Environmental effects on the body systems Flashcards
Definition of altitude
The height or elevation of an area above sea level
Definition of humidity
The amount of water vapour in the atmospheric air
Definition of barometric pressure
The pressure exerted. by the earths atmosphere at any given point
Definition of partial pressure
The pressure exerted by an individual gas held in a mixture of gas
What is the relationship between altitude, barometric pressure and partial pressure?
As altitude increases, barometric pressure decreases and the partial pressure of oxygen decreases
What is the impact of altitude on diffusion gradient?
As altitude increases, the diffusion gradient becomes shallower between blood and muscles
What are the short term effects of altitude on the CV and respiratory systems?
-The rate of oxygen diffusion decreases, reducing haemoglobin saturation, this results in poor transport of oxygen to the muscle tissues for aerobic energy production
-Breathing frequency increases in an attempt to maintain oxygen consumption
-Blood volume decreases, plasma volume decreases by up to 25% within the first few hours of altitude exposure, to increase the density of RBC’s to maximise oxygen transport
-Stroke volume decreases, which increases HR in an attempt to maintain cardiac output
-Maximal Q,SV,HR decrease with altitude during maximum-intensity exercise
-Rate of oxygen diffusion decreases, shallower gradient between blood and muscle, slower and less efficient gas exchange of O2, less O2 dissociates with haemoglobin, decreases O2 supply for aerobic energy production
What is the impact of altitude on aerobic performance?
Aerobic -
-decreased aerobic capacity, VO2 max = impacts intensity and duration
-little impact up to 1500m, after this for every 1000m increase in altitude, VO2 max drops by 8-11%
-decreased intensity and duration before fatigue, greater demand on anaerobic systems, increased lactic acid production and fatigue. Early lactate threshold and OBLA
What is the impact of altitude on aerobic performance?
-performance under 1 minute are mainly unaffected at moderate altitude
-higher altitudes, lower air density = decreased aerodynamic drag and air resistance = faster speeds
-higher altitudes affect timing and technical components in skill sports
eg. ski jumpers change angle of lean
Definition of acclimatisation
A process of gradual adaptation to change in environment
Definition of altitude training
A method which aims to acclimatise athletes to conditions with low O2 levers
What are the timing for acclimatisation?
-3-5 days for low altitude performance (1000-2000)
-1-2 weeks for moderate altitude performance (2000-3000)
-2+ weeks for high altitude performance (3000+)
athletes should sleep no higher than 300m higher each day and have regular rest days to prevent altitude sickness (hypoxia)
-4+ weeks for extreme altitude (5000-5500)
eg. climbers stay at least a month at Everest base camp before making a summit attempt
What are the benefits of acclimatisation?
-Increased release of EPO within 3 hours of exposure, peaking at 24-48 hours later. Within 6 weeks of exposure to 4540m altitude, increase RBC count by 14%, increased haemoglobin content in the blood
-Breathing and ventilation stabilises, but remains elevated compared to sea level
-Reduced SV and Q compared with arrival at altitude as O2 extraction becomes more efficient
-Increased strength of respiratory muscles
-Reduced effects of altitude sickness (hypoxia), headaches, dizziness
-Increased capillarisation, increased capacity of gaseous exchange
Definition of thermoregulation
The process of maintaining internal core temperatures
Definition of thermoreceptors
Sensory receptors which sense a change in temperature and relay information to the brain
Definition of dehydration
Loss of water in body tissues, largely caused by sweating
Definition of hyperthermia
Significantly raised core body temperature
What is normal human core body temperature?
37 degrees, with a daily rise of no more than 1 degree
What is the effect of humidity on sweating?
low humidity = increased sweating
high humidity = decreased sweating, cooling process
What is hyperthermia caused by?
High and prolonged exercise intensities
High air temperatures
High relative humidity
What happens if core temperature rises?
Metabolic heat is transported by the circulating blood to the surface of the body and released largely by convection and evaporation (sweat). Sweating cools the body, removing excess heat quickly. But athletes can loose up to 2-3 litres of fluid per hour if exercise in the heat, this leads to decreased blood volume and dehydration
Definition of cardiovascular drift
Upward drift in heart rate during sustained steady-state activity associated with an increase in body temperature
What causes cardiovascular drift?
During prolonged exercise in the heat, the increased rate of muscular contraction and chemical reactions produce metabolic heat, which may not be removed quickly enough to maintain core body temperatures. This causes an upward rise in core temperatures. The blood is redirected to the skin for cooling purposes, this limits blood flow to the muscles, reduces venous return and affect the rate of enzyme functioning
What are the effects of exercise in the heat on the cardiovascular system?
-Dilation of arteries and capillaries to the skin, leading to increases blood flow and blood pooling at the limbs
-Decreased blood volume, venous return, SV, Q and blood pressure leading to:
-Increased HR to compensate
-Increased strain on the CV system
-Reduced oxygen transport to the working muscles
