Upload
others
View
0
Download
0
Embed Size (px)
Citation preview
Which is the largest organ in human body……….?
1
Dr. Jitendra Patel (MBBS, MD, ACME, Ph.D…)
Medical Educator, Researcher & Academic Administrator
Associate Professor, Department of Physiology
Email: [email protected] Web: www.esphys.weebly.com2
Competency
3
No. PY 5.10* (CV Physiology)
CompetencyDescribe and discuss cutaneouscirculation
D/L/Core K/KH/Y
AM Written/Viva voce
Integration No
Imp. Concept Triple response
Phy. Trivia Axon reflex
OUTLINE
Physiological anatomy
Characteristic features
Regulation & Factor affecting
Clinical
4
Physiologic anatomy...cont
• Main function: Regulation of body temperature
• Blood flow;
Rest: 10-15 ml/min/100gm
Max: 150 ml/min/100gm
Min: 1 ml/min/100gm
(~500 ml/min)
• In microcirculation;
Arterioles, Meta-arterioles, pre capillary sphincters, Capillaries,
Venules
Characteristic features
Heat Exchange in the Skin
Regulation
8
Neural factors:-
VC: sympathetic stimulation
Hypothalamic response to temperature variation
– A-V anastomosis
– Sweat glands, Bradykinin
VD: no partasympathatic vasodilator nerves
– Reduction in VC activity
– Local bradykinin in sweat glands
– Local VD metabolites
Factor affecting
9
Exposure to cold: VC
Exposure to heat: VD
Exercise: Dual response
Emotional factors: (corticohypothalamis pathway)
Blanching (pale, in fear, VC)
Blushing (red, embarrassment, VD)
10
General responses & Color changes in skin• Fiery red color in reactive hyperemia – Re establishment of
circulation after a period of occlusion, Hypoxia dilates
arterioles
• Gray /cold blue skin – Arterioles are constricted and
capillaries are dilated
• Warm, red skin – Both are dilated
• Rudy complexion in cold – VD
• Emotional factors via corticohypothalamic fibers produces
– Blanching of skin e.g. pale with fear
– Blushing by anger / embarrassment
Applied Term
12
• White reaction:
(Constriction of pre-capillaries sphincter)
• Dermatographia:
(Striking triple response); Histamine
Applied Term
13
• Reactive hyperaemia (e.g. BP, CC)
• Trench foot (VC to cold, ischemia)
• Frost bite (VD to extreme cold)
• Triple response (mIMP)
14
Ruddy complexion
Trench foot
Frost bite
15
Triple response
RFW
Skin stroked more firmly with pointed object
– Red reaction – redness at the site appears in
about 10 second.
– Flare –Wheal– local edema.
– redness spread out from injury.
Triple response
Triple response - mechanism• Red reaction
• Dilatation of precapillary sphincter due to direct response of
capillaries to pressure
• No role of nerves so no effect of anesthesia
• Flare
• Dilatation of arteriole, precapillary sphincters by axon reflex
• Increased local blood flow increases local temperature
• Abolished by local anesthesia
• Wheal
• Increased capillary permeability by histamine / sub.P
• Increased capillary pressure due to dilatation of precapillary sphincter
Axon reflex
Flare is due to antidromicconduction insensory nerve branches
Nerve fiber: type CNT:
Substance P & CGRP
20
EXERCISE
A. SN: Triple response
B. SAQ (Trench foot Vs Frost bite) (NT released
in axon reflex) (full name of CGRP) (Axon
reflex)
C. Interactive question (mentimeter app)
D. MCQs (online – Google form)
Reference Reading
A. Indu khurna, G K Pal
B. Ganong
23
VALUE HAS A VALUE ONLY IF ITS VALUES IS VALUED
- Unknown
Physiological TriviaPatients in shock should not be warmed to
the point that their body temperature rises. This is
sometimes a problem because well-meaning
laymen have read in first-aid books that “injured
patients should be kept warm,” and they pile
blankets on accident victims who are in
shock.......:P
# stay home stay healthy stay happy stay safe #
# fight against nCORONA#
25