Biology ~ Transport of substances across plasma membrane

STRUCTURE OF PLASMA MEMBRANE
























THE FLUIDITY OF PLASMA MEMBRANE

Click to see flash animation
fluidity of membrane

http://www.stolaf.edu/people/giannini/flashanimat/lipids/membrane%20fluidity.swf

EXERCISE
1. Draw and label the plasma membrane
2. Describe each structure found in the plasma membrane
3. Explain why the plasma membrane is called fluid mosaic model

Biology ~ Regulating the internal environment

INTERNAL ENVIRONMENT

~> DEFINITION
The environment which cells body lives within and usually contains interstitial fluid and blood plasma

~> FACTORS AFFECTED
- Physical factors: body temperature, blood pressure, osmotic pressure
- Chemical factors : salt content, sugar content, PH value

~> Why need to maintain at optimal level??
- Because to enable cells to function properly
- So, the mechanism to maintain the constant internal environment is called HOMEOSTASIS




HOMEOSTASIS
- Involves various system
- Usually corrective mechanism that bring back to normal condition, called negative feedback mechanism
Examples of homeostasis is to maintain the body temperature, blood PH and maintain glucose level so that our cells were in optimum level to carry out life process efficiently.









WEBSITE LINK ~click below for note on homeostasis

http://72.14.235.132/search?q=cache:fMN4N0AhXSQJ:chatt.hdsb.ca/~obyrnet/FAV1-0007E3C9/FOV1-0008786D/HOMEOSTASIS%2520Part1%2520powerpoint.ppt%3FFCItemID%3DS0751895E+homeostasis+animation&cd=7&hl=en&ct=clnk

Examples of question:
Explain how body response towards the changed in the osmotic level
(10 points = 10 marks)

(ANSWER)
- When the osmotic pressure is above the normal level, it means that our body face the loss of water
- So, osmoreceptor in the brains will detect the high osmotic pressure in the blood and it will send impulse to the pituitary glands
- For corrective mechanism, the pituitary gland will secretes the antidiuretic hormones (ADH) into bloodstream
- ADH hormones acts on kidney to absorbs more water back into the body
- So, the osmotic pressure decrease and return to normal
- When the osmotic pressure is below the normal, it means that our body had large intake of water
- Osmoreceptor in the brain will detect the low osmotic pressure in the blood and send impulse to the pituitary gland.
- Corrective mechanism, pituitary gland will secrete less ADH hormone into bloodstream
- So less water is absorbed by kidney
- Negative feedback occur, the osmotic pressure returns to normal