Clin Phys Week 2 E Flashcards
What are the 3 ways ATP is replenished in the muscles?
Creatine phosphate
Aerobic respiration
Anaerobic respiration
What is oxygen consumption?
The amount of oxygen used by the body per minute. Normal aerobic metabolism is about 250ml/min. AKA oxygen uptake.
What are the two parameters measured when measuring oxygen uptake of an exercising patient?
1) minute ventilation: the amount of air the subject inspires or expires per minute
2) the oxygen and carbon dioxide concentration of expired air.
What is oxygen debt?
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
What is oxygen deficit?
The volume of oxygen difference between the ideal and real O2 uptak
What is muscle fatigue?
The physiological inability to contract due to the shortage of available ATP (accumulation of lactic acid)
What is an isometric contraction?
Where both ends of the muscle are fixed therefore the muscle doesn’t shorten or lengthen during the contraction
What is isotonic contraction:
Where the absolute weight remains the same but the changing lever creates a varying resistance through the range of motion.
What is a motor unit?
The motor neuron and all the muscles fibres it innervates
What is muscle twitch?
The response of a muscle to a single action potential on its motor neuron
What is muscle tone?
The phenomenon of muscles exhibiting slight contraction even when at rest, which keeps muscles firm and ready to respond.
What are the 3 kinds of graded muscle reponses?
Wave summation
Multiple motor unit summation (recruitment)
Treppe
What is the length tension curve?
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
What is the force- velocity relationship?
As load increases, the slower the velocity and shorter the duration of contraction.
What are the 3 types of muscle fibres?
Slow oxidative
Fast oxidative
Fast glycolytic
What is the effect of aerobic exercise on muscles?
Increase in:
Capillary penetration
Number of mitochondria
Synthesis of myoglobin
However, no hypertrophy
What is the impact of resistance exercise on muscles?
Increase in:
Number of mitochondria
Number of myofilaments
Number of myofibrils
Glycogen storage
Leads to hypertrophied cells
How does exercise impact fibre adaption and growth of muscles?
- 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
Explain the role of ATP during a skeletal muscle contractions.
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.
What are graded muscle responses
Variations in the degree of muscle contraction, required for proper control of skeletal movement.
How are graded muscle responses graded?
Changing frequency of stimulation
Changing strength of stimulus
What are the 4 grades of muscle response?
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.
What is the staircase effect in regards to treppe?
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.
List the causes of muscle fatigue
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
