UNIT 3

UNIT TITLE: HOMEOSTASIS

Area of interaction:Health and social

education

MYP unit question: What advantage or disadvantage is it

to be warm blooded?

Summative assestment:Exposition about the role of homeostatic processes

for the maintenance of life.

Summative Assessment

You will make a presentation of 5-8 minutes. It will be presented in class the 16th of april.

You should also write down a summary of 2-3 pages (with references in APA format) and present it the 11th of april (it should be send to me by phidias). I will correct them and send them to the whole class.

It must be a creative presentation of information. Subjects:

› role of the hypothalamus to control body temperature› role of sweat glands to control body temperature› role of the skin arterioles to control body temperature› role of shivering to control body temperature

• Include one advantage and one disadvantage of being warm blooded• Criteria Evaluated: B and C

Homeostasis

A state of balance in the body

What is Homeostasis?

“The maintenance of a constant environment in the body”.

Your body has many mechanisms that keep the cells surroundings constant even though your external environment is changing. This is homeostasis.

Body cells work best if they have the correct...

• Body temperature• Blood pH• Carbon dioxide concentration• Blood glucose concentration• Water balance

http://biocalaix.wordpress.com/2011/05/22/imatges-de-cel-lules-sanguinies/red-blood-cells-sem/

The endocrine system is involved directly in homeostatic processes…

Both, the endocrine system and nervous system are involved in controlling the internal environment of our bodies. The endocrine system consists of glands, which release hormones that are transported in the blood.

http://www.web-books.com/eLibrary/Medicine/Physiology/Endocrine/Endocrine.htm

http://www.faqs.org/health/Body-by-Design-V2/The-Nervous-System-Design-parts-of-the-nervous-system.html

Negative feedback

Occurs when feedback (from sensor to integrator) results in a reversal of the direction of change.

An example: thermostat's response causes temperature decrease to reverse and become a temperature increase.

Negative feedback tends to stabilize a system.

http://www.phys.unsw.edu.au/biosnippets/

Hire-wire Artist Model

High-wire artist uses negative feedback to maintain relatively constant position on wire.

Variable: position of bodySetpoint: directly over the

wireSensors: nerve receptors

(eyes, inner ears, muscle stretch receptors, etc.)

Integrator: brainEffectors: skeletal muscles http://www.popcrunch.com/16-entertainers-

who-died-in-the-act/philippe-petit/

Controlling Glucose levels Your cells also need an exact level of glucose in

the blood. Excess glucose gets turned into glycogen in the

liver This is regulated by 2 hormones (chemicals)

from the pancreas called:InsulinGlucagon

http://www.medicinayprevencion.com/pancreas.htm

Responses to high blood glucose levels

Responses to low blood glucose levels

• Insuline is produced in the pancreas.

• Insuline stimulates the liver and muscle cells to absorb glucose and convert it to glycogen.

• Glucagon is produced in the pancreas.

• Glucagon stimulates liver cells to break glycogen down into glucose and release the glucose into the blood.

http://www.medmovie.com/mmdatabase/mediaplayer.aspx

Ypu need to search Diabetes in the list on the left upper side, in order to see the animations