Module 3

Front 1

Discuss the sliding filament theory of contraction:

Back 1

During contraction of a muscle, Ca binds to troponin. This moves tropomyosin out of the way and uncovers binding sited for myosin on the actin myofilament. ADP and P are attached to the myosin head from the previous cycle of movement. The myosin heads attach to the exposed binding sites on the actin myofilaments to form cross-bridges and the phosphate is released (myosin becomes kinked). Energy stored in the head of the myosin myofilament is used to move the head. This causes the actin myofilament to slide past the myosin myofilament (power stroke). The ADP if released from the myosin head (myosin remains kinked). The bond between actin and the myosin is broken when an ATP molecule binds to the myosin head. The ATP is broken down to ADP and phosphate, releasing energy which is stored in the myosin head. The head of the myosin is ready to bind again to actin.

Front 2

What occurs when actin/myosin slide past one another?

Back 2

The z disc shortens, the sacromere shortes and the muscle finer shortens.

Front 3

Explain why rigour mortis takes place after death.

Back 3

When you die there is not ATP so myosin head remain attached to actin binding sites. This is where the muscle contraction stops at and muscles become stiff.

* Right after death there is some ATP still available in the body so you can see large muscle movements

Front 4

Tropomyosin is a filament that lies between double rows of G-actins. Troponin complex of molecules is attached to the tropomyosin at every 7 G actions.

Back 4

Remember

Front 5

Calcium is stored where?

What are T-tubules

Back 5

Sacroplasmic reticulum and T-tubules are tubes made of sacrolemma.

Front 6

Describe the events that take place concerning calcium and the sacroplasmic reticulum.

Back 6

* The skeletal muscle sacrolemma is an excitable membrane like plasma membrane of neurons.

The release of Ach at the neuromuscular junction causes depolarization of the sacrolemma. The action potentials travel down T-tubules. Voltage gated calcium channels in the SR and cistern open and calcium can move into the cell

Front 7

Define:

1) Twitch

2) summation

3) graded contractions

4) incomplete tetanus

5) complete tetanus

Back 7

1) a single action potential that will result in a contraction and relaxation of the muscle fiber innervated by the neuron

2) when a 2nd stimulus occurs and it is greater than the first

3) contractions varying in strength are achieved by stimulating more muscle fibers or increasing the amount of motor units involved.

4) a muscle is stimulated by an increasing amount of shocks it will increase to a maximum

5) the frequency of shocks are so fast that there is no relaxation

Front 8

What must occur for a muscle to become shorter?

Back 8

the force created must be greater than the load

* the lighter the load, the faster the contraction and the greater the load, the slower the contraption

Front 9

Define:

1) isometric contraction

2) isotonic contraction

3) eccentric contraction

4) concentric contraction

Back 9

1) The exerted force does not cause you to move the load. The length of the muscle stays the same.

2) The force is big enough to move a load. The force of contraction does not change but the muscle length does.

3) The load is greater than the force of the contraction. The muscle lengthens.

4) The force of muscle contraction is greater than the load. The muscle shortens. This can also be called isotonic.

Front 10

1) Complete tetanus will lead to muscle being unable to maintain contraction.This leads to ?

2) What is the Treppe or staircase effect.

3) It occurs because?

4) This proves that there is an advantage for what?

Back 10

1) fatigue

2) When a muscle is stimulated at maximum for individual twitches the successive twitched will get larger.

3) accumulation of intracellular calcium

4) warming up

Front 11

What are the two reasons that muscles return to there resting position?

Back 11

1) Anatagonist muscles

2) Connective tissue of muscles and tendons as well as the titian filaments

Front 12

What affects the strength of muscle contractions?

Back 12

1) the frequency of stimulation, the thickness of muscle filaments in the muscle finer, initial length of the muscle fiber

Front 13

Describe the optimum length theory.

Back 13

A muscle fiber will have the most strength of muscle contraction when it is at a normal resting length, myosin and actin can engage over a larger area.

- when stretched myosin/actin cannot interact as much

- overly contracted there are no where actin/myosin to interact

Front 14

Contract Type 1 fibers with Type 2 fibers

Back 14

Type 1 fibers: is called slow-twitch fibbers. It contracts slowly, slow to fatigue, has lots of mitochondria, myoglobin, red, rely on aerobic respiration, rich capillary supply, small neurons/fibers that transmit info more slowly

Type IIA (white fast oxidative): is in-between the other 2 fibers.

Type II (white fast glycolytic): rely on anaerobic metabolism, little mitochondria/myoglobin, capillaries.

Front 15

A less active person will have more of what type of fiber?

Back 15

they have more fast twitch.

* Marathon running will give you little fast fibers and more slow fiber.

Front 16

Lower motor neurons are influenced by two main factors.

Back 16

1) Upper neurons (brain and spinal cord)

2) sensory feedback from muscles and tendons

Front 17

Describe the muscle spindle apparatus.

Back 17

When a muscle contracts:

Gamma motor neurons cause extrafusal fibers to contract. When there is a change in position. It is sensed by intrafusal fibers that use alpha motor neurons to take up slack/tone.

Front 18

what is coactivation?

Back 18

when upper motor neurons stimulate alpha and gamma motor neurons.

Front 19

Describe the properties of cardiac muscles.

Back 19

- striated

- gap junctions

- involuntary

- intercalated discs separate them

Front 20

Describe the properties of smooth muscle

Dense bodies

Back 20

- not striated

- involuntary

- gap junctions

- no sacromeres (they can stretch more than skeletal muscle) They also have more actin

Dense bodies: how actin is anchored to the plasma membrane

Front 21

How does smooth muscle contraction occur.

What is latch state?

Back 21

Calcium enter through voltage gated channels and bind to calmodulin to form a complex. This activates myosin light chain kinase. This phosphorylates myosin so cross bridges can happen.

Smooth muscle has slower contractions**

It can form prolonged myosin-actin binding; latch state

Front 22

This occurs within smooth muscle:

Define what is a single unit smooth muscle

Define what is a multiunit system

Back 22

1) cells receive an action potential form a passing neuron and it can spread to neighbouring cells

2) every smooth muscle cell receives direct innervaton from a neuron