5

Connective tissue covering

Surrounds the bundles of muscle fires (fascicles)

Question 6

What is the endomysium

Answer 6

Connective tissue covering

Surrounds individual muscle fibres (cells)

Question 7

What is actin

Answer 7

A myofilaments
Made up of troponin and tropomyosin
Thin myofilament

Question 8

What is myosin

Answer 8

Thick filament

Question 9

What is the sarcolemma

Answer 9

Muscle cell membrane

Question 10

Describe the bands/lines within myofilaments

Answer 10

I bands- actin filaments alone
A bands- zones containing myosin
Z line- defines boundary between sarcomeres
M line- transverse line in the middle of the sarcomere that binds the myosin filaments

Question 11

Describe the mechanism of muscle contraction

Answer 11

• the myosin head has a region that binds actin
• the sliding is caused by the bending of the myosin heads
• myosin heads release actin
• straighten out and repeat

Question 12

Explain the sliding filament model of muscle contraction

Answer 12

• cross bridges form between actin and myosin filaments
• reducing distance between z lines of sarcomere
• driven by atp
• myosin heads have a region that binds to ATP and hydrolysed to ADP which actives the head
• calcium is the signalling molecule that drives the contraction process, when cytotoxic Ca 2+ is low, the myosin head cannot bind to actin

Question 13

Describe the structure and function of tropomyosin

Answer 13

Is located along the 2 chains of actin filaments and when calcium is low blocks the binding of myosin to the actin and the fibre is at rest

Question 14

What are the 3 types of troponin and what do they do

Answer 14

Troponin T- attaches to tropomyosin
Troponin I- binds to actin head
Troponin C- captures Ca2+ and undergoes a conformational change that lifts tropomyosin away from the actin filament- allwing myosin head to bind

Question 15

How can muscle fibre-type composition analysed

Answer 15

Immunohistochemistry- look for myosin antigens that are specific to each fibre type
Histochemistry- measures of ATPase can show contraction speed therefore different muscle fibre types