Midterm Flashcards
Lecture 1-11 (145 cards)
1
Q
What is the definition of exercise?
A
- Voluntary activation of skeletal muscle for recreational, sporting, or occupational activities
- something that is planned and that you prepare yourself for
2
Q
What are the major systems involved in exercise?
A
-Nervous system
- skeletal muscle
- cardiovascular
-Lungs
- neuroendocaine/metabolism
3
Q
What is the relationship between muscle contractions and homeostasis
A
- Muscle contractions disrupt homeostasis
- our body fights against the destructive changes via heat dissipation and removal of coz and metabolic by products
4
Q
How is allostasis used in exercise?
A
- Allostasis is stress specific adaptations that maintain homeostasis
- this is because our body loves constructive changes
- occurs wa the production of mediators
-Ex/ increased HR, BP, breakdown of fat, and glycogen
5
Q
What is the organization of the nervous system?
A
- Central nervous system (brain + spinal cord)
- peripheral nervous system (autonomic/somatic spinal nerves + muscle units)
6
Q
What are the 5 areas of the brain that contribute to initiation a control of voluntary athletic movements
A
-Cerebral Cortes
- basal ganglia
Hypothalamus
_Brain stem
-Cerebellum
7
Q
What is the cerebral cortex responsible for?
A
- Language, reasoning, abstract thinking, sensory and voluntary motor control
8
Q
What does the basal ganglia do?
A
- facilitate desired movements while inhibiting unwanted competing movements
- helps chose actions that are likely to lead to positive consequences to avoid aversion effects
Has the substantial nigra complex where dopamine is releases
9
Q
What is dopamine needed for?
A
- Everything is facilitated by dopamine
- cognitive, emotional sand movement related
10
Q
What is the hypothalamus responsible for?
A
_Metabolism and temperature (whole hormone system)
- autonomic nervous system, especially cardiovascular and cardio respiratory rhythm
11
Q
What is the limbic system responsible for
A
- Processing and interpreting sensory information
- release of neurotransmitters such as endorphins
- improved mood and reduced pain during physical activity calls exercise induced hypo Algeria
- controls motivation
- manages stress related hormones for allostatic response
12
Q
What are the three parts sot the brain stem
A
- Midbrain
-Pons - medulla oblongata
13
Q
What is the brainstem/what is it responsible for?
A
- A passage that connects motor and sensory neurons to the spinal cord
- contains nuclei that regulate the cardiac and respiratory functions
- reduced vagal tone vs sympathetic nerve activation
14
Q
which area(s) of the brain control the cardiovascular system
A
- hypothalamus
- pons
15
Q
what is the cerebellum responsible for?
A
- process the information necessary to regulate body posture and equilibrium
- receives sensory information from sensory afferents
- sends information to thalamus and cerebral cortex
16
Q
what is the corticospinal pathway?
A
- collection of axonal nerve bundles (white matter) initiating in the cerebral cortex, passing through the brainstem and terminating on lower motor neurons
17
Q
what is the pyramidal decussation
A
- area of the corticospinal pathway that crosses over (explaining that left brain controls the right side of the body and vice versa)
- cross occurs at the level of the medulla
- 90% crosses over, 10% doesn’t
- this is the most excitable part of the nerve bundle
18
Q
what nerves is the spinal cord constructed of?
A
1) motor nerves (efferent) - from CNS to effector
2) sensory nerves (afferent) - from muscle to spine
3) interneurons
19
Q
what is the spinal cord reflex
A
- fast response to stimulus that does not require the brain
- stimulus - afferent pathway - monosynaptic connection - efferent pathway
20
Q
what is a motor unit
A
- makes up the functional unit of movements
- consists of an alpha motor neuron and the specific muscle fibers that it innervates
21
Q
what are the differences on motor neurone:muscle fiber ratio?
A
- contributes to the variation in motor skills
- ex/ 1:5 for fine motor skills or 1:800 for crude movements (quads)
22
Q
what is the all or none principal
A
all of the muscle fibers innervated in a motor neuron are stimulated to contract
23
Q
where is an action potential initiated
A
brain or spinal cord
24
Q
what is an action potential
A
- a wave of depolarization that propagates along the surface of a nerve or muscle
- produced by changes in membrane potential
25
what are the three stages of an action potential
1) depolarization (influx of Na+)
2) repolarization (outflux of K+)
3) Ions returned back with Na+/K+ pumps
26
what is saltatory conduction
- speeds up signal conduction for an action potential
- myelin sheaths allow signals to jump to nodes of ranvier
- of there were no myelin sheaths, many AP would dissipate prior to where they need to go
27
what are the parts of a neuromuscular junction
- presynaptic terminal
- synaptic cleft
- postsynaptic terminal
- synaptic vesicles
- acetylcholine (NT)
28
what are the steps of the sliding filament theory
1. Myosin heads split ATP and become reoriented and energized
2. myosin heads bind to actin, becoming cross bridges
3. myosin heads rotate toward center of the sarcomere (power stroke)
4. As myosin heads bind ATP the cross bridges detach
29
What are the steps after an action potential is carried into the muscle
1. Sac like vesicles within terminal axon release ACh which diffuses across synaptic cleft and attaches to specialized ACh receptors on sarcolemma
2. Muscles action potential depolarizes transverse tubules at the sarcomeres A-I junction
3. T-tubule system depolarization causes Ca2+ release from sarcoplasmic reticulum lateral sacs
4. Ca2+ binds to troponin-tropomyosin in actin filaments which releases inhibition of actin combining with myosin
5. actin joins myosin ATPase to split ATP with energy release during muscle action. Tension from energy release produces myosin crossbridge movement
6. muscle shortening occurs after ATP binds to myosin crossbridge which break the actin-myosin bond and allows crossbridge dissociation from actin and sliding of thick and thin filaments
7. Ca2+ removal restores troponin-tropomyosin inhibitory action. With ATP present actin and myosin remain in dissociated relaxed state
8. when muscle stimulation ceases, Ca2+ moved back into the sarcoplasmic reticulum lateral sacs through active transport
9. crossbridge activation continues when Ca2+ concentration remains high (from membrane depolarization) to inhibit troponin-tropomyosin action
30
what muscle fibers do large motor neurons innervate
- large motor neurons = fast conduction velocity
- they innervate fast-fatigable (FF) and fast fatigue-resistant (FR) muscle fibers
31
what muscle fibers do small motor neurons innervate
- small motor neurons = slow conduction velocity
- innervate slow (S) muscle fibers
32
what does FF correspond to
FF - fast fatigable
- type IIx muscle fibers
- glycolytic
33
what does FR correspond to
FR - fast fatigue resistant
- type IIa muscle fibers
- fast oxidative
34
what does S correspond to
S - slow
- type I
- slow oxidative
35
what is the order of the muscle fibers in terms of maximum contractile speed and force
I < IIa < IIx
36
what are the mechanisms that the neuromuscular system can use to increase force output?
- recruitment: increasing the number of motor units recruited
- rate coding: increasing the frequency of motor unit discharge
37
what is the size principal
anatomic basis for the orderly recruitment of specific motor units to produce a smooth muscle action
- start with S and work up to IIx
38
which part of the NS determined the activation of muscle fibers?
- PNS!
- CNS sends signal to complete work, PNS determine what is required to do that work
39
What are muscle spindles
- proved mechano-sensitive information about changes in muscle fiber length and tension
- responds to any stretch of the muscle
- increased the level of muscle contration
40
what are the differences between nuclear bag vs chain fibers?
- both muscle spindles
- nuclear bag fibers: respond to phasic (while muscle is being stretched) stretch
- nuclear chain fibers: respond to static stretch
41
what is the stretch reflex
- it is also known as the myotatic reflex
- an involuntary contraction of muscles induced by the brisk stretch of said muscle
- reflex arc involves two nerves and one synapse
42
what do golgi tendon organs do
- responds to the tension created by muscle contraction (NOT stretching)
- protective sensory mechanism
- can reduce the level of contraction
43
what are two parameters that impact the force-velocity characteristics of muscle contraction?
1) number of cross bridge formation
2) environmental conditions (PH, ATP, Ca2+)
44
filament overlap during isometric
- the amount of filament overlap depends on the length at which the muscle is held prior to activation
45
filament overlap during shortening (concentric)
- the sliding movement allows the myosin filaments to become overlapped by actin
46
filament overlap during lengthening (essentric)
- the cross bridge generates less tension that the external stretching force applied to the muscle. Thus the opposing actin filaments in the sarcomeres are pulled away from each other.
47
what is the popping sarcomere hypothesis
- it is the uncontrolled extension of individual half-sarcomeres in each myofibril
- occurs one at a time from weakest to strongest
occurs when passive tension can still be maintained bu actinmyosin is dettactches (popped)
48
what are group III skeletal muscles fibers
- aka afferents
- responsive to mechanical deformation and the intramuscular substances which would cause pain
- these muscle fibers project to the CNS and promote the sensation of pain and muscle soreness
49
relationship between force and velocity
- in human muscles they are inversely related
- this is because increase in shortening V results in fewer crossbridges being able to attach
50
where is max power produced
- below 50% of both force and velocity
51
what is the F-V relationship of isolated muscles and single joint tasks?
- during fatiguing exercises increased H+ (acidosis) and Pi decrease power
- increased H+ decreases the rate of ca2+ binding to troponin
- increased H+ and Pi decrease the rate of actomyosin detachment
52
the ___________ of crossbridges determines force and velocity characteristics
arrangement
53
which arrangement of cross bridges is better
- series is more efficient in terms of displacement (velocity)
- parallel is more efficient in force production (force)
54
what is ACSA and PCSA
- ACSA: anatomical cross-section area is the largest cross sectional area along the length of that muscle
- PCSA: physiological cross-section area is the total cross section area of all the fibers within a muscle
55
what is fatigue?
a symptom of precept characterized by a feeling of tiredness and weakness in which physical and cognitive functions are limited
56
what is exercise induced fatigue
- a reduction in maximal muscle force output capacity
57
what is a super imposed twitch
- an additional stimulus is applied after a participant is already doing a MVC
- this shows the deficit of the brain to drive the muscle
58
how is voluntary activation measured
VA = (1-(SIT/RT))x100
59
what is MVC
- the maximal voluntary force that your central nervous system and your muscles (peripheral system) can produce
60
what does a larger SIT mean
- reduction in CNS to drive muscle voluntarily
61
what does a smaller RT mean
- reduction in the muscles ability to produce force
- this is peripheral fatigue
62
what are the mechanisms of peripheral fatigue
* neuromuscular junction
- inhibition of presynaptic ending
- limited transmitter substance
- inability of postsynaptic membrane to become excited
* sarcolemma
- changes in electrical property of the muscle surface membrane
- changes in the concentration of intra/extracellular Na+ and K+
* excitation- contraction coupling
- disruption in Ca2+ release or uptake
* metabolic alterations
- ATP availability
- metabolites accumulation
- PCr, glucose, glycogen concentrations
* slowing of relaxation
- disruption in Ca2+ release or uptake
63
what happens to fatigue when sensory afferent feedback is limited
- ex/ take fentanyl
- fentanyl group is able to start with higher force but dies out far more (all peripheral fatigue)
- the placebo group starts out with slightly higher force but does not fatigue as quickly
64
what is the psycho-biological model of perceived effort?
- interaction between psychological and physiological factors that contribute to effort
- corollary discharge = internal copy of motor commands that allow brain to predict the sensory consequences of the motor command
65
what type of exercise results in more central fatigue
- full body most, then big muscles, then small
- this is because the brain gets concerned about energy conservation and gives up
66
how do group III/IV muscle afferents play a role in fatigue?
they determine muscle cessation by inhibiting central motor drive to activate skeletal muscle and ultimately restricting the development of peripheral fatigue
67
fatigability of small muscle groups
- high peripheral fatigue, low central
- when the source of group III/IV afferent feedback is limited to a muscle mass, the CNS will tolerate a greater degree of peripheral fatigue
68
single vs double side exercises fatigue
- single leg will accumulate more peripheral and less central is it takes twice the demand to tell the brain it is fatigued
69
relationship between intensity and fatigue
- the higher the intensity the greater the peripheral fatigue
- the lower the intensity (and greater the duration) the greater the central fatigue
70
what are the benefits of resistance training
- develop musculoskeletal fitness
- increase lean mass
- prevent chronic disease
- prevent/rehan orthopedic injuries
71
static (isometric) resistance training
- external load is constant and unlimited
- velocity = 0m/s
72
Dynamic resistance training
- isotonic
- external load is constant
- velocity is variable
73
variable external resistance training
- external load is variable
- velocity is variable
- think banded workout
74
What does muscle strength mean
- maximum force output of a muscle or group
75
1-RM
the maximal weight an individual can lift once
76
Multiple repetition maximum
maximum weight individual can lift for a given amount of reps. Can be used to predict 1-RM
77
how do you measure maximal static strength in a lab
- isometric dynamometer
- it stays still (static)
- maximal force at certain joint angle
78
how do you measure dynamic strength in a lab
- isokinetic dynamometer
- moves at a CONSTANT velocity regardless of how much force is put in
79
what is progressive overload
- idea that you need to continue to increase load to progress
- increase frequency, load, sets, reps. volume
80
what is meant by the difficulty of progress
- the more trained you are, the harder to progress
- in untrained individuals, almost any method will increase strength
81
What are the mechanisms of strength gain
- neural adaptations
- muscle hypertrophy
82
what is the neural control of strength gain?
- increased motor unit recruitment and synchronization
- increased motor unit firing rate (rate coding)
- reduced autogenic inhibition (meaning the inhibitory effect of the golgi tendon organ is reduced)
- decreased coactivation
83
what is cross education
- exercising a limb on one side of the body can increase strength of opposite side limb without training it
84
what is the SAID principle
- Specific Adaptations to Imposed Demand
- if you use it right, it will adapt
85
what are myofibrils
- contractile units of muscle
86
what is the sarcoplasm
- cytoplasm of muscle cell including water, salts, inorganic molecules
87
what is transient (sarcoplasmic) hypertrophy
- occurs immediately after exercise and decreases in around an hour
- it is an increase in the volume of sarcoplasmic fluid
- fluid accumulation (edema) in the intracellular space
88
what is chronic (myofibrillar) hypertrophy
- structural changes due to long term resistance training
- increased number of myofibrils in parallel
_GOOGLE THIS ALSO SLIDE 5 of lec 8
89
Is there chronic sarcoplasmic hypertrophy?
- new idea, is a possibility
- expansion of the sarcoplasm not just the fluid in there
- increase in the mitochondria, sarcoplasmic reticulum, t-tubules, sarcoplasmic enzyme or substrate context
90
what percentage of muscle does each component take up
- myofibrils 85%
- sarcoplasmic enzymes/proteins 9%
- mitochondria 6%
91
what is protein synthesis
- transcription of DNA in pre-existing nuclei containing gene A
- transfer of the DNA to ribosome via mRNA
- translation of DNA to tRNAs
- then new protein
92
what is remodeling
- proliferation of satellite cells located under the muscle fiber
- differentiation of satellite cells based on needs of muscle
- creation of a new nucleus by satellite cell that contains gene B and produces protein B
- creation of a NEW protein the muscle needs
93
how many amino acids are essential/non essential
9 essential
11 non essential
94
which amino acid is most important for muscle synthesis
leucine
95
what causes muscle hypertrophy in resistance training
- mechanical stress
* causes mechano-chemical response
* activates gene transcription
* satellite cell activation
- metabolic stress
* metabolic accumulation (lactate, H+, Pi)
* acute muscle hypoxia
* Ca++
96
what is the intention of moderate intensity, high volume protocols like seen in body building?
- heighten metabolic buildup
- result in prolonged ischemia
- greater contribution of glycolysis
- multiple sets of 6-12 reps at 60-80% 1-RM with short rest
97
what is the intention of high intensity powerlifting style programs
- 90% 1-RM
- energy derived from PCr
- short ischemia
98
What are the benefits of blood occlusion (KAATSU) training
- cause metabolites to build up in the muscle
- provides benefits for hypertrophy
- 20% 1-RM is still helpful
- increase in anabolic growth factors
- increase protein synthesis
- increased heat shock proteins
- increased nitric oxide synthase
- decreased expression of myostatin (that contributes to muscle breakdown)
99
What % of RM is superior for hypertrophy
- doesnt matter as long as muscle is reaching true failure.
- benefits seen at 30%
100
does protein timing matter
- not really, just get the amount over the course of the day
- 20g in one sitting is maximal for body absorption
101
what is energy
capacity to do work
102
What is the 1st law of thermodynamics
- energy is not created nor destroyed, just transferred
103
what is bioenergetics
flow and exchange of energy in a living system
104
what is biosynthesis
molecules and atoms are activated and joined to synthesize biological compounds
105
what are endergonic reactions
- chemical reactions that store energy
- uphill
- anabolism
106
what are exergonic reactions
physical or chemical processes that release energy (downhill)
- catabolism
107
what are the three forms of work in humans
- mechanical (movement)
- chemical
- transport (active)
108
what is the phosphorylative coupling efficiency
- 60%
- this is the portion of potential energy retained as ATP
- endergonic reaction
109
mechanical coupling efficiency
- 50% (of the 60%)
- portion of total chemical energy that contributes to external work
110
overall efficiency
- 30%
- 70% lost as heat
111
how do we measure energy expenditure
- calroimitry
112
what is direct calorimetry
- heat production
- in a sealed chamber
113
What is indirect calorimetry
- O2 consumption and CO2 production
- "open-circuit spirometry"
- we measure o2 used because 1L of O2 is 5kcal
114
What is the total daily energy expenditure broken down into
- Thermic effect of feeding - 10%
- Thermic effect of PA - 15-30%
- Resting metabolic rate - 60-75%
115
what factors impact TDEE
- physical activity levels
- thermic effect of feeding/diet induced thermogenesis (DIT of carbs/protein > fats)
- climate, either extreme increases metabolism
116
what is basal metabolic rate
- minimum amount of energy required to maintain vital functions in a waking state
- 0.8-1.4kcal/min
117
what is resting metabolic rate
- less stringent criteria to allow for it to be tested
- 4-5hr after a meal
RMR > BMR
118
What are the factors affecting RMR
-body surface area
-sex - it's not a true sex difference but a product of more fat free mass in men
-age - RMR declines with age
119
What are the Harris Benedict equations for RDEE?
* Women: 655 + (9.6 * body mass, kg) + (1.85 * height, cm) – (4.7 * age, y)
* Men: 66 + (13.7 * body mass, kg) + (5.0 * height, cm) – (6.8 * age, y)
120
What is a met?
- one met equals a resting o2 consumption of 3.5 ml x kg x mins
121
HOw much energy is released when the first phosphate is broken off ATP
7.3 kcal
122
how much energy is released when the second phosphate is broken off ATP
10.3 kcal
123
How much ATP is stored in our body?
80-100 g
124
Why is there so little stored ATP
- ATP is too heavy to carry an adequate supply
- ATP is easily recycled
125
What is the benefit to the small amount of ATP
- changes in concentration of ATP will be rapidly detected and corresponding metabolic responses will be initiated
126
What are enzymes
- proteins that accelerate a chemical reaction by reducing its activation energy
- achieved by reactants in the correct order or closer to gether
127
What are important properties of enzymes
- do not cuase the reactions
- do not change the energy yield of the reactions
- are not consumed or changed during the reactions
- are sensitive to pH and temp
128
what is the lock and key hypothesis
- it's a hypothesis referring to how enzymes work
- substrate fits into the active site of the enzyme like a key fitting into a lock (highly specific)
129
what is the hydrolysis reaction
- water used to break bigger molecules into smaller molecules
130
what is a condensation reaction
- opposite of hydrolysis
- 2 molecules combine to build a single larger molecule with the loss of water
131
what is an oxidation reaction
losing electrons
132
What is a reduction reaction
gaining electrons
133
where do muscle cells use ATP
- 75% as myosins ATPase (breaking myosin actine cross bridges)
- 20% to sarcoplasmic / endoplasmic reticulum ATPase (calcium withdrawal / reuptake after contraction)
- 5% NA+ K+ ATPase
134
Does ATP decline a significant amount during exercise
no
135
which metabolites signals the system to increase ATP
- ADP, AMP, Pi
- CA2+
- NAD+
136
what is the immediate source of ATP
- stored ATP PCr
- power = 45 kcal / min
- capacity = 11 kcal
- duration = 15 sec
137
what is the glycolytic / lactic source of ATP
- glycogenolysis and glycolysis and lactate production
-- power + 22 kcal / min
- capacity = 15 kcal
- duration = 40 sec
138
What is the oxidative / aerobic source of ATP
- oxidative phosphorylation using carbs, lipids, proteins, lactate
- power + 22 kcal / min
- capacity = 1200 kcal
- duration = infinite
139
How is creatine kinase activated
- increase in ADP, decrease in ATP
140
How much energy is released by the breakdown of PCr
- 10.3kcal / mol
- this energy is more than seen in the breakdown of ATP
141
how does creatine kinase work
- it's the first line of defense as an ATP buffer
- we have 90 mmol / kg of dry muscle per PCr
- we have 25 mmol / kg of dry muscle per ATP
- because of the greater amount of PCr, it is willing to sacrifice itself for ATP
- PCr + ADP + H+ → ATP + Cr
142
what is the adenylate kinase
* ADP + ADP → ATP + AMP
* AMP + H+ → IMP + NH4+
- it combines to ADP molecules to create an ATP and AMP
- AMP is a very unstable molecule so it is rapidly converted into other compounds to be removed from the body
143
how much ATP does adenylate kinase contribute
- quantitatively insignificant source
- the body does not like using it because of the AMP production
144
when is adenylate kinase used
occurs during very high intensity exercises
removes adenine nucleotides from pool therefore increasing recovery time
145
can the ATP - PCr system work in the presence of o2
- yes, but o2 is not required, it happens faster than o2 would allow
