Clin Phys Week 2 E

Question 1

What are the 3 ways ATP is replenished in the muscles?

Answer 1

Creatine phosphate

Aerobic respiration

Anaerobic respiration

Question 2

What is oxygen consumption?

Answer 2

The amount of oxygen used by the body per minute. Normal aerobic metabolism is about 250ml/min. AKA oxygen uptake.

Question 3

What are the two parameters measured when measuring oxygen uptake of an exercising patient?

Answer 3

1) minute ventilation: the amount of air the subject inspires or expires per minute
2) the oxygen and carbon dioxide concentration of expired air.

Question 4

What is oxygen debt?

Answer 4

This is the oxygen that must be used in the oxidative energy processes are strenuous exercise to reconvert:

• lactic acid to glucose
• decomposed ATP
• hydrolysed creatine phosphate

to their original states

Question 5

What is oxygen deficit?

Answer 5

The volume of oxygen difference between the ideal and real O2 uptak

Question 6

What is muscle fatigue?

Answer 6

The physiological inability to contract due to the shortage of available ATP (accumulation of lactic acid)

Question 7

What is an isometric contraction?

Answer 7

Where both ends of the muscle are fixed therefore the muscle doesn’t shorten or lengthen during the contraction

Question 8

What is isotonic contraction:

Answer 8

Where the absolute weight remains the same but the changing lever creates a varying resistance through the range of motion.

Question 9

What is a motor unit?

Answer 9

The motor neuron and all the muscles fibres it innervates

Question 10

What is muscle twitch?

Answer 10

The response of a muscle to a single action potential on its motor neuron

Question 11

What is muscle tone?

Answer 11

The phenomenon of muscles exhibiting slight contraction even when at rest, which keeps muscles firm and ready to respond.

Question 12

What are the 3 kinds of graded muscle reponses?

Answer 12

Wave summation

Multiple motor unit summation (recruitment)

Treppe

Question 13

What is the length tension curve?

Answer 13

There is an optimal length tension relationship when the muscle is slightly stretched and there is a slight overlap between myofibrils. If the sacromere is shortened between contraction, there will be a lot of overlap of the myofilaments but no room for further shortening which will impact negatively on the force of the contraction.

Alternatively if the muscle is in a stretched state prior to contaction, there will be lot of room for muscle shortening but there will not be adequate overlap of the sarcomeres, therefore the force of contraction will not be optimal.

Optimal sacromere length is 80%-120% of resting sacromere length

Question 14

What is the force- velocity relationship?

Answer 14

As load increases, the slower the velocity and shorter the duration of contraction.

Question 15

What are the 3 types of muscle fibres?

Answer 15

Slow oxidative

Fast oxidative

Fast glycolytic

Question 16

What is the effect of aerobic exercise on muscles?

Answer 16

Increase in:

Capillary penetration

Number of mitochondria

Synthesis of myoglobin

However, no hypertrophy

Question 17

What is the impact of resistance exercise on muscles?

Answer 17

Increase in:

Number of mitochondria

Number of myofilaments

Number of myofibrils

Glycogen storage

Leads to hypertrophied cells

Question 18

How does exercise impact fibre adaption and growth of muscles?

Answer 18

• Exercise facilitates muscle cellular changes
• Myofibrils split and subdivide
• Z-lines split and divide
• Oblique pulling breaks the z-disc which constitutes a mechanical process
• The number of sarcomeres increases with increased function
• Contractures lead to a decrease in the numbers of sarcomeres

Question 19

Explain the role of ATP during a skeletal muscle contractions.

Answer 19

ATP binds to the myosin head and hydrolyses, cocking it into its high energy configuration. This also gives the myosin head energy to attach to the actin binding site. As the myosin head performs the power stroke the ADP+P are released. In order for the myosin head to detach from the actin a new ATP molecule must bind. Once this ATP has bound the myosin head returns to its low energy configuration.

Question 20

What are graded muscle responses

Answer 20

Variations in the degree of muscle contraction, required for proper control of skeletal movement.

Question 21

How are graded muscle responses graded?

Answer 21

Changing frequency of stimulation

Changing strength of stimulus

Question 22

What are the 4 grades of muscle response?

Answer 22

Muscle twitch: a single stimulus results in a single contractile response

Wave summation: frequently delivered stimuli increases contractile force (muscle does not have time to completely relax)

Incomplete tetanus: more rapidly delivered stimuli

Complete tetanus: results if stimuli are given quickly enough.

Question 23

What is the staircase effect in regards to treppe?

Answer 23

It is the creation of an increased contraction strength in response to mutilple stimuli of the same strength.

It is due to:

An increasing availability of Ca2+ in the sarcoplasm

Muscle enzyme systems become more efficient because heat is increased as muscle contracts.

Question 24

List the causes of muscle fatigue

Answer 24

ATP production isn’t fast enough for ATP use. There is a deficit of ATP causing Contractures.

Lactic acid accumulates in the muscleIonic imbalances are present