Muscles 2

Question 1

Steps that start a contraction

Question 2

Step 1.

Answer 2

Ach is released at the neuromuscular junction and binds to ACh receptors on the sarcolemma

Question 3

2.

Answer 3

An actuon potential is generated and spreads across the membrane surface of the muscle fibre and along the t tubules

Question 4

3.

Answer 4

The sarcoplasmic reticulum releases stored Ca ions

Question 5

4.

Answer 5

Ca ions bind troponin, exposing the active sites on the thin filaments. And cross bridges form when myosin heads bind to active sites

Question 6

5

Answer 6

The contraction cured repeats itself

Question 7

Steps that end a muscle contraction

Answer 7

6. ACh is broken down by acetylcholinesterase ending the action potential generation

Question 8

7.

Answer 8

Ca is pumped back into the the sarcoplasmic reticulum, decreasing its concentration

Question 9

8.

Answer 9

Th tropomyosin returns back to its normal position and the active sites are covered up

Question 10

9.

Answer 10

. Without have cross bridge formation, the co traction ends

Question 11

10.

Answer 11

The muscles returns to resting

Question 12

True or False
During muscle contraction, thin filaments become shorter while thick filaments stay the same length

Answer 12

False:
During contraction
- both thick and thin filaments don’t change in length, but they overlap more

Question 13

An individual muscle twitch

Answer 13

A brief contraction of a muscle
- follows the all or non response(if stimuli is too low none of the muscles will contract)
Recorded by an electromyography(EMG)

Question 14

Which period of a muscle twitch corresponds to excitation-contraction coupling?

Answer 14

The latent period
- stimulus is spread across the sarcolemma and the triad

Question 15

Which period of muscle twitch corresponds to the cross bridges cycle

Answer 15

The contraction period
- tension builds up to peak value

Question 16

The amount of tension developed in a skeletal muscle fibre depends on

Answer 16

Frequency of stimulation
Sacromere length

Question 17

Frequencies of stimulation

Answer 17

Temporal summation: no time to completely relax between receiving more stimuli(relaxes around halfway)
- tension in increased
Tetanus; no time to relax between contractions and receiving more stimuli
- all possible cross bridges are formed

Question 18

Sarcomere: Skeltal muscle fibres

Answer 18

• are elastic( like an elastic band, more tension is created to snap back the further it’s stretched)
• have a Rangel of ideal lengths that allow them to create max tension

Question 19

Muscle contraction

Answer 19

One motor unit has 1 motor neuron and multiple muscles fibres

Question 20

How do the functions of small and large motor units differ?

Answer 20

Small motor units produce smaller increments of tension
• E.g. extraocular eye muscles: 1 motor neuron + 3-6 muscle fibres

Large motor units produce larger increments of tension.
E.g. gastrocnemius muscle (calf): 1 motor neuron + 1000s fibres

Question 21

In 1 muscle what type of motor units will be recruited last?

Answer 21

Large motor units with larger, less excitable neurons

Question 22

Motor unit recruitment

Answer 22

The number of motor units activated at any one time
Follow the size principle
- for weaker contractions- happens in smaller increments
- for stronger contractions- happens in bigger increments

Question 23

Isotonic contraction

Answer 23

Muscles maintain a constant tension when contracting
Conventric: muscles shorten(lifting weights)
Eccentric: muscles lengthens(lowering weights)

Question 24

Isometric contractions

Answer 24

Muscles don’t change in length but tension increases

Question 25

What type of muscle contraction is used for core strength

Answer 25

Isometric

Question 26

Which type of muscle contraction causes the most damage to the muscle fibres?

Answer 26

Isotonic eccentric

Question 27

Where is ATP need through the muscle contraction?

Answer 27

• move and detach cross bridges
  • pump calcium from sarcoplasm back into SR
  • power the Na/K pump to reset the resting membrane potential in muscle cells
• can only power it for a few seconds

Question 28

There are 3 ways to refill ATP for muscle contractions

Answer 28

1. Use a creative phosphate
2. Anaerobic respiration
3. Aerobic respiration(preferred method)

Question 29

Creative phosphate

Answer 29

Donates its phosphate to ADO to make that into AtP

Question 30

Anaerobic Respiration

Answer 30

Creates ATP through glycolysis and without oxygen
Why is this an important energy source for high intensity activities?
- fast production and and when oxygen delivery doesn’t match muscle demand

Question 31

True or False
The delayed onset muscle soreness (DOMS) experienced few days after intense exercise is due to the production of lactic acid.

Answer 31

False:

The pain likely comes from microscopic muscle inflammation and damage.

Question 32

Aerobic Respiratiob

Answer 32

Creates ATP by breaking down different energy sources in the mitochondria
- goes through the kerb cycle and requires oxygen

Question 33

Skeletal Muscle fibre

Answer 33

• all differ in structure and functions
• look at chart

Question 34

Most skeletal muscles contain
A. muscle fibres of the same type
B.
a mixture of fibre types
C. a predominance of slow oxidative fibres
D. a predominance of fast oxidative fibres

Answer 34

B