CHEM AND BIO HELP AND TIPS HERE

[Raywin]

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..     

[Raywin]

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...  

[nid404]

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.

[Raywin]

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!! 

[Fastal]

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.

[Raywin]

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

[Simona 1234]

i have always hoped to pass AT LEAST ONE chemistry exam   (((( WHAT TO DOO ))))

[holtadit]

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.

[Fastal]

Thanks.. 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

[dodi23]

no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside)

[Raywin]

no i just checked, u only need 2 noe the positions of the xylem nd phloem nd cortex (xylems always inside)

Oh k..  thx!!

[dodi23]

nytime

[Helium]

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..     

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.

[Raywin]

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.. 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)..    

[princess12]

can any 1 tell me tips for paper 1 in chemistry