MSK Physiology

Question 1

What type of control does skeletal muscle have?

Answer 1

Voluntary control via the somatic nervous system

Question 2

What type of control does cardiac muscle have?

Answer 2

Involuntary control via the autonomic nervous system

Question 3

How does calcium function in skeletal muscle contraction?

Answer 3

Ca²⁺ is released from the sarcoplasmic reticulum (SR) and binds to troponin, enabling actin-myosin interaction

Question 4

How does calcium function in cardiac muscle contraction?

Answer 4

Ca²⁺ comes from both the extracellular fluid (ECF) and the SR to enhance contraction strength

Question 5

Which muscle type is non-striated and under involuntary control?

Answer 5

Smooth muscle - autonomic

Question 6

What is a motor unit?

Answer 6

A single alpha motor neuron and all the muscle fibers it innervates

Question 7

In which muscles are motor units smaller, and why?

Answer 7

Muscles for fine movements, like eye muscles, have smaller motor units for precision

Question 8

What is the functional unit of muscle contraction?

Answer 8

The sarcomere

Question 9

What proteins make up the thick and thin filaments in muscle?

Answer 9

Myosin (thick) and Actin (thin)

Question 10

What is the sliding filament theory?

Answer 10

Muscle tension is produced by the sliding of actin filaments over myosin filaments, requiring ATP and Ca²⁺

Question 11

What neurotransmitter is involved in muscle contraction?

Answer 11

Acetylcholine (ACh)

Question 12

Where is Ca²⁺ released from during muscle contraction?

Answer 12

Sarcoplasmic reticulum (SR)

Question 13

What is an example of muscles where power more important than precision

Answer 13

Thigh muscle

Question 14

Where is the sarcomere found?

Answer 14

between two Z lines - connect the thin filaments of 2 adjoining sarcomeres

Question 15

Explain the A band

Answer 15

Made up of thick filaments along with portions of thin filaments that overlap on both ends of thick filaments

Question 16

Where does the M line attach?

Answer 16

at thick myosin

Question 17

Where does the Z line attach?

Answer 17

at thin actin

Question 18

I band consists of what?

Answer 18

ONLY thin actin - light

Question 19

A band consists of what?

Answer 19

BOTH thin and thick - dark

Question 20

H zone consists of what?

Answer 20

ONLY thick myosin

Question 21

What occurs when the muscle is relaxed?

Answer 21

No cross-bridge binding because troponin-tropomyosin covers the binding site on actin.

Question 22

What occurs when the muscle contracts?

Answer 22

Actin and myosin bind, triggering a power stroke that pulls thin filaments inward.

Question 23

What occurs when the muscle is excited

Answer 23

Ca2+ binds to troponin, moving the complex and revealing the binding site for cross-bridges; cross-bridge binding occurs

Question 24

What does Ca²⁺ bind to?

Answer 24

troponin, causing tropomyosin to move, exposing binding sites on actin

Question 25

What does Myosin bind to?

Answer 25

Myosin binds to actin and pulls the filaments, using ATP

Question 26

Where is Ca2+ needed?

Answer 26

1. switch on cross-bridge formation
2. Ca2+ is the link between excitation and contraction
3. Ca2+ is entirely derived from the sarcoplasmic reticulum in skeletal muscle

Question 27

Where is ATP needed?

Answer 27

1. During muscle contraction:
   to power cross bridges
2. During relaxation to:
   release cross bridges
   to pump Ca2+ back into the sarcoplasmic reticulum

Question 28

During the action potential. Which is shorter? - duration of action potential or duration of resulting twitch

Answer 28

Duration of action potential

=

Question 29

Explain the difference between Isotonic contraction and Isometric contraction

Answer 29

Isotonic contraction is muscle tension constant but muscle length changes whereas isometric contraction is muscle tension increases but muscle length constant

Question 30

Intrafusal fibers function

Answer 30

Monitor muscle length and stretch

Question 31

Extrafusal fibres function

Answer 31

Generates force and movement

Question 32

What are the 3 types of joints?

Answer 32

1. Synovial - diarthrosis
2. Fibrosis - synarthrosis
3. Cartilaginous - amphiarthosis

Question 33

How are synovial joints separated and united?

Answer 33

Seperated = Cavity
United = capsule

Question 34

Rapid movement is associated with what?

Answer 34

decreased viscosity and increased elasticity

Question 34

Synovial fluid WBC increases inflammatory and septic arthritis. True or false?

Answer 34

True

Question 35

Functions of articular cartilage

Answer 35

(1) provides a low friction lubricated gliding surface which helps prevent wear and tear of joints

(2) Distributes contact pressure to the subchondral bone

Question 36

What causes joint disease to occur?

Answer 36

If the rate of ECM degradation exceeds the rate of its synthesis

Question 37

what is articular cartilage and why?

Answer 37

Avascular - poor healing which leads to osteoarthritis

Question 38

What causes osteoarthrosis joint disease?

Answer 38

Cartilage and synovial fluid decomposition and function deteriorate with age and repeated wear and tear

Question 39

What causes rheumatoid arthritis joint disease?

Answer 39

Synovial fluid proliferation and inflammation

Question 40

What causes gouty arthritis joint disease?

Answer 40

Deposition of salt crystals e.g. uric acid

Question 41

Explain the difference between a normal knee and an osteoarthritic knee in regards to;
1. Capsule
2. Cartilage
3. Synovium
4. Bone

Answer 41

Osteoarthritic knee;

1. Thickened Capsule
2. Fibrillated cartilage
3. Synovial hypotrophy
4. Oesteophyte formation
5. Cyst formation
6. Sclerosis in subchondral bone
   (abnormal hardening of bone)

Question 42

A “sarcomere” is a term that refers to the basic unit of striated muscle tissue.

What best describes the above term?

Answer 42

The distance between adjacent Z-lines

Question 43

The process of endochondral ossification is an important means of bone formation.

Which term best describes the site at which this process occurs?

Answer 43

Metaphysis