Maintain yourself!

What is it?HOMEOSTASIS- this means a state of

equilibriumhomeo--same stasis--standing stillA.The maintenance of a stable internal

environment Maintains conditions necessary to support

life

A.A.Homeostasis is the regulation and maintenance of the Homeostasis is the regulation and maintenance of the internal environment of the bodyinternal environment of the body

HOMEOSTASISIt works in all levels of the body:CellularTissuesOrgansOrgan Systems

Tell your table buddy what happens if your homeostasis goes out of normal ranges and the body cant bring it back.

HOMEOSTASISThere are 100’s of monitored events

in the body that must be maintained in order to function efficiently

A. these conditions are maintained by feedback systems

There are negative and positive feedback systems

HOMEOSTASIS

NEGATIVE FEEDBACK- this tells the body to stop what it is doing when it goes outside of the acceptable range.

NEGATIVE FEEDBACK EXAMPLESEXAMPLE: when you are asked to give a

report in front of the class. You are sometimes stressed!

Your heart starts beating faster and your blood pressure goes up

Little sensors called baroreceptors sense the change, and the negative feedback systems will stimulate the heart to decrease the force and frequency of the heartbeat. Once this kicks in, the body restores the normal blood pressure

POSITIVE FEEDBACK

POSITIVE FEEDBACK- this tells the body to continue doing what it is doing

POSITIVE FEEDBACKEXAMPLE OF POSITIVE FEEDBACK:

when contractions begin to push the baby into the birth canal, the pressure of the baby stimulates increased strength of contractions

The force of the contractions continue until the pressure of the baby in the birth canal is decreased

•Negative feedback loopNegative feedback loop•original stimulus reversed original stimulus reversed •most feedback systems in the body are negativemost feedback systems in the body are negative•used for conditions that need frequent adjustmentused for conditions that need frequent adjustment

•Positive feedback loopPositive feedback loop•original stimulus intensifiedoriginal stimulus intensified•seen during normal childbirthseen during normal childbirth

Feedback Loops: TypesFeedback Loops: Types

•Negative feed back loop consists of:Negative feed back loop consists of:•Receptor - structures that monitor a controlled condition and detect changesReceptor - structures that monitor a controlled condition and detect changes

•Control center - determines next action Control center - determines next action

•EffectorEffector•receives directions from the control centerreceives directions from the control center•produces a response that restores the controlled conditionproduces a response that restores the controlled condition

Homeostasis – Negative Feedback LoopHomeostasis – Negative Feedback Loop

•Stretch receptors in walls of uterus send Stretch receptors in walls of uterus send signals to the brainsignals to the brain•Brain induces release of hormone (oxytocin) Brain induces release of hormone (oxytocin) into bloodstreaminto bloodstream•Uterine smooth muscle contracts more Uterine smooth muscle contracts more forcefullyforcefully•More stretch, more hormone, more More stretch, more hormone, more contraction etc.contraction etc.•Cycle ends with birth of the baby & decrease Cycle ends with birth of the baby & decrease in stretchin stretch

Positive Feedback during ChildbirthPositive Feedback during Childbirth

OTHER METHODS OF HOMEOSTASISENDOCRINE AND NERVOUS SYSTEMS-

These work together to maintain homeostasis, and sometimes they work independently

Endocrine system delivers chemical messages

Nervous system delivers electrical messages

ENDOCRINE AND NERVOUSBoth of these systems are responsible

for blood sugar levels, electrolyte balance, blood pressure, internal temperature, skin temperature, blood O2 levels

BODY TEMPSThere are 2 ways of gaining heat in

our bodies1. internal heat production: muscle contractionother metabolic activities like

digestion2. environmental changes- outside

temperature

Heat lossThere are 4 different ways to loose heat from

your body:1.Evaporation- this is heat loss from

converting water from a liquid to a vapor2.Conduction- this is heat loss through direct

contact with something (like water)3.Convection- the process of conduction

where one object is in motion4.Radiation- loss of heat to the environment

due to the temperature gradient

Cool your body

1. sweating

2. Blood vessel dilation

Tell your table buddy why wearing heavy clothes in summer heat is a bad idea.

Okay, if I’m cold, how do I warm up?

Shivering- this is involuntary

Constriction of dermal blood vessels

•Homeostasis is continually being disrupted Homeostasis is continually being disrupted byby

•External stimuli External stimuli •heat, cold, lack of oxygen, pathogens, heat, cold, lack of oxygen, pathogens, toxinstoxins

•Internal stimuliInternal stimuli•Body temperatureBody temperature•Blood pressureBlood pressure•Concentration of water, glucose, salts, Concentration of water, glucose, salts, oxygen, etc.oxygen, etc.•Physical and psychological distressesPhysical and psychological distresses

•Disruptions can be mild to severeDisruptions can be mild to severe•If homeostasis is not maintained, death If homeostasis is not maintained, death may resultmay result

Control of HomeostasisControl of Homeostasis

tell your table buddy what is negative feedback and positive feedback.