Cutaneous circulation

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
Thursday, March 31, 2016

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.

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.

CUTANEOUS BLOOD FLOW
CHARACTERISTIC FEATURES.
 Main function.
 Resting blood flow.
 Exposure
 Regional variations
 Blood flow & skin
colour.

MAIN FUNCTION.
 To help in the
Regulation of body
Temperature.
 For Nutritive function –
skin need very less
blood.

RESTING BLOOD FLOW.
 When the person is at
thermal equilibrium
with the environment at
270
c
 10-15ml/min/100 gm
of skin tissue.

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)

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)

BLOOD FLOW & SKIN COLOUR.
 Basically its due to
pigment present
(Melanin)
 But skin colour also
affected by
 Amount of blood
 Degree of
oxygenation.

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.

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.

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.

NEURAL CONTROL
MECHANISMS
 Hypothalamic
Control Mechanism.
 Baroreceptor
mediated reflex.
 Cortical control
mechanism.

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

MECHANISM.
 Under resting condition.
–
 Person at rest with
thermal equilibrium at
270
c – sympathetic
vasoconstrictor has
mild tonic discharge
 Keep A-V anastomosis
closed.

MECHANISM.
 During exposure to
Heat Stress –
decreases
 A-V anastomosis,
cutaneous vessels
dilates.

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.

MECHANISM.
 During exposure to
cold stress – Increase
– cutaneous
Vasoconstriction.
 Total blood flow
Decreases
1ml/min/100gm.
 Leads to heat
conservation.

BARORECEPTOR MEDIATED
REFLEX.
 During circulatory stress
as exercise, Hamorrhage
 Causes vasoconstriction
 Do compensatory
mechanism to divert
blood.

CORTICAL CONTROL
MECHANISM.
 Through Cortico-
Hypothalamic
pathway.
 Corticohypothalamic
centers
 Thoracolumbar
sympathetic cell
bodies
 Skin vessels.

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.

CUTANEOUS VASCULAR
RESPONSE.
 White reaction
 Triple response.
 Axon reflex.
 Reactive hyperemia.
 Cold vasodilatation.
 Cold vasoconstriction.

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.

TRIPLE RESPONSE.
 When skin stroke
more firmly with
pointed objects
 3 parts response
occurs
 Red reaction
 Flare
 Wheal

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 control
Local 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).

DERMATOGRAPHIA
 Striking triple response
that occurs as an
unusual reaction.
 Anything drawn on
skin causes.
 Due to excessive
release of Histamine.

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.

COLD VASODILATATION.
 Exposure to Cold
 Cutaneous vasoconstriction
due to hypothalamic
mechanism.
 But prolonged & severe
vasoconstriction – Frost
bite.

COLD VASOCONSTRICTION.
 Exposure to cold
 Cutaneous
vasoconstriction due
to hypothalamic
mechanism.

Thank you.

Cutaneous circulation

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