Lectures 1-5 Flashcards
1
Q
What are the general benefits of S&C?
A
Helps prevent injury Promotes healthy bones Improved posture Increased fitness Increase metabolism Psychological well-being
2
Q
What are the athletic benefits of S&C?
A
Faster
Stronger
More mobile
3
Q
What is muscular strength?
A
Muscles ability to exert force (on slides)
The maximum amount of force that a muscle can exert against some form of resistance in a single effort (google)
4
Q
What is muscular endurance?
A
Sustained successive exertions (on slides)
The ability of a muscle or group of muscles to sustain repeated muscular contraction against a resistance for a prolonged period of time (google)
5
Q
What is muscular power?
A
Ability to exert force per unit of time (e.g., rate of force development)
The ability to exert a maximal force in as short a time as possible
6
Q
The proportion of people aged 60 and over is growing
Between 1970 and 2025, what is the predicted growth in older populations?
In 2025, how many people will be aged 60 and over?
(Ageing populations)
A
870 million / 380%
1.2 billion
7
Q
Definition of ageing?
Ageing populations
A
The process of growing old
8
Q
What is ageing?
Ageing populations
A
Complex and multidimensional phenomenon
Manifested differently between individuals throughout the lifespan
Highly conditional on interactions between genetic, environmental, behavioural, an demographic characteristics
9
Q
Even with healthy ageing (ageing in the absence of disease), what can ageing lead to?
(Ageing populations)
A
Reductions in physiological resilience, often leading to:
Physical disability Mobility impairment Falls Decreased independence Decreased quality of life
10
Q
What is ageing associated with in terms of skeletal muscle mass?
What is this called?
(Ageing populations)
A
A decline in skeletal muscle mass and muscle strength
Sarcopenia
11
Q
What is the age-related loss of muscle mass related to?
Ageing populations
A
The loss of innervating motor neurone and denervation of muscle fibres
12
Q
Anatomical counts estimate what loss in motor neurons in upper and lower limbs?
How many muscle fibres to each of these neurons innervate?
(Ageing populations)
A
Upper: 35000 (Gesslbauer et al. 2017)
Lower: 60000 (Tomlinson & Irving, 1977)
each neuron innervates hundreds or thousands of muscle fibres
13
Q
What may happen if a motor neuron is impaired or degraded during ageing?
(Ageing populations)
A
It’s muscle fibres may lose their innervation and will be vulnerable to apoptosis
14
Q
What is apoptosis?
Ageing populations
A
The death of cells which occurs as a normal and controlled part of an organism’s growth or development
15
Q
Observational studies indicate what percentage of muscle mass is lost per year after the fourth decade of life?
(Ageing populations)
A
1%
16
Q
What is the prevalence of Sarcopenia in:
Adults older than 60 years?
Adults older than 80 years?
(Ageing populations)
A
10%
50%
17
Q
What is sarcopenia part of?
Ageing populations
A
The causal pathway for strength loss, disability, and morbidity in older adult populations
18
Q
What is sarcopenia?
Ageing populations
A
The loss of skeletal muscle mass and strength as a result of ageing
19
Q
What does evidence (Slide 13, lecture 2) link muscular weakness to?
(Ageing populations)
A
Diabetes Disability Cognitive decline Osteoporosis Changes in dynamic balance Movement coordination Early mortality
20
Q
What must key strategies be with ageing populations?
Ageing populations
A
Preserving muscle mass which we lose with age
Strengthening bones to prevent osteoporosis
21
Q
What is the NCSA position with helping ageing populations?
Ageing populations
A
Current research has demonstrated that countering muscle disuse through resistance training is a powerful intervention to combat muscle strength loss, sarcopenia and frailty
22
Q
What has poor physical performance been shown to predict?
Ageing populations
A
Disability
Nursing home admission
Mortality
In community-dwelling older adults
23
Q
What do strength and rate of change of strength contribute to?
(Ageing populations)
A
The impact of sarcopenia on mortality
24
Q
What is muscular strength inversely and independently associated with?
(Ageing populations)
A
Death from all causes and cancer in men, even after adjusting for cardiorespiratory fitness and other potential cofounders
25
What percentage of people 65+ have sarcopenia?
How many Europeans are projected to have sarcopenia in 2045?
Ethgen et al. 2017
(Ageing populations)
10-20%
20-30 million
26
UK physical activity guidelines (adults and older adults), in terms of strength
(Ageing populations)
“To keep muscles, bones and joints strong”
Build strength on at least two days a week (e.g., resistance training, yoga etc)
27
UK physical activity guidelines (adults and older adults), in terms of duration of exercise
(Ageing populations)
At least 150 mins moderate intensity per week (E.g., swim, brisk walk, cycle)
Or
At least 75 mins vigorous intensity per week (e.g., run, stairs, sport)
28
UK physical activity guidelines (adults and older adults), other attempts that should be made
(Ageing populations)
Minimise sedentary time
Improve balance (for older adults to reduce chance of frailty and falls) (2 days a week)
29
What are the benefits of strength training?
| Ageing populations
Increased muscle and bone mass, muscle strength, flexibility, dynamic balance, self-confidence, and self-esteem
Helps reduce symptoms of various chronic diseases such as arthritis, depression, type-2 diabetes, osteoporosis, sleep disorders and heart disease
In addition research (lecture 2, slide 18) demonstrates that strength training in older adults with functional limitations reduces falls
30
Despite known benefits of resistance training, only X% of older adults (75+ years) in US participate in muscle-strengthening activities as part of their leisure time (Fragala et al. 2019)
(Ageing populations)
8.7%
31
Reported barriers to participation in resistance exercise for older adults include:
(Ageing populations)
```
Safety
Fear
Health concerns
Pain
Fatigue
Lack of social support
```
32
What is the evidence-based prescription? (Slide 21, lecture 2)
(Ageing populations)
Regular (2-3 days per week), intensity (70-85% of 1RM), volume (2-3 sets per exercise) of 1-2 multijoint exercises per major muscle group
33
With a periodised approach, resistance exercise results in what?
(Evidence-based prescription)
(Ageing populations)
Favourable neuromuscular adaptation in both health older adults and those with chronic conditions
Improve balance, preserve bone density, independence, reduce risk of numerous chronic diseases such as heart disease, arthritis
34
Favourable neuromuscular adaptation translate to what?
| Ageing populations
Functional improvements of daily living activities, especially when power training exercise is included
35
Cautions with resistance training in older adults?
| Ageing populations
Engaging in resistance exercise performed until exhaustion will increase blood pressure, HR and Q
Frailty in people older than 65 is high
Mobility limitations
Obesity
36
Classification of muscular tissue:
Cardiac muscle
(Muscle structure function lecture)
Striated
Branched cells
1-3 central nuclei
Involuntary
37
Classification of muscular tissue:
Skeletal muscle
(Muscle structure function lecture)
Striated
Elongated cells
Multinucleated cells
Voluntary
38
Classification of Muscular Tissue:
Smooth muscle
(Muscle structure function lecture)
Nonstriated
Single central nucleus
Involuntary
39
How many muscles in the human body?
| Muscle structure function lecture
~660 skeletal muscle in human body
40
What % of total bodyweight is muscle mass
| Muscle structure function lecture
40-45%
41
What are the largest cells in the body?
| Muscle structure function lecture
Skeletal muscle fibres
42
How are skeletal muscle fibres created?
| Muscle structure function lecture
By the fusion of many individual embryonic muscle cells
43
Mechanical roles of skeletal muscle
| Muscle structure function lecture
```
Generate force
Maintain posture
Produce movement
Maintain health
Independence
```
44
Metabolic roles of skeletal muscle
| Muscle structure function lecture
Basal energy production
Storage for amino acids and CHO
Production of heat
Consumption of oxygen and fuel for physical activity & exercise
45
Factors that influence muscle actions responsible for force generation
(Muscle structure function lecture)
Structure and architecture
Fiber types
Excitation-contraction coupling
Energy release
46
Slide 7, lecture 3 for diagram of muscle structure
| Muscle structure function lecture
Important
47
Connective tissues:
Epimysium
(Muscle structure function lecture)
Is the fibrous tissue envelope that surrounds skeletal muscle
48
Connective tissues:
Perimysium
(Muscle structure function lecture)
Is a sheath of connective tissue that groups muscle fibres into bundles (anywhere between 10 and 100 or more) or fascicles
49
Connective tissues:
Endomysium
(Muscle structure function lecture)
Wispy later of areolar connective tissue that ensheaths each individual myocyte (muscle fibre, or muscle cell).
It also contain capillaries and nerves
50
Make up of a muscle fibre
Lecture 3, slide 9
(Muscle structure function lecture)
Important
Probably recap as well
51
What is the thin filament?
| Muscle structure function lecture
Actin
52
What is the thick filament?
| Muscle structure function lecture
Myosin
53
What is myosin (thick filament)
| Muscle structure function lecture
A motor protein with the ability to create movement
54
What does each myosin contain?
And what is this?
(Muscle structure function lecture)
A smaller light chain & heavy chain
The motor domain
55
Which bit of myosin binds to ATP?
| Muscle structure function lecture
The heavy chain
56
Why does the heavy chain of myosin bind to ATP?
| Muscle structure function lecture
Because the motor domain acts as an enzyme
It is considered a myosin ATPase
The heavy chain also contains a binding site for actin
57
What is actin? (Thin filament)
| Muscle structure function lecture
A globular protein which polymerise to form long chains or filaments, called F-actin
58
Actin contains how many regulatory proteins?
What are they called?
(Muscle structure function lecture)
Two
Troponin & tropomyosin
59
What do troponin and tropomyosin control?
| Muscle structure function lecture
The interaction between actin and myosin
60
Where is troponin positioned?
What does it play a vital role in?
(Muscle structure function lecture)
Every 7 actin molecules
Plays a vital role in calcium reception
61
Where is tropomyosin positioned?
What is its main function?
(Muscle structure function lecture)
Distributed along the length of the actin filament, in the groove between 2 F-actin strands
Main function is to inhibit the coupling between actin and myosin
62
What do stochastic interactions of actin and myosin mean?
| Muscle structure function lecture
That all sites aren’t bound
63
What % of crossbridges are formed in an isometric contraction?
(Muscle structure function lecture)
~30%
64
The cross bridge model is good for predicting what?
And not good for predicting what?
(Muscle structure function lecture)
Isometric and concentric forces
But not eccentric contractions
65
What is Titin?
| Muscle structure function lecture
A 3rd contractile protein? (Slide 23 lecture 3)
66
What is Titin?
What does it do?
(Muscle structure function lecture)
A huge elastic molecule and the largest known protein, composed of more than 25,000 amino acids
It connects the Z line to the neighbouring M line
67
What are the multiple roles of Titin?
| Muscle structure function lecture
Stabilises the position of the contractile filaments
Prevents overstretching of sarcomere
It’s elasticity returns stretched muscles to their resting length
It also has a very important role in eccentric force production - as a third force regulating myofilament in sarcomere
The Titin spring can also trigger mechanical signalling events in the myocytes leading to: enhances muscle protein degradation and activation of protein synthesis
68
Recap Titin slides in lecture 3
| Muscle structure function lecture
Important
69
Titin has an emerging role in muscle function:
What does it do during muscle relaxation?
What does it do during muscle contraction?
What does this suggest ATP-driven motors also act as?
(Muscle structure function lecture)
It unwinds during relaxation
And folds during contraction
Latches, allowing Titin to fold, providing a powerful boost to muscle contraction
70
What is nebulin?
| Muscle structure function lecture
It is an inelastic giant protein that lies alongside thin filaments and attaches to the Z disk
71
What are the proposed roles of Nebulin?
| Muscle structure function lecture
Helps align the actin filaments of the sarcomere
Regulated actin-myosin interactions by inhibiting ATPase activity in a calcium-calmodulin sensitive manner
72
What are cytoskeletal proteins
| Muscle structure function lecture
A number of other proteins found in interior of a muscle fibre and in sarcomeres
73
What are the roles of cytoskeletal proteins?
| Muscle structure function lecture
Provide structural integrity
Allow lateral force transmission to adjacent sarcomeres
Connect myofibrils to cell membrane
74
Examples of cytoskeletal proteins
| Muscle structure function lecture
Vinculin
Alpha and beta integrins
Dystrophin
Alpha-actinin
C-protein
Desmin
75
Where are satellite cells located? And what are they like?
| Muscle structure function lecture
Adult skeletal muscle
Are stem-like cells
76
Where are satellite cells located?
| Muscle structure function lecture
Between basement membrane and plasma membrane
77
What are satellite cells?
| Muscle structure function lecture
Undifferentiated myoglobin precursors that have self-renewal properties
78
What happens when satellite cells are activated by myogenic factors?
(Muscle structure function lecture)
Satellite cells proliferate and differentiate into new muscle fibres
79
Recap questions
| Muscle structure function lecture
Slide 29, lecture 3
Crucial
80
Where are the longest muscle cells/fibres in the body?
| Muscle structure function lecture
The legs
81
Where are the smallest muscle cells/fibres in the body?
| Muscle structure function lecture
Inner ear
82
What is found in the myofibril?
| Muscle structure function lecture
Actin & Myosin
83
How many myofibrils can be in the muscle fibre?
| Muscle structure function lecture
100,000s
84
What is the muscle fibre wrapped in?
| Muscle structure function lecture
Endomysium
85
What is a sarcomere?
| Muscle structure function lecture
Functional unit of the muscle
Made up of thick (myosin) and thin (actin) filaments
86
How are sarcomeres bound?
What is found in the middle of this?
(Muscle structure function lecture)
By a Z disc
The M line
87
Look at A band, dark region of Z disc
| Muscle structure function lecture
Important couple of slides
88
Recap troponin C
Muscle structure function lecture
89
What is nebulin?
| Muscle structure function lecture
Acts to help with structure of troponin and tropomyosin
90
What are the central pillars of S&C?
| Intro lecture to module
Testing, monitoring & diagnostics to inform programmes
Planning & programming to maximise adaptation and optimise performance
Coaching to bring to life the programme in an appropriate climate aligned to the sport to maximise adaptations
91
Important diagram that was a question last year, Slide 3 lecture 4
Muscle contraction, sarcomere length thing
92
The force generated by the muscle directly depends on what?
| Muscle contraction
The length of the muscle or sarcomere
93
What is the optimum sarcomere length for maximum force to be generated in the muscle?
(Muscle contraction)
2-2.20 um (check what um is, lecture 4)
94
What can we do to change the length of a muscle?
| Muscle contraction
Contract it
Stretching
Move limbs
95
If a muscle gets longer what happens to the sarcomere?
What is the result of this?
(Muscle contraction)
The sarcomere lengthens
Therefore, less able to lift things
96
Equation for force
| Muscle contraction
Force = mass X acceleration
97
What is the sarcomere length?
| Muscle contraction
The distance between the two Z-bands
98
What is the plateau region in terms of sarcomere length (on the diagram)
(Muscle contraction)
The peak force that can be generated by a sarcomere
99
What does optimal overlap of sarcomere actually mean (when sarcomere length at 2-2.20 um)
(Muscle contraction)
Highest chance for actin and myosin to bind
100
What happens when the sarcomere length is at 3.65 um?
| Muscle contraction
The distance where there is no overlap in the sarcomeres
101
When are length-tension relationships obtained?
| Muscle contraction
During isometric contractions
102
The tension developed during a twitch is a direct reflection of what?
(Muscle contraction)
The length of individual sarcomeres before contraction begins
103
The sliding filament theory predicts that the tension generated by a muscle fibre is directly proportional to what?
(Muscle contraction)
The number of cross bridges formed between the thick and thin filaments
104
What is passive tension (passive length-tension curve)
| Muscle contraction
Where no ATP is used, uses recoil
E.g. someone else stretching your muscle (passive stretching)
105
How can you develop passive tension?
| Muscle contraction
Touching your toes
Passive stretching
106
Learn the passive length-tension curve
| Muscle contraction
Lecture 4, slide 10
107
When a muscle is slightly or moderately stretched, what contributes to most of the passive tension within the muscle?
(Muscle contraction)
Structural proteins (in particular Titin)
108
When a muscle is more extensively stretched, what contributes to most of the passive tension within the muscle?
(Muscle contraction)
Extracellular connective tissues (especially those that compose the tendon)
109
Does passive tension depend on active or volitional contraction?
(Muscle contraction)
No
110
What is the critical length on the passive length-tension curve?
(Muscle contraction)
A point at which all of the relaxed tissue has been brought to an initial level of tension
111
What happens after the critical length has been reached on the passive length-tension curve?
(Muscle contraction)
Tension progressively increases until the muscle reaches levels of very high stiffness
112
What can eventually happen during extreme levels of stiffness during passive tension?
(Muscle contraction)
Tissue eventually ruptures or fails
113
Useful purposes of passive tension within stretched muscles
| Muscle contraction
Moving or stabilising a joint against the forces of gravity, physical contact or other activated muscles
114
Look at total length tension curve
| Muscle contraction
Slide 10, lecture 4
115
What is the total length-tension curve
| Muscle contraction
The active length-tension curve, when combined with the passive length-tension curve
116
What does the total length-tension curve show?
| Muscle contraction
Why eccentric training is very beneficial and why eccentric loading is very damaging (in a good way) to the muscle
117
What does Herzog (2018) say about Titin
| Muscle contraction
Plays a key role in development of passive & active tension within the muscle
118
Does active and passive tension generated the same forces?
| Muscle contraction
No, some forces generated during passive tension actually exceed that of active tension
119
Recap slide 12
| Muscle contraction
Lecture 4
120
Slides 13 & 14 and PE BOOK
| Muscle contraction
Lecture 4
121
Definition of plasticity
| Muscle contraction
The ability of a muscle fibre to change its phenotype or the qualities within that muscle (e.g. from type I to type II)
122
What are the longest cells in the body?
| Muscle contraction
Muscle fibres
123
What plays a major role in phenotype alteration?
| Muscle contraction
```
Innervation
Mechanical loading (training)
Unloading (injury)
Corticosteroids
Hormone profile
Ageing
```
124
What are hybrid fibres?
What happens to these during ageing?
(Muscle contraction)
Single muscle fibres that may express more than one type of myosin chain simultaneously
The volume of these increases during training
125
What myogenic transcription factors play a role in the synthesis of muscle proteins that are specific for each muscle fibre type?
(Muscle contraction)
MyoD
| Myogenin
126
The process of fibre differentiation is influenced by what?
| Muscle contraction
MyoD and myogenin
Levels of thyroid hormones
Activity pattern of peripheral nerves
127
Learn Buller study
| Muscle contraction
Slide 16, lecture 4
128
What did Buller et al (1960)’s study show
| Muscle contraction
Shows neurons have an important role to play in the contractile properties of the muscle
129
Why are some muscle fibres at an angle?
| Muscle contraction
Can pack more muscle fibres into the area, so can generate greater forces
130
Different type of muscle architecture
| Muscle contraction
Slide 17, lecture 4
131
What do the myofibres in fusiform muscles cause?
| Muscle contraction
Force production to occur directly at the tendon
132
How are the muscle fibres arranges in fusiform muscle?
| Muscle contraction
Parallel
133
The parallel arrangement of fusiform muscles allows for what?
(Muscle contraction)
Fast muscle shortening
134
In pennate muscle, fascicle angle effects what?
| Muscle contraction
Force transmission and shortening velocity
135
High intensity strength training causes increase in what in pennate muscle?
(Muscle contraction)
Increase in pennation angle
Enhances muscle ability to pack more sarcomeres and myofibres
Thereby, increasing cross-sectional area
136
What does being able to pack more muscle fibres into an area (pennate muscle) increase, which compensated for what?
(Muscle contraction)
Increases force-generating capacity if the muscle
Compensating for loss in force transmission due to increases in pennation angle
137
How is pennation angle measured?
| Muscle contraction
By determining the average angle of the fibres relative to the axis of force generation of the muscle
138
Slide 20, lecture 4
| Muscle contraction
For trigonometry to work out pennation angle
139
How do you work out pennation angle?
| Muscle contraction
Using trigonometry
140
Definition of muscle length?
| Muscle contraction
The distance from the origin of the most proximal muscle fibres to the insertion of the most distal fibres
141
What is the physiological cross sectional area?
| Muscle contraction
Represents the sum of the cross-sectional areas of all the muscle fibres within the muscle
142
Physiological cross sectional area is the only architectural parameter that is directional proportional to what?
(Muscle contraction)
The maximum tetanus tension generated by the muscle
143
A muscle with a pennation angle of 30 degrees transmits what % through the tendon?
Why?
(Muscle contraction)
86%
The cosine of 30 degrees is 0.86
144
Most human muscles have pennation angles that range from what to what?
(Muscle contraction)
0-30 degrees
145
Different scenarios
| Muscle contraction
Lecture 4, slide 22-23
146
Which muscles best suited for force speed slide
| Muscle contraction
Lecture 4, slide 24
147
A simple fusiform muscle model shows that fibres in the outer region of the muscle are likely to undergo what type of strain, compared to those in the inner region of the muscle?
(Muscle contraction)
Lower strains
148
A simple pennate muscle model predicts that the fibres with a lower pennation angle will undergo what?
(Muscle contraction)
Larger strains for a given amount of muscle shortening
149
Recap questions
| Muscle contraction
Lecture 4, slide 27
150
Does a whole muscle just contraction at the same time?
| Neural control of human movement
No, subdivisions are activated individually eventually forming a collective at very high intensities
151
Why is there a higher density of neurons in areas such as the hands and face?
(Neural control of human movement)
Need greater dexterity in those areas
152
What is the motor cortex?
| Neural control of human movement
The part of the brain that drives muscular contraction
| Without motor cortex, can’t actually initiate contraction of the muscle
153
How do the cerebral and motor cortex’s work together?
| Neural control of human movement
Cerebral is integration of all the info, motor cortex is the thing that executed the demand to contract or not
154
A stimulus can be processed at varying different levels of the CNS, what are the 5 main levels of control?
(Neural control of human movement)
```
Cerebral cortex
Basal ganglia
Cerebellum
Brain stem
Spinal cord
```
155
Describe the cerebral cortex level of control in the CNS
| Neural control of human movement
Highest level of control - contains motor cortex
156
Describe the basal ganglia level of control in the CNS
| Neural control of human movement
Controls posture and balance
157
Describe the cerebellum level of control in the CNS
| Neural control of human movement
Major integrator of sensory info, controls timing
158
Describe the brain stem level of control in the CNS
| Neural control of human movement
Integrates all CNS activity
159
Describe the spinal cord level of control in the CNS
| Neural control of human movement
Pathway between CNS and PNS, it functions with both specific and complex control
160
Effective application of force during relatively complex movements depends on what?
(Neural control of human movement)
A series of coordinated neuromuscular patterns
161
What is the central nervous system made up of?
| Neural control of human movement
Brain and spinal cord
162
What is the peripheral nervous system made up of?
| Neural control of human movement
Nerves that transmit information to and from the CNS
163
Slide 7/8/9
| Neural control of human movement
Lecture 5
164
Make up of spinal cord
| Neural control of human movement
```
C1-C8
T1-T12
L1-L5
S1-S5
Coccygeal nerves (1 pair)
```
165
What are the two descending pathways travelled by the axons of Betz cells
(Neural control of human movement)
Corticospinal tract
Corticobulbar tract
166
How would you describe the axons of the corticobulbar tract?
| Neural control of human movement
Ipsilateral
167
What does ipsilateral mean
| Neural control of human movement
The side of the brain activated correlates to the side of the body functioning
Right->right
Left->left
168
How would you describe the axons of the corticospinal tract?
| Neural control of human movement
Largely contralateral (75-90%)
169
What does contralateral mean
| Neural control of human movement
Right part brain = left side of body
170
What is the defining landmark of the medullary-spinal border?
(Neural control of human movement)
The pyramidal decussation
171
What is the neuromuscular junction?
| Neural control of human movement
The part of the motor unit that interacts with the muscle
172
The somatic nervous system provides output strictly to what?
| Neural control of human movement
Skeletal muscles
173
Lower motor neuron lesion is characterised by what?
| Neural control of human movement
Flaccid paralysis - loss of muscle tone
174
Upper motor neuron lesion is what?
| Neural control of human movement
Spastic paralysis - paralysis accompanies by severe hypertonia (disordered spinal reflexes)
175
Diagram of motor unit
| Neural control of human movement
Lecture 5, slide 13
176
Definition of action potential
| Neural control of human movement
The change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell
177
Lecture action potential diagram
| Neural control of human movement
Lecture 5, slide 15
178
Are all neurons stimulated to form action potentials as quick as each other?
(Neural control of human movement)
No, some neurons can be stimulated much faster (sensory neurons) but others are more powerful (motor neurons)
179
Learn diagram of neuron
| Neural control of human movement
Lecture 5, slide 16
180
Does one neuron interact with one muscle fibre?
| Neural control of human movement
No, as there would be too many neurons then
181
Definition of a motor unit
| Neural control of human movement
It is the motor neuron and the skeletal muscle fibres innervatrd by that motor neurons axonal terminals
(Motor neuron & muscle fibres it controls)
182
What do we have in order to co-ordinate the contraction of all muscle fibres?
(Neural control of human movement)
Motor units
183
What does a motor unit consist of?
| Neural control of human movement
One motor neuron and all the muscle fibres it innervates
184
Can you have a motor unit that is part type I fibre and part type II fibre?
(Neural control of human movement)
No
185
What is heterogeneity
| Neural control of human movement
Effectively means difference
186
When we talk about different properties of a muscle fibre, what is this actually relating to?
(Neural control of human movement)
The motor unit
187
What is the all or none principal?
| Neural control of human movement
Regardless of number, individual muscle fibres within a given motor unit will either fire & contract maximally or not at all
(Either all muscle fibres contract or none do)
188
What is Henneman’s size principle
| Neural control of human movement
Under load, motor units are recruited from smallest to largest. Therefore, it is suggested that slow-twitch, low force, fatigue resistant muscle fibres are activated before fast-twitch, high force, less fatigue-resistant muscle fibres
189
Learns terms such as afferent and efferent
| Neural control of human movement
Lecture 5
190
Spinal stretch reflex
| Neural control of human movement
Lecture 5, when someone taps your knee on your tendon and your leg to move
191
What is the spinal stretch reflex?
| Neural control of human movement
A muscle contraction in response to stretching within the muscle
192
What is the H-reflex? (Hoffman reflex)
| Neural control of human movement
The electrical analogue to the spinal stretch reflex (SSR)
It is a neurological examination
193
How does the H-reflex work?
| Neural control of human movement
Instead of actually stretching the muscle with a hammer to lengthen the tendon, you electrically activate the muscle itself, using a stimulator
194
What does the H-reflex allow assessment of?
| Neural control of human movement
Issues in corticospinal tract
Can also be used to see if an individual has recovered from injury
195
How does the threshold compare for motor axons and sensory neurons? And why is this?
(Neural control of human movement)
Motor axons is higher than sensory neurons due to the layers smaller size
196
What is the primary difference between the H-reflex and the spinal stretch reflex?
(Neural control of human movement)
The H-reflex bypasses the muscle spindle
197
Exam question:
Explain the H-reflex and what is represents?
(Neural control of human movement)
??? Lecture 5
198
What is Hmax?
| Neural control of human movement
A measure of maximal reflex activation
199
Example, slide 24
| Neural control of human movement
Lecture 5
200
What is the purpose of the H-reflex?
| Neural control of human movement
Activating sensory and motor neurons to look at ??
201
What physiological pathway are you initiating by activating the sensory neurons?
(Neural control of human movement)
The monosynaptic reflex activity in the spinal cord
202
Slide 23, lecture 5
| Neural control of human movement
Learn diagrams - important slide
203
What is monosynaptic reflex activity?
| Neural control of human movement
Where on neuron synapses on another neuron to communicate that response without any further integration
204
Why is understanding the loop important?
Why is this useful for monitoring training status?
(Neural control of human movement)
The speed at which it occurs tells you how quick the monosynaptic reflex activity occurs
The size of it also gives info as to how much muscle activity you can actually exert in that muscle
Neural adaptations occur first during strength straining
Helpful to monitor progress
205
Why is Hmax useful during the rehab process?
| Neural control of human movement
In order to assess when Hmax has returned back to norm
206
When might Max decrease?
| Neural control of human movement
If the athlete has been bed bound for a long period of time
207
Process of neural conduction
| Neural control of human movement
As membrane potential increases, sodium channels open (more goes into cell)
Then potassium channels open (more goes out)
This leads to increase in positively charged ions which leads to depolarisation
Sodium channels close at peak of action potential
Potassium continues to leave the cells leading to repolarisation and an overshoot hyperpolarisation
208
What is the frequency of action potentials called?
| Neural control of human movement
Firing rate
209
What is excitation-contraction coupling?
| Neural control of human movement
Activation of muscle fibre allows calcium to move into the muscle and initiate cross-bridge cycling
210
What is the sarcoplasmic reticulum?
| Neural control of human movement
A specialised form of endoplasmic reticulum
211
Functions of the sarcoplasmic reticulum
| Neural control of human movement
1 - intracellular calcium storage
2 - release and uptake of calcium associated with muscle contraction
212
Release of calcium plays a major role in what?
| Neural control of human movement
Excitation-contraction coupling
213
What conducts electrical signals from the sarcolemmal surface to the interior of the muscle fibre and closely interact with the sarcoplasmic reticulum?
(Neural control of human movement)
Transverse T tubules
214
Recap questions
| Neural control of human movement
Slide 28, lecture 5
215
Focus on
| Neural control of human movement
Motor units
Hennemans size principal
Some stuff round Hoffman reflex
216
What does the A band represent?
The overlap between the thick filaments and thin filaments
