Lecture 8

Question 1

What is the earliest part in muscle stimulation where there is no change in sarcomere length?

Answer 1

Latent period

Question 2

The Latent Period is everything between

Answer 2

The formation of a graded potential in the sarcolemma of muscle cell to the power stroke of the myosin

Question 3

The end of the latent period is marked by the

Answer 3

First change in force

Question 4

Muscle contracts and sarcomeres shorten during the

Answer 4

Contraction period

Question 5

Relaxation Period is when the

Answer 5

Muscle relaxes and sarcomere returns to its relaxed length

Question 6

Why does the muscle relax?

Answer 6

Acetylcholinesterase breaks down acetylcholine and force decreases during the Relaxation Period

Question 7

The amount of force generated by a muscle during contraction is the result of the

Answer 7

Number of activated motor units

Question 8

Motor Units consist of

Answer 8

The motor neuron and any muscle cells that neurons are connected to it

Question 9

A large muscle would have

Answer 9

Many motor units

Question 10

A small muscle has

Answer 10

Fewer motor units

Question 11

In Isotonic Contraction, the force generated by the muscle is

Answer 11

Greater than the load

Question 12

Isotonic Contraction results in

Answer 12

Muscle shortening

Question 13

In Isotonic Contraction, the force generated by muscle is always equal to

Answer 13

The load trying to be moved

Question 14

What is Isometric Contraction?

Answer 14

Load is greater than the force generated by the muscle and muscle does not shorten (because the object is too heavy)

Question 15

What happens in Isometric Contraction?

Answer 15

Tension develops in the muscle as the myosin tries to pull on the actin, but sarcomeres do not shorten because the muscle is too weak to move the load

Question 16

The force that a muscle generates also depends on

Answer 16

How frequently the muscle is stimulated by action potentials from the nervous system

Question 17

Multiple APs arriving at the muscle in quick succession can

Answer 17

Activate more motor units than a single AP would, resulting in contractions that generate more force

Question 18

Summation is when

Answer 18

Muscle is restimulated by a second AP before it fully relaxes, generating more force

Question 19

Tetanus is when

Answer 19

A muscle is stimulated so rapidly that it does not relax at all

Question 20

Summation and Tetanus occur because

Answer 20

Each additional AP releases new Calcium ions from the Sarcoplasmic Reticulum, which in turn increases the number of actin-myosin cross bridges and powerstrokes to generate more force

Question 21

Contraction Velocity describes

Answer 21

How long it takes for the muscle to go from its relaxed length to contracted length

Question 22

Heavier loads require

Answer 22

More motor units to be activated, which takes more time, slowing contraction velocity