+
A.2 Environmental factors
and physical performance
+ 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


+
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
 These
needed to sustain vital functions
cells take in energy through fuel
(food) and convert into chemical energy,
which is converted into mechanical energy
(e.g. Muscle contraction)
+
A.2.1 Explain the relationship between
cellular metabolism and the production
of heat in the human body
 ATP
– Adenosine Triphosphate – energyrich 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.
+ A.2.1 Explain the relationship between
cellular metabolism and the production of
heat in the human body
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.
 Energy
 Cellular
metabolism
Food + O2 + ADP  ATP + H2O + CO2 + Heat
(entrophy)
http://www.colorado.edu/intphys/Class/IPHY3730/image/figure2a.jpg
+ A.2.1 Explain the relationship between
cellular metabolism and the production of
heat in the human body
+ 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.
+ 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
+ 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.

http://hypertextbook.com/facts/LenaWong.shtml
+ 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
+ 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
+ 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.
+ 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.
+ A2.4 Discuss the significance of humidity and
wind in relation to body heat loss



Research task: In pairs (2)
Humidity:
Wind:
+ 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.
+ 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
+ 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:

http://www.gssiweb.com/Article/sse-51-children%27s-responses-to-exercise-incold-climates-health-implications
+ 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
+ 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.
IB SEHS Course Guide
+ 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
+ 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
+ A.2.8 Outline what steps should be taken to
prevent and to subsequently treat heatrelated disorders.
Prevention
 Hydrate
 Cover
– hats, shade
 Take breaks or stop the activity
 Acclimatize – later discussion
 Massage/stretching – heat cramps
 Lower intensity
+ A.2.8 Outline what steps should be taken to
prevent and to subsequently treat heatrelated disorders.
Treatment
 Heat
cramps –
 Stop exercising
 Drink water
 Heat Exhaustion
 Stop exercising
 Move to a cool environment
 Drink water
+ A.2.8 Outline what steps should be taken to
prevent and to subsequently treat heatrelated disorders.
 Heat
Stroke
 Medical
attention
 Immerse in cold /ice water
 Move to cool environment
 Take off clothing
 Use ice packs
 Use cold, wet towels
+ 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.
+ A.2.10 Discuss the physiological and
metabolic adaptations that occur with heat
acclimatization.
 Read
and summarize the link below.
 http://www.answers.com/topic/heat-
acclimatization
+ A.2.10 Discuss the physiological and
metabolic adaptations that occur with heat
acclimatization.

plasma volume

sweat response

rate of muscle glycogen utilization
+ 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
 Peripheral
– fat (brown fat)
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.
+ A.2.12 Explain why the body surface area-tobody 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.
+ 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.
+ 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

+ A.2.15 Discuss the physiological responses
to exercise in the cold.
 Muscle
function –
 Metabolic
responses -
+ A.2.16 Describe the health risks of
exercising in the cold, including cold water.

Frostbite

Hypothermia
+ 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