By: Sophie Wilson

What is Homeostasis?Homeostasis are the changes in an organism

so that it can maintain a stable living environment for itself. Homeostasis is essential for the survival of all living things. Each part of a cell has functions and actions they must carry out to maintain homeostasis.

HomeostasisHomeostasis involves a series of mechanisms

that can sense and respond to changes in the exterior environment. For survival, the organisms must restore internal environment variables to an acceptable living rate.

Two systems that contribute to maintain homeostasis are the nervous system and the endocrine system.

Homeostasis Continued…To maintain homeostasis, unicellular

organism grow, respond to the changes in its internal and external environment, transform energy as well as reproduce! Homeostasis is needed to maintain balance in chemical and physical conditions.

AdaptationUnicellular organisms both include prokaryotes and

eukaryotes.Prokaryotes are very adaptable and can survive

almost everywhere due to the process of homeostasis.

Every organism must obtain certain amounts of different concentrates, food and water so that it may survive. Homeostasis allows organisms to change and use the resources in their environment whether it needs to make rapid or long term changes in its internal environment. However, sometimes the change in the environment can be so dramatized that the organism can not respond to the change so quickly and the entire population can become extinct. Take dinosaurs for example.

Working TogetherTo obtain homeostasis, different cells and

systems have to function together and communicate with eachother

Some cells are specialized to move, others to react to the environment, others to reproduce etc.

Just like in our previous explored investigations, cells form tissues, which from organs, which form organ systems which all play a role important to achieve homeostasis. Some organ systems important in homeostasis made up of organs and tissues and cells are the nervous and endocrine system. Everything is given a role using receptors.

Nervous SystemThe nervous system helps contribute to

homeostasis by:Controls activities within the organism,

responding to rapid changes needed in the internal environment due to changes in the external environment.

Nervous System also detects changes in the external environment so it can respond to these changes and make a stable living environment.

Endocrine SystemThe endocrine system helps maintain

homeostasis by:Responds to changes that require duration

and time rather than a rapid response.Endocrine System controls the stability of

nutrients by adjusting kidney function, controls environments volume, and lastly it controls electrolyte composition throughout the organism

What is Involved?Homeostasis consists of:Concentration of nutrientsAmount of water, food, salt, and other

various food substances.Amount of waste product and what is not

needed in the organism (what can be discarded)

Blood volumeBlood pressureTemperature

Why is Homeostasis Needed?Homeostasis is constantly being disrupted by

several factors such as:External:Heat, cold, lack of airPathogens and toxinsInternal:Blood TemperatureBlood PressureAmount of water, sugars, salts and other

substancesPhysical and mental stress

HomeostasisThe organism must be able to:1.Detect changes in the internal and external

environment2.Respond to these changes to make

appropriate adaptations to maintain homeostasis

Control SystemsIntrinsic Controls Extrinsic ControlsLocal Controls found in

organsMechanisms found

outside the organs.Achieved by nervous and

endocrine systems

Feed Back!Feed Forward Feed BackResponses made to

anticipate changeRefers to response after

change is made.Two types of feed back

are positive and negative

FeedbackNegative PositiveStimulus is reversedMost feedback systems

in the body are negativeUses for helping control

the organs and systems that need help to function regularly

Stimulus is intensifiedSeen during child birth:Stretch receptors send

signals to the brain and brain releases hormones into blood stream. The uterine contracts and the process ends with the decrease in stretch and birth of child

FeedbackThere are many elements composed in feedback loops

such as:1.Receptor- Structures that monitor and receive

impulses indicating change in the internal or external environment. This also consists of your five senses: taste, sight, touch, hear, smell.

2.Control Center- Determines the next action working within the organism. This is your brain.

3.Effector- Receives impulses from the control center and responds to it creating a balanced and stable environment making homeostasis achievable. This consists of muscles and things that make your body move and other characteristics throughout the body or organism.

Exploring ReceptorsWhen the body is performing an action, many

parts of small molecules send out chemical impulses and signals to other cells.

To receive these chemical signals a cell must have what is called a receptor which are mostly on the membrane but can sometimes be found in the cytoplasm

The chemical signals will work together to create change. For example, a series of impulses are necessary in pumping blood from the heart

Receptors include your five senses.

TemperatureThermo receptors can detect change in

temperature increase in the external and internal environment.

The brain will send out impulses to blood vessels and the sweat glands

Sweat is released which also causes a decrease in heat restoring normal body temperature

Homeostasis temperature controlhttp://www.southtexascollege.edu/nilsson/4_gb_lecturenotes_f/4_gb_16_anims_ho_j_spr2003.html

BiblyographyWorks Cited"Homeostasis - Credo Reference Topic." Credo Reference

Home. Web. 19 Nov. 2010. <http://www.credoreference.com/topic/homeostasis>.

"Homeostasis | Define Homeostasis at Dictionary.com." Dictionary.com | Find the Meanings and Definitions of Words at Dictionary.com. Web. 19 Nov. 2010. <http://dictionary.reference.com/browse/homeostasis>.

"Kids and Teens." AskColorado - Welcome! Web. 19 Nov. 2010. <http://www.askcolorado.org/k12/index.html>.

Miller, Jeffery. "Biology Investigation Resources." Biology. Wikispaces. Web. 19 Nov. 2010. <http://coloradoearthsystemsresearchcollaborative.wikispaces.com/Biology+Investigation+Resources>.