Twenty Questions -The Muscular Edition-

Movements

Twenty Questions

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

16 17 18 19 20

1. How do skeletal muscles provide movement/heat/posture

� Movement: During contraction of the muscles,

bones are tugged and caused to move. With

relaxation, the bones are at rest as well

� Heat: During the breakdown of ATP from food,

heat is produced. It being released to maintain

body temp. and warming the

muscles/surrounding tissues.

� Posture: Receiving acetelecholine from a motor

nerve triggers an action potential across the

muscle fibers causing a contraction.-All these functions are unique to muscles due to the chemicals and self produced heat.-

2. The characteristics of Excitability are shared with ______

� The Nervous System

(1)

3. What has the ability to shorten; creating body movements?

� Contractility

(Packet)

4. What is the ability to elongate and then return to the primary state?

� Extensibility

(Packet)

5. Do they perform a specific movement?

� Agonist muscles

(1)

6. During contraction, they oppose prime movers?

� Antagonist

(1)

7. What are unique to skeletal muscle fibers?

� Slow red fibers, Fast white fibers and

Intermediate fibers. (1)

8) What are different structures that differentiate contractility and excitability?

� Fast fibers are involved in excitability while

slow fibers are involved in contractility.

(1)

9. What are myofilaments?

� Four different types of protein molecules;

myosin, actin, tropomyosin and troponin.

� Myosin heads are chemically attracted to

actin molecules of nearby thin filaments,

angling toward them. When bridging the gap

between adjacent myofilaments, they’re then

called cross bridges.”

(1)

10. What contributes to the sliding filament theory in shortening muscle?

� When a myofibril changes length, the area

must slide past each other to increase their

area to overlap. The myosin filaments do not

move, but the actin filaments are pulled in.

(Packet)

11. What is the role of Ca++ in excitation?

� Ca++ is released from the SR into the

sarcoplasm; binding to troponin molecules in

the thin myofilaments. Tropomyosin

molecules then shift and expose actin sites

which in response, cross bridges are formed

for pulling thin myofilaments out toward thte

sarcomere. Repeats while the Atp is still

available resulting in contraction.

(1)

12. What is the role of Ca++ in relaxation of a muscle cell?

� The Sr pumps Ca++ back into its sacs. As

Ca++ is stripped from troponin molecules in

thin myofilaments, tropomyosin returns to

blocking the actin sites. The cross bridges

are then prevented from attaching and can’t

sustain the contraction.

(Packet)

13. What occurs within the muscle during an exercise burn?

� The myosin heads are attaching and moving

to actin, causing the heads to be ripped off,

which is the burning sensation. More,

stronger heads grow in return. (Packet)

14. What’s the anatomical arrangement of a motor unit?

� The motor unit consists of motor neurons as

well as the muscle fibers to which it attaches.

The gross motor unit consists of multiple

neurons and muscle fibers, a fine motor unit

consisting of less.

Gross motor unitFine motor unit

15. What muscle would a marathon runner have?

Marathon runner-

� 80% of their muscles are Slow fibers: produce

atp quickly enough to keep pace with the energy

needs of myosin; avoiding fatigue.

100- yrd dash-

� intermediate and fast fibers: contract rapidly and

quickly deliver Ca++, aslo using Atp quickly,

perfect for a short distance runner.

(1)

16. What is a unit of combined cells?

� syncytium being the branching exhibited by

individual cells, that allows cardiac fibers to form

a continuous, electrically coupled mass.

� I.e. cardiac muscle due to its low resistance

connections between adjacent cells such as

when an action potential is generated, the

atria and ventricle contract together. (1)

17. What is Rigor Mortis?

� Occurring several hours post someone’s

death; the joints of the body stiffen and

become locked in place due to the skeletal

muscles partially contracting and not allowing

the muscles to relax. (27)

18. What four factors describe the Graded Strength Principle of muscles?

� Skeletal muscles contract with varying

degrees of strength at different times.

1) The metabolic conditions of individual fibers

2) The number of fibers contracting simultaneously.

Greater number=stronger contraction

3) The number of motor units recruited

4) The intensity and frequency of the stimulation

(1)

19. What are twitch contractions?

� A quick jerk of a muscle as a result of a single,

brief threshold stimulus.

� The 3 phases involved are the

– Latent Phase: a nerve impulse traveling to the

sarcoplasmic reticulum, triggering the release of Ca++.

– Contraction Phase: Ca++ binding to troponin and

filaments sliding.

– Relaxation Phase: When the filaments cease to slide

(1)

20. What does the treppe effect have to do with athletes?

� When athletes warm-up, the treppe is

gradually increasing strength of contraction

and relaxation phases will dissapear.

(1)

It’s Muscular Physiology!