2. Lecture-1 :Topics
Core and Shell body temp.
Heat Balance
Factors promoting -
a) Heat gain
b) Heat loss
Temp. regulatory mechanisms
3. Learning Objectives
Normal Body Temperature
Ways of measuring Body Temp
List the mechanisms of heat
production & heat loss
Regulation of Body Temp.
4. Body Temperature
Normal Body Temperature (NBT) –
98.60F(370C)
Range of NBT ----- (970F to 990F)
Rectal Temp ----- (0.50F to 10F) above
the Oral
Rectal Temp reflects the internal body
Temp (Core Body Temp)
Core Body Temp remain almost constant
Skin Temp (Shell Temp)-----Variable
5. Temperature Homeostasis
Keep the body temp within a very narrow
range
Range of NBT (970F to 990F)
Temperatures above this:
denature enzymes and block metabolic
pathways
Temperatures below this:
slow down metabolism and affect the brain.
6. Heat Balance
Heat balance maintains the body temp
Balance between heat production &
heat loss (Heat Balance)
Heat Balance
Heat production= Heat loss
Heat production is called
thermogenesis
Heat loss is called as thermolysis
7.
8. Heat Production (Thermogenesis)
BMR
Specific Dynamic Action of food
Activity of skeletal muscle
Shivering
Exercise
Chemical Thermogenesis
Epinephrine &Norepinephrine
Thyroxine
Brown Fat-
Source of considerable heat production
Abundant in infants
9. Heat Loss (Thermolysis)
Radiation
Conduction
Convection
Evaporation
Perspiration
Respiration
Loss through urine & feces
14. Thermoregulation
Temperature is regulated by nervous
feedback mechanisms
Thermoregulatory center located in the
Hypothalamus
Thermoregulatory regulatory responses
include
Autonomic
Somatic
Endocrine
Behavioural changes
15. Feedback system
1) Receptor
◦ Sensor that responds to changes (stimuli)
2) Control Center
◦ Sets range of values
◦ Evaluates input and
◦ Sends output
3) Effector-
◦ Receives output from control centre
◦ Produces a response
16. Body Temperature Control System
Hypothalamus
◦ Acts as a thermostat
◦ Receives nerve impulses
from cutaneous
thermoreceptors
◦ Thermoreceptors Cold
&Heat
Hypothalamus- also has
thermoreceptors called
central thermoreceptors
These detect changes in
blood temperature
17.
18. Thermoregulatory regulatory responses
Activated by Exposure to Cold
1. Shivering
2. Increase voluntary activity
3. Increase TSH secretion
4. Increase Catecholamines
5. Vasoconstriction
6. Horripilation
7. Curling up
19. Thermoregulatory regulatory responses
Activated by Exposure to Heat
1. Vasodilatation
2. Sweating
3. Increase in Respiration
4. Anorexia
5. Apathy
6. Decrease TSH secretion
20. Thermoregulatory regulatory responses
Exposure to Cold
Shivering
Increase voluntary activity
Increase TSH secretion
Increase Catecholamines
Vasoconstriction
Horripilation
Curling up
Exposure to Heat
Vasodilatation
Sweating
Increase in Respiration
Anorexia
Apathy
Decrease TSH secretion
21. 1-A major source of heat
production in infants is
A. Increased muscular activity
B. Brown fat
C. Increased sympathetic activity
D. Specific dynamic action of food
22. 2-At normal room temperature
most body heat loss is by-
A. Convention
B. Conduction
C. Radiation
D. Sweating
23. 3-Constituents of secreted sweat are similar
to plasma except for
A. Proteins
B. Chloride
C. Bicarbonate
D. Potassium
24. 4-The only available mechanism of heat transfer
when the environmental temperature is greater than
the body temperature is
A. Radiation
B. Conduction
C. Convection
D. Evaporation
25. 5-Cause of thermogenesis in the
body is
A. Skeletal muscle relaxation
B. Assimilation of food
C. Decreased cardiac metabolism
D. Hypothyroidism
26. 6-A major factor resulting in increase
in body temperature during exercise
is-
A. Heat dissipating mechanisms
inefficient
B. Enormous thermogenesis
C. Vasoconstriction on non-working
muscles
D. Resetting of thermostat
27. 7-Site which reflects the true
value of core temperature
A. Oesophagus and rectum
B. Tympanic membrane
C. Vagina
D. All of the above
28. 8-BMR is dependent on
A. Body weight
B. Surface area
C. Amount of lean body mass
D. Height
29. 9-One feels hotter on a humid day
because-
A. Rate of sweating increases
B. Surrounding temperature is more
C. Heat loss by the body via process of
radiation decreases
D. Rate of evaporation of water from
body decreases
30. 10-A major factor resulting in increase
in body temperature during exercise
is-
A. Heat dissipating mechanisms
inefficient
B. Enormous thermogenesis
C. Vasoconstriction on non-working
muscles
D. Resetting of thermostat
33. Lecture-2 :Topics
Life in Hot environment
-Effect of acute heat
Thermoregulatory responses
Heat syndrome
-Heat cramps
-Heat exhaustion
-Heat stroke
34. Contd…
Life in cold environment
-effect of acute & long term
cold exposure on body
Applied
-Hypothermia
-Harmful effects of extreme
cold
35. Learning Objectives
Effect of Hot & Cold environment on
the body.
Thermo-receptors
Regulation of Body Temperature
36. Life in Hot environment
Hot climates- These are two types
a) Hot-dry
b) Warm-humid
Hot-dry climate-
Found in deserts
Temp >500 C
Not humid
Warm-humid climate –
Found in tropical forest
Temp usually<350 C
Humidity >75%
37. Contd----
Effects of acute heat -
Effects of acute exposure to heat
are divided into-
a) Thermoregulatory responses
b) Other effects
39. Contd----
Other effects of acute heat exposure on-
Cellular metabolism
Rate of respiration
Work of breathing
Pulse rate
Dehydration
Urinary volume
41. Life in cold environment
Effect of cold exposure on body-
a) Acute cold exposure
b) Long term cold exposure
Applied
-Hypothermia
-Harmful effects of extreme
cold
42. Contd----
Effect of acute cold exposure on body
Shivering
Increase voluntary
activity
Increase TSH secretion
Increase Catecholamines
Vasoconstriction
Horripilation
Curling up
43. Contd----
Effect of long term cold
exposure
Metabolic Responses
Insulative Responses
Hypothermic Responses
44. Contd----
Hypothermia –Body temp below
the normal lower limit (<970F)
Thermoregulatory responses
Greatly impaired at (<940F)
Lost at body temp(<850F)
45. Contd----
Frostbite
Occurs at very low temp
Surface area freezes
Ice crystals formed
Common sites-
Lobes of the ears
Digits of hands
Digits of feet
Cold induced vasodilatation-
Final protection against frostbite
47. 1- Thermal sweating differs from non-
thermal sweating in that
A. Eccrine glands are responsible for it
B. Occurs due to activation of sympathetic
cholinergic nerves
C. Found mainly over palm, sole and axilla
D. All of the above
48. Core temperature of 260C leads to death
due to:
a) Brain damage
b) Respiratory insufficiency
c) Cardiac failure
d) All of the above
49. 2- Which area of hypothalamus
functions as thermostat?
A. Preoptic
B. Paraventricular
C. Dorso medial
D. Lateral
50. 3- Insensible water loss (perspiration) will
be absent if humidity is
A. 50%
B. 70%
C. 90%
D. 100%
51. 4- Pyrogens raises body temperature
by
A. Setting the thermostat to higher level
B. Releasing interleukins
C. Decreasing peripheral heat liberating
mechanism
D. Causing peripheral vasoconstriction
52. 5- Heat loss process of the body not
directly under physiological control is
A. Radiation from body
B. Conduction and convection to
surroundings
C. Vaporization of sweat
D. Warming of inspired air
53. 6- Fever is usually caused by
A. Interleukin-1
B. Substance- p
C. Endorphins
D. Encephalin
54. 7- During exposure to cold, body
temperature is raised by
A. Vasoconstriction in the skin
B. Horripilation
C. Thermogenesis
D. All of the above
55. 8- Profound hypothermic signs include
all except
A. Show breathing
B. Bradycardia
C. Hypotension
D. Hyperactivity
56. 9- Aspirin decreases the body
temperature by
A. Inhibiting interleukin-1
B. Inhibiting pyrogens release
C. Killing fever producing organisms
D. Inhibiting prostaglandin synthesis
57. 10- When the core temperature of the body falls
below the hypothalamic set-point temperature
A. The blood vssels of the skin constrict
B. Heat production increases within
minutes
C. The basal metabolic rate increases
D. All of the above
