DR NILESH KATE

MBBS,MD

ASSOCIATE PROF

DEPT. OF PHYSIOLOGY

CUTANEOUS CIRCULATION

OBJECTIVES

Cutaneous circulation. Cutaneous blood flow- characteristics

features. Regulation of Cutaneous blood flow Cutaneous vascular response

Monday, May 1, 2023

CUTANEOUS BLOOD VESSELS. Cutaneous arterioles –

dense network just under dermis.

Meta arteriole – high resistance conduits between arterioles & capillaries.

Cutaneous capillaries – provide larger surface area for heat exchange.

Monday, May 1, 2023

CUTANEOUS BLOOD VESSELS. Venules – extensive sub

papillary venous plexus Hold large quantity of blood Important role in maintaining

body temperature. Arteriovenous anastomosis

– in distal parts of extremities (hands, feet, nose, lips & ear lobules) Wide, low resistance, serves as

shunt Important in body temperature.

Monday, May 1, 2023

CUTANEOUS BLOOD FLOW CHARACTERISTIC FEATURES.

Main function. Resting blood flow. Exposure Regional variations Blood flow & skin

colour.

Monday, May 1, 2023

MAIN FUNCTION. To help in the

Regulation of body Temperature.

For Nutritive function – skin need very less blood.

Monday, May 1, 2023

RESTING BLOOD FLOW. When the person is at

thermal equilibrium with the environment at 270 c

10-15ml/min/100 gm of skin tissue.

Monday, May 1, 2023

EXPOSURE To Cold –

Minimum sweating Flow decreases to 1/10th of

normal. (1ml/min/100gm) To Heat –

Maximum sweating Flow increases to 10 times

(100-150ml/min/100gm)

Monday, May 1, 2023

REGIONAL VARIATIONS Due to A-V

anastomosis in certain areas as hands, feet, nose & ear lobules.

During heat stress A-V anastomosis blood flow increases (75ml/min/100gm)

Monday, May 1, 2023

BLOOD FLOW & SKIN COLOUR. Basically its due to

pigment present (Melanin)

But skin colour also affected by Amount of blood Degree of

oxygenation.

Monday, May 1, 2023

REGULATION OF CUANEOUS BLOOD FLOW

Skin – very less metabolic activity.

O2 consumption – 0.3ml/min/100gm.

Regulation is mainly by Nervous Control than Metabolic Control.

Monday, May 1, 2023

NERVE SUPPLY OF CUTANEOUS VESSELS

Sympathetic Vaso- constrictor At rest Cutaneous

vessels have sympathetic constrictor discharge

Its more marked on A-V anastomosis than other vessels.

Monday, May 1, 2023

NERVE SUPPLY OF CUTANEOUS VESSELS

Parasympathetic Vasodilator – DO not supply Cutaneous vessels.

Vasodilation due to – Reduced sympathetic effect. Local Bradykinin in sweat

glands. Other local vasodilators.

Monday, May 1, 2023

NEURAL CONTROL MECHANISMS

Hypothalamic Control Mechanism.

Baroreceptor mediated reflex.

Cortical control mechanism.

Monday, May 1, 2023

HYPOTHALAMIC CONTROL MECHANISM.

Temperature Regulation centre of Hypothalamus mediate thermoregulation by increase & decrease of sympathetic discharge to Cutaneous vessels.

Monday, May 1, 2023

HYPOTHALAMIC CONTROL MECHANISM.

Under resting condition. –

Person at rest with thermal equilibrium at 270c – sympathetic vasoconstrictor has mild tonic discharge

Keep A-V anastomosis closed.

Monday, May 1, 2023

HYPOTHALAMIC CONTROL MECHANISM.

During exposure to Heat Stress – sympathetic discharge decreases

A-V anastomosis, cutaneous vessels dilates.

Monday, May 1, 2023

HYPOTHALAMIC CONTROL MECHANISM.

Sweat glands activated due to cholinergic discharge – local release of Bradykinin – increases blood flow to skin. (150ml/min/100gm)

Heat is dissipated by radiation, evaporation & conduction.

Monday, May 1, 2023

HYPOTHALAMIC CONTROL MECHANISM.

During exposure to cold stress – Increase sympathetic discharge – cutaneous Vasoconstriction.

Total blood flow Decreases 1ml/min/100gm.

Leads to heat conservation.

Monday, May 1, 2023

BARORECEPTOR MEDIATED REFLEX.

During circulatory stress as exercise, Hamorrhage

Causes vasoconstriction

Do compensatory mechanism to divert blood.

Monday, May 1, 2023

CORTICAL CONTROL MECHANISM.

Through Cortico-Hypothalamic pathway.

Corticohypothalamic centers

Thoracolumbar sympathetic cell bodies

Skin vessels.

Monday, May 1, 2023

CORTICAL CONTROL MECHANISM.

Blanching of skin – during fear due to vasoconstriction through cortical mechanism.

Phenomenon of blushing – during embarrassment - corticohypothalamic control discharge of sympathetic cholinergic fibres to sweat glands

Bradykinin release Vasodilation.

Monday, May 1, 2023

CUTANEOUS VASCULAR RESPONSE.

White reaction Triple response. Axon reflex. Reactive hyperemia. Cold vasodilatation. Cold vasoconstriction.

Monday, May 1, 2023

WHITE REACTION When pointed object is

stroked over a skin – Pale strike line appears

Cause – contraction of precapillary sphincters & blood drains out of capillaries & small veins.

Appears in 15 sec.

Monday, May 1, 2023

TRIPLE RESPONSE. When skin stroke

more firmly with pointed objects

3 parts response occurs

Red reaction Flare Wheal

Monday, May 1, 2023

Monday, May 1, 2023

TRIPLE RESPONSE

RED REACTION FLARE WHEAL

TIME 10 SEC AFTER A FEW MIN AT LAST

APPEARS RED LINE DIFFUSELY SPREADING IRREGULAR

OUTLINE REDNESS.

SWEALLING & LOCALISED OEDEMA.

CAUSE Dilatation of precapillary sphincters

Dilatation of arterioles & precapillary sphincters

Increased capillary permeability with extravasations of

fluid.

Control No neural controlLocal release of

Bradykinin.

Neural control Local release of histamine &

histamine like substances by mast

cells.

AXON REFLEX. Definitions:

1. a response elicited by peripheral nerve stimulation; attributed to impulses traveling proximally from the stimulation site along motor axons, encountering a branch point, and then passing distally down the other branch to activate local arterioles (to cause vasodilation) or muscle (to cause contractions).

Monday, May 1, 2023

DERMATOGRAPHIA Striking triple response

that occurs as an unusual reaction.

Anything drawn on skin causes.

Due to excessive release of Histamine.

Monday, May 1, 2023

REACTIVE HYPEREMIA. Phenomenon by vessel

control blood flow to the organ after ischemia due to occlusion.

Cause – local Hypoxia causes vasodilatation of arterioles & precapillary sphincters

So blood flow exceed the control level when occlusion is removed.

Monday, May 1, 2023

COLD VASODILATATION. Exposure to Cold

Cutaneous vasoconstriction due to hypothalamic mechanism.

But prolonged & severe vasoconstriction – Frost bite.

Monday, May 1, 2023

Monday, May 1, 2023

COLD VASOCONSTRICTION. Exposure to cold Cutaneous

vasoconstriction due to hypothalamic mechanism.

Monday, May 1, 2023

Monday, May 1, 2023

Thank you.

Monday, May 1, 2023