THERMOREGULATION
Homeostasis
Body temperature
•Temperature of periphery - Poikilothermie regulation •Temperature of core - homoiothermic regulation
Social thermoregulation
HEAT INTAKE
THERMOREGULATION
HEAT PRODUCTION
T.BEHAVIOUR
HEAT LOSS
HEAT OUTPUT
HEAT INTAKE
•Radiation (irradiation, without touch, IR) •Convection (temperature gradient, touch)
HEAT PRODUCTION
•Depends on energetic exchange (10% of BM - 1°C)
•Difference between rest and exercise (increases muscle rate - up to
90%)
•Shivering and nonshivering thermogenesis (voluntary and nonvoluntary thermogenesis)
•Brown adipose tissue (p3 adrenoreceptors, NA, lipolysis, expression of lipoproteinlipase and thermogenin, uncoupling of oxidative chain)
HEAT ^CONVECTION"
• Inner heat convection (between inner organs and skin)
• Outer heat convection - heat output
HEAT LOSS (OUTPUT)
Heat radiation
no touch
Convection of heat to environment (wind) touch
up to 36°C
•Evaporation - sweating perspiratio sensibilis, p. insensibilis (sweating glands, diffusion) 1 litre of evaporated sweat - 2428 kJ
Temperature limit: 33°C at high humidity
Piloerection and horripilation. Tachypnoe.
WAY OF OUTPUT	% (at 21°C)	Higher # temperatures I
radiation and convection	70	1
evaporation	27	
breathing	2	—
excrements	1	—
THERMOREGULATORY MECHANISMS
ACTIVATED BY COLD	Increase of heat production
Muscle shivering	+
Hunger	+
Increase of intentional movements	+
Increase of CA secretion	+
	Decrease of heat output
Skin vasoconstriction	+
Twisting	+
Horripilation	+
ACTIVATED BY HEAT	Increase of heat output
Skin vasodilatation	+
Sweating	+
Increase of ventilation	+
Loss of appetite, apathy, inactiveness	Decrease of heat production
CONTROL OF THERMOREGULATION
Afferentation: TRP channels - 2 types (TRPM8-cold, TRPVl-hot) •Central thermoreceptors •Peripheral thermoreceptors (skin - cold)
Mechanisms:
•Vegetative
•Somatic
•Endocrine (CA, thyroxin, TSH) •Modification of behaviour
Mediators:
•NA - mechanisms activated by heat
•Serotonin - m.a.cold
Thermoregulatory centres - CENTRAL THERMOSTAT: •Posterior hypothalamus - reaction to cold •Anterior hypothalamus - reaction to heat •Upper part of middle brain - ?
Temperature (C) Symptoms	
28	muscle failure
30	loss of body temperature control
33	loss of consciousness
37	normal
42	central nervous system breakdown
44	death
Constitution hyperthermia Malignant hyperthermia
Hypothermia
1. Diurnal variation of body temperature
2. Cyclic variation in women
3. Seasonal variation
18
Time
(hours)
3	3	3	3	3	3	3	3	3	3	3	3	3		3	3	3	3	3		3	3	3		3	3	3	3	3
2	2	2	2	2	2	2	2		2	2	2	2		2	2	2		2.	n		i		2			2	2	2
																												
1	1	1	1	1	1	1	1	i	1	1	1	JLJ		1	1		1		i	1	1	1	1	1	1		1	1
96	98	98	98	98	98	98	98	96	98	98	98	98		98		98	98	96	98	98	98	98	98	98	98	98		98
9	9	9	9	9	9	9	9	9	9	9	9	9	•	9	19	9	9	9	9	9	9	9	9	9	9	9		9
8	8	8	8	8	8	8	8	8		8	8	8		/ -		8	8	8	8	8	8	8	8	8	8	8		8
7	7	}	7	7	7	7	7	7		7	7	7			7	7	7	7	7		7	7	7	7	7	7	7	7
6 6		6	6	6	•	6	6	6	fe\	■	6	6			6	6	6	6	6	6	6	6	6	6	6	6	6	6
5			5	5	5	5	5	si	5	\5	5	5		[5	5	5	5	5	5	5	5	5	5	5	5	5	5	\
4	4	4		4	4	4	4		4		4	4 1		4	4	4	4	4	4	4	4	4	4	4	4	4	4	\
3	3	3	3		3		3		3	3>	V3	1		3	3	3	3	3	3	3	3	3	3	3	3	3	3	3
2	2	2	2	2		2		2	2	2				2	2	2	2	2	2	2	2	2	2	2	2	2	2	2
1	1	1	1	1	1	1	1	1	1	1	1	1 )		1	1	1	1	1	1	1	1	1	1	1	1	1	1	1
97	97	97	97	97	97	97	97	97	97	97	97 97			97	97 97 97			97	97	97	97	97	97	97	97 97		97	97
		9		9		9		9		9	9	9	9	9		9	9	9		9	9	•				9	9	
1	<	3	i	5		7	is	9	10	11	17		11	15	ii.	17	18	19	.-ii	?1	>.>	73	.-')	29		2?	28 29