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Physiology > Long answer questions > Flashcards

Long answer questions Flashcards

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
Q

How can thermoregulation of the skin limit blood flow to the cardiac system?

A

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

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26
Q

Describe the process of skin blood flow during exercise.

A

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

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27
Q

How is the brain blood flow autoregulated?

A

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

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28
Q

What is the relationship between brain blood flow and exercise intensity?

A

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

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29
Q

What are the overall circulatory responses to dynamic exercise?

A

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)

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30
Q

How is the cardiovascular system controlled during exercise?

A

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

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31
Q

What are the four factors regulating the metaboreflex?

A

Fibre type
Muscle fibre training status
Blood flow obstruction
Blood volume

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32
Q

When using a neck cuff, what effect does negative pressure production have on the arterial baroreceptors?

A

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

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33
Q

Injecting fentanyl opioids in unhealthy people has what effect on the exercise pressor reflex?

A

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

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34
Q

What are the four factors that stimulate the mechanoreflex?

A

Degree of stretch
Force of stretch
External pressure
Presence of metabolites (re-setting at new point)

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35
Q

How is RBC production stimulated due to endurance training?

A

Hypoxia of the kidneys
Stimulates production of EPO
Causes haemopoetic production of RBC’s

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36
Q

What are the central cardiac adaptations that occur due to endurance training that maximise blood flow to exercising muscles?

A 
Increased RBC content 
Increased RBC volume 
Increased force of contraction (wall thickness) 
Increased chamber size 
Decrease heart rate at every intensity
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37
Q

What are the peripheral adaptations to aerobic training?

A 
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
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38
Q

What are the inducers of vascular remodelling?

A

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

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39
Q

What are the limiters of O2 uptake during exercise?

A 
Cardiac circulation 
Heart size (pumping capacity) 
Blood flow 
Heamoconcentration 
Capillary Density 
HB-O2 affinity
Vascular conductance
40
Q

Describe the lactate graph.

A

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
Q

Why does the lactate threshold occur?

A

Lack of blood flow
Accelerated activity of LDH
Hypoxia
Increased presence of LDH in fast-twitch

42
Q

What are the fast and slow components of EPOC catering for?

A

Fast: resynthesis of PCR and O2 replenishment
Slow: lactate –> glucose, lowered heart rate and ventilation, adrenaline and noradrenaline synthesis

43
Q

What are the Balke and Bruce tests and what are the drawbacks?

A

Balke: increase in gradient - sore back
Bruce: increase in gradient and speed - very quick

44
Q

What are the factors that effect oxygen consumption?

A 
Mode of exercise 
Hereditary 
State of training 
Gender 
Body Composition * 
Age
45
Q

What are the three types of hormone? Give an example of each.

A

Protein: ADH
Amino acid: catacholamines
Steroid: gluccocorticoids

46
Q

What influences the blood hormone concentration?

A

Synthesis
Rate of excretion
Number of transport proteins
Blood volume

47
Q

What does the magnitude of hormonal effect depend on?

A

Hormone concentration
Number of receptors
Affinity of receptors for hormone

48
Q

How do hormones modify celullar activity?

A

Affect membrane transport
Activate second messenger model via G-protein
Increase protein synthesis via nuclear DNA
Alter enzyme activation

49
Q

Where is growth hormone produced and what does it cause?

A

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
Q

How and when does ADH secretion take its effect in exercise?

A

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
Q

What do each of the adregenic receptors cause?

A

Beta 1: glycogenolysis; lipolysis; heart rate
Beta 2: vasodilation; brochodilation
Alpha 1: vasoconstriction; phosphodiesterase
Alpha 2: opposes beta receptors

52
Q

What value does NE start and finish on on the y-axis?

A

0.5 –> 2

53
Q

How is sodium and blood volume maintained during exercise?

A

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
Q

How is cortisol production stimulated and what are the four effects it takes?

A

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
Q

How is an action potential stimulated on a membrane?

A

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
Q

What are the main functions of the skeletal muscle?

A

Postural support
Locomotion
Cold stress

57
Q

Discuss the connective tissue of the muscle in order of how deep they are.

A 
Epimysium (whole muscle) 
Perimysium (fibre bundles) 
Endomysium (individual muscle fibres) 
External Lamina (inside endomysium)
Sacrolemma (surrounds muscle cell membrane)
58
Q

What is the role of satellite cells?

A

Growth and repair
Increase the number of muscle cell nuclei
Therefore increased protein synthesis
This occurs after strength training

59
Q

Describe the process of action potential generation that causes skeletal muscle action.

A

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
Q

Describe the sliding filament theory.

A

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
Q

What does force generation depend on?

A

Muscle length
Nature of the stimulus (tetanus, temporal, spatial)
Number of MU’s firing

62
Q

What are the values for the length-tension relationship?

A

2.25 um is optimum (tension is just above 1) - optimal overlap of actin and myosin
x-axis is % resting length

63
Q

What do we stain for in slow and fast twitch muscle fibres?

A

Slow - SDH

Fast - phosphorylase

64
Q

Which myosin isoform is stable in acidic conditions?

A

Slow (MHC 1)

65
Q

What does muscle strength depend on?

A

Fibre size and number (not type!)

66
Q

What are the factors affecting ROM?

A 
Age 
Hereditary 
Disease 
Gender 
Posture
67
Q

What are the muscle adaptations to immobilisation?

A

In shortened position: loss of sarcomere’s
In lengthened position: gain of sarcomere’s
Units –> 3000 sarcomere’s

68
Q

What effect does muscle fibre length have on velocity and power?

A

Longer muscles have increased velocity and power

69
Q

Discuss the tendon-stress-strain curve.

A 
Strain = change in length/ length 
Stress = load/ CSA

Shorter tendons have increased strain
Muscle damage usually occurs at about 30% change in length

70
Q

What is the difference between creep training and stress-relaxation training?

A

Creep training: Constant force + lengthening

S-R training: decreased force + constant length

71
Q

How can jump height be increased?

A

Squatting
Creates more potential energy as there is overlap of myosin and actin
This satisfies the length-tension relationship
Increased power output

72
Q

What are the neural adaptations to training?

A 
Increased firing rate and synchronisation 
Increased excitability 
Increased activation of the CNS 
Inhibition of the GTO 
Potentiation of some reflexes 
Decreased inhibitory reflexes
73
Q

What evidence is there for neural influences on muscle strength training?

A

Resistance training in one leg increases strength of contralateral leg, without any increase in size
Improved MVC under hypnosis or with loud sound

74
Q

What is the classic tri-phasic EMG pattern?

A

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
Q

What is the effect of training on force neural firing?

A

Increased firing rate and summation
Doublet discharge

Lead to a greater rate rise in tension

76
Q

What do training effects depend on?

A

Duration
Intensity
Muscle used

77
Q

What is the effect of strength training on muscle profile?

A

Increased muscle CSA
Increased contractile protein
Decreased mitochondria

78
Q

What is the effect of endurance training on muscle profile?

A

Increased…

Capillarisation
Mitochondria
Fatigue resistance
2a

79
Q

What is the effect of speed training on muscle profile?

A

Increased…

Muscle size
Glycolytic enzymes
2b

80
Q

What are the factors that affect fibre type?

A 
Ageing 
Environment 
Disease 
Detraining 
Nutrition 
Disuse
81
Q

How do we know that there hasn’t been any fibre number changes?

A

Muscle fibre CSA change will be proportional to muscle CSA change

82
Q

What are methods of muscle weighting?

A

Anthropometry (length, width and circumference)
Scanners
X-ray

83
Q

What muscle differentiation occurs during disuse?

A

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
Q

What are the effects of disuse on muscle contractile properties?

A

Decreased MVC
Decreased firing rate
Decreased CSA
Decreased rate rise of torque

85
Q

Why do changes to contractile character occur with age?

A

Loss of fibres and therefore CSA

Loss of motor units

86
Q

What is colateral innervation?

A

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
Q

Why is there a decrease in power output with age?

A

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
Q

Why is the elderly twitch time course more prolonged?

A

Increased demand for a relaxation period by the muscle

89
Q

What are the sites of fatigue?

A 
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
Q

Describe the m-wave and the H-reflex.

A

M-wave: action potential of muscle causing activation

H-reflex: relex reaction due to afferent nerve stimulation (bypasses muscle spindle)

91
Q

What is high frequency fatigue?

A

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
Q

Why do we get high frequency fatigue?

A

Fatigue and pain pathways signal to ASIC purigenic receptors due to metabolite build up
Causes signalling to central command to reduce firing

93
Q

List some causes of muscle fibre necrosis.

A 
Alcohol 
Disease 
Stress 
Ischaemia 
Irradiation
Toxins
94
Q

What causes LFF?

A

Lower calcium release per contraction

95
Q

What are the events that occur after a plasmolemma tear?

A

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
Q

What causes DOMS?

A 
Upregulation of nerve growth factor 
Sensitisation of afferent nerve fibres 
Due to eccentric exercise 
More reps 
Unaccustomed exercise
97
Q

What is the flow of oxygenated blood through the heart?

A 
Pulmonary Vein 
Left atrium 
Bicuspid valve 
Left ventricle 
Aortic valva 
Aorta

Physiology (16 decks)

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