Introduction to temperature(animals,humans,regulation,disorders,temperature ranges,brain, skin areas)

1. Body Functions
Temperature

2. Why is temperature regulation
important?
Temperature regulation or thermoregulation is a
mechanism to maintain body temperature at a fixed
range, independently of the external surroundings
Type of homeostasis
Osilla, Sharma 2019
SURVIVAL
functioning
metabolic &
biochemical
processes

3. Temperatur
e
Regulation
Also important for:
a. Reproductive cells:
Need cooler temperatures to
maintain their properties
b. Proteins:
Need a regulated body
temperature otherwise
chemical bonds break above
40⁰C

4. Temperatur
e
Homeostasis:
Regulation of body’s variables in a fixed range
Set point:
The value our the body works to maintain
Negative feedback:
Aims to reduce any discrepancies from set point
Allostasis:
Ability to adapt to environmental changes
Basal metabolism:
The energy used to maintain body temperature
(around 36,5-37⁰C)

5. Temperature Regulation
Animals can be categorized as:
Endotherms: use energy to generate heat
internal temperature is independent of external temperature
to increase T: they shiver
to decrease T: they sweat
e.g. birds and mammals
Ectotherms: their temperature depends on the temperature of the environment
limited or no ability to control their body temperature

6. Thermoregulation
Mechanisms
afferent sensing
determine if the body is
experiencing either too
hot or too cold of a
stimulus
central control
the hypothalamus
efferent responses
body’s behavioral
reactions to changes in
body temperature e.g.
sweating, shivering
We have heat & cold receptors around all over our body
Skin receptors send input to hypothalamus

7. Brain as thermometer
Regulation starts in the brain
The hypothalamus checks our
temperature, compares it with the
normal temperature (around 37°C) and
sends messages to initiate processes
Example
During exercise our temperature rises
The hypothalamus sends signals to the
cells of the skin to produce sweat
Sweating cools down our body

8. Skin as Equalizer
The skin balances heat
production and heat loss
The dermis (thicker inner portion)
is the connective tissue layer of
skin
•It is important for sensation,
protection and thermoregulation
•It contains nerves, the blood
supply, fibroblasts, etc.
•It contains sweat glands

9. Human Body
Temperatures
• 40-44°C life-threatening, multiple organ
failure, brain lesions
• 39-40°C high fever
• 38-39°C mild fever infections or illness
• 36-37.2°C Normal Range
• 34-36°C mild hypothermia
• 30-34°C temperature regulation is
impaired
• 27-29°C cardiac fibrillation

10. Fever
Fever is the elevation of our body temperature
•It is a natural response to an ‘’invader’’
•Our body’s defense against viruses and bacteria
or
reaction to substances made by our body (e.g.
prostaglandins)
•Invaders are pyrogens (fever-producing
substances) and trigger the body's immune
response
•Pyrogens signal the hypothalamus to increase body
temperature to fight off the infection

11. too hot or too cold?
When too hot
Vasodilation: arterioles dilate, more blood
enters skin and heat is lost
Sweating: glands secrete sweat
evaporative heat loss
Stretching out:
Body occupies larger surface area
When too cold
Vasoconstriction: arterioles constrict, less
blood enters skin, keep core warm
Shivering: muscles contract and relax
rapidly, heat production by respiration
Release of hormones: thyroid, adrenal
cortical (e. thyroxin, epinephrine)
Curling up:
occupy less surface

12. Related
Disorders
Hyperthermia: abnormally high body temperature.
The body produces or absorbs more heat than it
dissipates
Hypothermia: abnormally low body temperature,
usually caused by prolonged exposure to cold
temperatures
Dysautonomia: failure of the autonomic nervous
system to regulate certain body functions, such as
heart rate, blood pressure, temperature etc.
Small fiber neuropathies: severe pain attacks that
typically begin in the feet or hands
Diabetic neuropathy: nerve damage that can occur if
you have diabetes

13. Useful links
https://www.ncbi.nlm.nih.gov/books/NBK507838/
https://academic.oup.com/cid/article/31/Supplement_5/S178/333323
https://www.sciencedirect.com/science/article/pii/S1566070216300017
https://www.healthline.com/health/thermoregulation#process
https://www.frontiersin.org/articles/10.3389/fpsyg.2015.00464/full
https://www.ncbi.nlm.nih.gov/pubmed/24365362