Body Systems- Chap 1

Question 1

What is epimysium

Answer 1

Fibrous connective tissue covering muscles.

Question 2

What are fasciculi

Answer 2

Bundles of up to 150 mm fibers.

Question 3

What is perimysium

Answer 3

Connective tissue sheath covering fasiculi.

Question 4

What is endomysium

Answer 4

Connective tissue sheath covering EACH mm fiber

Question 5

Motor end plate/NM junction

Answer 5

Junction between mm fiber and nerve.

Question 6

What is a motor unit

Answer 6

A single motor neuron and all it’s fiber (usu. several hundred)

Question 7

Desc structure of sarcomere

Answer 7

Z line, H-zone, I band, M line, A-band

Question 8

Describe mechanism of depolarization

Answer 8

Sarcoplasmic reticulum surrounds myofibril running parallel, vesicles at the Z line carry calcium ions. Stimulation of the motor N releases the Ca2+. Perpendicular T-tubules between each Z line are continuous with sarcolemma and carry action potential to all depths of the cell.

Question 9

Describe roles or troponin and tropomyosin.

Answer 9

Troponin- on actin filament, binds with Ca2+. Tropomyosis- runs length actin filaments at groove of double helix

Question 10

How is energy for myosin crossbridge movement and fx made?

Answer 10

ATP is broken is hydrolized into ADP + Phospate. Hydrolysis is catalyzed by ATPase (myosin adenosine triphosphate ase). It takes another molecule of ATP for myosin to disengage and recock. Basically each stoke takes a molecule of ATP.

Question 11

What is the role of calcium in myosin cross bridge movement/mm contraction.

Answer 11

As long is Ca2+ is available from sarcoplasmic reticulum contraction can continue. Relaxation occurs if Ca2+ is unavailable to bind to troponin.

Question 12

How does the nervous system differentiate between fine motor and gross motor control?

Answer 12

Fine motor- few (as few as 1) mm fiber/motor neuron.

Gross motor- many mm fibers per mm neuron

Question 13

What neurotransmitter diffuse across NMJ to excite sarcolemma?

Answer 13

Acetylcholine.

Question 14

Describe fiber typing nomenclature (fast vs slow twitch)

Answer 14

Slow = Type 1(I). Fast=Type 2a(IIa). Type 2b(IIb= 2x)/2ax(IIax)

Question 15

Comp/contrast Type 2a and Type 2x (b) fibers.

Answer 15

Type 2a= more capillaries, greater aerobic capacity.

Question 16

What are the 2 mechanisms for modulating force output?

Answer 16

1) increase freq of firing 2) increase motor unit recruitment.

Question 17

Comp/Contrast mm spindle and GTO

Answer 17

MM spindle facilitates activation/inhibits stretch. GTO inhibits mm activation/facilitates relaxation (protective a/g overload)

Question 18

Def/Desc sarcopenia.

Answer 18

Dec mm size/strength due to age. More Type 2 loss than type I. Trunk and LE ext&raquo_space;> LE flex&raquo_space;> UE ext/flx