Author Topic: CHEM AND BIO HELP AND TIPS HERE  (Read 353752 times)

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1515 on: May 23, 2010, 05:06:36 am »
can any1 explain wata  a negative feedback wid sum defination thnaku  :)
Heyy.. see all the time the hypothalamus is monitoring small changes in the temperature of the blood. Like if it rises above normal, then it places actions to lower it. Then, as soon as the hypothalamus senses the lowered temperature, it stops these actions from taking place and starts off another action to help raise the temperature of the blood. This is known as Negative feedback.

The "feedback" refers to the fact tht when the hypothalamus has made the skin take actions to increase heat loss, information abt the effects of these action are FED BACK to the hypothalamus, as it senses the drop in blood temperature.

The "Negative" is because the information that the blood has cooled stops the hypothalamus making the skin do thses things..

I hope u have understood..  ;D   
;D

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1516 on: May 23, 2010, 05:13:12 am »
Heyy guys.. can someone explain wht happens during the process of blood clotting? :S because different books say different things and im confused.. :S Thx in advance...  :D
« Last Edit: May 23, 2010, 05:28:32 am by Raywin »
;D

nid404

  • Guest
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1517 on: May 23, 2010, 07:03:17 am »
The evolution of high-pressure blood circulation in vertebrates has brought with it the risk of bleeding after injury to tissues. Mechanisms to prevent bleeding (i.e., hemostatic mechanisms) are essential to maintain the closed blood-circulatory system. Normal homeostasis is the responsibility of a complex system of three individual components: blood cells (platelets), cells that line the blood vessels (endothelial cells), and blood proteins (blood-clotting proteins). The blood platelet is a no nucleated cell that circulates in the blood in an inactive, resting form. Endothelial cells line the wall of the blood vessel and inhibit blood from clotting on the vessel wall under normal conditions. Blood-clotting proteins circulate in the blood plasma in an inactive form, poised to participate in blood coagulation upon tissue injury. Blood-clotting proteins generate thrombin, an enzyme that converts fibrinogen to fibrin, and a reaction that leads to the formation of a fibrin clot.

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1518 on: May 23, 2010, 07:15:29 am »
The evolution of high-pressure blood circulation in vertebrates has brought with it the risk of bleeding after injury to tissues. Mechanisms to prevent bleeding (i.e., hemostatic mechanisms) are essential to maintain the closed blood-circulatory system. Normal homeostasis is the responsibility of a complex system of three individual components: blood cells (platelets), cells that line the blood vessels (endothelial cells), and blood proteins (blood-clotting proteins). The blood platelet is a no nucleated cell that circulates in the blood in an inactive, resting form. Endothelial cells line the wall of the blood vessel and inhibit blood from clotting on the vessel wall under normal conditions. Blood-clotting proteins circulate in the blood plasma in an inactive form, poised to participate in blood coagulation upon tissue injury. Blood-clotting proteins generate thrombin, an enzyme that converts fibrinogen to fibrin, and a reaction that leads to the formation of a fibrin clot.

Thanks a lot!!  :D
;D

Offline Fastal

  • SF Citizen
  • ***
  • Posts: 181
  • Reputation: 341
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1519 on: May 23, 2010, 07:16:48 am »
blood clotting---

usully the inner walls of the blood vessels have a "smooth' lining and when the are cut, they get a jagged lining. when the platelets touch this, 2 things happen--
1)they release thrombin which sets off a chain of reactions turning fibronogen into fibrin forming a mesh od fibres trapping RBCs.
2)they stick to each other at the wound to cover it up.

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1520 on: May 23, 2010, 07:31:53 am »
blood clotting---

usully the inner walls of the blood vessels have a "smooth' lining and when the are cut, they get a jagged lining. when the platelets touch this, 2 things happen--
1)they release thrombin which sets off a chain of reactions turning fibronogen into fibrin forming a mesh od fibres trapping RBCs.
2)they stick to each other at the wound to cover it up.

Thanks.. :D and do v need to know the elements of the xylem and phloem (like tracheids, vessels, parenchyma)  for the exam? :S
;D

Offline Simona 1234

  • Newbie
  • *
  • Posts: 23
  • Reputation: 40
  • Gender: Female
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1521 on: May 23, 2010, 07:40:22 am »
i have always hoped to pass AT LEAST ONE chemistry exam :( :(  :-[ :-[ :-[ :-[ :-[ (((( WHAT TO DOO ))))
?

holtadit

  • Guest
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1522 on: May 23, 2010, 07:44:10 am »
i have always hoped to pass AT LEAST ONE chemistry exam :( :(  :-[ :-[ :-[ :-[ :-[ (((( WHAT TO DOO ))))

Do past papers - its your only hope. :)

AND READ the textbook.

Offline Fastal

  • SF Citizen
  • ***
  • Posts: 181
  • Reputation: 341
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1523 on: May 23, 2010, 08:04:30 am »
Thanks.. :D and do v need to know the elements of the xylem and phloem (like tracheids, vessels, parenchyma)  for the exam? :S

im not sure, lemme check the syllabus and tell you :)

Offline dodi23

  • Before you meet your prince you have to kiss a lot of toads.
  • SF Master
  • ******
  • Posts: 1418
  • Reputation: 2963
  • Gender: Female
  • MAN made beer, GOD made weed. Who do you trust?
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1524 on: May 23, 2010, 08:17:54 am »
no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside) :)
_________________________________
l__l__l__l__l__ll__ll__ll__ll__ll__l__l\_?_\___
l__dodi23's_ limousine___________________l=
""(@)@)''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''(@)

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1525 on: May 23, 2010, 08:19:58 am »
no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside) :)

Oh k..  thx!! :D
;D

Offline dodi23

  • Before you meet your prince you have to kiss a lot of toads.
  • SF Master
  • ******
  • Posts: 1418
  • Reputation: 2963
  • Gender: Female
  • MAN made beer, GOD made weed. Who do you trust?
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1526 on: May 23, 2010, 08:22:57 am »
nytime ;)
_________________________________
l__l__l__l__l__ll__ll__ll__ll__ll__l__l\_?_\___
l__dodi23's_ limousine___________________l=
""(@)@)''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''(@)

Offline Helium

  • SF Citizen
  • ***
  • Posts: 216
  • Reputation: 672
  • Knowledge is light
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1527 on: May 23, 2010, 08:57:28 am »
Heyy.. see all the time the hypothalamus is monitoring small changes in the temperature of the blood. Like if it rises above normal, then it places actions to lower it. Then, as soon as the hypothalamus senses the lowered temperature, it stops these actions from taking place and starts off another action to help raise the temperature of the blood. This is known as Negative feedback.

The "feedback" refers to the fact tht when the hypothalamus has made the skin take actions to increase heat loss, information abt the effects of these action are FED BACK to the hypothalamus, as it senses the drop in blood temperature.

The "Negative" is because the information that the blood has cooled stops the hypothalamus making the skin do thses things..

I hope u have understood..  ;D   

So you can get a negative feedback in many ways besides blood monitoring,
you can get negative geotropism and phototropism or negative phototaxis.

Thanks for ur explanation.
Aiming for the top

Offline Raywin

  • SF Geek
  • ****
  • Posts: 393
  • Reputation: 409
  • Gender: Male
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1528 on: May 23, 2010, 09:07:19 am »
So you can get a negative feedback in many ways besides blood monitoring,
you can get negative geotropism and phototropism or negative phototaxis.

Thanks for ur explanation.

Np.. :D And i dont think Negative feedback implys to plant, Negative geotropism is when a plant's shoot grows away from gravity or in the opposite direction from the gravity. This is due to auxins (plant growth hormone).. :)   
;D

Offline princess12

  • SF Master
  • ******
  • Posts: 1234
  • Reputation: 1650
  • Gender: Female
Re: CHEM AND BIO HELP AND TIPS HERE
« Reply #1529 on: May 23, 2010, 09:20:42 am »
can any 1 tell me tips for paper 1 in chemistry
We should be kind to after teachers