Muscle Tissue

Question 1

What is Muscle Tissue

Answer 1

Muscles are composed of cells that are elongated and form fibres. Muscle cells contain protein filaments called actin and myosin that enable muscles to contract and cause movement

Question 2

What are the 3 types of muscle tissue

Answer 2

Skeletal Muscle
Cardiac Muscle
Smooth Muscle

Question 3

What is Skeletal Muscle

Answer 3

Skeletal muscle is found attached to bones. You can control its contraction and relaxation, and it sometimes contracts in response to reflexes.

Question 4

What is Cardiac Muscle

Answer 4

Cardiac muscle is found only in the heart. It contracts at a steady rate to make the heartbeat. It is not under voluntary control.

Question 5

What is Smooth Muscle

Answer 5

Smooth muscle is found in the walls of hollow organs, such as the stomach and bladder. It is also not under voluntary control.

Question 6

Function and Structure of Skeletal Muscle Fibre

Answer 6

 Muscle tissue needs to be able to contract (shorten in length) to move bones.
 In a muscle, cells join up to make muscle fibres. These are long strands of cells sharing nuclei and cytoplasm, which
is known as the sarcoplasm.
 Inside the muscle cell cytoplasm are many mitochondria, specialised endoplasmic reticulum known as sarcoplasmic
reticulum and several microfibrils.
 Each muscle fibre is surrounded by a cell surface membrane called the sarcolemma.
 Skeletal muscle shows a stripy/banding appearance under a microscope.
 Skeletal muscle is made up of thousands of muscle fibres. Each muscle fibre is made up of myofibrils.

Question 7

What is Sarcomere

Answer 7

Sarcomere: The span from one z-line to the next is known as the sarcomere. When the muscle is relaxed, it is approximately 2.5 μm in length. This length reduces when the muscle contracts because the I-band and H-zone lengths are reduced. The A-band does not change in length during contraction.
There are two protein filaments found in muscle cells. This filament is made of actin and thick filaments made of myosin.
During muscle contraction, the thin actin filaments move and overlap the thick myosin
filaments. The sarcomere shortens, decreasing the size of the overall muscle.

Question 8

What is Slow Twitch Muscle Fibres

Answer 8

Slow twitch muscles are more effective at using oxygen to generate energy in the form of ATP for continuous and extended muscle contractions over a long time. These fibres help marathon runners and endurance cyclists to continue for hours. Slow twitch fibres have:
Fast-twitch oxidative muscle fibres are similar in structure to slow-twitch muscle fibres. They contain many mitochondria, myoglobin and blood capillaries, but they can hydrolyse ATP much more quickly and, therefore, contract quickly. They are relatively resistant to fatigue.
 less sarcoplasmic reticulum
 more mitochondria for sustained contraction
 more myoglobin
 a dense capillary network
 these fibres release ATP slowly by aerobic respiration

Question 9

What is Fast Twitch Muscle Fibres?

Answer 9

Fast-twitch oxidative muscle fibres are similar in structure to slow-twitch muscle fibres. They contain many mitochondria, myoglobin and blood capillaries, but they can hydrolyse ATP much more quickly and, therefore, contract quickly. They are relatively resistant to fatigue. Fast twitch glycolytic muscle fibres have relatively less myoglobin, few mitochondria and few capillaries. They contain a large concentration of glycogen that provides fuel for aerobic respiration. They contract rapidly but also fatigue.