Physio I Lecture 1
Transcript of Physio I Lecture 1
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WINDSORUNIVERSITY SCHOOL OF MEDICINE
HOMEOSTATICREGULATION
Dr.VishalSurender.MD.
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Learnin O!"e#$i%es•Defnition o physiology•Review o organ systems
•Explain homeostasis• Discuss the relationship between external andinternal environments•List the main body uid compartments, theirconstituents and their relationship to each other
•Defne equilibrium and steady state•ive examples o homeostatic mechanisms•Explain negative eedbac!•Defne controlled variable, sensor, comparitor and
set point and give examples o each in a negativeeedbac! loop•Discuss actors that may change set points•Defne redundancy and hierarchy with respect tohemoestatic control mechanisms•Explain positive eedbac!
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• &h'si(l(' is the studyo the normal unctioningo a living organism and
its component parts,including all its chemicaland physical processes#
&h'si(l(' de)ned
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$
Organization of the human body
Cells
Tissues
Organs
Organ
systems
Organisms
(Human body)
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%rgan &ystems in Review
• 'ntegumentary
• (usculos!eletal
• Respiratory• Digestive
• Reproductive and )rinary
• *irculatory• +ervous and Endocrine
• 'mmune
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%rgan &ystems in Review he integration between systems o the body
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Body Fluid Compartments
Intracellular Fluid; 28
Interstitial Fluid; 11
Plasma; 3
Average Total Liters of Fluid-40(60%)
-./
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Compartments and their
Relationship
Blood Plasma
3 L
Interstitial
11 LIntracellular
28 L
Transcellular
1 L
•most cases substances within the plasma mustpass through the interstitial uid beore enteringcells#• hereore the interrelationships between these $
compartments are crucial in underlying whole body
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!ternal and Internal n"ironments“all the vital mechanisms, however varied they may be, have only oneobject, that of preserving constant the conditions of life in the internal
environment.” Claude Bernard (1!"#
• The *asis (+&h'si(l(i#al Reula$i(
• A S$a!le In$ernalEn%ir(n,en$ Is Esse
+(r N(r,al Cell Fun#$
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n"ironments
p# $%&
&' mm #('%23 mm #(PC)2
Pa)2 *+ mm #(1,' mm #(P)2
3$ -C.1' and /&' -CTemperature
InsideOutsideVariable
#• stability o the internal environment is the
primary condition or a ree and independentexistence"By controllin( its internal en"ironment the
or(anism is no lon(er at the mercy o0 the en"ironment % –
p# "ariale
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o summari0e1
H(,e(s$asis is $he
,ain$enan#e (+ a s$ead' s$a$e(+ $he in$ernal en%ir(n,en$ (+$he !(d'.
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Body Fluid Constituents
45a/6 7 1&+
4/6 7 &%+
4Cl.6 7 11,
4Protein6 7 ' m9
)smolality
2*' m)sm
45a/6 7 1&2
4/6 7 &%&
4Cl.6 7 1'2
4Protein6 7 1
)smolality
2*' m)sm
45a/6 7 1+
4/6 7 12'
4Cl.6 7 2'
4Protein6 7 &
)smolality
2*' m)sm
Plasma Interstitial Cellular
•su!s$an#es aren-$ in euili!riu,/ !u$$here is a !alan#ethere is a di2erence between the basicconstituents o the body"uid compartments# hismeans that homeostasis is not about reachingequilibrium, but about maintaining a steady"state#
&ince the system is not necessarily in equilibrium
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34
Homeostasis & Controls
•Successfulcompensation
• Homeostasis
reestablished•Failure to compensate
• Pathophysiology
• Illness
• Death
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Feedac: ow o inormation along a closed
loop < = 5e(ati"e or Positi"e
• Negative = chan(e is sensed and action
ta:en to pre"ent 0urther chan(e e%(.
re(ulation o0 secretion o0 hormones%
• ositive = chan(e is sensed and action
ta:en to ampli0y chan(e usuallyassociated >ith a discrete end point?
e%(% irth? o"ulation<
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#omeostatic 9echanisms
• 9ost homeostatic mechanisms are ased
on ne(ati"e 0eedac:
• specifc terms that are used to describe the
processes involved"
C(n$r(lled Varia!le
Sens(r
C(,0ara$(r/ se$ 0(in$
E1e#$(rs
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Blood Pressure Re(ulation
Blood Loss
Blood Pressure
controlled "ariale<
Baroreceptor
sensor<
Brain
comparitor<
@asoconstrictionA Cardiac )utput
e00ectors<
Cardio"ascular
control
center = compares
BP to
set !oint andadusts
"ascular tone and
cardiac output
accordin(ly
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Blood lucose ."e Feedac:
β.cell
@ariale
Blood lucose
β.celllucose
Insulin
secretion
Cells
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Cutaneous Blood @essels
Dnticipation o0 e!ercise and durin( e!erciseEympathetic out0lo> increases
to maintain lood pressure
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Cutaneous Blood @essels
Dnticipation o0 strenous e!erciseEympathetic out0lo> increases
to maintain lood pressure
#ypothalamus detects heat increase
Dnd inhiits sympathetic out0lo>
@asodilation helps to di"ert lood 0lo> to the s:in
For heat loss
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Cutaneous Blood @essels
ith e!treme e!ercise the need to controlBlood pressure ta:es priority and the
@essels constrict
#ypothalamus detects heat increase
Dnd inhiits sympathetic out0lo>
@asodilation helps to di"ert lood 0lo> to the s:in
For heat loss
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Feed.0or>ard Control
• Dnticipation o0 chan(e = (ets ody ready
0or chan(e
• e%(% heart rate and "entilation can
increase e"en e0ore e!ercise e(ins
• )r sali"ation and di(esti"e enGyme
production e(ins e0ore a meal is eaten
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Redundancy
• #omeostatic mechanisms are important =
there0ore o0ten there is more than 1 control
mechanism
• I0 1 mechanism 0ails = then there is a ac:upsystem e%(% DTPadenosine in air>ay sur0ace
liHuid secretion or control o0 cutaneous lood
"essels y oth cardio"ascular control center
and temperature control center<• )r lood pressure ne!t slide<
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"#!ovole$i &'o
B%P% 0alls
idne#*u+taglo$erular ells Aorti ar',arotid sinusenin
Ativit# dro!
"#!ot'ala$us
osterior ituitar#
.edulla
oblongata
Angiotensinogen
in blood
Angiotensin I
L/N
Angiotenin II
A,1
Adrenal
,orte+
"eart rate
ontratilit#
2lood
Vessels
idne#
&alt 3ater onservation
Aldosterone
A"
&#$!at'eti out!ut
Inc% "olume
In5 vas5 resistane
Inc%
B%P%
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Eummary I
• "o$eostasis = maintenance o0 a staleinternal en"ironment
• &tead# state = unchan(in( >ith time
• 1uilibriu$ = >hen parameters aremaintained in an ener(etically 0a"oralesituation
• edundan# = more than 1 system tocontrol a "ariale ac:up systems<
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Eummary II
• 5e(ati"e 0eedac: = 0eedac: causes a
perturation to e minimiGed or re"ersed
>ith "ie> to :eepin( parameter at a set
point
• Positi"e 0eedac: = ampli0ication o0 a
de"iation usually de0ined end point<