Muscle Structure and Contraction

Question 1

Describe the process of muscle tissue
development.

Answer 1

Muscle tissue development, known as
myogenesis, involves the differentiation of
embryonic cells into myoblasts, which then
fuse to form myotubes, and ultimately
develop into myofibres.

Question 2

Identify the three types of muscle tissue
found in mammals.

Answer 2

The three types of muscle tissue in mammals
are skeletal muscle, cardiac muscle, and
smooth muscle.

Question 3

Explain the characteristics of skeletal muscle.

Answer 3

Skeletal muscle is voluntary, attached to the
skeleton, and is responsible for movement at
the joints.

Question 4

Define cardiac muscle and its unique feature.

Answer 4

Cardiac muscle is specialized tissue found in
the heart that is myogenic, meaning it can
contract without nervous input.

Question 5

How does smooth muscle function in the
body?

Answer 5

Smooth muscle is involuntary and is found in
the digestive system, reproductive tracts,
vascular system, bladder, and bowels

Question 6

Describe the structure of a muscle fibre.

Answer 6

A muscle fibre, or muscle cell, is made up of
long, strong myofibrils, surrounded by the
sarcolemma, and contains a network of tubes
called the sarcoplasmic reticulum

Question 7

What are myofibrils and their role in muscle
structure?

Answer 7

Myofibrils are long, strong fibres that make up muscle fibres, and multiple myofibrils constitute a single muscle fibre

Question 8

Identify the components surrounding
myofibrils

Answer 8

Myofibrils are surrounded by the sarcolemma, and they are associated with the
sarcoplasmic reticulum and T-tubules

Question 9

Explain the significance of striations in
muscle tissue.

Answer 9

Striations are alternating bands of thick
myosin and thin actin proteins that are visible in striated muscle tissues like skeletal and cardiac muscle.

Question 10

Define a sarcomere and its function.

Answer 10

A sarcomere is the smallest functional unit of
a myofibril that can contract, defined by the
distance between two Z lines.

Question 11

How are mitochondria related to muscle
fibres?

Answer 11

Mitochondria are embedded in the
sarcoplasm between muscle fibres and are
essential for energy production during muscle contraction

Question 12

Describe the role of T-tubules in muscle
contraction.

Answer 12

T-tubules are extensions of the sarcolemma
that open into the muscle fibre and facilitate
the transmission of electrical signals to the
sarcoplasmic reticulum

Question 13

Describe the structure of actin in muscle
fibers.

Answer 13

Actin is a thin filament composed of globular
subunits twisted together like a double strand of beads

Question 14

Define the role of tropomyosin in muscle
contraction.

Answer 14

Tropomyosin is a thin protein that lies within a groove between actin molecules, regulating
access to binding sites.

Question 15

How does troponin function in muscle fibres?

Answer 15

Troponin is a globular protein that binds to actin chains at regular intervals, playing a crucial role in muscle contraction

Question 16

Explain the composition of a myosin
molecule.

Answer 16

Each myosin molecule consists of a tail and two head regions, making it a thick, contractile protein

Question 17

What initiates the process of muscle
contraction?

Answer 17

A nervous impulse arrives at the neuromuscular junction, triggering the release of acetylcholine

Question 18

Describe the role of acetylcholine in muscle
contraction.

Answer 18

Acetylcholine is released in the gap between the neuron and the sarcolemma, transmitting the signal down the T-tubules

Question 19

How do calcium ions contribute to muscle
contraction?

Answer 19

Calcium ions are released from the sarcoplasmic reticulum and bind to troponin, leading to a change in tropomyosin that reveals binding sites on actin

Question 20

What is the sliding filament theory?

Answer 20

The sliding filament theory explains how muscle contraction occurs through the sliding of actin and myosin filaments past each other

Question 21

Identify the components of a muscle fibre.

Answer 21

A muscle fibre includes the nucleus, mitochondrion, sarcolemma, myofibril, sarcoplasmic reticulum, sarcomere, actin, and myosin

Question 22

How does the sarcoplasmic reticulum function in muscle contraction?

Answer 22

The sarcoplasmic reticulum releases calcium ions when stimulated, which are essential for muscle contraction

Question 23

What happens to tropomyosin during muscle
contraction?

Answer 23

Tropomyosin changes shape when calcium binds to troponin, revealing binding sites on the actin filaments

Question 24

Describe the role of myosin heads in muscle
contraction.

Answer 24

Myosin heads attach to actin, forming a cross-bridge, which is essential for muscle contraction

Question 25

How does the power stroke occur during muscle contraction?

Answer 25

The myosin heads tilt towards the centre, pulling the actin filament inwards and releasing ADP and Pi

Question 26

Define the process that occurs when ATP is hydrolysed in muscle contraction.

Answer 26

ATP is hydrolysed into ADP and Pi, releasing energy that causes the cross-bridge to break

Question 27

Explain the ratchet mechanism in muscle contraction.

Answer 27

The ratchet mechanism refers to the myosin head returning to its original conformation after ATP hydrolysis, allowing it to attach to actin further down the filament

Question 28

What is the sequence of events in muscle contraction as outlined by the acronym IACTAPMC?

Answer 28

Impulse arrives at the neuromuscular junction, acetylcholine is released, calcium ions are released, troponin binds to calcium, actin binding sites are exposed, power stroke occurs, myosin is released using ATP, and myosin conformation returns

Question 29

Identify the segments that make up myofibrils.

Answer 29

The segments that make up myofibrils are called sarcomeres

Question 30

What is the name of the thin protein filament involved in muscle contraction?

Answer 30

The thin protein filament involved in muscle contraction is called actin

Question 31

How is calcium released in the first stage of muscle contraction?

Answer 31

Calcium is released when an impulse arrives at the neuromuscular junction and acetylcholine is released

Question 32

Define tropomyosin and its function in muscle contraction

Answer 32

Tropomyosin is a protein that changes shape to reveal binding sites on actin filaments, allowing myosin heads to attach and facilitate muscle contraction

Question 33

How do myosin heads contribute to muscle contraction?

Answer 33

Myosin heads pull on actin filaments during the power stroke, which is a key step in muscle contraction

Question 34

Explain the concept of the power stroke in muscle physiology.

Answer 34

The power stroke refers to the action of myosin heads pulling on actin filaments, resulting in muscle contraction

Question 35

Discuss the importance of understanding skeletal muscles and myofibrils.

Answer 35

Understanding skeletal muscles and myofibrils is crucial for comprehending how muscles contract and function in the body