Muscles

Question 1

What are the three types of muscle tissue?

Answer 1

Cardiac muscle
Skeletal muscle
Smooth muscle

Question 2

What is the structure, type and function of skletal muscle tissue?

Answer 2

Long cylindrical fibres with peripherally located nuclei. Striated and voluntary, attached to the skeletal system.

The function of most skeletal muscles is to move the skeleton.

Question 3

What is the structure, type and function of cardiac muscle tissue?

Answer 3

Branched cylindrical fibres with centrally located nucleus. Striated but involuntary; they form the walls of the heart.

Their function is the contraction and relaxation of the heart.

Question 4

What is the structure, type and function of smooth muscle tissue?

Answer 4

Spindle-shaped fibres with centrally located nucleus. Non-striated and involuntary.

They form the walls of the luminal structures such as blood vessels, airways and most pelvic and abdominal organs.

Question 5

What are the four features of muscle tissue?

Answer 5

Excitability
Contractility
Extensibility
Elasticity

Question 6

What is muscle tissue excitability?

Answer 6

The ability of the muscles to respond to stimuli.

Question 7

What is muscle tissue contactibilty?

Answer 7

The ability of the muscles to contract forcefully after stimulation.

Question 8

What is muscle tissue extensibilty?

Answer 8

The ability of the muscles to stretch without being damaged.

Question 9

What is muscle tissue elasticity?

Answer 9

The ability of the muscles to return to their normal size after contraction and relaxation.

Question 10

What is the function of muscles?

Answer 10

Producing all body movements.
Stabilising the positions of the body, such as standing and sitting.
Storing and moving materials within the body, such as the blood in the heart and blood vessels.
Maintaining body temperature.

Question 11

What is the structure of skeletal muscle tissue?

Answer 11

Each skeletal muscle consists of thousands of muscle fibers wrapped together by connective tissue sheaths. The individual bundles of muscle fibers in a skeletal muscle are known as fasciculi. The outermost connective tissue sheath surrounding the entire muscle is known as epimysium.

Question 12

What is a tendon?

Answer 12

A tendon is a band of fibrous connective tissue that attaches muscles to the periosteum of bones and moves the bone when the muscle contracts.

Question 13

How does a muscle attached to two bones move these bones?

Answer 13

Once the muscle contracts, it pulls one of the articulating bones toward the other.
Only one of the articulating bones is moved and the other one remains at its position.

Question 14

What are the three sections of muscles and how are they defined?

Answer 14

The attachment of the muscle tendon to the stationary bone is called the origin of the muscle.

The attachment of the muscle tendon to the movable bone is called the insertion of the muscle.

The portion of the muscle between the tendons of origin and insertion is called the belly.

Question 15

How many skeletal muscles are there?

Answer 15

About 700 skeletal muscles.

Question 16

What are the two main parts of the skeletal muscle system?

Answer 16

The axial muscular system. approx 60%
The appendicular muscular system. approx 40%

Question 17

What is the axial muscle system and its function?

Answer 17

The axial muscular system includes the muscles of the axial skeleton.

These muscles position and support the head and vertebral column and assist in the respiration process by moving the thoracic cage.

Question 18

What is the difference between tendons and ligaments?

Answer 18

A tendon serves to move the bone or structure. A ligament is a fibrous connective tissue that attaches bone to bone, and usually serves to hold structures together and keep them stable.

Question 19

Which muscles are included in the axial muscular system?

Answer 19

The muscles of the face, head and neck
-responsible for facial expression, chewing and swallowing.

The muscles of the vertebral column
-flexors and extensors of the head and spine.

The muscles of the trunk
-muscles of the walls of the thoracic, abdominal and pelvic cavities.

The muscles of the perineum (the floor of the pelvic cavity)
-connect the sacrum and coccyx to the lower part of the hip bones.

Question 20

What is the appendicular muscle system?

Answer 20

The appendicular muscular system supports and moves the appendicular skeleton and includes:

The muscles of the shoulders and upper limbs.
The muscles of the pelvic girdle and lower limbs.

Question 21

How is skeletal muscle innervated?

Answer 21

• Transmission of action potentials through to the motoneuron causes depolarization and opening of voltage-gated calcium (Ca2+) channels of the presynaptic membrane.
• Inward Ca2+ flow causes the release of acetylcholine (ACh) at the neuromuscular junction, which diffuses to the postsynaptic membrane at the muscle fibre (motor endplate).
• ACh binds to the nicotinic receptors located at the motor endplate, depolarizing it, which initiates the action potentials in the muscle fibre.

Question 22

Which substance helps muscle produce movement?

Answer 22

Myosin helps convert ATP to mechnical energy

Question 23

What is the basic cycle of muscle contaction?

Answer 23

Ca2+ released
Ca2+ binds with troponin
Tropomyosin shifts, binding sights available
ATPase splits ATP into ADP + Pi + ENERGY
Myosin S1 (Subfragment -1) unit binds actin
Power stroke
Impulse stops; Ca2+ returns to sarcoplasmic reticulum (SR)
Tropomyosin returns over binding sights

Question 24

Which neurotransmitter innervates skeletal muscles at the neuromuscular junction?

Answer 24

Acetylcholine