Option A.2 Flashcards
Explain the relationship between cellular metabolism and the production of heat in the human body.
We detect that our bodies are under thermal stress with the help of temperature sensors around the body, such as the skin.
These sensors send messages to the body’s thermostat, which is the hypothalamus in the brain.
The hypothalamus regulates the careful balance between heat produced and heat lost.
What are the 4 different heat movements sources
Heat movement comes from 4 main sources, conduction, convection, radiation and metabolism/respiration.
A.2.2 - State the normal physiological range for core body temperature.
To function correctly, the human body’s Core Temperature needs to stay within the range of 36 - 38oC
A.2.3 - State how the body thermoregulates in hot and cold environments.
Hot environemtn:
Sweat glands are activated by heat – water and salt evaporates through the skin
Heart rate increases to pump more blood to the skin
If someone is in a hot environment for a prolonged period of time the evaporation process fails as there are no more fluids to lose
Wind increases the speed of evaporation as it carries the sweat particles away. The wind increases the thermal gradient.
Cold environment:
Blood vessels constrict and more towards the centre of the blood to protect the organs
Extremities loose heat first
Majority of heat is lost through your head
Talk about sweating in the thermoregulating process
plasma is the source of sweat formation ✔
sympathetic nervous system activates sweat glands ✔
sweat is produced in the coiled hollow/tubular glands in the dermis of the skin ✔
the amount of sweat the body can produce is dependent on the amount of sweat the gland can produce ✔
dependent on the number/density of sweat glands «per cm2» of sweat glands an individual has ✔
amount of sweat depends on the individual/ exercise intensity/ acclimatization/ hydration status ✔
Discuss the significance
of humidity and wind in
relation to body heat loss.
«relative» high water content of ambient air decreases capacity to accept more water molecules ✔
impacts the efficiency of the sweating mechanism/response/skin evaporation «temperature regulation» ✔
lack of evaporation of sweat inhibits cooling ✔
core temperature rises, having a negative effect on physiological functioning ✔
leads to potential decreased performance ✔
4 main sources of heat movement
conduction, convection, radiation and metabolism/respiration.
Discuss body surface area to body mass ratio for heat preservation
Increased surface area to volume ratio means increased exposure to the environment
Colder climates: greater exposed surface → greater loss of heat and energy
Low surface area to volume ratio helps conserve heat
Warmer climates: high surface area to volume ratio → helps lose heat
Fat acts as an insulator, limiting heat transfer to the environment.
Short people with high body masses are better at preserving body heat.
Tall people with low body mass lose heat quickly.
Optimal heat preservation requires more body mass and less surface area.
Small children tend to have a large body surface
area to body mass ratio compared to adults.
This makes it more difficult for them to maintain
normal body temperature in the cold.
Describe the formation
of sweat and the sweat
response.
-Sweating decreases core body temperature.
-Heat from blood is transferred to skin via vasodilation for evaporation.
-Evaporation of sweat occurs down a concentration gradient.
-Sweating is more common in hot environments to maintain optimal body temperature (homeostasis).
-In humid climates, sweating is more persistent due to lower evaporation rates.
-Factors affecting sweat rate include exercise intensity, environmental conditions, fitness level, acclimatization, and the type and amount of clothing worn.
Discuss the physiological responses that occur during prolonged exercise in the heat.
Physiological Adaptations
Maximal sweat rates can reach 2-3 L per hour which means:
o Loss of fluid
o Loss of body mass
o Decrease in plasma volume
o Altered electrolyte balance
o Less urine production due to the retention of sodium and fluids
o Decreased central blood volume and stroke
o Decreased stroke volume
o Increased heart rate and thus more cardiac work
(talk about cardiovascular drift)
Discuss different health risks associated with exercising in the heat
Heat cramps
Symptoms: painful cramps (legs), flushed and moist skin
Treatment: move to a cool place and rest, remove excess clothing and place cool cloths on the skin, fan skin, drink sports drinks
containing salt and sugar (gatorade), stretch cramped
muscles slowly and gently.
Heat exhaustion
Symptoms: muscle cramps, pale moist skin, high fever, nausea, vomitting, diarrhea, headache, fatigue, weakness, anxiety and faint feeling
Treatment: move to a cool place and rest, remove excess clothing and place cool cloths on the skin, fan skin, drink sports drinks containing salt and sugar (gatorade), if no improvement or unable to take fluids, go to an emergency department immediately, IV (intravenous) fluids may be needed
Heat stroke.
Symptoms: warm and dry skin, high fever, increased heart rate, loss of appetite, vomitting, diarrhea, headache, fatigue, confusion, agitation, lethargy, stupor, seizure, coma, death
Treatment: move to a cool place and rest, call 911, medical emergency, remove excess clothing and drench skin in cool water, fan skin, place ice bags on armpits and groin areas, offer cool fluids is alert and able to drink
Discuss the physiological and metabolic adaptations that occur with heat acclimatization.
1: Increased plasma volume To decrease the viscosity of blood and increase stroke volume. Also, to counteract the loss of plasma that occurs through sweating.
2: Increased sweat response Enabled by the increase in plasma volume, the body sweats more and is able to better cool itself to avoid heat-related disorders.
3: Reduced rate of utilisation of muscle glycogen The body becomes more effective at using its stored form of energy, using it at a reduced rate, and allowing it to support exercise for a longer period of time.
Outline the principle means by which the body maintains core temperature in cold environments.
Shivering - when core body temperature drops beneath 36 degrees Celsius, the skin sends messages to the hypothalamus that the body needs to be warmed. The brain then instructs muscles all over the body to loosen and tighten quickly, causing shivering, and creating heat.
Non-shivering thermogenesis - the metabolism of brown fat can produce heat without shivering. This is the more common form of thermogenesis among babies and young children, whose muscles can contract with little force and speed and therefore do not produce much heat.
Peripheral vasoconstriction - when blood vessels constrict, blood flow is restricted. This reduces the flow of blood to the peripheries and ensures that warmth remains in the core of the body.
Outline what steps should be taken to prevent and subsequently treat heat-related disorders.
-Acclimatise to heat gradually
-Accounting for both heat and humidity
-Continuous rehydration
-Avoidance of salt tablets
-Weighing of athletes before and after practice
-Avoiding wet or heavy clothing
-Identification of risks in both the environment and individual participants
-Provision of frequent breaks
-Awareness of the signs of heat exhaustion
Treatment: The use of shade and cool places for recovery Ice baths or ice jackets Saline drips
What is heat acclimatisation
Heat acclimatisation refers to biological changes that reduce physiological strain, to improve physiological capability and comfort when exercising in hot conditions, as well as to prevent heat-related injuries.
