MUNI
MED
THERMOREGULATION
Spring 2019, prof. MUDr. Marie Noväkovä, Ph.D.
Endothermic (warm-blooded) vs. ectothermic (cold-blooded) species Arctic (20° - 40°C) vs. tropic (22° - 27°C water, 32° - 35°C) animals
THERMOREGULATION
All processes keeping body temperature within (relatively) narrow range
HEAT INTAKE
HEAT PRODUCTION
HEAT LOSS
HEAT OUTPUT
• Core temperature - homoeothermic regulation
• Peripheral temperature - Poikilothermie regulation
THERMOREGULATORY BEHAVIOUR
Social thermoregulation
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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
Hypothermia
Hyperthermia
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HEAT „CONVECnON"
• Inner heat convection (among inner organs and skin)
• Outer heat convection - heat output
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HEAT INTAKE/LOSS
HEAT OUTPUT
• Radiation (irradiation, without touch, IR)
• Convection (temperature gradient, touch) (+ Conduction - wind)
up to 36°C
HEAT PRODUCTION
Evaporation
perspiratio sensibilis (sweat glands) p. insensibilis (diffusion - skin and mucosae)
1 litre of evaporated sweat - 2428 kJ
• 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 non-voluntary thermogenesis)
• Brown adipose tissue (b3 adrenoreceptors, NA, lipolysis, expression of lipoproteinlipase and thermogenin, uncoupling of oxidative chain)
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THERMOREGULATION CONTROL
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
Thermoregulatory centres - CENTRAL THERMOSTAT: Posterior hypothalamus - reaction to cold Anterior hypothalamus - reaction to heat (Upper part of middle brain - ?)
THERMOREGULATORY MECHANISMS
COLD ACTIVATED	Decrease of heat output
Skin vasoconstriction	+
Twisting	+
Horripilation	+
	Increase of heat production
Muscle shivering	+
Hunger	+
Increase of intentional movements	+
Increase of CA secretion	+
HEAT ACTIVATED	Increase of heat output
Skin vasodilatation	+
Sweating	+
Increase of ventilation	+
Loss of appetite, apathy, inactiveness	Decrease of heat production
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1. Circadian variation of body temperature
2. Cyclic variation in women (basal temperature)
3. Seasonal variation
0
18 Time(hours)
OVULATION
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Winter
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8 12 Hours
16 20
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PHYSIOLOGY OF EXERCISE
Spring 2019, prof. MUDr. Marie Noväkovä, Ph.D.
What is it work???
MUSCLE TYPES
• Skeletal
• Heart
• Smooth
EXERCISE:
1. Dynamic (positive/negative)
2. Static
CHANGES DURING EXERCISE:
1. Cardiovascular
2. Respiratory
3. Metabolic
HOMEOSTASIS
THERMOREGULATION
Ergotropic system - sympathetic nervous system
ANTICIPATION OF EXERCISE
„Fight or flight" - EVOLUTIONARY ASPECT
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CARDIOVASCULAR REACTIONS DURING EXERCISE
1. Heart reactions
2. Circulation reactions
1. Increase of cardiac output (heart reserve !)
2. Increase in coronary blood flow
3. Hyperaemia in lung circulation
4. Hyperaemia in muscles (difference between contraction and relaxation!!!)
5. Higher supply of 02 and metabolites, higher removal of C02 and catabolites
METABOLIC AUTOREGULATION OF BLOOD FLOW
Decreased pH, decreased p02, increased pC02, increased K+, increased body temperature nm
ED
CARDIAC RESERVE = maximal CO / resting CO
4-7
CORONARY RESERVE = maximal CF / resting CF 3.5
CHRONOTROPIC RESERVE = maximal HR / resting HR 3-5 VOLUME RESERVE = maximal SV / resting SV 1.5
CO - cardiac output (l/min), CF - coronary flow (l/min/100gr), HR - heart rate (min-1), SV - stroke volume (ml)
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CARDIAC RESERVE in healthy and diseased heart
CO (l/min)
ATHLETHS HEART
WORKLOAD (W/kg)
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PARAMETER	REST	EXERCISE	INCREASE (x)
Cardiac output (1/min)	5-6	25 (35)	4-5 (7) Cardiac reserve
Heart rate (t/min)	70	210 (250-190) depends on age	3-5 Chronotropic reserve
Stroke volume (ml)	75	115	1.5 Volume reserve
Systolic BP (mmHg)	120	t ?	-
Diastolic BP (mmHg)	70	t ?	-
Pulse BP (mmHg)	50	70-100	1.5-2
Mean BP (mmHg)	-	-	minor increase
Muscle perfusion (ml/min/100g)	2-4	60-120	30 (10%MVmax)
RESPIRATORY REACTIONS DURING EXERCISE
Demands on respiratory system:
1. Higher gases exchange - higher diffusion
2. Higher ventilation
3. Higher perfusion (hyperaemia in lung circulation)
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PARAMETER	REST	EXERCISE	INCREASE (x)
Minute ventilation (1/min)	6-12	90-120	15-20
Respiratory frequency (d/min)	12-16	40-60	4-5
Tidal volume (ml)	0,5-0,75	2	3-4
Blood flow (1/min)	5,5	20-35	4-6
02 intake (ml/min) -V02	250-300	3000	10-12
Total C02 (ml/min)	200	8000	40
p02 (Torr)	40	25	
02 extraction (%)	+	+	++
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Ventilation (I / min)
recovery
Psychic Proprioception
hyperpnoe| tachypnoe Time
tachypnoe (oxygen debt) „Humourar stimulation t H+a
(K+, temperature, C02, 02)
R = 1.5-2.0
R = 0.5
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OVERVIEW OF MUSCLE METABOLISM
ATP for muscle contraction is continuously produced by aerobic metabolism of glucose and fatty acids. During short bursts of activity, when ATP demand exceeds the rate of aerobic ATP production, aerobic glycolysis produces ATP, lactate, and hT\
Intestine
Glucose -absorbed
Muscle tissue
Amino acids
Lactate
Adipose Glycerol + fatty acids tissue |
Lipids stored in adipose tissue
Gas exchange at the lungs: q2
co2
Glycogen
Exercise
Glycolysis (anaerobic)
Pyruvate I
Acetyl CoA 1
Oxidative phosphorylation and citric acid
cycle (aerobic)
A DP
1 Glucose comes © Fatty acids can be Q Lactate from anaerobic Q Both aerobic and anaerobic from liver glycogen used only in aerobic        metabolism can be converted      metabolism provide ATP for
or dietary intake. metabolism. to glucose by the liver. muscle contraction.
D.U.Silverthorn: Human Physiology (An Integrated Approach)
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AEROBIC VERSUS ANAEROBIC METABOLISM
AnaGrobic metabolism produces ATP 2.5 times faster than aerobic metabolism, but aerobic metabolism can support Gxercise for hours.
ATP 3 produced (moles/min)
2
4?
1
Hours
Endurance time for maximal muscle activity
- 1 min
KEY
ATP production Muscle endurance
Phosphocreatine
can sustain only 10 soconds of maximal GxercisG.
Anaerobic metabolism
produces ATP 2.5 times faster than aerobic metabolism but can support only 1 minute of maximal exercise.
Aerobic metabolism
supports exercise for hours.
D.U.Silverthorn: Human Physiology (An Integrated Approach)
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ENERGY SUBSTRATE USE DURING EXERCISE
At low-intensity exercise, muscles get more energy from fats than from glucose (CHO). During high-intensity exercise (levels greater than 70% of maximum), glucose becomes the main energy source.
a>   100%
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a 0-
80% 60% 40% 20% 0%
				
Fat				
CHO				
				
				
Rest
20 40 60 80
Exercise intensity {% maximum)
100
Data from G. A. Brooks and J. Mercier, J App Physiol 76: 2253-2261, 1994
D.U.Silverthorn: Human Physiology (An Integrated Approach)
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OXYGEN CONSUMPTION AND EXERCISE
Oxygen supply to exercising cells lags behind energy use, D.u.Silverthorn: Human Physiology (An integrated Approach)
creating an oxygen deficit. Excess postexercise oxygen consumption compensates for the oxygen deficit.
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Cellular energy use exceeds oxygen uptake (oxygen deficit)
Excess postexercise oxygen consumption
							
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		Resting level c		►f			
		02 consumptio 1		n			
2
▲
Exercise begins
4 6 8
Time (min)
10
▲
Exercise ends
12
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BLOOD GASES AND EXERCISE
Arterial blood gases and pH remain steady with submaximal exercise.
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Arterial pH			
			
1 1		1	h
0      20       40       60       30 100 02 consumption {% of maximum)
D.U.Silverthorn: Human Physiology (An Integrated Approach)
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'Cortisol
Gluconeogenesis from lactate
Glucagon
Anerob metaboli
Glucose
Glycogenosis
Free Fatty Acid Mobilization
Protein Synthesis
♦
Hypothalamus
Growth Hormone Releasing Hormone
Growth Hormone
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FITNESS
• Spiroergometry	
• Types of ergometers	
• Index W170	
• Training	
• Fatigue (aerobic, anaerobic	
threshold)	
• Adaptation to exercise