Biology 3.4

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Biology 3.4 Demonstrate understanding of how an animal maintains a stable internal environment

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Biology 3.4. Demonstrate understanding of how an animal maintains a stable internal environment. Homeostasis. - PowerPoint PPT Presentation

Transcript of Biology 3.4

Page 1: Biology 3.4

Biology 3.4Demonstrate understanding of

how an animal maintains a stable internal environment

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Homeostasis“The tendency of an organism or a cell to regulate its internal conditions, usually by a system of feedback controls, so as to stabilize health and functioning, regardless of the outside changing conditions”

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Why?

• Cells only function within a narrow range of conditions such as:– pH– Osmotic pressure– Temperature

• These conditions must be kept relatively the same, despite internal activity and changes in the external environment

• The body must be constantly working using various organs / systems / physiological processes to achieve a stable equilibrium

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How?• Feedback control systems control the internal

environment and involve:– Input: a stimulus (internal or external, eg temp change)– Receptors / sensors: detect stimulus (nerves, organs)– Controllers: signal a response, (brain, esp hypothalamus)– Effectors: action the response, (glands / muscles / organs)– Output: the response / action of effector

• Feedback means that the level of output will affect input and thus the system is cyclical.

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Where’s the hypothalamus?

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Negative Feedback• High output inhibits further output (system

receives high input which halts output)• For example:– Its cold in the room– Thermostat detects cold temperature, turns on heater

(output)– The room gets hot– Thermostat detects hot temperature, turns off heater

(output): this is negative feedback– Room gets cold…

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Biology 3.4 Requirements…

• Comprehensive understanding of a control system that regulates ONE of these:– Body temperature– Blood pressure– Osmotic balance– Blood glucose levels– Levels & balance of respiratory gases in tissues

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When good control systems go bad…

• Efficiency of control systems decreases with aging…results in:– Unstable internal environment– Disorders• Hypothermia, hyperthermia….• Death

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• http://www.gizmag.com/wello-iphone-case-health-tracker-heart-rate-blood-pressure/31043/pictures#5

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Purchasing

• Oximeter• http://www.fishpond.co.nz/c/Health/q/Blood

+Oxygen+Monitor• http://www.emech.co.nz/Medical+Supplies/E

NT++Diagnostic/Pulse+Oximeters.html?gclid=CLPd6Oa-4b4CFZYGvAodsFMAEg

• http://www.emech.co.nz/Medical+Supplies/Weekly+Specials.html

• http://www.aliexpress.com/wholesale?SearchText=oximeter&catId=0&initiative_id=SB_20140604195300

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Urine Strips

• http://www.fishpond.co.nz/c/Health/q/Urine+Glucose+Test+Strips