A&P AS Flashcards
What is a motor unit
A motor neurone plus all the muscle fibres it innervates.
What is a neurone
A type of nerve cell
What is an axon
Carries action potential (AP)/electrical impulse from the cell body to the neuromuscular junction.
Why is neuromuscular junction
Where the motor neurone communicates with the muscle fibres across the synapse .
What is a synapse
The space between the neuromuscular junction and skeletal muscle.
What’s the motor end plate
Area of muscle fibres which establishes synaptic contact with motor neurone.
What is resting potential
Where there is a lower charge inside the neurone than outside the neurone.
What is action potential
The electrical impulse carried down the axon.
What are neurotransmitters
chemical transmitters which diffuse across a synapse binding to receptor to initiate muscular contraction.
What is Acetyl choline
The neurotransmitter released at the neuromuscular junction and diffuses across the synapse .
What is the all or non law
If the AP threshold is reached, all the muscle fibres in the motor unit are initiated. If the AP threshold is NOT reached then none of the muscle fibres are initiated.
What is the step by step guide to answering motor unit questions
- define what a motor unit is.
- resting potential.
- AP threshold reached.
- AP carried down axon to neuromuscular junction.
- Neuromuscular junction releases ACh which diffusers across the synapse .
- ACh bind to receptors on the motor end plate and all the muscle fibres in that motor unit contract(as the AP threshold was reached).
- If the AP threshold wasn’t reached then none of the muscle fibres in the motor unit would contract.
What is the effect of number of motor units recruited
- The greater the strength of the stimulus from the CNS.
- The greater the number of motor units recruited.
3.The greater force of muscular contraction.
Effect of the type of motor unit recruited
1.Type 1 are small and produce low force of contraction over a long period.
2.Type 2a size and time of contraction are between type 1 and 2b
3. Type 2b are large and produce a large force of contraction over a short period of time.
What is isotonic contraction
The muscle is changing length while exerting a force
There are 2 types:
1. Concentric isotonic - muscle shortens
2. Eccentric isotonic - muscle lengthens
Eg lifting and lowering phases of a weight training exercise
What is isometric contraction
The muscle remains the same length while exerting a force.
Isometric contraction stops movement.
Eg crouch phase of a rugby scrum
What is concentric contraction and give a sporting example
The muscle shortens while exerting a force.
Concentric contraction causes movement.
Eg triceps brachii and pectoralis major when preforming the upwards phase of a press up.
What Is eccentric contraction and give a sporting example
The muscle lengthens while exerting a force
Eccentric contraction controls the movement
The muscle acts like a break to control the lowering movement
The muscle s usually working against gravity
Eg triceps brachii and pectoralis major when preforming the downward phase of a press up.
What is the function of a motor unit
To carry electrical impulses form the CNS to the muscle fibres to initiate muscle contraction.
Effect of synchronisation of motor units.
Not all motor units are fruited at the same time
1st motor units recruited are type 1-force of contraction low
2nd motor units recruited are type 2a-force of contraction increases
3rd motor units recruited are type 2b- force of contraction increases further
What are the 3 types of muscle fibre
Type 1 : slow oxidative (SO)-endurance fibres
Type 2a:fast oxidative glycolic (FOG)- speed endurance fibres
Type 2b:fast glycolic (FG)-speed/power fibres
Games players have a mix of all fibres
What is myoglobin
Myoglobin: a protein in muscle cells that stores oxygen for cellular respiration
What is a phosphocreatine
A chemical compound that stores energy in muscles Brain and heart its a rapid energy source for muscle contractions.
It regenerates ATP form ADP.
What is the primary type of muscle fiber characterized by high endurance?
Type 1 muscle fibers
Which muscle fiber type is known for rapid contraction and high force production?
Type 2b muscle fibers
True or False: Type 2a muscle fibers are a hybrid of type 1 and type 2b fibers.
True
Fill in the blank: Type 1 muscle fibers are also known as __________ fibers.
slow-twitch
What is the main energy source for type 1 muscle fibers?
Aerobic metabolism
Which muscle fiber type has a higher resistance to fatigue?
Type 1 muscle fibers
What color are type 1 muscle fibers typically described as?
Red
Which muscle fiber type has a larger diameter, type 2a or type 2b?
Type 2b muscle fibers
Which type of muscle fibers are primarily used for short bursts of speed and power?
Type 2b muscle fibers
True or False: Type 2a muscle fibers are exclusively anaerobic.
False
What is the predominant energy source for type 2b muscle fibers?
Anaerobic glycolysis
Fill in the blank: Type 2a muscle fibers are also referred to as __________ fibers.
fast-twitch oxidative
Which muscle fiber type is most suited for endurance activities?
Type 1 muscle fibers
How do type 2a muscle fibers perform compared to type 2b during extended exercise?
They perform better due to higher oxidative capacity.
What is the primary function of type 2b muscle fibers?
Explosive strength and power
True or False: Type 1 fibers have a high density of mitochondria.
True
Which type of muscle fiber has a greater capillary density?
Type 1 muscle fibers
What type of muscle fiber is more likely to be recruited during long-distance running?
Type 1 muscle fibers
Fill in the blank: Type 2b fibers are primarily fueled by __________.
carbohydrates
Which muscle fiber type is likely to have a faster contraction speed?
Type 2b muscle fibers
What is a key structural characteristic of type 1 muscle fibers?
High myoglobin content
Fill in the blank: Type 2a fibers can utilize both __________ and __________ for energy.
aerobic metabolism, anaerobic metabolism
Which type of muscle fiber is characterized by a moderate resistance to fatigue?
Type 2a muscle fibers
True or False: Type 2b muscle fibers are more fatigue-resistant than type 1 fibers.
False
What is a common training adaptation for type 2a muscle fibers?
Increased oxidative capacity
Which muscle fiber type is likely to be predominant in sprinters?
Type 2b muscle fibers
Where is the SA (sino-atrial) node nd what is its function
It’s found in the right atrial wall
It generates electrical impulses and fires it through the atrial walls causing them to contract
It is the pacemaker of the heart as it determines heart rate.
Where is the (AV) node found and what is its function
It is found in the right atrium
Its function is to collect the impulse and delay it for 0.1 seconds to allow the atria to finish contracting.
It then releases the impulse to the bundle of his
Here is the bundle of his found and what is its function
Found in the septum (divides the heart into left and right side)
Function:it splits the impulse in two to be distributed through each separate ventricle.
Where are bundles branches found and why is there function
Bundle branches are found in the septum there function is to carry the impulse to the base of each ventricle.
Where are Purkinje fibres found and what are there function
Found in the ventricle walls
Function is to distribute the impulse though the wall causing the ventricle to contract
What happens once the electrical impulses journey thought the heart is complete
The atria and the ventricles relax the heart refills with blood this process is a heartbeat
What is the formula for cardiac output
Cardiac output (Q)=stroke volume(SV) x heart rate (HR)
What is heart rate, what Is the average value at rest and what is it for a endurance athlete
The number of times the heart beats per minute (BPM)
70 BPM
50BPM
What is bradycardia?
Resting HR lower than 60bpm
What is cardiac hypertrophy?
Increased size and strength of heart in endurance athletes
How do you calculate max HR?
max HR = 200bpm -age
What is stroke volume?
He amount of blood ejected from the left ventricle per beat. (Units = ml)
Average stroke volume at rest
70 ml
Stroke volume for endurance athlete
100 ml
What is Starling’s law (Frank- Starling mechanism)?
It shows us how SV is dependent on venous return.
An increased vol of blood returning to the heart leads to an increased end-diastolic volume in the ventricles and therefore greater stretch on ventricle walls.
This greater stretch increases the force of ventricular contraction, ejecting a larger volume of blood from the ventricles.
The lower the HR, the more time available to maximise this effect, this is why we see greater exercising SV’s in trained athletes.
When does SV reach a plateau?
It plateaus during sub-maximal intensity due to:
- increased HR towards maximal intensities does not allow enough time for the ventricles to completely fill with blood in the diastolic phase.
- this limits the Frank-Starling mechanism.
