Skeletal Muscle Histology and Pathology

Flashcards on Histology and Pathology of Skeletal muscle

What is found on the perimeter of healthy muscle fibres?

Myonuclei

What is the connective tissue that surrounds each muscle?

Epimysium

What is formed when tissue is organized into bundles of muscle cells?

Fascicles

What separates individual fascicles?

Perimysium

What connective tissue surrounds individual muscle cells called myofibres?

Endomysium

What is the plasma membrane of skeletal muscle called?

Sarcolemma

What is the invagination of sarcolemma that extends deep into muscle fibre?

T-tubule

What is the ER of muscle and surrounds each myofibril?

Sacroplasmic reticulum (SR)

What ends near the T-tubule region and is also called terminal cisternae?

Sacroplasmic reticulum (SR)

What is the region where one T-tubule is flanked by two terminal cisternae?

Triad

What is the bundle of contractile filaments within muscle fibre?

Myofibril

What major proteins is Myofibril made of?

Actin and Myosin

Which band in a myofibril is quite dark and the length of thick filaments?

A Band

Which band in a myofibril is a very light region and a region with thin but no thick filaments?

I Band

Does the length of the I band increase or decrease during contraction?

Decrease

What protein disc onto which thin filaments attach bisects the I band?

Z line

Which zone is the region where only thick filaments are present?

H Zone

Does the length of the H Zone increase or decrease during contraction?

Decrease

What is the middle of A band called where thick filaments attach?

M line

What mnemonic helps remember the components needed for the sliding filament theory?

ACT-4

What does Myosin require to make thick filaments?

ATP

What does Ca2+ bind to on thin filaments?

Troponin

What protein keeps thin filaments kept in order?

Nebulin

Which protein keeps thick filaments linear?

Titin

What is the function of Titin?

responsible for passive force production

What innervates many muscle fibers?

Motor nerve

In muscle fibers, what are 'Slow-twitch' fibres?

Type I

In muscle fibers, what are ‘fast-twitch’ fibres?

Type II

What type of muscle fibre is red, aerobic, high myoglobin, many mitochondria, and highly fatigue resistant?

Slow twitch (type I)

What type of muscle fibre is white, high glycogen, low myoglobin, and low fatigue resistance?

Fast twitch (type II)

What happens to muscle during eccentric exercise?

Muscle lengthens during active force generation

What cells are involved in muscle repair?

Satellite cells

What occurs in diseases such as Muscular Dystrophy or Atrophy?

Muscle loss

What is Sarcopenia

Loss of muscle mass during aging

What are two effects of weight training on humans aged 90+?

Increase in knee extensor strength and Muscle hypertrophy

What is reduced number of sarcomeres in series an effect of?

Immobilisation/unloading

What is severe wasting of the body (mainly muscle and fat) due to chronic illness?

Cachexia

Which muscular condition is characterized by increased muscle mass and reduced adipogenesis?

Inhibition of Myostatin

What muscular condition was described by Guillaume Duchenne in 1868?

Duchenne Muscular Dystrophy

What is the function of Dystrophin?

Stabilises Muscle

What muscular pathology shows a progressive loss of muscle fibres and Muscle replaced by fat and scar tissue?

Muscular Dystrophy

What percentage of normal levels does gene therapy need to replace in the Dystrophin gene?

at least ~4%

What is the typical DNA capacity of the Adeno-Associated Virus?

4000 bp

What is the largest human gene, which needs replacement in gene therapy?

DYSTROPHIN

What are the current conventional therapies for muscular diseases?

Steroids, surgery, ventilation, heart drugs, physiotherapy

Which muscular condition is caused by mutations in the gene called DYSTROPHIN?

Duchenne Muscular Dystrophy (DMD)