Exercise Physiology Revision

Question	Answer
hormonal adjustments to increased temperature	Antidiuretic hormone is released by the posterior pituitary gland in response to increased blood osmolarity- promotes water conservation by increasing plasma volume. Aldosterone is released by the adrenal cortex in response to decreased blood pressure, promotes sodium reabsorption in the kidneys to increase plasma volume.
Acquired thermal tolerance	resistance to exertional heat injuries severe, non-lethal heat exposure- increased subsequent heat load heat shock proteins
heat shock proteins	-are synthesised in response to cellular stress - protect cells from thermal injury by stabilising and refolding damaged proteins - play a role in thermo-tolerance an protect body cells from the heat loads associated with prolonged exercise expression is associated with resistance to stress and may be central to the understanding at a cellular level of thermo-tolerance after acclimatization
fluid replacement	prevents dehydration 800ml/hr emptied from stomach
problems of dehydration	less blood volume- less blood supply to tissues and skin increased body temperature and HR decreased thermal regulation and exercise performance
dehydration decreases:	rate of gastric emptying; liver/kidney blood flow; plasma volume; ventricular filling pressure; stroke volume; cardiac output; sweat rate; peripheral flow and appetite
dehydration increases:	GI distress; fluid-regulatory hormones; plasma osmolarity; core temperature; body temperature at which sweating occurs; heart rate; lethargy; hyperthermia risk
define heat acclimatisation	natural adaptation in a hot and humid environment
what must happen for heat acclimatisation to occur?	must increase core temperature; must increase sweat rate; last at least 60 minutes at 50% VO2max; last at least 1 week
define heat acclimation	adaptation in an artificial hot and humid environment
what conditions must be met for heat acclimation to occur?	must increase core temperature; must increase sweat rate; must have repeated exposure; optimum at 40-50% VO2max for 90-120 minutes for 7-10 days; should have a gradual increase in duration and/or intensity
define hormone	chemical messengers secreted into the blood or lymph which travel long distances to their target cell
Central Fatigue	fatigue of the brain and spinal cord
Image: Electrical_stimulation_of_muscle_to_determine_fatigue_type (image/png)	electrical stimulation of the muscle can determine if fatigue is central or peripheral if fatigue is central then electrical stimulation generates full muscle force
what are the three types of hormone	amine- hydrophillic peptide/ protein- hydrophillic steroid- hydrophobic
define target cell	the cells that respond to a particular hormone
what do motor neurones do to reduce the fatigue rate during fatiguing contractions?	motor neurones fire more slowly during fatiguing contractions in order to reduce the fatigue rate
what feedback does the CNS receive from muscles?	contraction force speed accuracy
Group 1 Fibres	connected to muscle spindles travel from the muscle to the CNS at 80-100m/s control ongoing muscle contractions and make adjustments to force
Group II fibres	travel from the muscle spindle to the CNS not as fast as group I fibres control ongoing muscle contractions and make adjustments to force
Group III and Group IV fibres	travel from the muscle to the CNS slower than groups I and II Group III fibres possibly send feedback on blood pressure Group IV fibres possibly send feedback on metabolic state
what is Noake's cardioprotective hypothesis?	fatigue is a protective mechanism for the heart
body heat is gained from	metabolic heat and environmental heat
body heat is lost through	-radiation -convection -conduction -evaporation
heat stress	load from the environment
heat strain	response to heat stress
environmental variables affecting heat stress	air temperature air velocity humidity amount of thermal radiation
why is it harder to perform on hot and humid conditions?	humidity decreases heat loss from evaporation
thermal balance	equilibrium between core and periphery hypothalamus set at about 37C
what is responsible for causing rapid changes in body temperature?	peripheral thermal receptors
the role of the hypothalamus in body temperature control	body temperature is monitored mainly by the temperature of the blood perfusing the hypothalamus posterior control heat conservation anterior controls heat loss
changes in blood flow due to exercise in the heat	the greater the heat stress during exercise, the more vasodilation of muscle and subcutaneous blood vessels and vasoconstriction of organ blood vessels
how and why does oxygen consumption change at higher temperatures?	more oxygen is required at higher temperatures due to the inefficiency of the respiratory system at high temperatures
name three ways of measuring core body temperature	oesophageal intestinal rectal
mechanisms for heat loss and thermoregulation	integration of heat dissipating mechanisms circulatory responses hormonal responses sweat response fluid intake
describe the circulatory response to increased temperature	vasodilatory response redirection of blood to skin to dissipate heat increased thermal conductance of peripheral tissue activation of sweat glands cooled blood goes back to core and absorbs more heat increased HR & Q; decreased SV
Sweat response to increased temperature	Eccrine glands- cholinergic sympathetic nerve fibre control secretion of weak hypotonic saline solution skin cooled if evaporative means available cooled skin allows further cooling of shunted blood to the periphery as ambient temperature increases- sweat rate increases
what does heat loss from sweating depend on?	-total surface area exposed -the temperature and humidity of ambient air- if relative air humidity is high this can lead to dangerous states of dehydration and overheating; if relative humidity is low, relatively high temperatures can be tolerated -the convective air currents

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	Created by JMortimer93 about 11 years ago