functions of skin regulation of body temperature

Murugavel.R.MSc Nursing, Associate professor.

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Functions of skin regulation of body

TemperatureMurugavel.R, MSc Nursing, Associate

professor.

Murugavel.R.MSc Nursing, Associate professor.

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Introduction

• Anatomy of the skin Epidermis Dermis Color of the skin• Pigmentation of the skin• Hemoglobin in the blood

Glands of the skin Sebaceous gland Sweat gland

Murugavel.R.MSc Nursing, Associate professor.

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Function of the skin:Protective function

Protection from Bacteria and toxic substances Protection from mechanical blow Protection from ultraviolet rays

Sensory function (touch, pain, pressure, temp)Storage function(fat, H2O, chloride, sugar)Synthetic function (vit D3)Regulation of body temperatureRegulation of water and electrolyte balance(sweat)Excretory function (urea, salt, fatty substances)Absorptive function(ointment, fat)Secretory function(sweat & sebum)

Murugavel.R.MSc Nursing, Associate professor.

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Maintaining body

temperature

Murugavel.R.MSc Nursing, Associate professor.

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Introduction

• 2 types of organism: Homeothermic animals

Animals which maintain constant Body temp e.g birds mammals. Also called warm blooded animals.

Poikilothermic animalsAnimals which doesn’t maintain constant body temp. e.g Amphibians and reptiles. Also called cold blooded animals

Murugavel.R.MSc Nursing, Associate professor.

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Body temperature• Oral temp.• Axilla temp.• Rectum temp.• Over the skin ( surface temp).Normal body temp 37°C or 98.6°FVaries between 35.8 37.3C or 98.4 - 99.1.Temp varies in site e.g axilla, rectum, oralCore temp is the average temp of structures present in

deeper part if the body. Normal Core temp 37.8°C or 100°F

Murugavel.R.MSc Nursing, Associate professor.

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Variation of body temperature Physiological variations

Age Sex Diurnal variation(early morning 1°C less) After meals (0.5°C) Exercise Sleep Emotion menstrual cycle.

Pathological variation.Hyperthermia, fever, hypothermia

Murugavel.R.MSc Nursing, Associate professor.

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Heat balanceHeat gain or heat production in the body

Metabolic activityMuscular activityRole of hormonesRadiation of heat from the environmentshivering

Heat loss from the body Conduction Radiation Convection Evaporation – insensible perspiration panting

Murugavel.R.MSc Nursing, Associate professor.

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Metabolic activity

• Metabolism of food stuff produce heat• About 9 calories of heat is produced during

metabolism of fat, when 1 L of O2 is utilized.• For CHO 4.7 calories

Murugavel.R.MSc Nursing, Associate professor.

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Muscular activity• Heat is produced in the muscle both at rest

and during activity• 80% of heat is produced by musculoskeletal

activity.

Murugavel.R.MSc Nursing, Associate professor.

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Role of hormones• Thyroxine and adrenaline increase the heat by

accelerating the metabolic activity.

Murugavel.R.MSc Nursing, Associate professor.

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Radiation of heat from the environment

• Body gain heat by radiation. Especially when environment temp increases.

Murugavel.R.MSc Nursing, Associate professor.

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shivering

• It means rapid involuntary contraction or twitching of the muscle during exposure to cold.

• It is a compensatory mechanism in the body, during which enormous heat is produce.

Murugavel.R.MSc Nursing, Associate professor.

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Heat loss of the body• Maximum heat is lost from the body through skin and

small amount through respiration, kidney, and GI.• When environment temp is less the heat is lost from the

body.• Lost through

Conduction (by surface) Radiation(by means of transfer heat by infrared

electromagnetic radiation) Convection ( conducted to the surrounding air) Evaporation (evaporate through skin lung). Panting ( rapid shallow breathing with dribbling of saliva)

Murugavel.R.MSc Nursing, Associate professor.

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Regulation of body temp

• Body temp is regulated by hypothalamus which has 2 centersHeat loss center

Situated in preoptic nucleus of anterior hypothalamus . neurons are heat sensitive nerve cells called thermoreceptors. It stimulate cutaneous vasodilatation and sweating . Removal or lesion of this nucleus increase the body temp.

Heat gain center;Otherwise called as heat production center. Situated in posterior hypothalamic nucleus. If it stimulated cause shivering. Removal or lesion lead fall in body temp

Murugavel.R.MSc Nursing, Associate professor.

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Mechanism of temperature regulation:• When body temp ↑• blood temp also↑, • Blood stimulates thermoreceptor • Now it brings the temp to normal by

two mechanisms. Promotion of heat loss

i. Increasing the secretion of sweatii. Inhibiting the sympathetic center in posterior

hypothalamus. ( this cause cutaneous vasodilation, so blood flow through skin causing excess sweating)

Prevention of heat productionBy shivering and chemical reaction

Murugavel.R.MSc Nursing, Associate professor.

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Mechanism of temperature regulation:

• When body temp ↑• 2 mechanism activated to bring back to normal

tempi. prevention of heat loss.ii. Promotion of heat production.

• Prevention of heat loss;When body temp decreases , the preoptic thermoreceptors are not inhibited. This causes cutaneous vasoconstriction.The blood flow ↓, so heat loss is prevented.

Murugavel.R.MSc Nursing, Associate professor.

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Mechanism of temperature regulation:

ii. Promotion of heat production: Shivering .

The primary motor center for shivering is situated in posterior hypo thalamus near the wall of the III ventricle.When body temp is low, it is activated by heat gain center & shivering occurs.

Increased metabolic reaction.Sympathetic center is stimulated by heat gain centerThis stimulates adrenaline & noradreline, these hormones accelerating cellular metabolism activities & produce heat.

Murugavel.R.MSc Nursing, Associate professor.

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Mechanism of temperature regulation:

• Hypothalamus secretes thyrotrophic releasing hormone, it cause release of thyroid stimulating hormone from pituitary gland, it in turn increases release of thyroxine from thyroid, that also increases metabolic activities in the body & increase heat production.

Murugavel.R.MSc Nursing, Associate professor.

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Mechanism of temperature regulation:Hypothalamus secretes thyrotrophic releasing hormone

it release thyroid stimulating hormone from pituitary gland

it increases release of thyroxine from thyroid

increases metabolic activities in the body

increase heat production.

Murugavel.R.MSc Nursing, Associate professor.

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Murugavel.R.MSc Nursing, Associate professor.

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Murugavel.R.MSc Nursing, Associate professor.

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