General Homeostasis

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GENERAL PRINCIPLES OFGENERAL PRINCIPLES OF

HOMEOSTASISHOMEOSTASIS

Denny AgustiningsihDenny Agustiningsih

Dept. of PhysiologyDept. of Physiology


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introduction

A person threatened by the environment (or informed of an approachingpleasure or danger) prepares for action.

The body mobilizes reserves of energy and produces certain hormones

such as adrenalin, which prepare it for conflict or flight.

In the presence of emotion, danger, or physical effort the heart beats faster

and respiration quicens. The face turns red or pales and the bodyperspires. The individual may e!perience shortness of breath, cold sweats,

shivering, trembling legs.

These physiological manifestations reflect the efforts of the body to maintain its

internal equilibrium ("omeostasis)

Action can be voluntary##to drin when one is thirsty, to eat when hungry, to put

on clothing when cold, to open a window when one is too warm##or involuntary##

shivering, sweating.


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$oncept of homeostasis wasformulated by a %rench&hysiologist $laude 'ernard in*+

"e noticed that La fixit du milieuintrieurest la condition de la vielibre (it is the fi!ity ofmilieuintrieur which is the condition offree and independent life)

WHAT IS HOMEOSTASIS


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%rom -ree words "omeo same /tasis to stand or stay

Term proposed by American&hysiologist 0alter '$annon, 122


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0hat is homeostasis3 The process by which an organism maintains the

4constancy5 of its internal environment in response tochanges in e!ternal environment

0ors to maintain the organism6s internalenvironmentwithin narrow range of conditions

consistent with the continuation of life The cellular environment is a fluidone, with aqueous

(water) solutions of ions and compounds. correct type of ionsmust be maintained

correct concentrationsmust be maintained correct distribution of ionsmust be maintained


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Internal components of homeostasis

$oncentration of o!ygen andcarbon dio!ide

p" of the internalenvironment

$oncentration of nutrientsand waste products

$oncentration of salt andother electrolytes

7olume and pressure of

e!tracellular fluid


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Distribusi cairan badan antar kompartemen

67%

27%

7%

Intracellular fluid(28 litres)

Intercellular fluid

(11.2 litres)

Plasma

(2.8 litres)

Adapted from Pocock !ic"ards #i$ 2.1


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$ontrol 8echanisms in "omeostasis

The organs and tissues which maintain homeostasis arecalled control systems. Autoregulation (local control)

when cells, tissues, organs or systems automatically change inresponse to signals within themselves.

Intrinsic control controls that generate a response to change that built intothe

organ. Extrinsic control

changes stimulated by signals from outside of the cell, organ, or system 8ediated by

Nervous system

brain 9 spinal cord signals cause change: response is rapidbut short term.

Endocrine system glands produce hormones that cause changes: response is slower, but lasts longer


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oordinasi or$an&or$an


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$omponents of a 'iological$ontrol /ystem


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$omponents of %eedbac 8echanisms

!timulus The change from ideal or resting conditions.

"eceptor The cells or tissue which detects the change due to the stimulus

"elay The transmission of the message# via nerves or hormones or both#

to the effector. Effector

The cells or tissue# usually a gland or muscles# which cause theresponse to happen.

"esponse An action# at cell# tissue or whole organism level which would not

have occurred in the absence of the stimulus $eedbac%

The conse&uence of the response on the stimulus. 'ay be positiveor negative.


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;egative %eedbac

'ost common homeostatic feedbac% mechanism responses that resists any change from normal range.

"estoration of homeostasis because ;egative feedbac causes action that a value is falling too low. ;egative feedbac causes action that a value is rising too high.

7alues fluctuate within /et limits, 7alues change from hour to hour, sometimes with regular

diurnal cycles ( circadian rhythms).


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&ositive feedbac "are homeostatic feedbac% mechanism

The response enhances the original stimulus

&ositive feedbac promoteschanges that are developing, sothey become more e!treme

&ositive feedbac causes action

that a value is falling causing itto fall farther. &ositive feedbac causes action

that a value is rising causing itto rise higher.

&ositive feedbac in disease #

e!. "ypothalamus increases setpoint. ,evelopment of a fever.

Examples.-emorrhage.*hildbirth.+actation


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nstable system It is used to trigger a sudden event or phenomenon $an not continue forever, always has a limit Boes not result in homeostasis 'eneficial only in special circumstances

secretion, more muscle contractions: loop is broen uponbirth of a baby


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;egative feedbac loops e!iston all levels


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'ody $ore TemperatureBuring


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'lood &ressure at Cest


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"omeostatic Imbalances inthe 'ody

Integumentary !ystem urns#*utaneous+egions (*old !ores# Impetigo# soriasis)# !%in*ancer

!%eletal !ystem "ic%ets# Abnormal !pinal*urvatures (!coliosis#/yphosis# +ordosis)#0steoporosis

'uscular !ystem 'uscular ,ystrophy#'yasthenia 1ravis

Nervous !ystem 'ultiple !clerosis#-untington2s ,isease# ar%inson2s ,isease#Al3heimer2s ,isease


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Endocrine !ystem 1oiter# 1raves2 ,isease#ituitary ,warfism# Infertility

*ardiovascular !ystem ericarditis# 4alvular!tenosis# 4aricose 4eins# Atherosclerosis

+ymphatic !ystem Allergies#Immunodeficiencies (!*I,# AI,!)# Autoimmune,isease (+upus# "heumatoid Arthritis# etc)

"espiratory !ystem !inusitis# Tonsillitis#leurisy# Emphysema# ronchitis# *ystic $ibrosis


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,igestive !ystem 1allstones# -eartburn#1astric 5lcers

5rinary !ystem /idney !tones# Addison2s

,isease# olycystic /idney ,isease "eproductive !ystem elvic

Inflammatory ,isease# *ervical *ancer#Testicular *ancer

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General Homeostasis

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