3.3.8 Responses to Extremes

Higher Tier Only

• The mechanisms of homeostasis allow the human body to survive in a range of environmental conditions whilst maintaining optimum internal conditions for enzyme action and healthy cell function
• If the body is unable to adjust to extremes of environmental conditions, it may result in illness or even death
• Extreme conditions could include
  • Temperature challenges: Very high or very low temperatures
  • Osmotic challenges: Excessively high salt intake, water intake or dehydration

High Temperatures

• When body temperature exceeds 37.5 °C. it is called a fever
• At a temperature of 38.3 °C or more, hyperthermia develops
• If not treated carefully, the results could be severe and even fatal
• Hyperthermia may occur in response to 
  • Drugs e.g. stimulants such as cocaine, ecstasy or methamphetamine
  • Heat stroke from dehydration and prolonged exposure to heat e.g. sun
• Symptoms include:
  • Tiredness, dizziness and headaches
  • Low blood pressure
  • Muscle cramps
  • Heavy sweating and intense thirst
  • Urine produced will be low in volume and darkly coloured
  • Nausea
  • Cramps in arms, legs and stomach
• Treatments include:
  • Moving to a cool place
  • Lie down and raise legs
  • Drink fluids e.g. rehydration drinks
  • Apply cool flannels or spray with cool water

Low temperatures

• When body temperature drops below 35 °C, hypothermia develops
• If not treated, hypothermia can worsen to become exhaustion hypothermia and eventually death
• Hypothermia may happen in response to
  • Sudden or prolonged exposure to cold (e.g. falling into cold water)
  • Getting cold whilst wearing wet clothes
  • Exposure to lesser extremes could have the same outcome in babies or elderly people who are more at risk
• Symptoms include:
  • Shivering
  • Slow breathing
  • Slurred speech
  • Tiredness
  • Pale skin
  • Low energy
• Treatment includes:
  • Warming the patient up slowly
  • Removing wet clothes and wrapping in dry blankets or towels
  • Ensure they are sheltered, ideally indoors
  • Warm sugary drinks (non-alcoholic)
  • In serious cases, treatment in hospital may be required to provide oxygen or intravenous warm fluids

Dehydration

• If the body loses more water than it takes in, dehydration occurs
  • This can happen in hot conditions when sweating increases and fluid intake isn't sufficient
  • Vomiting or diarrhoea will increase the chances of dehydration
  • Diabetes is also a risk factor
• Dehydration can impact the kidneys as they try to reabsorb as much water as possible
• Symptoms include:
  • Feeling thirsty
  • A dry mouth
  • Tiredness
  • Dizziness
  • Small volumes of concentrated dark coloured urine
• Treatment includes
  • Consuming more water
  • Intake of salts to replace those lost through sweating

Over hydration

• Consuming too much water is also dangerous as it can lead to water intoxication
• The results can be fatal as the excess water leads to swelling in the body, particularly the brain
• Symptoms include
  • Headaches
  • Personality or behavioural changes
  • Irritation
  • Disorientation and confusion
  • Drowsiness
  • Nausea
• In serious cases
  • Seizure
  • Brain damage
  • Coma or death
• Treatment includes:
  • Reduce fluid intake
  • Use diuretics to increase urine production

Excess salt intake

• High salt levels (or hypernatremia) may occur due to excessive intake of salt or due to increased water loss (e.g. through sweating, vomiting or diarrhoea)
• Excessive salt intake can impact the kidneys
• Diabetics, babies and the elderly are at a higher risk than others
• Symptoms include:
  • Thirst
  • Confusion
  • Muscle twitching
  • Fatigue
• In serious cases,
  • Seizures
  • Bleeding in the brain
  • Kidney damage or kidney failure 
• Treatment includes:
  • Careful control of fluid and sodium intake
  • In serious cases, an intravenous supply of balanced fluids may be required