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Physiology Block 2 > 21- Exercise Physiology > Flashcards

21- Exercise Physiology Flashcards

1
Q

Three functions of exercise

A

most essential aspect during muscular activity is coordination of 3 functions

  1. Communication (signals from brain)
    - brain must stimulate muscles
  2. Energy Production (ATP)
    - fuel available for the energy
  3. O2 and CO2 transport
    - O2 provided and waste products eliminated (CO2 gets eliminated)
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2
Q

exercise is voluntary movement which requires what parts of the brain to originate the signal

A
  • cortex
  • basal ganglia
  • cerebellum
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3
Q

once you have an idea to exercise of get up.. what happens from there

A

two steps

  1. PLAN
    - cortical association areas go to basal ganglia and lateral cerebellum
    - this signal goes tot he premotor and motor cortex for execution
  2. EXECUTE
    - movement occurs and this includes the intermediate cerebellum as well
  • movement signal via corticospinal tracts
  • cerebellum provides feedback to adjust and smooth movements
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4
Q

Corticospinal tract

A

all participate in sending appropriate cycles from proper posture to fine tune to regulate complex movement then others actually stimulate muscle

  • 31% of its neurons are from the primary motor cortex
  • 29% from the premotor and supplementary motor cortex
  • 40% from neurons in primary somatic sensory cortex and posterior parietal cortex
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5
Q

basal ganglia

A

composed of several nuclei and biochemical pathways

  • dopaminergic
  • cholinergic
  • gabaergic systems

influence motor cortex
-thalamus

diseases

  • hyperkinetic (parkinsons)
  • hypokinetic (akinesia) muscle conditions
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6
Q

possible reason for ataxia

A

disease of cerebellum

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7
Q

muscle strength (Kg/cm^2)

A
  • determined by its size
  • increased through training or anabolic steroids

ex: weight lifting

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8
Q

muscle power (Kg-meters)

A
  • differs from strength
  • (power = force x distance) over a period of time
  • power output declines with duration of muscle contraction

ex: high jump or running 100-meter dash

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9
Q

muscle endurance

A
  • time a task can be sustained

- dependent on muscle glycogen store

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10
Q

what energy is used for exercise

A

ATP

  • source of energy for muscle contraction
  • bonds:
  • -last 2 phosphate radicals
  • -adenosine molecule
  • -high energy phosphate bonds
  • -each bond storing 7300 calories of energy/mole ATP

–removing both bonds results in release of 14,400 calories of energy and formation of ADP and AMP

-can sustain maximal muscle power for 3 seconds so you need a continuous supply of ATP

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11
Q

different pathways that generate ATP

A
  1. phosphocreatine —> createine
  2. Glycogen —> lactic acid
  3. glucose/fatty acids/amino acids + O2 —> CO2 + H2O+ Urea

all of these end up breating ATP which is used for muscle contraction

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12
Q

Phosphagen system of energy

A

Phosphagen system:
Stored ATP plus phosphocreatine which is broken down to creatine and phosphate releasing of 10,300 calories/mole.

-fastest system (as compared to glycogen-lactic acid system and aerobic system)

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13
Q

phosphagen system vs glycogen-lactic acid system vs aerobic system

A

phosphagen system: used for power surgest of a few seconds (weight lifting, 100m dash) — 4moles of ATP/min

Glycogen-lactic acid system: used for intermediate athletic activities (tennis, 400-m dash) — 2.5 moles of ATP/min

Aerobic System: used for prolonged athletic activity (jogging, 10,000 meter skating) — 1 mole of ATP/min

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14
Q

glycogen with oxygen

A

Glycogen
(through glycolysis) split into glucose
-Two pyruvic acid molecules
-Pyruvic acid enters mitochondria and reacts with oxygen to form ATP molecules

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15
Q

glycogen without oxygen

A

pyruvic acid coverted to lactic acid (anaerobic metabolism

Forms ATP 2.5 times more rapidly than oxidative pathway but only 50% of the rate of phosphagen energy system

Provide maximum muscle activity for about 1.5 minutes

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16
Q

exercise intensity and O2 consumption

A
  • Work intensity and oxygen consumption are proportional until oxidative pathway maximum is reached
  • Increased work beyond maximum oxygen consumption due to anaerobic metabolism
17
Q

ATP from oxidative pathway

A

Glucose, Fatty Acids, Amino Acids

  • Oxidation in mitochondria to form ATP
  • slower than phosphogen and glycogen-lactic acid systems

Provides for endurance of muscle
-32 ATP molecules/glucose

18
Q

what does increased epinephrine cause

A

increase in…
• Glucose output from the liver
• Output of fatty acid from adipose tissue

– high carbohydrate diet increases stored glycogen

19
Q

Post exercise oxygen consumption

A

• Post Exercise
– Oxygen consumption above rest

Oxygen debt

– Alactacid phase
—-Reconstituting the phosphagen system

– Lactic acid phase
—-Conversion of lactic acid
to glucose

*Oxygen consumption remains elevated after exercise to reconstitute the phosphagen system and convert lactic acid to glucose

20
Q

Cardiovascular Adjustments to Exercise

A

Note all variables are linearly related to work rate to about 60% maximal O2 consumption, but particularly stroke volume plateaus thereafter.

21
Q

Systolic Blood Pressure and Peripheral Resistance during exercise

A

• Tissue perfusion enhanced by increased systolic blood pressure and decreased peripheral resistance.

-diastolic changes very little during exercise

22
Q

rhythmic muscle blood flow during exercise

A

Locally mediated vasodilation

increases blood flow to the muscles which is rhythmic due to capillary compression during muscle contraction

23
Q

Cardiac output distribution during exercise

A
  • Cardiac output to the muscle is about 20% at rest
  • Can increase up to 75% during exercise

-blood flow to abdomen is sacrificed for blood flow to muscles during exercise

24
Q

Mechanism of cardiovascular changes during exercise

A
  • Brain “Exercise” centers and feedback from contracting muscles to medullary cardiovascular neurons regulate cardiovascular responses to exercise.
  • There is a decrease in parasympathetic output to the heart and Increase sympathetic output to the heart and blood vessels
  • Chemical changes in the muscles induce local vasodilation.
25
Q

Pulmonary adjustments to exercise

A

Pulmonary responses to exercise
– Meet increased needs for gas exchange
– Exercise increases breathing by unknown mechanism

Low work rates
– IncreasedVentilationby increased tidal volume
– More fresh air reaches the lung with each breath
– Decreased dead space to tidal volume ratio

Limit
– Hightidalvolumes,lung
compliance is reduced
– Additional increases in ventilation are achieved to a greater extent by increasing breathing frequency

26
Q

arterial blood gases during exercise

A

Homeostasis
– 60% of maximal exercise capacity

– Signal for the hyperpnea not from increased stimulation of carotid and intracranial chemoreceptors

– During exercise above 60% of maximal capacity,
• Lactacidosis
• Hyperventilation of unknown cause

27
Q

alveolar to capillary gas exchange during exercise

A

DLCO increasing
– Recruitment of alveolar
–capillary units
– Increases the surface area for gas exchange.

Increase in the A-a PO2 difference
– Hyperventilation Increase in PAO2
– Driving pressure for
diffusion of oxygen

28
Q

Increased demands for alveolar to capillary gas exchange during exercise

A

• At Rest
– Arterial-venous content
difference is 5 vol%
– Mixed venous PO2 is 40 mmHg

• During Exercise
– Need for exchange is increased
– Greater extraction of oxygen
---Decrease O2 bound to
hemoglobin in venous blood
---Blood vessel (vasodilation) dilation
– Arterial-venous content difference may exceed 15 vol%
– Mixed venous PO2 is less than 20 mmHg
29
Q

Classification of exercise hyperpnea theories

A

1) Neural, feed-forward : signal originates in the brain
2) Neural feedback: signal originates in muscles
3) Humoral: blood-born feedback

30
Q

Exercise: Body Temperature

A

• Temperature control center receives input from thermo receptors in the skin (environmental temperature)
• The hypothalamus (body temperature).
• Regulation of body temperature during exercise
– Hydration
– Electrolyte balance

• Work results in conversion of energy to large amounts of heat
– 98.6 ° (degrees) - 102° Fahrenheit
• Heat loss
– Vasodilation of arterioles in the skin
– Heat transfer from the blood to the skin
– To environment 
---Sweating
---Evaporation

• Sweat production
– Increased by the thermal control center in the hypothalamus
– Increasing activity of sympathetic nerves to the sweat glands in the skin.

31
Q

neuroendocrine responses to exercise

A

Principal pathways activated by stress:
-hypothalamic-pituitary-adrenal axis and sympathetic nervous system

increases in:

  • growth hormone
  • TSH
  • cortisol
  • catecholamines
  • glucagon
  • endorphins

stimulation of:

  • hepatic glycogenolysis and gluconeogenesis
  • muscle glycogenolysis

Suppressed release of:
-insulin

32
Q

exercise: effects of physical training

A

Training :
Enhances Athletic Performances
– 2-3 days a week (4-6 weeks)

Increase of work rate related to Intensity and Duration
– Increase in maximal cardiac output primarily in stroke volume
– Increased muscle and myocyte size
– Increased vascularization of the heart

Increased vascularization of skeletal muscle including
– Locomotor muscles
– Respiratory muscles
– Enhanced blood delivery
– Reduced diffusion distance for diffusion of gas
—Between the vasculature and the muscle

Little evidence of respiratory system enhancement

Enhances endocrine, thermoregulatory and metabolic responses to exercise

  • changes in sympathetic nerve activity
  • enhance mobilization of glucose and fatty acids
  • elimination of heat
33
Q

limiting factors of exercise

A

Limiting factors to maximal O2 consumption
Fatigue (mental or physical)
– Boredom
– Staleness
– Drugs
– Illness.
– Depletion or non-availability of stores of energy
– Accumulation of metabolic waste products
– Alteration of physical-chemical state
– Breakdown of homeostasis

Highly elite endurance athletes can have a PaO2 of 60 mmHg during maximal exercise

  • at rest respiratory muscles only consume 2% of total O2
  • at maximal exercise the respiratory muscle consumes nearly 25% of O2 consumption
34
Q

forced vital capacity

A

as much as you can breathe in at once (forcefully)

35
Q

forced exhaled volume

A

amount you can exhale at once (forcefully)

36
Q

during exercise, muscle capillary PO2 and PCO2 decrease and increase respectively relative to rest. These changes cause…?

A
  • dissociation curve of capillary blood shifts to the right cause of a high CO2
  • at any given O2 content, the diffusion gradient for O2 from the capillaries to tissues is greater than at rest

Physiology Block 2 (21 decks)

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