Substance & energy exchange.

Substance & energy exchange

Anabolism – biosynthesis of complex substances of the cellCatabolism - breakdown of complex molecules to form simple substances

metabolism

FoodP. F. C.

catabolism

Phosphoglycerate,piryvate.

Anabolismbiosynthesis

work

Amino acids, nucleotides, hormones

Growth, development,

Structure renewal

Cell membranes,organels, proteins,

Nucleic acids

PROTEINS FATS CARBOHYDRATES

BIOLOGYCAL OXYDATION

Н2О+СО2+АТP + primary heat

Mechanical work

Chemical synthesis,Structure renewal

Active transport ofsubstances,Electrical work

Secondary heat

Active state BASAL METABOLISM

Basal metabolismTotal intensity of exchange processes measured at the state of rest

STANDARD CONDITIONS TO MEASURE BASAL METABOLISM

1. IN THE MORNING (after waking up)2. AFTER 12-16 hours FASTING3. AT THE STATE OF PHYSICAL REST ( in

the lying posture)4. AT THE STATE OF MENTAL &

EMOTIONAL REST5. IN COMFORTABLE TEMPERATURE (18-

220С for dressed body. 25-260С for naked)

FACTORS INFLUENCING BASAL METABOLISM

1. AGE2. SEX3. HEIGHT4. WEIGHTPROPER BASAL METABOLISM (TO BE

DEFINED BY THE TABLES)WORK ALLOWANCE - energy spent

above basal metabolism to perform work

Energy expenditure in different occupations

group Peculiarities of occupation

Quotient of physical activity

Daily energy expenditurekcal

I Mental work 1,4 2100-2450II Light physical

work 1,6

2500-2800III Partially

mechanized physical work

1,9 2950-3300

IV Heavy physical work

2,23400-3850

Methods of BIOCALORYMETRY

DIRECT BIOCALORYMETRYINDIRECT BIOCALORYMETRY

1. GASEOUS EXCHANGE METHOD2. DAILY DIET METHOD

Atwater-Benedict BIOCALORIMETER

Respiratory apparatus

INDIRECT IOCALORYMETRYGASEOUS EXCHANGE METHOD

RESPIRATORY QUOTIENT – RATIO BETWEEN THE VOLUME OF СО2 RELEASED & THE VOLUME OF О2 CONSUMED

С6Н12О6 + 6О2 = 6СО2 + 6Н2ОRQ= 6СО2/ 6О2 = 1CALORIC VALUE OF OXYGEN – NUMBER OF KCAL LIBERATED BY THE UTILIZATION OF 1L OF О2

Duglas bag in respiratory method

HEAT OF COMBUSTION VALUE OF A NUTRIENT

– THE QUANTITY OF HEAT PRODUCED ON COMBUSTION OF 1g of NUTRIENTDetermined by means of Berthelot bomb calorimeter

water

nutrient

termometer

Bomb calorimeter

burning

1 kJ heats 1 l of water by 0,240С

Heated water

water

Energy value of food substances

Substance RQ CVKcal

Heat of combustion value (kcal)

PROTEINS 0,6-0,8

4,46 - 4,8 4,1

FATS 0,7 4,7 9,3

CARBOHYDRATES 1 5,05 4,1

MIXED FOOD 0,86 4,86

RECOMMENDED PROPORTIONS OF NUTRIENTS

Dynamics of metabolism at work

Level of О2 demand

О2 demand

О2 debt (formation)

О2 debt (paying back)

vo2

time1 2 3

THERMOREGULATION

Homoiothermia – consistency of body temperature, regardless of external environment temperature changes.Homoiothermic – are warm-blooded animalsPoikilothermia – body temperature depends on the external environment temperature Poikilothermic – are cold-blooded animals

«shell» - skin, adipose tissue poikilothermic

«nucleus» - internal organs, skeletal muscles

homoiothermic

Shell temperature

External environmentТemperature, humidity, wind

Intensity of heat transport from nucleus

Role of skin vessels in termoregulation

Warm blood

Warm bloodcapillaries

АVА

Cooled blood

Superficial vein

artery

370С 360СPhysical Termoregulation

Chemical termoregu

lation

Cell metabolism

RadiationConvectionConductionVaporation

ISOTERMIA

PHYSICAL THERMOREGULATION

WAYS OF HEAT LOSS1) RADIATION – heat is given off by the skin directly into the air or to the objects immediately in contact with its surface (66%)2) CONVECTION – heat release in the process of water or air movement(15%)

WAYS OF HEAT LOSS3) CONDUCTION – heat is lost at the contact of the body with some substance (e.g.clothing)4) EVAPORATION with the sweat glands (19%)

External environment factors influencing heat loss

Air temperature

Humidity

Wind

Regulation of heat loss Sympathetic N.S. (adrenergic fibers)

noradrenalin adrenoreceptors

Pre-capillary sphincters & arterio-venous anastomoses

Changed blood flow in the skin

Changed temperature gradient

Regulation of heat loss

Changed temperature gradient with environment

Changes in

radiationconvection

Heat condactance

Regulation of heat loss Sympathetic N.S. (cholinergic fibers)

acetylcholine

Sweat glands

Changes in sweat production

Sweat evaporation

Chemical thermoregulation

Heat productionContractile thermogenesis

Skeletal muscles

Muscle tone

ShiveringVoluntarily movements

Heat production Non-contractile thermogenesis

Fatty acids oxidation

Glycogen breakdown Glucone

ogenesis

Intensified oxidation

Fatty acids oxidation in newborns

Sympathetic n.s.

Brown fat – membrane enzyme thermogenin

Cytochromic enzymes

Quick fatty acids oxidationheat

No ATP synthesis & hydrolysis

Peculiarities of thermoregulation in newborns

Heat production per 1 kg of body weight in newborns is 1,4 times higher than in adults;Heat loss is 2 times more intensive than in adults

Peculiarities of thermoregulation in newbornsGreater body square surface in comparison to body weight;More intensive blood circulation in the skin ;Thin skin;In sufficient sweat evaporation.

Skin thermo-receptorsCold receptors – Krause colbs - free nerve endings in the basal layer of epidermis. Play important role in body protection from overcooling.

Skin thermo-receptorsWarmth receptors – Ryffini bodies– free nerve endings in the papillar layer of epidermis.There are a lot more of cold receptors than warmth receptors

Skin thermo-receptorsCold receptors Warmth receptors

Skin thermo-receptorsCold receptors are active at –

20 tо 400СWarmth receptors are active at–25 tо 470С

Peripheral thermoregulation

Protects the body from coldExcitation of cold receptors switches on central mechanisms enabling :

Heat production increaseHeat loss decrease

THERMORECEPTORS OF BODY«NUCLEUS» central & intravascular)

Protect the body from OVERHEATINGExcitation of «nucleus» thermoreceptors switches on central mechanisms enabling :

INCREASED HEAT LOSS

HYPOTALAMUSANTERIOR HYPOTALAMUS –

AFFERENT SYNTHESIS OF TEMPERATURE INFOPOSTERIOR HYPOTALAMUS– FORMATION OF EFFERENT COMMAND

Neuronsreceptors

Neuronseffectors

Skin temperature

Skintermoreceptors

shell temperature

blood

CORTEX behaviour

SOMATIC N.S.

CONTRACTILETERMOGENESIS

Sympathetic N.S.

HYPOPHYSISNONCONTRACTILETERMOGENESIS

SKIN VESSELS,EVAPORATION

Heat loss

HEAT LOSS

HEAT PRODUCTION

Temperature of body«nucleus »

(homeostatic parameter)