MUSCULAR SYSTEM

Question 1

What is the diaphragm and why is it an important muscle?

Answer 1

The diaphragm is a dome-shaped muscle that separates the thoracic cavity from the abdominal cavity. It is important as the chief muscle of inhalation because it allows breathing to occur

Question 2

What is curare?

Answer 2

A drug acting as a skeletal muscle blocker for surgeries and operations

Question 3

Why is curare used for surgeries?

Answer 3

It promotes muscle relaxation and paralysis because ACh can’t bind to receptor sites as an effect, so muscle contraction is prevented

Question 4

What is the sartorius? What is its function and location?

Answer 4

Sartorius is a long muscle that crosses obliquely (diagonal) over the anterior thigh; its origin is on ilium; inserts in the tibia. It flexes/abducts, laterally rotates thigh at hip

Question 5

define the origins of muscles

Answer 5

the immobile or stationary part of the muscle (ie. clavicle)

Question 6

what is the masseter and its function?

Answer 6

A chewing muscle that works synergistically with the temporalis muscle. It closes/retracts jaw.

Question 7

what is the sternocleidomastoid ?

Answer 7

Two neck muscles running bilaterally each side of neck; extends obliquely from sternum and clavicle upward to mastoid process of temporal bone; during contraction, both muscles flex the head at the neck–contraction of one rotates head towards opposite side

Question 8

What is the quadriceps femoris group and its’ function(s)?

Answer 8

Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius–muscles located on anterior thigh; they all insert on tibia; rectus femoris originates on ilium but all others originate on femur. Their goal is to extend leg at knee (femoris can flex at hip); lateralis common site for pediatric IM injections

Question 9

What is the sliding filament theory?

Answer 9

The chemical process that makes muscles contract and move

Question 10

What are the components of the sliding filament mechanism theory and their function(s)?

Answer 10

Actin and Tropomyosin-troponin complex are the thin filaments, with actin being a contractile protein also. Myosin is the thick filament, and the other contractile protein. They form cross-bridge.
Tropomysoin-troponin complex are inhibiting proteins. Actin and mysoin connect, form a bridge, then slide past one another.

Question 11

What happens to muscles and its system as we age?

Answer 11

They lose mass, become small, weaker, dehydrated; motor neurons are lost to muscle atrophy; decreased muscle strength, slowing of reflexes

Question 12

Define ACh and its function in the NMJ

Answer 12

ACh is a neurotransmitter that acts as a signal stimulant to initiate an impulse to the muscle membrane

Question 13

What is cholinesterase and its relation to acetylcholine?

Answer 13

It is an enzyme; Cholinesterase destroys ACh after it has unbound from the receptor site.

Question 14

What is recruitment?

Answer 14

The addition of motor units, which allows variety of force of contraction

Question 15

Describe a consequence of recruitment.

Answer 15

Recruitment itself is a consequence; a consequence within recruitment is increased force of muscle contraction

Question 16

Describe the ACh in the first 2 steps of information transfer in at the NMJ

Answer 16

1. ACh introduced as chemical substance stored in vesicles found at a neuron’s ending
2. Released ACh is released into synaptic cleft

Question 17

What action do ACh take post-release to the synaptic cleft?

Answer 17

It diffuses across the space (cleft) and binds to the receptor sites on the muscle membrane

Question 18

What role does calcium play in the sliding filement mechanism?

Answer 18

Ca, stored away in the SR away from the filaments, is released during muscle stimulation and floods the sarcomere, so it’s essential for cross-bridges (actin-myosin connection). It’s pumped back to SR during muscle relaxation.

Question 19

What is Clostridium tetani (tetanus)?

Answer 19

A neurotoxin produced by bacteria that causes excessive motor neuron stimulation, followed by excessive release of ACh, and resulting in muscle spasms and tetanic contractions; i.e. “lockjaw”

Question 20

Myalgia

Answer 20

Pain

Question 21

What is Myasthenia gravis and effects?

Answer 21

A NMJ-effecting disease caused by damaged receptor sites (which cant effectively bind to receptors) on the muscle membrane. It effects muscle contraction, resulting in initial muscle weakness, then progressed respiratory issues

Question 22

Because muscles require a rich ATP energy source, what is the 1st chemical to be broken down?

Answer 22

Creatine phosphate, which can also be used as an energy storage

Question 23

What is the 2nd energy source/breakdown for ATP?

Answer 23

Glycolysis (anaerobic metabolism), which causes lactic acid build up

Question 24

What is the 3rd ATP source for muscles?

Answer 24

Aerobic metabolism, which facilitates fat breakdown and ATP production for muscle contraction

Question 25

What is myoglobin?

Answer 25

Muscular protein that supplies mitochondria with oxygen

Question 26

What is atrophy? Also give an example

Answer 26

Atrophy, i.e. a casted broken leg unable to be properly exercised, is the wasting away/size decrease of muscle; can be restored; 3 types of atrophy: senile (age); denervation (severed nerves); disuse (broken leg)

Question 27

What is Hypertrophy?

Answer 27

An overusing of muscles, leading to increased size; good example is athletes pumping up for their sport, bad example is cardiac atrophy (we don’t want to overuse/overwork our heart)

Question 28

Explain Contracture.

Answer 28

An abnormal muscular, fibrous tissue formation wherein the muscle “Freezes” in a flexed position, restricting joint mobility

Question 29

Define Tonus and give an example

Answer 29

Normal, continuous state of partial muscle contraction caused by the contraction of different muscle groups within a whole muscle; i.e. presence in back of neck prevents head from falling forward

Question 30

Define Fascia

Answer 30

Thin, fibrous connective connective tissues sheaths surrounding muscle, extending into in 3 layers (Epimysium, perimysium, endomysium)

Question 31

What are tendons and their relation to muscles?

Answer 31

A long, cordlike structure attaching muscles to bones

Question 32

What is an antagonist?

Answer 32

A muscle that opposes the action of another

Question 33

What is a synergist?

Answer 33

Helper muscles working with other muscles i.e. biceps brachii flexing the forearm at the elbow

Question 34

Describe the relationship between a synergist and an antagonist?

Answer 34

Muscles must be arranged in synergist-antagonist pairs and have opposing functions to each other

Question 35

Explain Cardiac Muscle

Answer 35

It is one of the main muscles; striated; involuntary; doesn’t regenerate; helps heart pump blood throughout body

Question 36

Define Skeletal Muscle

Answer 36

1 of main muscles; little to no regeneration; striated, contributes to body temperature; helps move skeleton; has long, cylindrical proteins; attached firmly to bone

Question 37

Define Smooth Muscle

Answer 37

Visceral; fusiform; promotes continuous contraction; allows for expansion, expulsion, found in STOVE; smooth muscle tone

Question 38

What do all 3 muscle types have in common?

Answer 38

they make up 40-50% of body weight, have cells, support movement, maintenance of posture, production of heat

Question 39

Where does the Sliding Filament Mechanism occur?

Answer 39

At the Sarcomere