MB.1.6. Detection and response - homeostasis (HSC biology)
Channel: Letslearnscience
Date: 18/01/2012

Covers the HSC biology syllabus dot point: "explain that homeostasis consists of two stages: detecting changes from the stable state and counteracting changes from the stable state"

• In case of a heater
- Detection -- thermometer an 
- Control centre - central processing area
- Response -- heater switch on when door was opened and cold air was let in.
• Thermoregulation -- human body.
- Detect change -- thermoreceptor (nerve bundle)
- Too much heat is detected -- nervous impulse sent to hypothalamus
- Signal is sent to the skin gland (effector) where the excess heat can be lost by producing sweat - SWEAT IS THE RESPONSE
- The consequential evaporation cools and brings about heat equilibrium once again -- body temp returns to normal.
• Osmoregulation -- human body
- If dehydrated - osmoregulators will detect a relative change in water concentration in plasma, interstitial fluids
- Signal is sent to the hypothalamus -- control centre processes data and sends a message along the nervous system to the pituitary gland
- Pituitary produces ADH (response) this travels to nephron, which increase its permeability to water and thus water is conserved in the body
• Effector is usually gland or muscle.
• Once optimum has been reached positive feedback is sent back to the hypothalamus and it stops the response

Maintaining a balance module playlist:
http://www.youtube.com/playlist?list=PL8C9FB38DABFE8322

Blueprint of life module playlist:
http://www.youtube.com/playlist?list=PLC1B7EEA2D9BE7FAC