Cutaneous circulation

CUTANEOUS CIRCULATION

1. DR NILESH KATE
MBBS,MD
ASSOCIATE PROF
DEPT. OF PHYSIOLOGY
CUTANEOUS
CIRCULATION

2. OBJECTIVES
Cutaneous circulation.
Cutaneous blood flow- characteristics
features.
Regulation of Cutaneous blood flow
Cutaneous vascular response
Thursday, March 31, 2016

3. 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.
Thursday, March 31, 2016

4. 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.
Thursday, March 31, 2016

5. CUTANEOUS BLOOD FLOW
CHARACTERISTIC FEATURES.
Main function.
Resting blood flow.
Exposure
Regional variations
Blood flow & skin
colour.
Thursday, March 31, 2016

6. MAIN FUNCTION.
To help in the
Regulation of body
Temperature.
For Nutritive function –
skin need very less
blood.
Thursday, March 31, 2016

7. RESTING BLOOD FLOW.
When the person is at
thermal equilibrium
with the environment at
27
0
c
10-15ml/min/100 gm
of skin tissue.
Thursday, March 31, 2016

8. EXPOSURE
To Cold –
Minimum sweating
Flow decreases to 1/10
th

of normal.
(1ml/min/100gm)
To Heat –
Maximum sweating
Flow increases to 10
times (100-
150ml/min/100gm)
Thursday, March 31, 2016

9. 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)
Thursday, March 31, 2016

10. BLOOD FLOW & SKIN COLOUR.
Basically its due to
pigment present
(Melanin)
But skin colour also
affected by
Amount of blood
Degree of
oxygenation.
Thursday, March 31, 2016

11. 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.
Thursday, March 31, 2016

12. 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.
Thursday, March 31, 2016

13. 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.
Thursday, March 31, 2016

14. NEURAL CONTROL
MECHANISMS
Hypothalamic
Control Mechanism.
Baroreceptor
mediated reflex.
Cortical control
mechanism.
Thursday, March 31, 2016

15. HYPOTHALAMIC CONTROL
MECHANISM.
Temperature
Regulation centre of
Hypothalamus
mediate
thermoregulation by
increase & decrease of
sympathetic discharge
to Cutaneous vessels.
Thursday, March 31, 2016

16. HYPOTHALAMIC CONTROL
MECHANISM.
Under resting condition.
–
Person at rest with
thermal equilibrium at
27
0
c – sympathetic
vasoconstrictor has
mild tonic discharge
Keep A-V anastomosis
closed.
Thursday, March 31, 2016

17. HYPOTHALAMIC CONTROL
MECHANISM.
During exposure to
Heat Stress –
sympathetic discharge
decreases
A-V anastomosis,
cutaneous vessels
dilates.

Thursday, March 31, 2016

18. 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.
Thursday, March 31, 2016

19. HYPOTHALAMIC CONTROL
MECHANISM.
During exposure to
cold stress – Increase
sympathetic discharge
– cutaneous
Vasoconstriction.
Total blood flow
Decreases
1ml/min/100gm.
Leads to heat
conservation.
Thursday, March 31, 2016

20. BARORECEPTOR MEDIATED
REFLEX.
During circulatory stress
as exercise, Hamorrhage
Causes vasoconstriction
Do compensatory
mechanism to divert
blood.
Thursday, March 31, 2016

21. CORTICAL CONTROL
MECHANISM.
Through Cortico-
Hypothalamic
pathway.
Corticohypothalamic
centers
Thoracolumbar
sympathetic cell
bodies
Skin vessels.
Thursday, March 31, 2016

22. 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.
Thursday, March 31, 2016

23. CUTANEOUS VASCULAR
RESPONSE.
White reaction
Triple response.
Axon reflex.
Reactive hyperemia.
Cold vasodilatation.
Cold vasoconstriction.
Thursday, March 31, 2016

24. 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.
Thursday, March 31, 2016

25. TRIPLE RESPONSE.
When skin stroke
more firmly with
pointed objects
3 parts response
occurs
Red reaction
Flare
Wheal
Thursday, March 31, 2016

26. Thursday, March 31, 2016
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.

27. 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).
Thursday, March 31, 2016

28. DERMATOGRAPHIA
Striking triple response
that occurs as an
unusual reaction.
Anything drawn on
skin causes.
Due to excessive
release of Histamine.
Thursday, March 31, 2016

29. 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.
Thursday, March 31, 2016

30. COLD VASODILATATION.
Exposure to Cold
Cutaneous vasoconstriction
due to hypothalamic
mechanism.
But prolonged & severe
vasoconstriction – Frost
bite.
Thursday, March 31, 2016

31. Thursday, March 31, 2016

32. COLD VASOCONSTRICTION.
Exposure to cold
Cutaneous
vasoconstriction due
to hypothalamic
mechanism.
Thursday, March 31, 2016

33. Thursday, March 31, 2016

34. Thank you.
Thursday, March 31, 2016