Lect 6

Question 1

What is the muscoskeletal system?

Answer 1

Bones and joints and muscles working together to provide essential function

Question 2

What are essential functions of the muscoskeletal system?

Answer 2

Protection (brain and internal organs), support (posture), blood cell formation and hematopoiesis in bone marrow, mineral homeostasis and storage of fat, minerals and calcium, and leverage for movement and force

Question 3

What are the levers and axes in the body?

Answer 3

Levers are the long bones and axes are the joints

Question 4

What are the 5 tissue comprising the musculoskeletal system?

Answer 4

Bones, ligaments (for bone to bone attachment), cartilage, skeletal muscle and tendons (muscle to bone)

Question 5

What are the types of muscle tissue?

Answer 5

Skeletal, cardiac and smooth

Question 6

What is muscle tissue specialized for?

Answer 6

Movement by contraction

Question 7

Which muscle type is voluntary and which is not striated?

Answer 7

Skeletal is voluntary and smooth is not striated

Question 8

Where are the nuclei located in skeletal muscle?

Answer 8

On periphery of cell

Question 9

Where are the nuclei on cardiac muscle and what can be seen holding in together?

Answer 9

Centrally located and intercalated disks of junctional components hold together

Question 10

What is muscle organization from large to small?

Answer 10

Muscles made up of muscle fascicle made up of muscle fibers made up of myofibrils made up of sarcomeres

Question 11

What are the membranes and cytoplasms involved in muscles?

Answer 11

Perimysium surrounds fascicle, sarcolemma surrounds fibers and sarcoplasm is the cytoplams

Question 12

What are the different muscle fiber types?

Answer 12

Red, intermediate and white

Question 13

Where is the color of muscle coming from?

Answer 13

The amount of myoglobin

Question 14

What muscle fibers are fast or slow?

Answer 14

White and intermediate are fast and red is slow

Question 15

Which muscle fiber is resistant to fatigue or gets fatigued?

Answer 15

Red and intermediate are resistant but white becomes fatigued

Question 16

What is the numerical association with muscle fiber types?

Answer 16

Red is I

Intermediate is IIa and White is IIb

Question 17

Which muscle fiber types has many and large mitochondria and which has sparse and small?

Answer 17

Red is large and many and white is sparse and small

Question 18

Which muscle fiber is small and which is large?

Answer 18

Red is small and white is large

Question 19

What muscle fiber has a lot of motoneuron innervation and high sensitivity?

Answer 19

White and red is small and low

Question 20

What is the contractile element within muscle?

Answer 20

The sarcomere which shortens with contraction

Question 21

What allows electric impulse to travel into the fiber and causes release of calcium from sarcoplasmic reticulum?

Answer 21

T-tubules

Question 22

What is the T-tubule par tof?

Answer 22

A triad

Question 23

What end of the moves during contraction?

Answer 23

Proximal end near body or head remains stationary while distal end moves

Question 24

What type of motion does muscle contraction produce?

Answer 24

Force producing the bending is always exerted as pulling to make muscle shorter

Question 25

Can muscle push?

Answer 25

Not actively -- antagonist muscle groups counteract contracting muscles exerting an opposing pull

Question 26

What are the two main proteins involved in muscle contraction?

Answer 26

Actin and myosin

Question 27

What triggers the muscle contraction?

Answer 27

The motor nerve attached to each muscle fiber -- neuromuscular junction

Question 28

What is the anchoring point for actin?

Answer 28

The Z-line

Question 29

What is the binding site for myosin?

Answer 29

Head binds to actin in presence of calcium

Question 30

What is the troponin complex?

Answer 30

Troponin T, C and I -- to bind tropomyosin, calcium and inhibit actin-myosin interaction

Question 31

What is the I band in a sarcomere?

Answer 31

Distance from actin to myosin and becomes shorter during contraction

Question 32

What is the A band in a sarcomere?

Answer 32

Spans the myosin filament -- stays constant during contraction

Question 33

What is the H band in a sarcomere?

Answer 33

Distance between actin molecules that also gets shorter during contractions

Question 34

What is bound to the myosin binding site on actin in resting muscle?

Answer 34

Troponin I and ADP is tightly bound

Question 35

What happens when an action potential leads to increased calcium during muscle contraction?

Answer 35

Troponin C binds calcium weakening troponin I interaction with actin and myosin binds to actin 00 ADP is released and myosin bends toward the H zone pulling actin in same direction

Question 36

When does myosin release actin?

Answer 36

When ATP binds to myosin and there is hydrolysis of ATP back to ADP and head is reset back to resting position

Question 37

What happens in rigor mortis?

Answer 37

There is no ATP so binding can not be released and muscle can not relax

Question 38

What lies at the neuromuscular junction?

Answer 38

Synaptic contact point between axon terminal and muscle fiber -- synaptic cleft between -- mitochondria and nuclei in close proximity

Question 39

What is the pathway of nerve firing within the muscle?

Answer 39

1) nerve impulse travels along the axon 2) acetylcholine released andbinds sodium channels and depolarization of sarcolemma occurs 3) sodium channels open and sodium enters 4) depolarization spreads over plasma membrane to t-tubules 5) voltage sensor protein confirmation changes in PM 6) calcium release channels are activated at triads 7) calcium is rapidly released from sarcoplasmic reticulum into sarcoplasm 8) calcium binds to TnC 9) contraction cycle is initiated and calicum returns to terminal cisternae of sarcopasmic reticulum

Question 40

How many contact points does one neuron have?

Answer 40

One neurons makes contact with several muscle fibers of the same type (makes up the motor unit)

Question 41

Does cardiac muscle have triads?

Answer 41

No diads instead -- t-tubules found here

Question 42

What are the classes of muscle levers?

Answer 42

``` First class has load at end close to fulcrum - such as the jaw Second class has load evenly between fulcrum and forme -- such as in leg and foot Third class has load on opposite end from fulcrum such as arm (elbow as fulcrum) ```

Question 43

What is the shape of smooth muscle?

Answer 43

Fusiform with no striations

Question 44

Where does calcium bind during smooth muscle contraction?

Answer 44

Calmodulin

Question 45

What signals for smooth muscle contraction?

Answer 45

Autonomic nervous system and hormonal circulation

Question 46

What muscle type doesn'tt have t-tubules?

Answer 46

Smooth

Question 47

What muscle types uses somatic innervation?

Answer 47

Skeletal

Question 48

Which muscle type allows for regeneration and has mitosis present?

Answer 48

Smooth

Question 49

What are the joints found between bones?

Answer 49

Sutures in skull that don't allow movement and synovial that allow movement with a cavity space and capsule enclosing joint space with synovial fluid with ligament attachments

Question 50

What happens to joints in osteoarthritis?

Answer 50

Capsule becomes thicker, synovium becomes thicker, cartilage degrades and cysts develop

Question 51

What are the catabolic pathways in osteoarthritis?

Answer 51

Elevated MMPs breakdown collagen and lower MMP inhibitors result in loss of control, elevated pro-inflammatory cytokines

Question 52

What are the poor repair potentials of osteoarthritis?

Answer 52

No blood supply - less progenitor cells available - dense matrix prevents cell migration or proliferation - constant inflammatory state