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Long answer questions Flashcards

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1
Q

What are the mechanisms by which an endurance athlete’s resting heart rate decreases, and their stroke volume increases?

A

Greater parasympathetic influence and decreased sympathetic influence on the heart at rest
Increased blood volume
Increased contractility & compliance

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2
Q

Describe the PQRST movement of the heart.

A

P: depolarisation of the atria
QRS: depolarisation of the ventricles and repolarisation of the atria
T: repolarisation of the atria

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3
Q

What are the methods used to measure cardiac output?

A

Direct Fick method
Dye method (Thermodilution)
Doppler Echocardiography

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4
Q 
What are the standard measurements for cardiac function: 
Elite CO 
EDV
ESV
O2:CO 
Elite SV 
Blood O2 content range for graph 
Muscle blood flow rest-->exercise
Artery-Venous oxygen content during exercise
Oxygen Consumption rest --> exercise 
Blood flow at max intensity 
Coronary circulation blood flow & O2 extraction 
Skin cutaneous system blood flow 
Systolic BP range
A

Elite CO: 42 L.min
EDV: 130 ml
ESV: 60 ml
O2:CO: 1:6
Elite SV: 215 ml
02 content range: 0–> 24 ml.Dl
Muscle blood flow: rest (0.75-1L.min) exercise (22 L.min)
A-VO2: Artery (20 ml.100ml) –> Veins (2 ml.100ml)
O2 consumption: rest (60 ml.min) exercise (3.9L.min)
Blood flow: 8 L/min
Coronary circulation blood flow: 0.25 L/min –> 1.25 L/min
30% –> 90%
Skin: 100 - 300 ml/min –> 7-8 L/min
Systolic BP range: 120 –> 200 mmHg
Diastolic BP range: 80 mmHg –> 70mmHg

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5
Q

What are the factors influencing stroke volume?

A

Preload
Afterload
Heart Rate
Contractility

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6
Q

What are the factors influencing preload?

A 
Muscle Pump
Respiratory Pump 
Venous Tone 
Blood Volume 
Posture
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7
Q

What are the causes of increased contractility?

A

Sympathetic nerve activity
Circulating catcholamines
Calcium
Inotropic drugs

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8
Q

What are the determinants of afterload?

A

Sympathetic and parasympathetic tone (TPR)
Intrathoracic pressure (exhalation)
Anatomical impedence
Static muscle contraction

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9
Q

Important equations.

A 
CO = SV * HR 
Ejection Fraction = SV/EDV * 100 
Stroke Volume = EDV - ESV 
Flow = Pressure/Resistance 
MAP = CO * TPR 
Resistance = 1/R^4 (Pouiselle's Law) 
Blood O2 capacity: Haemoglobin carry capacity * Haemoglobin number
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10
Q

What are the vasoconstrictory mechanisms of the vascular system?

A

Neural (noradrenaline, alpha 1 & 2)
Myogenic (vasoconstriction when blood flow is too high)
Metabolic
EDRF’s (NO & prostaglandins)
Mechanical (calcium)
Hormonal (circulating catacholamines, adrenaline on alpha to vasoconstrict & beta to vasodilate // kidney - renin - angiotensin 2 - vasoconstriction)

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11
Q

What does central command regulate?

A

Heart rate
Contractility
Sympathetic stimulation
Adrenal medulla

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12
Q

What is the process of myogenic autoregulation?

A 
Increased arterial pressure 
Increased transmural pressure 
Stretch of smooth muscle 
Contraction of smooth muscle
Decreased blood flow
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13
Q

What are the vessels of the macro and micro circulation?

A

Macro: conduit & feed arteries (more vasoconstriction & EDRF’s)
Micro: resistance arteries and arterioles & capillaries

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14
Q

What are the measures of skeletal muscle blood flow, and what values do they offer?

A

Venous-Occlusion Plethysmyography (50-70 ml.100g.min)
Thermodilution (250 ml.100g.min)
Doppler Ultrasound (300 ml.100g.min)
Microdialysis (500 ml.100g.min)

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15
Q

What are the pros and cons of each blood flow measurement technique?

A

VOP:
Pros: easy and non-invasive
Cons: non-exercising and effected by fat and muscle

Thermodilution:
Pros: exercising
Cons: invasive and skilled medical personel

Doppler Ultrasound:
Pros: exercising, non-invasive, continuous
Cons: expensive and larger arteries

Microdialysis:
Pros: exercising and measure of metabolites
Cons: effected by tissue damage and highly invasive

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16
Q

What are the reasons for the huge increase in skeletal muscle blood flow at exercise onset? Also comment on steady state.

A

Mechanical: skeletal muscle pump
Metabolic: adenosine, potassium
Steady state: neural, EDRF’s, metabolites, mechanical

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17
Q

What are the metabolic vasodilatory factors in exercising muscle?

A 
Hypoxia 
Acidosis 
Lactate 
Potassium 
Adenosine 
Osmolarity
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18
Q

What is functional sympatholysis?

A

Vasodilatory factors ‘overriding’ vasoconstrictory factors to cause vasodilation

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19
Q

What is the relationship between blood flow and isometric exercise?

A

Huge vasoconstriction due to mechanical pressure by muscle
Build up of metabolites
Contraction stops causing massive vasodilation due to metaboreflex
Massive increase in blood flow

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20
Q

What are the four factors that determine skeletal muscle blood flow?

A

Fibre type composition
Static vs. dynamic
Force of contraction
Method of blood flow measurement

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21
Q

What are the 5 factors that determine the amount of oxygen delivery to skeletal muscle?

A

Capillary density
Diffusion distance (tortuosity)
Transit time
Capillary perfusion (smooth muscle contraction) Haemoconcentration

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22
Q

How can chronic anaemia be indentified using an exercise stress test?

A

Enough perfusion at rest
Exercise increases heart rate, therefore less time for filling
Causes hypoxia due to ischaemia by blockage
Shown on an echocardiomyograph, shown by prolonged S - T

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23
Q

Give a summary of coronary blood flow.

A

Adenosine via alpha 2 receptors causes vasodilation
High O2 extraction even at rest
Flow during diastole
Potential for ischaemia

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24
Q

Summarise the blood flow to hairy and non-hairy skin during heat stress.

A

Cold: adregenic vasoconstriction to non-hairy skin
Warmer: withdrawal of adregenic vasoconstriction to non-hairy skin
Temperature threshold met: cholinergenic vasodilation to hairy skin

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25
How can thermoregulation of the skin limit blood flow to the cardiac system?
Temperature threshold met causes vasodilation and therefore loss of central blood volume via sweating This lowers venous return and therefore stroke volume As exercise intensity increases, cutaneous system blood flow is restricted via vasoconstriction which prevents central blood volume falling any lower
26
Describe the process of skin blood flow during exercise.
Initial vasoconstriction at exercise onset to allow for the massive increase in vasodilation at exercise onset Vasodilation occurs at a higher temperature threshold than at rest in order to allow for heat loss Vasoconstriction then re-occurs at an earlier stage of blood flow to maximise venous return by maintaining central blood volume
27
How is the brain blood flow autoregulated?
Autonomic nervous system detects drop in blood pressure This causes a myogenic response: contraction of systemic arteries and a systemic response: baroreflex of increased heart rate This increases brain blood flow
28
What is the relationship between brain blood flow and exercise intensity?
Increases at low intensity exercise Increases until lactate threshold is met, therefore conditions become more acidic This causes an increase in ventilation, which removes CO2 from the body This causes a lowering of brain blood flow as there is a lower PCO2
29
What are the overall circulatory responses to dynamic exercise?
Increased heart rate (plateau near top) Increased stroke volume (rapid at onset; may carry on increasing in elite athletes) Reduced TPR Slight increase in MAP (systolic blood pressure increases, diastolic pressure decreases slightly)
30
How is the cardiovascular system controlled during exercise?
Central Command: increases vagus withdrawal at exercise onset; can increase SNA at high intensities Exercise Pressor Reflex: Metaboreflex = increased SNA; HR via sympathetic activation Mechanoreflex = increased heart rate at exercise onset Arterial baroreflex: increased/ decreased HR * SNA in response to BP increase/ decrease
31
What are the four factors regulating the metaboreflex?
Fibre type Muscle fibre training status Blood flow obstruction Blood volume
32
When using a neck cuff, what effect does negative pressure production have on the arterial baroreceptors?
Increases mechanical pressure on circulation This simulates an increase in blood pressure via acute hypertension This causes the arterial baroreceptors to change firing rate to the brain, which will lower HR and SNA and therefore BP
33
Injecting fentanyl opioids in unhealthy people has what effect on the exercise pressor reflex?
Prevented sensory information returning to the brain via exercise pressor reflex This meant there was no increase in BP and HR stimulated by the pressor reflex Minute ventilation was therefore lower Unhealthy individuals can exercise for longer
34
What are the four factors that stimulate the mechanoreflex?
Degree of stretch Force of stretch External pressure Presence of metabolites (re-setting at new point)
35
How is RBC production stimulated due to endurance training?
Hypoxia of the kidneys Stimulates production of EPO Causes haemopoetic production of RBC's
36
What are the central cardiac adaptations that occur due to endurance training that maximise blood flow to exercising muscles?
``` Increased RBC content Increased RBC volume Increased force of contraction (wall thickness) Increased chamber size Decrease heart rate at every intensity ```
37
What are the peripheral adaptations to aerobic training?
``` Increased flow to non-exercising muscles Increased muscle blood flow Increased vascular conductance Increased artery number Increased haemoglobin affinity Increased capillary density Increased transit time Decreased diffusion distance ```
38
What are the inducers of vascular remodelling?
Metabolic: Inducing hypoxia during training causes a long-term increase in blood flow Hypoxia causes increased VEGF secretion Mechanical: Increased blood flow - Increased sheer stress - Increased NO production - NO production stimulates growth - Current level of shear stress becomes normalised - Increased potential for more NO production Growth Hormones: VEGF stimulate growth of vascular tissue that increases ability to vasodilate
39
What are the limiters of O2 uptake during exercise?
``` Cardiac circulation Heart size (pumping capacity) Blood flow Heamoconcentration Capillary Density HB-O2 affinity Vascular conductance ```
40
Describe the lactate graph.
Lactate threshold: systematic lactate rise OBLA: point where lactate begins to accumulate Ventilatory threshold: point where ventilation rate is faster than oxygen consumption Side graph is 10 --> 170 (VE L/min BTPS) Bottom axis: oxygen consumption/ intensity (2.5) Other axis: lactate (0-12)
41
Why does the lactate threshold occur?
Lack of blood flow Accelerated activity of LDH Hypoxia Increased presence of LDH in fast-twitch
42
What are the fast and slow components of EPOC catering for?
Fast: resynthesis of PCR and O2 replenishment Slow: lactate --> glucose, lowered heart rate and ventilation, adrenaline and noradrenaline synthesis
43
What are the Balke and Bruce tests and what are the drawbacks?
Balke: increase in gradient - sore back Bruce: increase in gradient and speed - very quick
44
What are the factors that effect oxygen consumption?
``` Mode of exercise Hereditary State of training Gender Body Composition * Age ```
45
What are the three types of hormone? Give an example of each.
Protein: ADH Amino acid: catacholamines Steroid: gluccocorticoids
46
What influences the blood hormone concentration?
Synthesis Rate of excretion Number of transport proteins Blood volume
47
What does the magnitude of hormonal effect depend on?
Hormone concentration Number of receptors Affinity of receptors for hormone
48
How do hormones modify celullar activity?
Affect membrane transport Activate second messenger model via G-protein Increase protein synthesis via nuclear DNA Alter enzyme activation
49
Where is growth hormone produced and what does it cause?
Anterior pituitary gland Protein synthesis: Increased AA uptake Increased RNA activity Increased ribosomal activity Glucose uptake: Increased glucose uptake Increased gluconeogenesis Mobilisation of fatty acids
50
How and when does ADH secretion take its effect in exercise?
Sweating causes a decrease in blood volume Increases haemoconcentration and osmolality This causes osmoreceptors to increase firing to the hypothalamus ADH secretion is increased from the posterior pituitary gland This increases reabsorption in the collecting ducts Increase in blood volume ADH secretion occurs at 60% VO2 max Up to an 800% rise
51
What do each of the adregenic receptors cause?
Beta 1: glycogenolysis; lipolysis; heart rate Beta 2: vasodilation; brochodilation Alpha 1: vasoconstriction; phosphodiesterase Alpha 2: opposes beta receptors
52
What value does NE start and finish on on the y-axis?
0.5 --> 2
53
How is sodium and blood volume maintained during exercise?
Sweating causes lack of blood flow to the kidneys Stimulates secretion of renin Renin converted to angiotensin 1 and then angiotensin 2 Angiotensin 2 causes the production of aldosterone from the adrenal cortex This causes sodium ion absorption and therefore H20 reabsorption
54
How is cortisol production stimulated and what are the four effects it takes?
Stress and circadian rhythm Causes increased production of CRH from the hypothalamus Increased secretion of ACTH from the anterior pituitary Increased secretion of cortisol from adrenal cortex Causes: a) Lipid mobilisation b) Protein breakdown c) Decreased glucose uptake d) Gluconeogenesis
55
How is an action potential stimulated on a membrane?
2 potassium in, 3 sodium out at resting Action potential causes depolarisation and opening of sodium channels Sodium floods in making the inside more positive Membrane repolarises, causing the sodium channels to shut and the potassium channels to open This causes the inside to become more negative again
56
What are the main functions of the skeletal muscle?
Postural support Locomotion Cold stress
57
Discuss the connective tissue of the muscle in order of how deep they are.
``` Epimysium (whole muscle) Perimysium (fibre bundles) Endomysium (individual muscle fibres) External Lamina (inside endomysium) Sacrolemma (surrounds muscle cell membrane) ```
58
What is the role of satellite cells?
Growth and repair Increase the number of muscle cell nuclei Therefore increased protein synthesis This occurs after strength training
59
Describe the process of action potential generation that causes skeletal muscle action.
Achetylcholine attaches to receptors on sarcolemma Stimulates action potential generation in the t-tubules at the A-I junction (found at z-line) This stimulates release of calcium from the t-tubule lateral sacs
60
Describe the sliding filament theory.
ATP is hydrolysed by myosin ATPase binding to an actin binding site This creates the energy for tension generation Pi is then released which causes movement of the myosin head and therefore muscle shortening ATP binds which removes the myosin head
61
What does force generation depend on?
Muscle length Nature of the stimulus (tetanus, temporal, spatial) Number of MU's firing
62
What are the values for the length-tension relationship?
2.25 um is optimum (tension is just above 1) - optimal overlap of actin and myosin x-axis is % resting length
63
What do we stain for in slow and fast twitch muscle fibres?
Slow - SDH | Fast - phosphorylase
64
Which myosin isoform is stable in acidic conditions?
Slow (MHC 1)
65
What does muscle strength depend on?
Fibre size and number (not type!)
66
What are the factors affecting ROM?
``` Age Hereditary Disease Gender Posture ```
67
What are the muscle adaptations to immobilisation?
In shortened position: loss of sarcomere's In lengthened position: gain of sarcomere's Units --> 3000 sarcomere's
68
What effect does muscle fibre length have on velocity and power?
Longer muscles have increased velocity and power
69
Discuss the tendon-stress-strain curve.
``` Strain = change in length/ length Stress = load/ CSA ``` Shorter tendons have increased strain Muscle damage usually occurs at about 30% change in length
70
What is the difference between creep training and stress-relaxation training?
Creep training: Constant force + lengthening | S-R training: decreased force + constant length
71
How can jump height be increased?
Squatting Creates more potential energy as there is overlap of myosin and actin This satisfies the length-tension relationship Increased power output
72
What are the neural adaptations to training?
``` Increased firing rate and synchronisation Increased excitability Increased activation of the CNS Inhibition of the GTO Potentiation of some reflexes Decreased inhibitory reflexes ```
73
What evidence is there for neural influences on muscle strength training?
Resistance training in one leg increases strength of contralateral leg, without any increase in size Improved MVC under hypnosis or with loud sound
74
What is the classic tri-phasic EMG pattern?
Initial agonist burst of EMG (less inhibition) Secondary burst of EMG activity due to antagonist, which acts as a breaking force for the agonist (C-B cycling) Final burst of EMG is due to the agonist, which is fine-tuning the movement
75
What is the effect of training on force neural firing?
Increased firing rate and summation Doublet discharge Lead to a greater rate rise in tension
76
What do training effects depend on?
Duration Intensity Muscle used
77
What is the effect of strength training on muscle profile?
Increased muscle CSA Increased contractile protein Decreased mitochondria
78
What is the effect of endurance training on muscle profile?
Increased... Capillarisation Mitochondria Fatigue resistance 2a
79
What is the effect of speed training on muscle profile?
Increased... Muscle size Glycolytic enzymes 2b
80
What are the factors that affect fibre type?
``` Ageing Environment Disease Detraining Nutrition Disuse ```
81
How do we know that there hasn't been any fibre number changes?
Muscle fibre CSA change will be proportional to muscle CSA change
82
What are methods of muscle weighting?
Anthropometry (length, width and circumference) Scanners X-ray
83
What muscle differentiation occurs during disuse?
Fast: phasic firing Slow: lengthened position = suppression of fast gene and stimulation of slow gene // stimulation in stretched position causes hypertrophy Muscle stiffness: disuse = collagen build up Enzyme activity: Dedifferentiation --> slow = oxidative enzyme capacity decrease / fast = glycolytic enzyme capacity decrease Sarcomere number: lengthened position = increase / shortened position = decrease
84
What are the effects of disuse on muscle contractile properties?
Decreased MVC Decreased firing rate Decreased CSA Decreased rate rise of torque
85
Why do changes to contractile character occur with age?
Loss of fibres and therefore CSA | Loss of motor units
86
What is colateral innervation?
Denervation of a motor unit due to age Lateral growth of neurones that are lateral to denervated muscle fibre Muscle fibre type changes dependent on the firing pattern of the new nerve (part of a new MU)
87
Why is there a decrease in power output with age?
Colateral inervation occurs, therefore there are more fibres belonging to the same motor units With age, there is more tonic firing by neurones This means there is a conversion to more slow fibres Therefore there is decreased power, as there are fewer fast-twitch fibres, which have a greater speed of contraction
88
Why is the elderly twitch time course more prolonged?
Increased demand for a relaxation period by the muscle
89
What are the sites of fatigue?
``` Excitation to the motor cortex Drive to the motor neuron Excitability of the motor neuron Neuromuscular transmission Excitability of the sarcolemma Excitation-contraction coupling Contractile mechanism ATP supply ```
90
Describe the m-wave and the H-reflex.
M-wave: action potential of muscle causing activation | H-reflex: relex reaction due to afferent nerve stimulation (bypasses muscle spindle)
91
What is high frequency fatigue?
Decreased force output over time when high frequency contractions have been stimulated This is shown by a loss of amplitude on an EMG Amplitude can be regenerated by lowering the stimulation frequency Therefore more force can be stimulated for longer if the frequency is gradually reduced
92
Why do we get high frequency fatigue?
Fatigue and pain pathways signal to ASIC purigenic receptors due to metabolite build up Causes signalling to central command to reduce firing
93
List some causes of muscle fibre necrosis.
``` Alcohol Disease Stress Ischaemia Irradiation Toxins ```
94
What causes LFF?
Lower calcium release per contraction
95
What are the events that occur after a plasmolemma tear?
Dead tissue formation due to ischaemia Calcium enters tear Calcium signals for macrophages to enter and consume debris Satellite cells produce nuclei to form a new membrane The nuclei form myoblasts that form a myotube, which forms a new membrane
96
What causes DOMS?
``` Upregulation of nerve growth factor Sensitisation of afferent nerve fibres Due to eccentric exercise More reps Unaccustomed exercise ```
97
What is the flow of oxygenated blood through the heart?
``` Pulmonary Vein Left atrium Bicuspid valve Left ventricle Aortic valva Aorta ```

Physiology (16 decks)

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