1. A.2 Environmental factors and physical performance

2. In Pairs (2), research the following. Cellular metabolism
A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
In Pairs (2), research the following.
Cellular metabolism
Exothermic reaction
Endothermic reaction
An exothermic reaction is a chemical reaction that releases energy by light or heat.
Endothermic process describes a process or reaction in which the system absorbs energy from its surroundings; usually, but not always, in the form of heat.

3. A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
Cellular metabolism – all chemical reactions taking place within the body, including respiration of working cells during physical exercise.
Energy needed to sustain vital functions
These cells take in energy through fuel (food) and convert into chemical energy, which is converted into mechanical energy (e.g. Muscle contraction)

4. A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
ATP – Adenosine Triphosphate – energy- rich compound that powers all of the cell’s energy-requiring processes.
Cell respiration – the controlled release of energy in the form of ATP
In humans, ATP is created through cellular respiration, which uses O2 to convert glucose into CO2 and H2O.
Catabolic reactions break down large molecules to produce energy. For example, digestion.
Anabolic reactions involve creating large molecules out of smaller molecules. For example, when the body makes fat out of extra nutrients.
ATP – stores and uses energy

5. A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
Energy liberation - The energy liberated (released) from dietary nutrients through reactions occurring in metabolism results in both heat production and the conservation of energy within the compound ATP.
Cellular metabolism
Food + O2 + ADP  ATP + H2O + CO2 + Heat (entrophy)
Digestion of carbohydrates begins in your mouth. As soon as you start chewing food, your teeth and enzymes in your saliva begin to break down your food. Once it passes through your stomach and into your small intestine, the food you ate as a polysaccharide eventually gets broken down. Digestive enzymes convert polysaccharides into the simple sugar, glucose. Once carbohydrates are converted into glucose, sodium-glucose transport proteins remove the glucose from the small intestine and send them to the bloodstream, where they are transported to your liver.Read more:

6. A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body

7. A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
The energy released when glucose (sugar) reacts with O2 is used to produce ATP. However, only a fraction of the released energy goes into the high-energy bonds of ATP. Since the overall reaction is exergonic, some energy is lost as heat.
Exergonic (catabolism) – to release energy in the form of work. Breaking down energy.
Energy released = an  in body temperature.

8. As cellular metabolism increases so does the production of heat
A.2.1 Explain the relationship between cellular metabolism and the production of heat in the human body
As cellular metabolism increases so does the production of heat
Factors that affect the metabolic rate:
Physical activity
Food
Environmental temperature

9. A.2.2 State the normal physiological range for core body temperature
Normal core body temperature of a healthy, resting adult human is 98.6 (+.4) degrees Fahrenheit or 37.0 (+.6 to 1) degrees Celsius.
Elevated body temperature is usually above 39o C or 102o F. (Hyperthermia)
Hypothermia – low body temperature (around 34 to 35o C or 93.2o F.

10. A.2.3 Outline how the body thermoregulates in hot and cold environments.
Conduction: Involves skin contact with an object of a different temperature. The body will lose temperature when in contact with colder surfaces (e.g. ice packs snow, wet clothing, cold water). Conversely, the body will increase in temperature when in contact with warmer surfaces (e.g. a hot road, warm water, electric blanket)
Browne et.al 2000

11. Cyclists gain a cooling effect through convection.
A.2.3 Outline how the body thermoregulates in hot and cold environments.
Convection: Body temperature is influenced by the flow of air across the skin – as in the cooling experience from a fan.
Cyclists gain a cooling effect through convection.
In cold climates, strong air currents are a serious threat. This is commonly known as “wind chill.” If the air currents are warmer than body temperature, the body will gain heat.
Browne et.al 2000

12. A.2.3 Outline how the body thermoregulates in hot and cold environments.
Radiation: Transfer of energy waves (e.g. sun, fireplace, radiator)
Sent out from one object, absorbed by another.
The body absorbs radiant heat energy when temperature of the environment is higher than skin temperature.

13. A.2.3 Outline how the body thermoregulates in hot and cold environments.
Evaporation: Is the most important avenue for heat loss from the body. As sweat evaporates from the skin, a cooling effect is achieved, thus releasing heat from the body.

14. A2.4 Discuss the significance of humidity and wind in relation to body heat loss
Research task: In pairs (2)
Humidity:
Wind:

15. A2.5 Describe the formation of sweat and the sweat response
Sweat glands are located over most of the body, and release fluids through the pores onto the surface of the body. This is one of the mechanisms the body uses to regulate temperature through the evaporation of sweat as it spreads over the surface of the skin.
Individuals vary hugely in their capacity to sweat.
Sweat - a solution containing a wide variety of organic and inorganic solutes through small openings or pores onto the surface of the body.Women sweat less than men, despite having more heat-activated sweat glands per unit skin area. Sweating less actually protects women from dehydration during exercise at high ambient temperatures (McArdle, Katch & Katch, p. 659.

16. A2.5 Describe the formation of sweat and the sweat response
Sweating is a response to the rise in core temperature
Sweating causes a decrease in core temperature (this is a release of what?)
Cooled venous blood returns to the body’s core
Sweat Response
Sweat is releasing heat energy from the body….remember, we would suffer from a heat-related illness or death if sweating did not occur.

17. A2.5 Describe the formation of sweat and the sweat response
Because of their relatively large body surface area and immature sweat response, infants, children and young adolescents are more susceptible to complications associated with exercise performed in the heat and cold.
Refer to the link below:
cold-climates-health-implications

18. A.2.6 Discuss the physiological responses that occur during prolonged exercise in the heat.
Submaximal exercise performed for more than 15 minutes produces progressive water loss through sweating and a fluid shift from plasma to tissues (McArdle, Katch & Katch, 2007)
An increase of body temperature results in a lower venous return to the heart, and a small decrease in blood volume from sweating.
A reduction in SV causes the HR to increase to maintain cardiac output.
What is this phenomenon called?
IB SEHS Course Guide
Cardiovascular drift

19. A.2.6 Discuss the physiological responses that occur during prolonged exercise in the heat.
Energy metabolism
The reduced muscle blood flow in high temperatures results in increased glycogen breakdown in the muscle, and higher levels of muscle and blood lactate in comparison to the same exercise performed in a cooler environment.
Glycogen is carbohydrates stored in muscle – Excess glucose is stored as glycogen or turns into fat
Lactate waste product responsible for muscle fatigue, however, is used for energy during isometric contractions as it helps ATP turnover faster when oxygen is not present. That being said, a clear understanding of lactate is still under investigation.
IB SEHS Course Guide

20. A.2.6 Discuss the physiological responses that occur during prolonged exercise in the heat.
Elevated heart rate
Increased vasodilation to assist with cooling
Reduced muscle blood flow in high temperatures resulting in increased glycogen breakdown in the muscle and higher levels of muscle and blood lactate in comparison to the same exercise performed in a cooler environment.
Reduced blood volume due to excessive sweating. Thus a reduced cooling ability of circulating blood.
Reduced sweating response: this increases core temperature.
Death

21. A.2.7 Discuss the health risks associated with exercising in the heat.
Hyperthermia – core body temperature has risen dangerously high
Confusion, hot skin, headache, and in severe cases, can lead to coma and death.
Heat Cramps -
Heat Exhaustion
Heat Stroke
Heat Related Illnesses

22. A.2.8 Outline what steps should be taken to prevent and to subsequently treat heat-related disorders.
Prevention
Hydrate
Cover – hats, shade
Take breaks or stop the activity
Acclimatize – later discussion
Massage/stretching – heat cramps
Lower intensity

23. Treatment Heat cramps – Stop exercising Drink water Heat Exhaustion
A.2.8 Outline what steps should be taken to prevent and to subsequently treat heat-related disorders.
Treatment
Heat cramps –
Stop exercising
Drink water
Heat Exhaustion
Move to a cool environment

24. A.2.8 Outline what steps should be taken to prevent and to subsequently treat heat-related disorders.
Heat Stroke
Medical attention
Immerse in cold /ice water
Move to cool environment
Take off clothing
Use ice packs
Use cold, wet towels

25. A.2.9 Describe how an athlete should acclimatize to heat stress.
Performing training sessions in similar environmental conditions (heat and humidity) from 5 to 10 days results in total heat acclimatization.
In pairs – Research and discuss how you would prepare your national soccer team ( to compete in the hot environment (>40oC/104oF) of the 2022 Qatar soccer World Cup.
Intensity of training should be reduced to avoid heat-related problems in these conditions.
What about costs associated with acclimatization of athletes using environmental chambers and/ or expensive overseas training facilities could be explored. This also raises an ethical implication that poorer nations will be unable to afford such support mechanisms and so their athletes are disadvantaged in comparison to athletes from wealthier nations.

26. A.2.10 Discuss the physiological and metabolic adaptations that occur with heat acclimatization.
Read and summarize the link below.
acclimatization

27.  rate of muscle glycogen utilization
A.2.10 Discuss the physiological and metabolic adaptations that occur with heat acclimatization.
 plasma volume
 sweat response
 rate of muscle glycogen utilization

28. Shivering – method used to raise temperature
A.2.11 Outline the principal means by which the body maintains core temperature in cold environments.
Shivering – method used to raise temperature
Non-shivering – fat (brown fat)
Peripheral vasoconstriction – prevents blood from going to the skin in order to retain heat…the vessels need to close here, unlike vasodilation, which is needed when exercising in the heat.

29. A.2.12 Explain why the body surface area-to-body mass ratio is important for heat preservation.
Tall, heavy individuals have a small body surface area-to-body-mass ratio, which makes them less susceptible to hypothermia.
Small children tend to have a large body surface area-to-body mass ratio compared to adults.
more difficult to maintain normal body temperature in the cold.

30. A.2.13 Outline the importance of wind-chill in relation to body heat.
A chill factor created by the increase in the rate of heat loss via convection and conduction caused by wind.
Look on page 185 of your text.

31. A.2.14 Explain why swimming in cold water represents a particular challenge to the body’s ability to thermoregulate.
Cold water immersion =
loss of body heat
Risk of hypothermia – low core body temperature
Increase in body heat loss due to convective heat loss
As with other cold conditions, increasing intensity of activity (e.g. going faster), the metabolic rate can compensate for the increase in heat loss

32. A.2.15 Discuss the physiological responses to exercise in the cold.
Muscle function –
Metabolic responses -

33. A.2.16 Describe the health risks of exercising in the cold, including cold water.
Frostbite
Hypothermia

34. A.2.17 Discuss the precautions that should be taken when exercising in the cold.
Appropriate clothing
Used as a barrier/protection
Insulation offered is measured in a unit called clo
1 clo = 0.155m2 KW-1